Building Programmable Wireless Networks: An Architectural Survey
---
paper_title: Open Signaling for ATM, INTERNET and Mobile Networks (OPENSIG'98)

paper_content:

The ability to rapidly create and deploy new transport, control and management architectures in response to new service demands is a key factor driving the programmable networking community. Competition between service providers may hinge on the speed at which one provider can respond to new market demands over another. The notion of open programmable networks is having broad impact on service providers and vendors across a range of telecommunication sectors calling for major advances in open network control architecture, network programmability and distributed systems technology. In this paper we discuss the origins of the Open Signalling Working Group (OPENSIG) and present a summary of the fifth Workshop on Open Signaling for ATM, Internet and Mobile Networks (OPENSIG'98), which was held at the University of Toronto, Ontario, October, 1998. We also discuss a number of new initiatives in the area of open programmable networks that have recently emerged.
---
paper_title: Towards an active network architecture

paper_content:

Active networks allow their users to inject customized programs into the nodes of the network. An extreme case, in which we are most interested, replaces packets with "capsules" - program fragments that are executed at each network router/switch they traverse. Active architectures permit a massive increase in the sophistication of the computation that is performed within the network. They enable new applications, especially those based on application-specific multicast, information fusion, and other services that leverage network-based computation and storage. Furthermore, they will accelerate the pace of innovation by decoupling network services from the underlying hardware and allowing new services to be loaded into the infrastructure on demand. In this paper, we describe our vision of an active network architecture, outline our approach to its design, and survey the technologies that can be brought to bear on its implementation. We propose that the research community mount a joint effort to develop and deploy a wide area ActiveNet.
---
paper_title: The networking philosopher's problem

paper_content:

While computer networking is an exciting research field, we are far from having a clear understanding of the core concepts and questions that define our discipline. This position paper, a summary of a talk I gave at the CoNext'10 Student Workshop, captures my current frustrations and hopes about the field.
---
paper_title: Frontiers of Wireless and Mobile Communications

paper_content:

The field of wireless and mobile communication has a remarkable history that spans over a century of technology innovations from Marconi's first transatlantic transmission in 1899 to the worldwide adoption of cellular mobile services by over four billion people today. Wireless has become one of the most pervasive core technology enablers for a diverse variety of computing and communications applications ranging from third-generation/fourth-generation (3G/4G) cellular devices, broadband access, indoor WiFi networks, vehicle-to-vehicle (V2V) systems to embedded sensor and radio-frequency identification (RFID) applications. This has led to an accelerating pace of research and development in the wireless area with the promise of significant new breakthroughs over the next decade and beyond. This paper provides a perspective of some of the research frontiers of wireless and mobile communications, identifying early stage key technologies of strategic importance and the new applications that they will enable. Specific new radio technologies discussed include dynamic spectrum access (DSA), white space, cognitive software-defined radio (SDR), antenna beam steering and multiple-input-multiple-output (MIMO), 60-GHz transmission, and cooperative communications. Taken together, these approaches have the potential for dramatically increasing radio link speeds from current megabit per second rates to gigabit per second, while also improving radio system capacity and spectrum efficiency significantly. The paper also introduces a number of emerging wireless/mobile networking concepts including multihoming, ad hoc and multihop mesh, delay-tolerant routing, and mobile content caching, providing a discussion of the protocol capabilities needed to support each of these usage scenarios. In conclusion, the paper briefly discusses the impact of these wireless technologies and networking techniques on the design of emerging audiovisual and multimedia applications as they migrate to mobile Internet platforms.
---
paper_title: Report of the DIMACS working group on abstractions for network services, architecture, and implementation

paper_content:

A workshop on Abstractions for Network Services, Architecture, and Implementation brought together researchers interested in creating better abstractions for creating and analyzing networked services and network architectures. The workshop took place at DIMACS on May 21-23, 2012. This report summarizes the presentations and discussions that took place at the workshop, organized by areas of abstractions such as layers, domains, and graph properties.
---
paper_title: 1 Languages for Software-Defined Networks

paper_content:

Modern computer networks perform a bewildering array of tasks, from routing and traffic monitoring, to access control and server load balancing. However, managing these networks is unnecessarily complicated and error-prone, due to a heterogeneous mix of devices (e.g., routers, switches, firewalls, and middleboxes) with closed and proprietary configuration interfaces. Softwaredefined networks are poised to change this by offering a clean and open interface between networking devices and the software that controls them. In particular, many commercial switches support the OpenFlow protocol, and a number of campus, data center, and backbone networks have deployed the new technology. However, while SDNs make it possible to program the network, they does not make it easy. Today's OpenFlow controllers offer low-level APIs that mimic the underlying switch hardware. To reach SDNs full potential, we need to identify the right higher-level abstractions for creating (and composing) applications. In the Frenetic project, we are designing simple and intuitive abstractions for programming the three main stages of network management: monitoring network traffic, specifying and composing packet forwarding policies, and updating policies in a consistent way. Overall, these abstractions make it dramatically easier for programmers to write and reason about SDN applications.
---
paper_title: A survey of programmable networks

paper_content:

In this paper we present a programmable networking model that provides a common framework for understanding the state-of-the-art in programmable networks. A number of projects are reviewed and discussed against a set of programmable network characteristics. We believe that a number of important innovations are creating a paradigm shift in networking leading to higher levels of network programmability. These innovations include the separation between transmission hardware and control software, availability of open programmable network interfaces, accelerated virtualization of networking infrastructure, rapid creation and deployment of new network services and environments for resource partitioning and coexistence of multiple distinct network architectures. We present a simple qualitative comparison of the surveyed work and make a number of observations about the direction of the field.
---
paper_title: OpenFlow: enabling innovation in campus networks

paper_content:

This whitepaper proposes OpenFlow: a way for researchers to run experimental protocols in the networks they use every day. OpenFlow is based on an Ethernet switch, with an internal flow-table, and a standardized interface to add and remove flow entries. Our goal is to encourage networking vendors to add OpenFlow to their switch products for deployment in college campus backbones and wiring closets. We believe that OpenFlow is a pragmatic compromise: on one hand, it allows researchers to run experiments on heterogeneous switches in a uniform way at line-rate and with high port-density; while on the other hand, vendors do not need to expose the internal workings of their switches. In addition to allowing researchers to evaluate their ideas in real-world traffic settings, OpenFlow could serve as a useful campus component in proposed large-scale testbeds like GENI. Two buildings at Stanford University will soon run OpenFlow networks, using commercial Ethernet switches and routers. We will work to encourage deployment at other schools; and We encourage you to consider deploying OpenFlow in your university network too
---
paper_title: Architecting for innovation

paper_content:

We argue that the biggest problem with the current Internet architecture is not a particular functional deficiency, but its inability to accommodate innovation. To address this problem we propose a minimal architectural "framework" in which comprehensive architectures can reside. The proposed Framework for Internet Innovation (FII) --- which is derived from the simple observation that network interfaces should be extensible and abstract --- allows for a diversity of architectures to coexist, communicate, and evolve. We demonstrate FII's ability to accommodate diversity and evolution with a detailed examination of how information flows through the architecture and with a skeleton implementation of the relevant interfaces.
---
paper_title: B4: experience with a globally-deployed software defined wan

paper_content:

We present the design, implementation, and evaluation of B4, a private WAN connecting Google's data centers across the planet. B4 has a number of unique characteristics: i) massive bandwidth requirements deployed to a modest number of sites, ii) elastic traffic demand that seeks to maximize average bandwidth, and iii) full control over the edge servers and network, which enables rate limiting and demand measurement at the edge. These characteristics led to a Software Defined Networking architecture using OpenFlow to control relatively simple switches built from merchant silicon. B4's centralized traffic engineering service drives links to near 100% utilization, while splitting application flows among multiple paths to balance capacity against application priority/demands. We describe experience with three years of B4 production deployment, lessons learned, and areas for future work.
---
paper_title: The power of abstraction

paper_content:

Abstraction is at the center of much work in Computer Science. It encompasses finding the right interface for a system as well as finding an effective design for a system implementation. Furthermore, abstraction is the basis for program construction, allowing programs to be built in a modular fashion. This talk will discuss how the abstraction mechanisms we use today came to be, how they are supported in programming languages, and some possible areas for future research.
---
paper_title: Active networking: one view of the past, present, and future

paper_content:

All distributed computing systems face the architectural question of the location (and nature) of programmability in the telecommunications networks, computers, and other peripheral devices comprising them. The perspective of this paper is that network elements should be as programmable as possible, to enable the most flexible distributed computing systems. There has been a persistent confluence among operating systems, programming languages, networking and distributed systems. We demonstrate how these interactions led to what is called "active networking," and in the spirit of "vox audita peril, littera scripta manel" (the spoken word perishes, but the written word remains), include an account of how it was made to happen. Lessons are drawn both from the broader research agenda, and the specific goals pursued in the SwitchWare project. We speculate on likely futures for active networking.
---
paper_title: Open Signaling for ATM, INTERNET and Mobile Networks (OPENSIG'98)

paper_content:

The ability to rapidly create and deploy new transport, control and management architectures in response to new service demands is a key factor driving the programmable networking community. Competition between service providers may hinge on the speed at which one provider can respond to new market demands over another. The notion of open programmable networks is having broad impact on service providers and vendors across a range of telecommunication sectors calling for major advances in open network control architecture, network programmability and distributed systems technology. In this paper we discuss the origins of the Open Signalling Working Group (OPENSIG) and present a summary of the fifth Workshop on Open Signaling for ATM, Internet and Mobile Networks (OPENSIG'98), which was held at the University of Toronto, Ontario, October, 1998. We also discuss a number of new initiatives in the area of open programmable networks that have recently emerged.
---
paper_title: A survey of active network research

paper_content:

Active networks are a novel approach to network architecture in which the switches (or routers) of the network perform customized computations on the messages flowing through them. This approach is motivated by both lead user applications, which perform user-driven computation at nodes within the network today, and the emergence of mobile code technologies that make dynamic network service innovation attainable. The authors discuss two approaches to the realization of active networks and provide a snapshot of the current research issues and activities. They illustrate how the routers of an IP network could be augmented to perform such customized processing on the datagrams flowing through them. These active routers could also interoperate with legacy routers, which transparently forward datagrams in the traditional manner.
---
paper_title: Programming telecommunication networks

paper_content:

The move toward market deregulation and open competition has sparked a wave of serious introspection in the telecommunications service industry. Telecom providers and operators are now required to open up their primary revenue channels to competing industries. The competition for product differentiation increasingly depends on the level of sophistication, degree of flexibility, and speed of deployment of services that a future provider can offer. These factors in turn depend heavily on the flexibility of the software architecture in place in a provider's operational infrastructure. Within this context, we examine the service architecture of two major global communication networks-the telephone network and the Internet and explore their weaknesses and strengths. We discuss the realization of an open programmable networking environment based on a new service architecture for advanced telecommunication services that overcomes the limitations of the existing networks. Our approach to network programmability stems from two angles-one conceptual, the other implementational. In the first, we attempt to develop a service model that is open and reflects the economic market structure of the future telecommunications service industry. Furthermore, we introduce an extended reference model for realizing the service marketplace and present it as a vehicle for creating multimedia services with QoS guarantees. In the second, we investigate the feasibility of engineering the reference model from an implementation standpoint. We describe a realization of the open programmable networking environment as a broadband kernel. Called xbind, the broadband kernel incorporates IP and CORBA technologies for signaling, management, and service creation, and ATM for transport. We also address some of the important QoS, performance, scalability, and implementation issues.
---
paper_title: A survey of programmable networks

paper_content:

In this paper we present a programmable networking model that provides a common framework for understanding the state-of-the-art in programmable networks. A number of projects are reviewed and discussed against a set of programmable network characteristics. We believe that a number of important innovations are creating a paradigm shift in networking leading to higher levels of network programmability. These innovations include the separation between transmission hardware and control software, availability of open programmable network interfaces, accelerated virtualization of networking infrastructure, rapid creation and deployment of new network services and environments for resource partitioning and coexistence of multiple distinct network architectures. We present a simple qualitative comparison of the surveyed work and make a number of observations about the direction of the field.
---
paper_title: The Tempest, a Framework for Safe, Resource Assured, Programmable Networks

paper_content:

Most research in network programmability has stressed the flexibility engendered by increasing the ability of users to configure network elements for their own purposes, without addressing the larger issues of how such advanced control systems can coexist both with each other and with more conventional ones. The Tempest framework presented here extends beyond the provision of simple network programmability to address these larger issues. In particular, we show how network programmability can be achieved without jeopardizing the integrity of the network as a whole, how network programmability fits in with existing networks, and how programmability can be offered at different levels of granularity. Our approach is based on the Tempest's ability to dynamically create virtual private networks over a switched transport architecture (e.g., an ATM network). Each VPN is assigned a set of network resources which can be controlled using either a well-known control system or a control system tailored to the specific needs of a distributed application. The first level of programmability in the Tempest is fairly coarse-grained: an entire virtual network can be programmed by a third party. At a finer level of granularity the Tempest allows user supplied code to be injected into parts of an operational virtual network, thus allowing application specific customization of network control. The article shows how the Tempest framework allows these new approaches to coexist with more conventional solutions.
---
paper_title: Active network vision and reality: lessons from a capsule-based system

paper_content:

Although active networks have generated much debate in the research community on the whole there has been little hard evidence to inform this debate. This paper aims to redress the situation by reporting what we have learned by designing, implementing and using the ANTS active network toolkit over the past two years. At this early stage, active networks remain an open research area. However, we believe that we have made substantial progress towards providing a more flexible network layer while at the same time addressing the performance and security concerns raised by the presence of mobile code in the network. In this paper, we argue our progress towards the original vision and the difficulties that we have not yet resolved in three areas that characterize a "pure" active network: the capsule model of programmability; the accessibility of that model to all users; and the applications that can be constructed in practice.
---
paper_title: Towards an active network architecture

paper_content:

Active networks allow their users to inject customized programs into the nodes of the network. An extreme case, in which we are most interested, replaces packets with "capsules" - program fragments that are executed at each network router/switch they traverse. Active architectures permit a massive increase in the sophistication of the computation that is performed within the network. They enable new applications, especially those based on application-specific multicast, information fusion, and other services that leverage network-based computation and storage. Furthermore, they will accelerate the pace of innovation by decoupling network services from the underlying hardware and allowing new services to be loaded into the infrastructure on demand. In this paper, we describe our vision of an active network architecture, outline our approach to its design, and survey the technologies that can be brought to bear on its implementation. We propose that the research community mount a joint effort to develop and deploy a wide area ActiveNet.
---
paper_title: Introducing new internet services: why and how

paper_content:

Active networks permit applications to inject programs into the nodes of local and, more important, wide area networks. This supports faster service innovation by making it easier to deploy new network services. In this article, we discuss both the potential impact of active network services on applications and how such services can be built and deployed. We explore the impact by suggesting sample uses and arguing how such uses would improve application performance. We explore the design of active networks by presenting a novel architecture, ANTS (active network transport system), that adds extensibility at the network layer and allows for incremental deployment of active nodes within the Internet. In doing so, ANTS tackles the challenges of ensuring that the flexibility offered by active networks does not adversely impact performance or security. Finally, we demonstrate how a new network service may be expressed in ANTS.
---
paper_title: A survey of active network research

paper_content:

Active networks are a novel approach to network architecture in which the switches (or routers) of the network perform customized computations on the messages flowing through them. This approach is motivated by both lead user applications, which perform user-driven computation at nodes within the network today, and the emergence of mobile code technologies that make dynamic network service innovation attainable. The authors discuss two approaches to the realization of active networks and provide a snapshot of the current research issues and activities. They illustrate how the routers of an IP network could be augmented to perform such customized processing on the datagrams flowing through them. These active routers could also interoperate with legacy routers, which transparently forward datagrams in the traditional manner.
---
paper_title: Snow on Silk: A NodeOS in the Linux Kernel

paper_content:

Transferring active networking technology from the research arena to everyday deployment on desktop and edge router nodes, requires a NodeOS design that simultaneously meets three goals: (1) be embedded within a wide-spread, open source operating system; (2) allow non-active applications and regular operating system operation to proceed in a regular manner, unhindered by the active networking component; (3) offer performance competitive with that of networking stacks of general purpose operating systems. Previous NodeOS systems, Bowman, Janos, AMP and Scout, only partially addressed these goals. Our contribution lies in the design and implementation of such a system, a NodeOS within the Linux kernel, and the demonstration of competitive performance for medium and larger packet sizes. We also illustrate how such a design easily renders to the deployment of other networking architectures, such as peer-to-peer networks and extensible routers.
---
paper_title: The Tempest, a Framework for Safe, Resource Assured, Programmable Networks

paper_content:

Most research in network programmability has stressed the flexibility engendered by increasing the ability of users to configure network elements for their own purposes, without addressing the larger issues of how such advanced control systems can coexist both with each other and with more conventional ones. The Tempest framework presented here extends beyond the provision of simple network programmability to address these larger issues. In particular, we show how network programmability can be achieved without jeopardizing the integrity of the network as a whole, how network programmability fits in with existing networks, and how programmability can be offered at different levels of granularity. Our approach is based on the Tempest's ability to dynamically create virtual private networks over a switched transport architecture (e.g., an ATM network). Each VPN is assigned a set of network resources which can be controlled using either a well-known control system or a control system tailored to the specific needs of a distributed application. The first level of programmability in the Tempest is fairly coarse-grained: an entire virtual network can be programmed by a third party. At a finer level of granularity the Tempest allows user supplied code to be injected into parts of an operational virtual network, thus allowing application specific customization of network control. The article shows how the Tempest framework allows these new approaches to coexist with more conventional solutions.
---
paper_title: Architectures for the future networks and the next generation Internet: A survey

paper_content:

Networking research funding agencies in USA, Europe, Japan, and other countries are encouraging research on revolutionary networking architectures that may or may not be bound by the restrictions of the current TCP/IP based Internet. We present a comprehensive survey of such research projects and activities. The topics covered include various testbeds for experimentations for new architectures, new security mechanisms, content delivery mechanisms, management and control frameworks, service architectures, and routing mechanisms. Delay/disruption tolerant networks which allow communications even when complete end-to-end path is not available are also discussed.
---
paper_title: Extending Networking into the Virtualization Layer

paper_content:

The move to virtualization has created a new network access layer residing on hosts that connects the various VMs. Virtualized deployment environments impose requirements on networking for which traditional models are not well suited. They also provide advantages to the networking layer (such as software flexibility and welldefined end host events) that are not present in physical networks. To date, this new virtualization network layer has been largely built around standard Ethernet switching, but this technology neither satisfies these new requirements nor leverages the available advantages. We present Open vSwitch, a network switch specifically built for virtual environments. Open vSwitch differs from traditional approaches in that it exports an external interface for fine-grained control of configuration state and forwarding behavior. We describe how Open vSwitch can be used to tackle problems such as isolation in joint-tenant environments, mobility across subnets, and distributing configuration and visibility across hosts.
---
paper_title: PlanetLab: an overlay testbed for broad-coverage services

paper_content:

PlanetLab is a global overlay network for developing and accessing broad-coverage network services. Our goal is to grow to 1000 geographically distributed nodes, connected by a disverse collection of links. PlanetLab allows multiple service to run concurrently and continuously, each in its own slice of PlanetLab. This paper discribes our initial implementation of PlanetLab, including the mechanisms used to impelment virtualization, and the collection of core services used to manage PlanetLab.
---
paper_title: The Genesis Kernel: a virtual network operating system for spawning network architectures

paper_content:

The deployment of network architectures is often manual, ad hoc and time consuming. In this paper we introduce a new paradigm for automating the life cycle process for the creation, deployment and management of network architectures and envision programmable networks capable of spawning distinct "child" virtual networks with their own transport, control and management systems. A child network operates on a subset of its "parent's" network resources and in isolation from other virtual networks. Child networks support the controlled access to communities of users with specific connectivity, security and quality of service requirements. In this paper we introduce the Genesis Kernel, a virtual network operating system capable of profiling, spawning and managing virtual network architectures on-the-fly.
---
paper_title: Overcoming the Internet impasse through virtualization

paper_content:

The Internet architecture has proven its worth by the vast array of applications it now supports and the wide variety of network technologies over which it currently runs. Most current Internet research involves either empirical measurement studies or incremental modifications that can be deployed without major architectural changes. Easy access to virtual testbeds could foster a renaissance in applied architectural research that extends beyond these incrementally deployable designs.
---
paper_title: Network Virtualization: Technologies, Perspectives, and Frontiers

paper_content:

Network virtualization refers to a broad set of technologies. Commercial solutions have been offered by the industry for years, while more recently the academic community has emphasized virtualization as an enabler for network architecture research, deployment, and experimentation. We review the entire spectrum of relevant approaches with the goal of identifying the underlying commonalities. We offer a unifying definition of the term “network virtualization” and examine existing approaches to bring out this unifying perspective. We also discuss a set of challenges and research directions that we expect to come to the forefront as network virtualization technologies proliferate.
---
paper_title: OpenFlow: enabling innovation in campus networks

paper_content:

This whitepaper proposes OpenFlow: a way for researchers to run experimental protocols in the networks they use every day. OpenFlow is based on an Ethernet switch, with an internal flow-table, and a standardized interface to add and remove flow entries. Our goal is to encourage networking vendors to add OpenFlow to their switch products for deployment in college campus backbones and wiring closets. We believe that OpenFlow is a pragmatic compromise: on one hand, it allows researchers to run experiments on heterogeneous switches in a uniform way at line-rate and with high port-density; while on the other hand, vendors do not need to expose the internal workings of their switches. In addition to allowing researchers to evaluate their ideas in real-world traffic settings, OpenFlow could serve as a useful campus component in proposed large-scale testbeds like GENI. Two buildings at Stanford University will soon run OpenFlow networks, using commercial Ethernet switches and routers. We will work to encourage deployment at other schools; and We encourage you to consider deploying OpenFlow in your university network too
---
paper_title: Experiences and challenges in deploying openflow over a real wireless mesh network

paper_content:

Wireless Mesh Networks propose a decentralized architecture for establishing multi-hop wireless communications. The decentralized architecture brings benefits such as ease of deployment and maintenance., scalability and reliability. However., wireless mesh networks lack high level services such as handoff and mobility management or admission control. OpenFlow is an interface for remotely controlling the flow table of switches., routers and access points. The OpenFlow protocol separates the control plane and the data plane of network devices, proposing a centralized architecture for controlling the forwarding of data packets. Furthermore., it offers a framework for developing high level services over the network. Combining this solution with the characteristics of wireless mesh networks allows better performance., by the use of high level services. However., it introduces challenges regarding the opposition between the centralized control of OpenFlow and the distributed architecture of wireless mesh networks. In this paper we expose our experiences deploying an OpenFlow controller over a wireless mesh network based on the 802.11s standard. First., we describe the scenarios used in our testbed. Then., we discuss the considerations for each scenario. Finally we propose some applications using OpenFlow over a Wireless Mesh Network.
---
paper_title: The networking philosopher's problem

paper_content:

While computer networking is an exciting research field, we are far from having a clear understanding of the core concepts and questions that define our discipline. This position paper, a summary of a talk I gave at the CoNext'10 Student Workshop, captures my current frustrations and hopes about the field.
---
paper_title: FlowVisor: A Network Virtualization Layer

paper_content:

Network virtualization has long been a goal of of the network research community. With it, multiple isolated logical networks each with potentially different addressing and forwarding mechanisms can share the same physical infrastructure. Typically this is achieved by taking advantage of the flexibility of software (e.g. [20, 23]) or by duplicating components in (often specialized) hardware[19]. In this paper we present a new approach to switch virtualization in which the same hardware forwarding plane can be shared among multiple logical networks, each with distinct forwarding logic. We use this switch-level virtualization to build a research platform which allows multiple network experiments to run side-by-side with production traffic while still providing isolation and hardware forwarding speeds. We also show that this approach is compatible with commodity switching chipsets and does not require the use of programmable hardware such as FPGAs or network processors. We build and deploy this virtualization platform on our own production network and demonstrate its use in practice by running five experiments simultaneously within a campus network. Further, we quantify the overhead of our approach and evaluate the completeness of the isolation between virtual slices.
---
paper_title: Carving research slices out of your production networks with OpenFlow

paper_content:

1. SLICED PROGRAMMABLE NETWORKS OpenFlow [4] has been demonstrated as a way for researchers to run networking experiments in their production network. Last year, we demonstrated how an OpenFlow controller running on NOX [3] could move VMs seamlessly around an OpenFlow network [1]. While OpenFlow has potential [2] to open control of the network, only one researcher can innovate on the network at a time. What is required is a way to divide, or slice, network resources so that researchers and network administrators can use them in parallel. Network slicing implies that actions in one slice do not negatively affect other slices, even if they share the same underlying physical hardware. A common network slicing technique is VLANs. With VLANs, the administrator partitions the network by switch port and all traffic is mapped to a VLAN by input port or explicit tag. This coarse-grained type of network slicing complicates more interesting experiments such as IP mobility or wireless handover. Here, we demonstrate FlowVisor, a special purpose OpenFlow controller that allows multiple researchers to run experiments safely and independently on the same production OpenFlow network. To motivate FlowVisor’s flexibility, we demonstrate four network slices running in parallel: one slice for the production network and three slices running experimental code (Figure 1). Our demonstration runs on real network hardware deployed on our production network at Stanford and a wide-area test-bed with a mix of wired and wireless technologies.
---
paper_title: PlanetLab: an overlay testbed for broad-coverage services

paper_content:

PlanetLab is a global overlay network for developing and accessing broad-coverage network services. Our goal is to grow to 1000 geographically distributed nodes, connected by a disverse collection of links. PlanetLab allows multiple service to run concurrently and continuously, each in its own slice of PlanetLab. This paper discribes our initial implementation of PlanetLab, including the mechanisms used to impelment virtualization, and the collection of core services used to manage PlanetLab.
---
paper_title: Virtualizing the network forwarding plane

paper_content:

Modern system design often employs virtualization to decouple the system service model from its physical realization. Two common examples are the virtualization of computing resources through the use of virtual machines and the virtualization of disks by presenting logical volumes as the storage interface. The insertion of these abstraction layers allows operators great flexibility to achieve operational goals divorced from the underlying physical infrastructure. Today, workloads can be instantiated dynamically, expanded at runtime, migrated between physical servers (or geographic locations), and suspended if needed. Both computation and data can be replicated in real time across multiple physical hosts for purposes of high-availability within a single site, or disaster recovery across multiple sites.
---
paper_title: Programming telecommunication networks

paper_content:

The move toward market deregulation and open competition has sparked a wave of serious introspection in the telecommunications service industry. Telecom providers and operators are now required to open up their primary revenue channels to competing industries. The competition for product differentiation increasingly depends on the level of sophistication, degree of flexibility, and speed of deployment of services that a future provider can offer. These factors in turn depend heavily on the flexibility of the software architecture in place in a provider's operational infrastructure. Within this context, we examine the service architecture of two major global communication networks-the telephone network and the Internet and explore their weaknesses and strengths. We discuss the realization of an open programmable networking environment based on a new service architecture for advanced telecommunication services that overcomes the limitations of the existing networks. Our approach to network programmability stems from two angles-one conceptual, the other implementational. In the first, we attempt to develop a service model that is open and reflects the economic market structure of the future telecommunications service industry. Furthermore, we introduce an extended reference model for realizing the service marketplace and present it as a vehicle for creating multimedia services with QoS guarantees. In the second, we investigate the feasibility of engineering the reference model from an implementation standpoint. We describe a realization of the open programmable networking environment as a broadband kernel. Called xbind, the broadband kernel incorporates IP and CORBA technologies for signaling, management, and service creation, and ATM for transport. We also address some of the important QoS, performance, scalability, and implementation issues.
---
paper_title: 1 Languages for Software-Defined Networks

paper_content:

Modern computer networks perform a bewildering array of tasks, from routing and traffic monitoring, to access control and server load balancing. However, managing these networks is unnecessarily complicated and error-prone, due to a heterogeneous mix of devices (e.g., routers, switches, firewalls, and middleboxes) with closed and proprietary configuration interfaces. Softwaredefined networks are poised to change this by offering a clean and open interface between networking devices and the software that controls them. In particular, many commercial switches support the OpenFlow protocol, and a number of campus, data center, and backbone networks have deployed the new technology. However, while SDNs make it possible to program the network, they does not make it easy. Today's OpenFlow controllers offer low-level APIs that mimic the underlying switch hardware. To reach SDNs full potential, we need to identify the right higher-level abstractions for creating (and composing) applications. In the Frenetic project, we are designing simple and intuitive abstractions for programming the three main stages of network management: monitoring network traffic, specifying and composing packet forwarding policies, and updating policies in a consistent way. Overall, these abstractions make it dramatically easier for programmers to write and reason about SDN applications.
---
paper_title: A clean slate 4D approach to network control and management

paper_content:

Today's data networks are surprisingly fragile and difficult to manage. We argue that the root of these problems lies in the complexity of the control and management planes--the software and protocols coordinating network elements--and particularly the way the decision logic and the distributed-systems issues are inexorably intertwined. We advocate a complete refactoring of the functionality and propose three key principles--network-level objectives, network-wide views, and direct control--that we believe should underlie a new architecture. Following these principles, we identify an extreme design point that we call "4D," after the architecture's four planes: decision, dissemination, discovery, and data. The 4D architecture completely separates an AS's decision logic from pro-tocols that govern the interaction among network elements. The AS-level objectives are specified in the decision plane, and en-forced through direct configuration of the state that drives how the data plane forwards packets. In the 4D architecture, the routers and switches simply forward packets at the behest of the decision plane, and collect measurement data to aid the decision plane in controlling the network. Although 4D would involve substantial changes to today's control and management planes, the format of data packets does not need to change; this eases the deployment path for the 4D architecture, while still enabling substantial innovation in network control and management. We hope that exploring an extreme design point will help focus the attention of the research and industrial communities on this crucially important and intellectually challenging area.
---
paper_title: Network Innovation using OpenFlow: A Survey

paper_content:

OpenFlow is currently the most commonly deployed Software Defined Networking (SDN) technology. SDN consists of decoupling the control and data planes of a network. A software-based controller is responsible for managing the forwarding information of one or more switches; the hardware only handles the forwarding of traffic according to the rules set by the controller. OpenFlow is an SDN technology proposed to standardize the way that a controller communicates with network devices in an SDN architecture. It was proposed to enable researchers to test new ideas in a production environment. OpenFlow provides a specification to migrate the control logic from a switch into the controller. It also defines a protocol for the communication between the controller and the switches. As discussed in this survey paper, OpenFlow-based architectures have specific capabilities that can be exploited by researchers to experiment with new ideas and test novel applications. These capabilities include software-based traffic analysis, centralized control, dynamic updating of forwarding rules and flow abstraction. OpenFlow-based applications have been proposed to ease the configuration of a network, to simplify network management and to add security features, to virtualize networks and data centers and to deploy mobile systems. These applications run on top of networking operating systems such as Nox, Beacon, Maestro, Floodlight, Trema or Node.Flow. Larger scale OpenFlow infrastructures have been deployed to allow the research community to run experiments and test their applications in more realistic scenarios. Also, studies have measured the performance of OpenFlow networks through modelling and experimentation. We describe the challenges facing the large scale deployment of OpenFlow-based networks and we discuss future research directions of this technology.
---
paper_title: The case for separating routing from routers

paper_content:

Over the past decade, the complexity of the Internet's routing infrastructure has increased dramatically. This complexity and the problems it causes stem not just from various new demands made of the routing infrastructure, but also from fundamental limitations in the ability of today's distributed infrastructure to scalably cope with new requirements.The limitations in today's routing system arise in large part from the fully distributed path-selection computation that the IP routers in an autonomous system (AS) must perform. To overcome this weakness, interdomain routing should be separated from today's IP routers, which should simply forward packets (for the most part). Instead, a separate Routing Control Platform (RCP) should select routes on behalf of the IP routers in each AS and exchange reachability information with other domains.Our position is that an approach like RCP is a good way of coping with complexity while being responsive to new demands and can lead to a routing system that is substantially easier to manage than today. We present a design overview of RCP based on three architectural principles path computation based on a consistent view of network state, controlled interactions between routing protocol layers, and expressive specification of routing policies and discuss the architectural strengths and weaknesses of our proposal.
---
paper_title: OpenFlow: enabling innovation in campus networks

paper_content:

This whitepaper proposes OpenFlow: a way for researchers to run experimental protocols in the networks they use every day. OpenFlow is based on an Ethernet switch, with an internal flow-table, and a standardized interface to add and remove flow entries. Our goal is to encourage networking vendors to add OpenFlow to their switch products for deployment in college campus backbones and wiring closets. We believe that OpenFlow is a pragmatic compromise: on one hand, it allows researchers to run experiments on heterogeneous switches in a uniform way at line-rate and with high port-density; while on the other hand, vendors do not need to expose the internal workings of their switches. In addition to allowing researchers to evaluate their ideas in real-world traffic settings, OpenFlow could serve as a useful campus component in proposed large-scale testbeds like GENI. Two buildings at Stanford University will soon run OpenFlow networks, using commercial Ethernet switches and routers. We will work to encourage deployment at other schools; and We encourage you to consider deploying OpenFlow in your university network too
---
paper_title: Large-scale virtualization in the Emulab network testbed

paper_content:

Network emulation is valuable largely because of its ability to study applications running on real hosts and "somewhat real" networks. However, conservatively allocating a physical host or network link for each corresponding virtual entity is costly and limits scale. We present a system that can faithfully emulate, on low-end PCs, virtual topologies over an order of magnitude larger than the physical hardware, when running typical classes of distributed applications that have modest resource requirements. This version of Emulab virtualizes hosts, routers, and networks, while retaining near-total application transparency, good performance fidelity, responsiveness suitable for interactive use, high system throughput, and efficient use of resources. Our key design techniques are to use the minimum degree of virtualization that provides transparency to applications, to exploit the hierarchy found in real computer networks, to perform optimistic automated resource allocation, and to use feed-back to adaptively allocate resources. The entire system is highly automated, making it easy to use even when scaling to more than a thousand virtual nodes. This paper identifies the many problems posed in building a practical system, and describes the system's motivation, design, and preliminary evaluation.
---
paper_title: In VINI veritas: realistic and controlled network experimentation

paper_content:

This paper describes VINI, a virtual network infrastructure that allows network researchers to evaluate their protocols and services in a realistic environment that also provides a high degree of control over network conditions. VINI allows researchers to deploy and evaluate their ideas with real routing software, traffic loads, and network events. To provide researchers flexibility in designing their experiments, VINI supports simultaneous experiments with arbitrary network topologies on a shared physical infrastructure. This paper tackles the following important design question: What set of concepts and techniques facilitate flexible, realistic, and controlled experimentation (e.g., multiple topologies and the ability to tweak routing algorithms) on a fixed physical infrastructure? We first present VINI's high-level design and the challenges of virtualizing a single network. We then present PL-VINI, an implementation of VINI on PlanetLab, running the "Internet In a Slice". Our evaluation of PL-VINI shows that it provides a realistic and controlled environment for evaluating new protocols and services.
---
paper_title: Onix: A Distributed Control Platform for Large-scale Production Networks

paper_content:

Computer networks lack a general control paradigm, as traditional networks do not provide any network-wide management abstractions. As a result, each new function (such as routing) must provide its own state distribution, element discovery, and failure recovery mechanisms. We believe this lack of a common control platform has significantly hindered the development of flexible, reliable and feature-rich network control planes. ::: ::: To address this, we present Onix, a platform on top of which a network control plane can be implemented as a distributed system. Control planes written within Onix operate on a global view of the network, and use basic state distribution primitives provided by the platform. Thus Onix provides a general API for control plane implementations, while allowing them to make their own trade-offs among consistency, durability, and scalability.
---
paper_title: OpenQoS: An OpenFlow controller design for multimedia delivery with end-to-end Quality of Service over Software-Defined Networks

paper_content:

OpenFlow is a Software Defined Networking (SDN) paradigm that decouples control and data forwarding layers of routing. In this paper, we propose OpenQoS, which is a novel OpenFlow controller design for multimedia delivery with end-to-end Quality of Service (QoS) support. Our approach is based on QoS routing where the routes of multimedia traffic are optimized dynamically to fulfill the required QoS. We measure performance of OpenQoS over a real test network and compare it with the performance of the current state-of-the-art, HTTP-based multi-bitrate adaptive streaming. Our experimental results show that OpenQoS can guarantee seamless video delivery with little or no video artifacts experienced by the end-users. Moreover, unlike current QoS architectures, in OpenQoS the guaranteed service is handled without having adverse effects on other types of traffic in the network.
---
paper_title: Rethinking end-to-end congestion control in software-defined networks

paper_content:

TCP is designed to operate in a wide range of networks. Without any knowledge of the underlying network and traffic characteristics, TCP is doomed to continuously increase and decrease its congestion window size to embrace changes in network or traffic. In light of emerging popularity of centrally controlled Software-Defined Networks (SDNs), one might wonder whether we can take advantage of the global network view available at the controller to make faster and more accurate congestion control decisions. In this paper, we identify the need and the underlying requirements for a congestion control adaptation mechanism. To this end, we propose OpenTCP as a TCP adaptation framework that works in SDNs. OpenTCP allows network operators to define rules for tuning TCP as a function of network and traffic conditions. We also present a preliminary implementation of OpenTCP in a ~4000 node data center.
---
paper_title: Virtual routers as a service: the RouteFlow approach leveraging software-defined networks

paper_content:

The networking equipment market is being transformed by the need for greater openness and flexibility, not only for research purposes but also for in-house innovation by the equipment owners. In contrast to networking gear following the model of computer mainframes, where closed software runs on proprietary hardware, the software-defined networking approach effectively decouples the data from the control plane via an open API (i.e., OpenFlow protocol) that allows the (remote) control of packet forwarding engines. Motivated by this scenario, we propose RouteFlow, a commodity routing architecture that combines the line-rate performance of commercial hardware with the flexibility of open-source routing stacks (remotely) running on general purpose computers. The outcome is a novel point in the design space of commodity routing solutions with far-reaching implications towards virtual routers and IP networks as a service. This paper documents the progress achieved in the design and prototype implementation of our work and outlines our research agenda that calls for a community-driven approach.
---
paper_title: QuagFlow: partnering Quagga with OpenFlow

paper_content:

Computing history has shown that open, multi-layer hardware and software stacks encourage innovation and bring costs down. Only recently this trend is meeting the networking world with the availability of entire open source networking stacks being closer than ever. Towards this goal, we are working on QuagFlow, a transparent interplay between the popular Quagga open source routing suite and the low level vendor-independent OpenFlow interface. QuagFlow is a distributed system implemented as a NOX controller application and a series of slave daemons running along the virtual machines hosting the Quagga routing instances.
---
paper_title: B4: experience with a globally-deployed software defined wan

paper_content:

We present the design, implementation, and evaluation of B4, a private WAN connecting Google's data centers across the planet. B4 has a number of unique characteristics: i) massive bandwidth requirements deployed to a modest number of sites, ii) elastic traffic demand that seeks to maximize average bandwidth, and iii) full control over the edge servers and network, which enables rate limiting and demand measurement at the edge. These characteristics led to a Software Defined Networking architecture using OpenFlow to control relatively simple switches built from merchant silicon. B4's centralized traffic engineering service drives links to near 100% utilization, while splitting application flows among multiple paths to balance capacity against application priority/demands. We describe experience with three years of B4 production deployment, lessons learned, and areas for future work.
---
paper_title: The power of abstraction

paper_content:

Abstraction is at the center of much work in Computer Science. It encompasses finding the right interface for a system as well as finding an effective design for a system implementation. Furthermore, abstraction is the basis for program construction, allowing programs to be built in a modular fashion. This talk will discuss how the abstraction mechanisms we use today came to be, how they are supported in programming languages, and some possible areas for future research.
---
paper_title: The Tempest, a Framework for Safe, Resource Assured, Programmable Networks

paper_content:

Most research in network programmability has stressed the flexibility engendered by increasing the ability of users to configure network elements for their own purposes, without addressing the larger issues of how such advanced control systems can coexist both with each other and with more conventional ones. The Tempest framework presented here extends beyond the provision of simple network programmability to address these larger issues. In particular, we show how network programmability can be achieved without jeopardizing the integrity of the network as a whole, how network programmability fits in with existing networks, and how programmability can be offered at different levels of granularity. Our approach is based on the Tempest's ability to dynamically create virtual private networks over a switched transport architecture (e.g., an ATM network). Each VPN is assigned a set of network resources which can be controlled using either a well-known control system or a control system tailored to the specific needs of a distributed application. The first level of programmability in the Tempest is fairly coarse-grained: an entire virtual network can be programmed by a third party. At a finer level of granularity the Tempest allows user supplied code to be injected into parts of an operational virtual network, thus allowing application specific customization of network control. The article shows how the Tempest framework allows these new approaches to coexist with more conventional solutions.
---
paper_title: NOX: towards an operating system for networks

paper_content:

As anyone who has operated a large network can attest, enterprise networks are difficult to manage. That they have remained so despite significant commercial and academic efforts suggests the need for a different network management paradigm. Here we turn to operating systems as an instructive example in taming management complexity. In the early days of computing, programs were written in machine languages that had no common abstractions for the underlying physical resources. This made programs hard to write, port, reason about, and debug. Modern operating systems facilitate program development by providing controlled access to high-level abstractions for resources (e.g., memory, storage, communication) and information (e.g., files, directories). These abstractions enable programs to carry out complicated tasks safely and efficiently on a wide variety of computing hardware. In contrast, networks are managed through low-level configuration of individual components. Moreover, these configurations often depend on the underlying network; for example, blocking a user’s access with an ACL entry requires knowing the user’s current IP address. More complicated tasks require more extensive network knowledge; forcing guest users’ port 80 traffic to traverse an HTTP proxy requires knowing the current network topology and the location of each guest. In this way, an enterprise network resembles a computer without an operating system, with network-dependent component configuration playing the role of hardware-dependent machine-language programming. What we clearly need is an “operating system” for networks, one that provides a uniform and centralized programmatic interface to the entire network. Analogous to the read and write access to various resources provided by computer operating systems, a network operating system provides the ability to observe and control a network. A network operating system does not manage the network itself; it merely provides a programmatic interface. Applications implemented on top of the network operating system perform the actual management tasks. The programmatic interface should be general enough to support a broad spectrum of network management applications. Such a network operating system represents two major conceptual departures from the status quo. First, the network operating system presents programs with a centralized programming model; programs are written as if the entire network were present on a single machine (i.e., one would use Dijkstra to compute shortest paths, not Bellman-Ford). This requires (as in [3, 8, 14] and elsewhere) centralizing network state. Second, programs are written in terms of high-level abstractions (e.g., user and host names), not low-level configuration parameters (e.g., IP and MAC addresses). This allows management directives to be enforced independent of the underlying network topology, but it requires that the network operating system carefully maintain the bindings (i.e., mappings) between these abstractions and the low-level configurations. Thus, a network operating system allows management applications to be written as centralized programs over highlevel names as opposed to the distributed algorithms over low-level addresses we are forced to use today. While clearly a desirable goal, achieving this transformation from distributed algorithms to centralized programming presents significant technical challenges, and the question we pose here is: Can one build a network operating system at significant scale?
---
paper_title: Software radio: a modern approach to radio engineering

paper_content:

Software-based approaches enable engineers to build wireless system radios that are easier to manufacture, more flexible, and more cost-effective. Software Radio: A Modern Approach to Radio Engineering systematically reviews the techniques, challenges, and tradeoffs of DSP software radio design. Coverage includes constructing RF front-ends; using digital processing to overcome RF design problems; direct digital synthesis of modulated waveforms; A/D and D/A conversions; smart antennas; object-oriented software design; and choosing among DSP microprocessors, FPGAs, and ASICs. This is an excellent book for all RF and signal processing engineers building advanced wireless systems.
---
paper_title: Realizing the future of wireless data communications

paper_content:

Technologies are available to unlock radio spectrum as consumers need it.
---
paper_title: Sora: high-performance software radio using general-purpose multi-core processors

paper_content:

This paper presents Sora, a fully programmable software radio platform on commodity PC architectures. Sora combines the performance and fidelity of hardware software-defined radio (SDR) platforms with the programmability and flexibility of general-purpose processor (GPP) SDR platforms. Sora uses both hardware and software techniques to address the challenges of using PC architectures for high-speed SDR. The Sora hardware components consist of a radio front-end for reception and transmission, and a radio control board for high-throughput, low-latency data transfer between radio and host memories. Sora makes extensive use of features of contemporary processor architectures to accelerate wireless protocol processing and satisfy protocol timing requirements, including using dedicated CPU cores, large low-latency caches to store lookup tables, and SIMD processor extensions for highly efficient physical layer processing on GPPs. Using the Sora platform, we have developed a few demonstration wireless systems, including SoftWiFi, an 802.11a/b/g implementation that seamlessly interoperates with commercial 802.11 NICs at all modulation rates, and SoftLTE, a 3GPP LTE uplink PHY implementation that supports up to 43.8Mbps data rate.
---
paper_title: WARP: a flexible platform for clean-slate wireless medium access protocol design

paper_content:

The flexible interface between the medium access layer and the custom physical layer of the Rice University Wireless Open-Access Research Platform (WARP) provides a high performance research tool for clean-slate cross layer designs. As we target a community platform, we have implemented various basic PHY and MAC technologies over WARP. Moreover, we are implementing cross-layer schemes such as rate adaptation and crosslayer MIMO MAC protocols. In this demo, we demonstrate the flexibility of the interaction between the the WARP PHY and MAC layers by showing the capability to instantaneously change the modulation scheme, disabling/enabling MAC features such as carrier sensing or RTS/CTS 4-way handshake, and different multi-rate schemes.
---
paper_title: Software Defined Radio: Challenges and Opportunities

paper_content:

Software Defined Radio (SDR) may provide flexible, upgradeable and longer lifetime radio equipment for the military and for civilian wireless communications infrastructure. SDR may also provide more flexible and possibly cheaper multi-standard-terminals for end users. It is also important as a convenient base technology for the future context-sensitive, adaptive and learning radio units referred to as cognitive radios. SDR also poses many challenges, however, some of them causing SDR to evolve slower than otherwise anticipated. Transceiver development challenges include size, weight and power issues such as the required computing capacity, but also SW architectural challenges such as waveform application portability. SDR has demanding implications for regulators, security organizations and business developers.
---
paper_title: Airblue: a system for cross-layer wireless protocol development

paper_content:

Over the past few years, researchers have developed many cross-layer wireless protocols to improve the performance of wireless networks. Experimental evaluations of these protocols have been carried out mostly using software-defined radios, which are typically two to three orders of magnitude slower than commodity hardware. FPGA-based platforms provide much better speeds but are quite difficult to modify because of the way high-speed designs are typically implemented. Experimenting with cross-layer protocols requires a flexible way to convey information beyond the data itself from lower to higher layers, and a way for higher layers to configure lower layers dynamically and within some latency bounds. One also needs to be able to modify a layer's processing pipeline without triggering a cascade of changes. We have developed Airblue, an FPGA-based software radio platform, that has all these properties and runs at speeds comparable to commodity hardware. We discuss the design philosophy underlying Airblue that makes it relatively easy to modify it, and present early experimental results.
---
paper_title: Cognitive radio: brain-empowered wireless communications

paper_content:

Cognitive radio is viewed as a novel approach for improving the utilization of a precious natural resource: the radio electromagnetic spectrum. The cognitive radio, built on a software-defined radio, is defined as an intelligent wireless communication system that is aware of its environment and uses the methodology of understanding-by-building to learn from the environment and adapt to statistical variations in the input stimuli, with two primary objectives in mind: /spl middot/ highly reliable communication whenever and wherever needed; /spl middot/ efficient utilization of the radio spectrum. Following the discussion of interference temperature as a new metric for the quantification and management of interference, the paper addresses three fundamental cognitive tasks. 1) Radio-scene analysis. 2) Channel-state estimation and predictive modeling. 3) Transmit-power control and dynamic spectrum management. This work also discusses the emergent behavior of cognitive radio.
---
paper_title: Artificial Intelligence Based Cognitive Routing for Cognitive Radio Networks

paper_content:

Cognitive radio networks (CRNs) are networks of nodes equipped with cognitive radios that can optimize performance by adapting to network conditions. While cognitive radio networks (CRN) are envisioned as intelligent networks, relatively little research has focused on the network level functionality of CRNs. Although various routing protocols, incorporating varying degrees of adaptiveness, have been proposed for CRNs, it is imperative for the long term success of CRNs that the design of cognitive routing protocols be pursued by the research community. Cognitive routing protocols are envisioned as routing protocols that fully and seamless incorporate AI-based techniques into their design. In this paper, we provide a self-contained tutorial on various AI and machine-learning techniques that have been, or can be, used for developing cognitive routing protocols. We also survey the application of various classes of AI techniques to CRNs in general, and to the problem of routing in particular. We discuss various decision making techniques and learning techniques from AI and document their current and potential applications to the problem of routing in CRNs. We also highlight the various inference, reasoning, modeling, and learning sub tasks that a cognitive routing protocol must solve. Finally, open research issues and future directions of work are identified.
---
paper_title: Security Aspects in Software Defined Radio and Cognitive Radio Networks: A Survey and A Way Ahead

paper_content:

Software Defined Radio (SDR) and Cognitive Radio (CR) are promising technologies, which can be used to alleviate the spectrum shortage problem or the barriers to communication interoperability in various application domains. The successful deployment of SDR and CR technologies will depend on the design and implementation of essential security mechanisms to ensure the robustness of networks and terminals against security attacks. SDR and CR may introduce entirely new classes of security threats and challenges including download of malicious software, licensed user emulation and selfish misbehaviors. An attacker could disrupt the basic functions of a CR network, cause harmful interference to licensed users or deny communication to other CR nodes. The research activity in this area has started only recently and many challenges are still to be resolved. This paper presents a survey of security aspects in SDR and CR. We identify the requirements for the deployment of SDR and CR, the main security threats and challenges and the related protection techniques. This paper provides an overview of the SDR and CR certification process and how it is related to the security aspects. Finally, this paper summarizes the most critical challenges in the context of the future evolution of SDR/CR technologies.
---
paper_title: A Survey of Artificial Intelligence for Cognitive Radios

paper_content:

Cognitive radio (CR) is an enabling technology for numerous new capabilities such as dynamic spectrum access, spectrum markets, and self-organizing networks. To realize this diverse set of applications, CR researchers leverage a variety of artificial intelligence (AI) techniques. To help researchers better understand the practical implications of AI to their CR designs, this paper reviews several CR implementations that used the following AI techniques: artificial neural networks (ANNs), metaheuristic algorithms, hidden Markov models (HMMs), rule-based systems, ontology-based systems (OBSs), and case-based systems (CBSs). Factors that influence the choice of AI techniques, such as responsiveness, complexity, security, robustness, and stability, are discussed. To provide readers with a more concrete understanding, these factors are illustrated in an extended discussion of two CR designs.
---
paper_title: NeXt generation/dynamic spectrum access/cognitive Radio Wireless Networks: A Survey

paper_content:

Today's wireless networks are characterized by a fixed spectrum assignment policy. However, a large portion of the assigned spectrum is used sporadically and geographical variations in the utilization of assigned spectrum ranges from 15% to 85% with a high variance in time. The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. This new networking paradigm is referred to as NeXt Generation (xG) Networks as well as Dynamic Spectrum Access (DSA) and cognitive radio networks. The term xG networks is used throughout the paper. The novel functionalities and current research challenges of the xG networks are explained in detail. More specifically, a brief overview of the cognitive radio technology is provided and the xG network architecture is introduced. Moreover, the xG network functions such as spectrum management, spectrum mobility and spectrum sharing are explained in detail. The influence of these functions on the performance of the upper layer protocols such as routing and transport are investigated and open research issues in these areas are also outlined. Finally, the cross-layer design challenges in xG networks are discussed.
---
paper_title: CogNet: an architectural foundation for experimental cognitive radio networks within the future internet

paper_content:

This paper describes a framework for research on architectural tradeoffs and protocol designs for cognitive radio networks at both the local network and the global internetwork levels. Several key architectural issues for cognitive radio networks are discussed, including control and management protocols, support for collaborative PHY, dynamic spectrum coordination, flexible MAC layer protocols, ad hoc group formation and cross-layer adaptation. The overall goal of this work is the design and validation of the control/management and data interfaces between cognitive radio nodes in a local network, and also between cognitive radio networks and the global Internet. Protocol design and implementation based on this framework will result in the CogNet architecture, a prototype open-source cognitive radio protocol stack. Experimental evaluations on emerging cognitive radio platforms are planned for future work, first in a wireless local-area radio network scenario using wireless testbeds such as ORBIT, and later as part of several end-to-end experiments using a wide-area network testbed such as PlanetLab (and GENI in the future).
---
paper_title: Sora: high-performance software radio using general-purpose multi-core processors

paper_content:

This paper presents Sora, a fully programmable software radio platform on commodity PC architectures. Sora combines the performance and fidelity of hardware software-defined radio (SDR) platforms with the programmability and flexibility of general-purpose processor (GPP) SDR platforms. Sora uses both hardware and software techniques to address the challenges of using PC architectures for high-speed SDR. The Sora hardware components consist of a radio front-end for reception and transmission, and a radio control board for high-throughput, low-latency data transfer between radio and host memories. Sora makes extensive use of features of contemporary processor architectures to accelerate wireless protocol processing and satisfy protocol timing requirements, including using dedicated CPU cores, large low-latency caches to store lookup tables, and SIMD processor extensions for highly efficient physical layer processing on GPPs. Using the Sora platform, we have developed a few demonstration wireless systems, including SoftWiFi, an 802.11a/b/g implementation that seamlessly interoperates with commercial 802.11 NICs at all modulation rates, and SoftLTE, a 3GPP LTE uplink PHY implementation that supports up to 43.8Mbps data rate.
---
paper_title: Breaking layer 2: A new architecture for programmable wireless interfaces

paper_content:

This paper introduces a new architecture for programmable wireless interfaces, aiming at responding to the emerging request of wireless access flexibility and adaptability. Instead of implementing a specific MAC protocol stack, the proposed architecture supports a set of programmable services, devised to customize the wireless access operations according to specific network and application scenarios. The services are composed by means of simpler functions, which in turns work on system primitives (i.e. elementary non-programmable functionalities, natively provided by the system) dealing with the physical transmission and reception of the frames. Our approach significantly differs from software-radio solutions, since we argue that most practical needs for promptly adapting and customizing network features and performance may be accomplished by means of advanced and programmable interfaces exposed at a layer higher than the physical one (PHY). This choice does not rule out the possibility of using (i.e. dynamically selecting) advanced PHY mechanisms provided, as elementary primitives, by the interface manufacturers.
---
paper_title: The WINLAB Network Centric Cognitive Radio Hardware Platform - WiNC2R

paper_content:

This paper presents the design goals and architecture of WiNC2R--the WINLAB Network Centric Cognitive radio hardware platform. The platform has been designed for flexible processing at both the radio physical layer and MAC/network layers with sustained bit-rates of ∼10 Mbps and higher. The hardware prototype supports multi band operation with fast spectrum scanning, the ability to dynamically switch between a number of OFDM and DSSS modems and multiple MAC protocols. The radio modems, MAC, and network-layer protocols are implemented in a flexible manner using general-purpose processing engines and a set of dynamically configurable hardware accelerators. An FPGA based platform implementation currently in progress is described in terms of key hardware components including the software-defined modem, the flexible MAC engine and network-level processor. Preliminary prototyping results are reported, and a roadmap for further evolution of the WiNC2R board is provided.
---
paper_title: OpenRadio: a programmable wireless dataplane

paper_content:

We present OpenRadio, a novel design for a programmable wireless dataplane that provides modular and declarative programming interfaces across the entire wireless stack. Our key conceptual contribution is a principled refactoring of wireless protocols into processing and decision planes. The processing plane includes directed graphs of algorithmic actions (eg. 54Mbps OFDM WiFi or special encoding for video). The decision plane contains the logic which dictates which directed graph is used for a particular packet (eg. picking between data and video graphs). The decoupling provides a declarative interface to program the platform while hiding all underlying complexity of execution. An operator only expresses decision plane rules and corresponding processing plane action graphs to assemble a protocol. The scoped interface allows us to build a dataplane that arguably provides the right tradeoff between performance and flexibility. Our current system is capable of realizing modern wireless protocols (WiFi, LTE) on off-the-shelf DSP chips while providing flexibility to modify the PHY and MAC layers to implement protocol optimizations.
---
paper_title: Wireless MAC processors: Programming MAC protocols on commodity Hardware

paper_content:

Programmable wireless platforms aim at responding to the quest for wireless access flexibility and adaptability. This paper introduces the notion of wireless MAC processors. Instead of implementing a specific MAC protocol stack, Wireless MAC processors do support a set of Medium Access Control “commands” which can be run-time composed (programmed) through software-defined state machines, thus providing the desired MAC protocol operation. We clearly distinguish from related work in this area as, unlike other works which rely on dedicated DSPs or programmable hardware platforms, we experimentally prove the feasibility of the wireless MAC processor concept over ultra-cheap commodity WLAN hardware cards. Specifically, we reflash the firmware of the commercial Broadcom AirForce54G off-the-shelf chipset, replacing its 802.11 WLAN MAC protocol implementation with our proposed extended state machine execution engine. We prove the flexibility of the proposed approach through three use-case implementation examples.
---
paper_title: WARP: a flexible platform for clean-slate wireless medium access protocol design

paper_content:

The flexible interface between the medium access layer and the custom physical layer of the Rice University Wireless Open-Access Research Platform (WARP) provides a high performance research tool for clean-slate cross layer designs. As we target a community platform, we have implemented various basic PHY and MAC technologies over WARP. Moreover, we are implementing cross-layer schemes such as rate adaptation and crosslayer MIMO MAC protocols. In this demo, we demonstrate the flexibility of the interaction between the the WARP PHY and MAC layers by showing the capability to instantaneously change the modulation scheme, disabling/enabling MAC features such as carrier sensing or RTS/CTS 4-way handshake, and different multi-rate schemes.
---
paper_title: MAClets: active MAC protocols over hard-coded devices

paper_content:

We introduce MAClets, software programs uploaded and executed on-demand over wireless cards, and devised to change the card's real-time medium access control operation. MAClets permit seamless reconfiguration of the MAC stack, so as to adapt it to mutated context and spectrum conditions and perform tailored performance optimizations hardly accountable by an once-for-all protocol stack design. Following traditional active networking principles, MAClets can be directly conveyed within data packets and executed on hard-coded devices acting as virtual MAC machines. Indeed, rather than executing a pre-defined protocol, we envision a new architecture for wireless cards based on a protocol interpreter (enabling code portability) and a powerful API. Experiments involving the distribution of MAClets within data packets, and their execution over commodity WLAN cards, show the flexibility and viability of the proposed concept.
---
paper_title: Enabling MAC Protocol Implementations on Software-Defined Radios

paper_content:

Over the past few years a range of new Media Access Control (MAC) protocols have been proposed for wireless networks. This research has been driven by the observation that a single one-size-fits-all MAC protocol cannot meet the needs of diverse wireless deployments and applications. Unfortunately, most MAC functionality has traditionally been implemented on the wireless card for performance reasons, thus, limiting the opportunities for MAC customization. Software-defined radios (SDRs) promise unprecedented flexibility, but their architecture has proven to be a challenge for MAC protocols. ::: ::: In this paper, we identify a minimum set of core MAC functions that must be implemented close to the radio in a high-latency SDR architecture to enable high performance and efficient MAC implementations. These functions include: precise scheduling in time, carrier sense, backoff, dependent packets, packet recognition, fine-grained radio control, and access to physical layer information. While we focus on an architecture where the bus latency exceeds common MAC interaction times (tens to hundreds of microseconds), other SDR architectures with lower latencies can also benefit from implementing a subset of these functions closer to the radio. We also define an API applicable to all SDR architectures that allows the host to control these functions, providing the necessary flexibility to implement a diverse range of MAC protocols. We show the effectiveness of our split-functionality approach through an implementation on the GNU Radio and USRP platforms. Our evaluation based on microbenchmarks and end-to-end network measurements, shows that our design can simultaneously achieve high flexibility and high performance.
---
paper_title: KNOWS: Cognitive Radio Networks Over White Spaces

paper_content:

FCC has proposed to allow unlicensed operations in the TV broadcast bands. This portion of the spectrum has several desirable properties for more robust data communication as compared to the ISM bands. However, there are a number of challenges in efficiently using the TV bands. For example, the available spectrum is fragmented, and its availability may vary over time. In this paper, we present a cognitive radio system, called KNOWS, to address these challenges. We present the design of our prototype, which includes a new hardware platform and a spectrum-aware Medium Access Control (MAC) protocol. We have implemented the MAC protocol in QualNet, and our results show that in most scenarios KNOWS increases the throughput by more than 200% when compared to an IEEE 802.11 based system.
---
paper_title: A real time cognitive radio testbed for physical and link layer experiments

paper_content:

Cognitive radios have been advanced as a technology for the opportunistic use of under-utilized spectrum. Cognitive radio is able to sense the spectrum and detect the presence of primary users. However, primary users of the spectrum are skeptical about the robustness of this sensing process and have raised concerns with regards to interference from cognitive radios. Furthermore, while a number of techniques have been advanced to aid the sensing process, none of these techniques have been verified in a practical system. To alleviate these concerns, a real time testbed is required, which can aid the comparison of these techniques and enable the measurement and evaluation of key interference and performance metrics. In this paper, we present such a testbed, which is based on the BEE2, a multi-FPGA emulation engine. The BEE2 can connect to 18 radio front-ends, which can be configured as primary or secondary users. Inherent parallelism of the FPGAs allows the simultaneous operation of multiple radios, which can communicate and exchange information via high speed low latency links
---
paper_title: Decomposable MAC Framework for Highly Flexible and Adaptable MAC Realizations

paper_content:

Cognitive radios are slowly becoming a reality. Besides the need for hardware reconfigurability and the capability to sense spectrum opportunities, adaptability in the MAC designs are required so that the wireless communication systems can support cognitive radio functionalities. In this demo paper, we propose a MAC design framework which enables fast composition of MAC protocols which are best fitted to the application requirements, communication capabilities of the radio and current regulations and policies. Our design is based on decomposition principle and allows on-the-fly realization of the required MAC protocol from a set of basic functional components. By exposing extended meta-data and hardware functionalities for the MAC implementation through our granular components together with the support for run-time re-configuration, spectrum agile and cognitive MAC solutions can easily be realized. We validate our approach through realization of a few MAC solutions on the WARP board from Rice University, USA. We also demonstrate the ease of MAC realization, fast on-the-fly adaptation based on the spectral characteristics and high degree of code reuse.
---
paper_title: The Mobiware Toolkit: Programmable Support for Adaptive Mobile Networking

paper_content:

Existing mobile systems (e.g., mobile IP, mobile ATM, and third-generation cellular systems) lack the intrinsic architectural flexibility to deal with the complexity of supporting adaptive mobile applications in wireless and mobile environments. We believe that there is a need to develop alternative network architectures from the existing ones to deal with the tremendous demands placed on underlying mobile signaling, adaptation management, and wireless transport systems in support of new mobile services (e.g., interactive multimedia and Web access). We present the design, implementation, and evaluation of mobiware, a mobile middleware toolkit that enables adaptive mobile services to dynamically exploit the intrinsic scalable properties of mobile multimedia applications in response to time-varying mobile network conditions. The mobiware toolkit is software-intensive and is built on CORBA and Java distributed object technology. Based on an open programmable paradigm developed by the COMET Group, mobiware runs on mobile devices, wireless access points, and mobile-capable switch/routers providing a set of open programmable interfaces and algorithms for adaptive mobile networking.
---
paper_title: NetFPGA--An Open Platform for Gigabit-Rate Network Switching and Routing

paper_content:

The NetFPGA platform enables students and researchers to build high-performance networking systems in hardware. A new version of the NetFPGA platform has been developed and is available for use by the academic community. The NetFPGA 2.1 platform now has interfaces that can be parameterized, therefore enabling development of modular hardware designs with varied word sizes. It also includes more logic and faster memory than the previous platform. Field Programmable Gate Array (FPGA) logic is used to implement the core data processing functions while software running on embedded cores within the FPGA and/or programs running on an attached host computer implement only control functions. Reference designs and component libraries have been developed for the CS344 course at Stanford University. Open-source Verilog code is available for download from the project website.
---
paper_title: NetFPGA: reusable router architecture for experimental research

paper_content:

Our goal is to enable fast prototyping of networking hardware (e.g. modified Ethernet switches and IP routers) for teaching and research. To this end, we built and made available the NetFPGA platform. Starting from open-source reference designs, students and researchers create their designs in Verilog, and then download them to the NetFPGA board where they can process packets at line-rate for 4-ports of 1GE. The board is becoming widely used for teaching and research, and so it has become important to make it easy to re-use modules and designs. We have created a standard interface between modules, making it easier to plug modules together in pipelines, and to create new re-usable designs. In this paper we describe our modular design, and how we have used it to build several systems, including our IP router reference design and some extensions to it.
---
paper_title: TRUMP: Supporting efficient realization of protocols for cognitive radio networks

paper_content:

Cognitive radios require fast reconfiguration of the protocol stack for dynamic spectrum access and run-time performance optimization. In order to provide rapid on-the-fly adaptability of PHY/MAC protocols, we have designed and implemented TRUMP: a Toolchain for RUn-tiMe Protocol realization. It includes a meta-language compiler, logic controller and an optimizer. TRUMP allows run-time realization and optimization of cognitive network protocols for the requirements of a particular application, communication capabilities of the radio, the current spectrum regulation and policies. TRUMP supports efficient multi-threading for multi-core platforms in order to meet variable computational requirements and to allow parallelization of PHY/MAC processing for cognitive radio systems. We have carried out the performance evaluation for different metrics on WARP SDR platform and embedded Linux based PCs. Our results indicate that TRUMP allows reconfiguration of protocols in the order of a few microseconds through run-time linking of different components, thus meeting the strict timeliness requirements imposed by PHY/MAC processing.
---
paper_title: The Genesis Kernel: a virtual network operating system for spawning network architectures

paper_content:

The deployment of network architectures is often manual, ad hoc and time consuming. In this paper we introduce a new paradigm for automating the life cycle process for the creation, deployment and management of network architectures and envision programmable networks capable of spawning distinct "child" virtual networks with their own transport, control and management systems. A child network operates on a subset of its "parent's" network resources and in isolation from other virtual networks. Child networks support the controlled access to communities of users with specific connectivity, security and quality of service requirements. In this paper we introduce the Genesis Kernel, a virtual network operating system capable of profiling, spawning and managing virtual network architectures on-the-fly.
---
paper_title: RouteBricks: exploiting parallelism to scale software routers

paper_content:

We revisit the problem of scaling software routers, motivated by recent advances in server technology that enable high-speed parallel processing--a feature router workloads appear ideally suited to exploit. We propose a software router architecture that parallelizes router functionality both across multiple servers and across multiple cores within a single server. By carefully exploiting parallelism at every opportunity, we demonstrate a 35Gbps parallel router prototype; this router capacity can be linearly scaled through the use of additional servers. Our prototype router is fully programmable using the familiar Click/Linux environment and is built entirely from off-the-shelf, general-purpose server hardware.
---
paper_title: Wireless MAC processors: Programming MAC protocols on commodity Hardware

paper_content:

Programmable wireless platforms aim at responding to the quest for wireless access flexibility and adaptability. This paper introduces the notion of wireless MAC processors. Instead of implementing a specific MAC protocol stack, Wireless MAC processors do support a set of Medium Access Control “commands” which can be run-time composed (programmed) through software-defined state machines, thus providing the desired MAC protocol operation. We clearly distinguish from related work in this area as, unlike other works which rely on dedicated DSPs or programmable hardware platforms, we experimentally prove the feasibility of the wireless MAC processor concept over ultra-cheap commodity WLAN hardware cards. Specifically, we reflash the firmware of the commercial Broadcom AirForce54G off-the-shelf chipset, replacing its 802.11 WLAN MAC protocol implementation with our proposed extended state machine execution engine. We prove the flexibility of the proposed approach through three use-case implementation examples.
---
paper_title: A survey of dynamically adaptable protocol stacks

paper_content:

The continuous development of new networking standards over the last decade has resulted in an unprecedented proliferation of interfacing technologies and their associated protocol stacks. Never before was such a wide gamut of network architectures, protocol configurations and deployment options available to network designers. Alas, this significant increase in flexibility has come at the cost of an increased complexity in network management tasks, particularly with regard to the accommodation of performance requirements. Especially in mobile settings, this is due to the greater probability of unforeseen communication contexts that renders the efficient provisioning of multiple dissimilar protocol stacks a challenging task. To address this unpredictability, several approaches based on the dynamic adaptation of protocol stacks during runtime have been proposed and investigated over the years. This article surveys major research efforts dealing with the introduction of a dynamic adaptation capacity into protocol stack subsystems. To this end, we present the respective architectures with a focus on their functional entities and their particular mode of operation. Most importantly, we elaborate on the various design approaches to adaptability and the entailed degree of coupling between protocol stack-and layer-entities and their impact on resource allocation models. Furthermore, we classify these research efforts according to a taxonomy for non-monolithic protocol stacks and discuss design trade-offs inherent in each class. We conclude the article with a summary of the key design principles for adaptable protocol stack architectures.
---
paper_title: MAClets: active MAC protocols over hard-coded devices

paper_content:

We introduce MAClets, software programs uploaded and executed on-demand over wireless cards, and devised to change the card's real-time medium access control operation. MAClets permit seamless reconfiguration of the MAC stack, so as to adapt it to mutated context and spectrum conditions and perform tailored performance optimizations hardly accountable by an once-for-all protocol stack design. Following traditional active networking principles, MAClets can be directly conveyed within data packets and executed on hard-coded devices acting as virtual MAC machines. Indeed, rather than executing a pre-defined protocol, we envision a new architecture for wireless cards based on a protocol interpreter (enabling code portability) and a powerful API. Experiments involving the distribution of MAClets within data packets, and their execution over commodity WLAN cards, show the flexibility and viability of the proposed concept.
---
paper_title: The Tempest, a Framework for Safe, Resource Assured, Programmable Networks

paper_content:

Most research in network programmability has stressed the flexibility engendered by increasing the ability of users to configure network elements for their own purposes, without addressing the larger issues of how such advanced control systems can coexist both with each other and with more conventional ones. The Tempest framework presented here extends beyond the provision of simple network programmability to address these larger issues. In particular, we show how network programmability can be achieved without jeopardizing the integrity of the network as a whole, how network programmability fits in with existing networks, and how programmability can be offered at different levels of granularity. Our approach is based on the Tempest's ability to dynamically create virtual private networks over a switched transport architecture (e.g., an ATM network). Each VPN is assigned a set of network resources which can be controlled using either a well-known control system or a control system tailored to the specific needs of a distributed application. The first level of programmability in the Tempest is fairly coarse-grained: an entire virtual network can be programmed by a third party. At a finer level of granularity the Tempest allows user supplied code to be injected into parts of an operational virtual network, thus allowing application specific customization of network control. The article shows how the Tempest framework allows these new approaches to coexist with more conventional solutions.
---
paper_title: SwitchBlade: a platform for rapid deployment of network protocols on programmable hardware

paper_content:

We present SwitchBlade, a platform for rapidly deploying custom protocols on programmable hardware. SwitchBlade uses a pipeline-based design that allows individual hardware modules to be enabled or disabled on the fly, integrates software exception handling, and provides support for forwarding based on custom header fields. SwitchBlade's ease of programmability and wire-speed performance enables rapid prototyping of custom data-plane functions that can be directly deployed in a production network. SwitchBlade integrates common packet-processing functions as hardware modules, enabling different protocols to use these functions without having to resynthesize hardware. SwitchBlade's customizable forwarding engine supports both longest-prefix matching in the packet header and exact matching on a hash value. SwitchBlade's software exceptions can be invoked based on either packet or flow-based rules and updated quickly at runtime, thus making it easy to integrate more flexible forwarding function into the pipeline. SwitchBlade also allows multiple custom data planes to operate in parallel on the same physical hardware, while providing complete isolation for protocols running in parallel. We implemented SwitchBlade using NetFPGA board, but SwitchBlade can be implemented with any FPGA. To demonstrate SwitchBlade's flexibility, we use SwitchBlade to implement and evaluate a variety of custom network protocols: we present instances of IPv4, IPv6, Path Splicing, and an OpenFlow switch, all running in parallel while forwarding packets at line rate.
---
paper_title: XORP: an open platform for network research

paper_content:

Network researchers face a significant problem when deploying software in routers, either for experimentation or for pilot deployment. Router platforms are generally not open systems, in either the open-source or the open-API sense. In this paper we discuss the problems this poses, and present an eXtensible Open Router Platform (XORP) that we are developing to address these issues. Key goals are extensibility, performance and robustness. We show that different parts of a router need to prioritize these differently, and examine techniques by which we can satisfy these often conflicting goals. We aim for XORP to be both a research tool and a stable deployment platform, thus easing the transition of new ideas from the lab to the real world.
---
paper_title: NetFPGA--An Open Platform for Gigabit-Rate Network Switching and Routing

paper_content:

The NetFPGA platform enables students and researchers to build high-performance networking systems in hardware. A new version of the NetFPGA platform has been developed and is available for use by the academic community. The NetFPGA 2.1 platform now has interfaces that can be parameterized, therefore enabling development of modular hardware designs with varied word sizes. It also includes more logic and faster memory than the previous platform. Field Programmable Gate Array (FPGA) logic is used to implement the core data processing functions while software running on embedded cores within the FPGA and/or programs running on an attached host computer implement only control functions. Reference designs and component libraries have been developed for the CS344 course at Stanford University. Open-source Verilog code is available for download from the project website.
---
paper_title: RouteBricks: exploiting parallelism to scale software routers

paper_content:

We revisit the problem of scaling software routers, motivated by recent advances in server technology that enable high-speed parallel processing--a feature router workloads appear ideally suited to exploit. We propose a software router architecture that parallelizes router functionality both across multiple servers and across multiple cores within a single server. By carefully exploiting parallelism at every opportunity, we demonstrate a 35Gbps parallel router prototype; this router capacity can be linearly scaled through the use of additional servers. Our prototype router is fully programmable using the familiar Click/Linux environment and is built entirely from off-the-shelf, general-purpose server hardware.
---
paper_title: SwitchBlade: a platform for rapid deployment of network protocols on programmable hardware

paper_content:

We present SwitchBlade, a platform for rapidly deploying custom protocols on programmable hardware. SwitchBlade uses a pipeline-based design that allows individual hardware modules to be enabled or disabled on the fly, integrates software exception handling, and provides support for forwarding based on custom header fields. SwitchBlade's ease of programmability and wire-speed performance enables rapid prototyping of custom data-plane functions that can be directly deployed in a production network. SwitchBlade integrates common packet-processing functions as hardware modules, enabling different protocols to use these functions without having to resynthesize hardware. SwitchBlade's customizable forwarding engine supports both longest-prefix matching in the packet header and exact matching on a hash value. SwitchBlade's software exceptions can be invoked based on either packet or flow-based rules and updated quickly at runtime, thus making it easy to integrate more flexible forwarding function into the pipeline. SwitchBlade also allows multiple custom data planes to operate in parallel on the same physical hardware, while providing complete isolation for protocols running in parallel. We implemented SwitchBlade using NetFPGA board, but SwitchBlade can be implemented with any FPGA. To demonstrate SwitchBlade's flexibility, we use SwitchBlade to implement and evaluate a variety of custom network protocols: we present instances of IPv4, IPv6, Path Splicing, and an OpenFlow switch, all running in parallel while forwarding packets at line rate.
---
paper_title: XORP: an open platform for network research

paper_content:

Network researchers face a significant problem when deploying software in routers, either for experimentation or for pilot deployment. Router platforms are generally not open systems, in either the open-source or the open-API sense. In this paper we discuss the problems this poses, and present an eXtensible Open Router Platform (XORP) that we are developing to address these issues. Key goals are extensibility, performance and robustness. We show that different parts of a router need to prioritize these differently, and examine techniques by which we can satisfy these often conflicting goals. We aim for XORP to be both a research tool and a stable deployment platform, thus easing the transition of new ideas from the lab to the real world.
---
paper_title: Towards programmable enterprise WLANS with Odin

paper_content:

We present Odin, an SDN framework to introduce programmability in enterprise wireless local area networks (WLANs). Enterprise WLANs need to support a wide range of services and functionalities. This includes authentication, authorization and accounting, policy, mobility and interference management, and load balancing. WLANs also exhibit unique challenges. In particular, access point (AP) association decisions are not made by the infrastructure, but by clients. In addition, the association state machine combined with the broadcast nature of the wireless medium requires keeping track of a large amount of state changes. To this end, Odin builds on a light virtual AP abstraction that greatly simplifies client management. Odin does not require any client side modifications and its design supports WPA2 Enterprise. With Odin, a network operator can implement enterprise WLAN services as network applications. A prototype implementation demonstrates Odin's feasibility.
---
paper_title: SoftRAN: software defined radio access network

paper_content:

An important piece of the cellular network infrastructure is the radio access network (RAN) that provides wide-area wireless connectivity to mobile devices. The fundamental problem the RAN solves is figuring out how best to use and manage limited spectrum to achieve this connectivity. In a dense wireless deployment with mobile nodes and limited spectrum, it becomes a difficult task to allocate radio resources, implement handovers, manage interference, balance load between cells, etc. We argue that LTE's current distributed control plane is suboptimal in achieving the above objective. We propose SoftRAN, a fundamental rethink of the radio access layer. SoftRAN is a software defined centralized control plane for radio access networks that abstracts all base stations in a local geographical area as a virtual big-base station comprised of a central controller and radio elements (individual physical base stations). In defining such an architecture, we create a framework through which a local geographical network can effectively perform load balancing and interference management, as well as maximize throughput, global utility, or any other objective.
---
paper_title: Sensor OpenFlow: Enabling Software-Defined Wireless Sensor Networks

paper_content:

While it has been a belief for over a decade that wireless sensor networks (WSN) are application-specific, we argue that it can lead to resource underutilization and counter-productivity. We also identify two other main problems with WSN: rigidity to policy changes and difficulty to manage. In this paper, we take a radical, yet backward and peer compatible, approach to tackle these problems inherent to WSN. We propose a Software-Defined WSN architecture and address key technical challenges for its core component, Sensor OpenFlow. This work represents the first effort that synergizes software-defined networking and WSN.
---
paper_title: SoftCell: scalable and flexible cellular core network architecture

paper_content:

Cellular core networks suffer from inflexible and expensive equipment, as well as from complex control-plane protocols. To address these challenges, we present SoftCell, a scalable architecture that supports fine-grained policies for mobile devices in cellular core networks, using commodity switches and servers. SoftCell enables operators to realize high-level service policies that direct traffic through sequences of middleboxes based on subscriber attributes and applications. To minimize the size of the forwarding tables, SoftCell aggregates traffic along multiple dimensions---the service policy, the base station, and the mobile device---at different switches in the network. Since most traffic originates from mobile devices, SoftCell performs fine-grained packet classification at the access switches, next to the base stations, where software switches can easily handle the state and bandwidth requirements. SoftCell guarantees that packets belonging to the same connection traverse the same sequence of middleboxes in both directions, even in the presence of mobility. We demonstrate that SoftCell improves the scalability and flexibility of cellular core networks by analyzing real LTE workloads, performing micro-benchmarks on our prototype controller as well as large-scale simulations.
---
paper_title: Software Defined Wireless Networks: Unbridling SDNs

paper_content:

The {\it software defined networking} (SDN) paradigm promises to dramatically simplify network configuration and resource management. Such features are extremely valuable to network operators and therefore, the industrial (besides the academic) research and development community is paying increasing attention to SDN. Although wireless equipment manufacturers are increasing their involvement in SDN-related activities, to date there is not a clear and comprehensive understanding of what are the opportunities offered by SDN in most common networking scenarios involving wireless infrastructure less communications and how SDN concepts should be adapted to suit the characteristics of wireless and mobile communications. This paper is a first attempt to fill this gap as it aims at analyzing how SDN can be beneficial in wireless infrastructure less networking environments with special emphasis on wireless personal area networks (WPAN). Furthermore, a possible approach (called \emph{SDWN}) for such environments is presented and some design guidelines are provided.
---
paper_title: A survey of mobile cloud computing: architecture, applications, and approaches

paper_content:

Together with an explosive growth of the mobile applications and emerging of cloud computing concept, mobile cloud computing (MCC) has been introduced to be a potential technology for mobile services. MCC integrates the cloud computing into the mobile environment and overcomes obstacles related to the performance (e.g., battery life, storage, and bandwidth), environment (e.g., heterogeneity, scalability, and availability), and security (e.g., reliability and privacy) discussed in mobile computing. This paper gives a survey of MCC, which helps general readers have an overview of the MCC including the definition, architecture, and applications. The issues, existing solutions, and approaches are presented. In addition, the future research directions of MCC are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
---
paper_title: MPAP: virtualization architecture for heterogenous wireless APs

paper_content:

This demonstration shows a novel virtualization architecture, called Multi-Purpose Access Point (MPAP), which can virtualize multiple heterogenous wireless standards based on software radio. The basic idea is to deploy a wide-band radio front-end to receive wireless signals from all wireless standards sharing the same spectrum band, and use separate software base-bands to demodulate information stream for each wireless standard. Based on software radio, MPAP consolidates multiple wireless devices into single hardware platform, and allows them to share the same general-purpose computing resource. Different software base-bands can easily communicate and coordinate with one another. Thus, it also provides better coexistence among heterogenous wireless standards. As an example, we demonstrate to use non-contiguous OFDM in 802.11g PHY to avoid the mutual interference with narrow-band ZigBee communication.
---
paper_title: Cooperative spectrum sensing in TV White Spaces: When Cognitive Radio meets Cloud

paper_content:

A Cognitive Radio Cloud Network (CRCN) in TV White Spaces (TVWS) is proposed in this paper. Under the infrastructure of CRCN, cooperative spectrum sensing (SS) and resource scheduling in TVWS can be efficiently implemented making use of the scalability and the vast storage and computing capacity of the Cloud. Based on the sensing reports collected on the Cognitive Radio Cloud (CRC) from distributed secondary users (SUs), we study and implement a sparse Bayesian learning (SBL) algorithm for cooperative SS in TVWS using Microsoft's Windows Azure Cloud platform. A database for the estimated locations and spectrum power profiles of the primary users are established on CRC with Microsoft's SQL Azure. Moreover to enhance the performance of the SBL-based SS on CRC, a hierarchical parallelization method is also implemented with Microsoft's dotNet 4.0 in a MapReduce-like programming model. Based on our simulation studies, a proper programming model and partitioning of the sensing data play crucial roles to the performance of the SBL-based SS on the Cloud.
---
paper_title: CloudMAC: towards software defined WLANs

paper_content:

Traditional enterprise WLAN management systems are hard to extend and require powerful access points (APs). In this paper we introduce and evaluate CloudMAC, an architecture for enterprise WLANs in which MAC frames are generated and processed on virtual APs hosted in a datacenter. The APs only need to forward MAC frames. The APs and the servers are connected via an OpenFlow-enabled network, which allows to control where and how MAC frames are transmitted.
---
paper_title: Virtual basestation: architecture for an open shared WiMAX framework

paper_content:

This paper presents the architecture and performance evaluation of a virtualized wide-area "4G" cellular wireless network. Specifically, it addresses the challenges of virtualization of resources in a cellular base station to enable shared use by multiple independent slice users (experimenters or mobile virtual network operators), each with possibly distinct flow types and network layer protocols. The proposed virtual basestation architecture is based on an external substrate which uses a layer-2 switched datapath, and an arbitrated control path to the WiMAX basestation. The framework implements virtualization of base station's radio resources to achieve isolation between multiple virtual networks. An algorithm for weighted fair sharing among multiple slices based on an airtime fairness metric has been implemented for the first release. Preliminary experimental results from the virtual basestation prototype are given, demonstrating mobile network performance, isolation across slices with different flow types, and custom flow scheduling capabilities.
---
paper_title: LTE wireless virtualization and spectrum management

paper_content:

Many research initiatives have started looking into Future Internet solutions in order to satisfy the ever increasing requirements on the Internet and also to cope with the challenges existing in the current one. Some are proposing further enhancements while others are proposing completely new approaches. Network Virtualization is one solution that is able to combine these approaches and therefore, could play a central role in the Future Internet. It will enable the existence of multiple virtual networks on a common infrastructure even with different network architectures. Network Virtualization means setting up a network composed of individual virtualized network components, such as nodes, links, and routers. Mobility will remain a major requirement, which means that also wireless resources need to be virtualized. In this paper the Long Term Evolution (LTE) was chosen as a case study to extend Network Virtualization into the wireless area.
---
paper_title: Wireless Going in the Cloud: A Promising Concept or Just Marketing Hype?

paper_content:

Cloud computing is a computing service paradigm which attracts increasing attention from academia and industry. In this paper we investigate the use of the terms cloud and cloud computing in the wireless communications and networking domain. We identify four distinct usages of the term cloud in this context and analyze their meaning and relevance to the cloud computing concept. For one of these meanings (which we term Wireless Networking Functionality as a Service) we provide more extensive descriptions of commercial services and proposed architectural designs that illustrate this concept and discuss their advantages and technical challenges. We conclude that the introduction of certain cloud computing ideas in the field of wireless telecommunications and networking not only has the potential to bring along some of the generic advantages of cloud computing but, in some cases, can offer added benefits that are wireless domain specific.
---
paper_title: Wireless network cloud: architecture and system requirements

paper_content:

With the growth of the mobile communication network, from second-generation to third-generation or fourth-generation networks, technologists in the mobile industry continue to consider advanced wireless network architectures that have the potential to reduce networking costs and provide increased flexibility with respect to network features. In this paper, we propose the wireless network cloud (WNC), a wireless system architecture for a wireless access network. This system makes use of emerging cloud-computing technology and various technologies involved with wireless infrastructure, such as software radio technology and remote radio head technology. Based on open information technology architecture, the WNC provides all the necessary transmission and processing resources for a wireless access network operating in a cloud mode. Note that it is useful to separate the hardware and software for different wireless standards and various services and business models, as well as to meet the new system requirements for emerging wireless technologies, such as collaborative processing at different scales of network use. We analyze several important system challenges involving computational requirements of virtual base stations, I/O throughput, and timing networks for synchronization. Based on current information technologies, we make several suggestions with respect to future system design.
---
paper_title: Radio access network virtualization for future mobile carrier networks

paper_content:

This article presents a survey of cellular network sharing, which is a key building block for virtualizing future mobile carrier networks in order to address the explosive capacity demand of mobile traffic, and reduce the CAPEX and OPEX burden faced by operators to handle this demand. We start by reviewing the 3GPP network sharing standardized functionality followed by a discussion on emerging business models calling for additional features. Then an overview of the RAN sharing enhancements currently being considered by the 3GPP RSE Study Item is presented. Based on the developing network sharing needs, a summary of the state of the art of mobile carrier network virtualization is provided, encompassing RAN sharing as well as a higher level of base station programmability and customization for the sharing entities. As an example of RAN virtualization techniques feasibility, a solution based on spectrum sharing is presented: the network virtualization substrate (NVS), which can be natively implemented in base stations. NVS performance is evaluated in an LTE network by means of simulation, showing that it can meet the needs of future virtualized mobile carrier networks in terms of isolation, utilization, and customization.
---
paper_title: Enable flexible spectrum access with spectrum virtualization

paper_content:

Enabling flexible spectrum access (FSA) in existing wireless networks is challenging due to the limited spectrum programmability - the ability to change spectrum properties of a signal to match an arbitrary frequency allocation. This paper argues that spectrum programmability can be separated from general wireless physical layer (PHY) modulation. Therefore, we can support flexible spectrum programmability by inserting a new spectrum virtualization layer (SVL) directly below traditional wireless PHY, and enable FSA for wireless networks without changing their PHY designs. SVL provides a virtual baseband abstraction to wireless PHY, which is static, contiguous, with a desirable width defined by the PHY. At the sender side, SVL reshapes the modulated baseband signals into waveform that matches the dynamically allocated physical frequency bands - which can be of different width, or non-contiguous - while keeping the modulated information unchanged. At the receiver side, SVL performs the inverse reshaping operation that collects the waveform from each physical band, and reconstructs the original modulated signals for PHY. All these reshaping operations are performed at the signal level and therefore SVL is agnostic and transparent to upper PHY. We have implemented a prototype of SVL on a software radio platform, and tested it with various wireless PHYs. Our experiments show SVL is flexible and effective to support FSA in existing wireless networks.
---
paper_title: Software Defined Wireless Networks: Unbridling SDNs

paper_content:

The {\it software defined networking} (SDN) paradigm promises to dramatically simplify network configuration and resource management. Such features are extremely valuable to network operators and therefore, the industrial (besides the academic) research and development community is paying increasing attention to SDN. Although wireless equipment manufacturers are increasing their involvement in SDN-related activities, to date there is not a clear and comprehensive understanding of what are the opportunities offered by SDN in most common networking scenarios involving wireless infrastructure less communications and how SDN concepts should be adapted to suit the characteristics of wireless and mobile communications. This paper is a first attempt to fill this gap as it aims at analyzing how SDN can be beneficial in wireless infrastructure less networking environments with special emphasis on wireless personal area networks (WPAN). Furthermore, a possible approach (called \emph{SDWN}) for such environments is presented and some design guidelines are provided.
---
paper_title: OpenRadio: a programmable wireless dataplane

paper_content:

We present OpenRadio, a novel design for a programmable wireless dataplane that provides modular and declarative programming interfaces across the entire wireless stack. Our key conceptual contribution is a principled refactoring of wireless protocols into processing and decision planes. The processing plane includes directed graphs of algorithmic actions (eg. 54Mbps OFDM WiFi or special encoding for video). The decision plane contains the logic which dictates which directed graph is used for a particular packet (eg. picking between data and video graphs). The decoupling provides a declarative interface to program the platform while hiding all underlying complexity of execution. An operator only expresses decision plane rules and corresponding processing plane action graphs to assemble a protocol. The scoped interface allows us to build a dataplane that arguably provides the right tradeoff between performance and flexibility. Our current system is capable of realizing modern wireless protocols (WiFi, LTE) on off-the-shelf DSP chips while providing flexibility to modify the PHY and MAC layers to implement protocol optimizations.
---
paper_title: OpenRoads: empowering research in mobile networks

paper_content:

We present OpenRoads, an open-source platform for innovation in mobile networks. OpenRoads enable researchers to innovate using their own production networks, through providing an wireless extension OpenFlow. Therefore, you can think of OpenRoads as "OpenFlow Wireless". The OpenRoads' architecture consists of three layers: flow, slicing and controller. These layers provide flexible control, virtualization and high-level abstraction. This allows researchers to implement wildly different algorithms and run them concurrently in one network. OpenRoads also incorporates multiple wireless technologies, specifically WiFi and WiMAX. We have deployed OpenRoads, and used it as our production network. Our goal here is for those to deploy OpenRoads and build their own experiments on it.
---
paper_title: Towards programmable enterprise WLANS with Odin

paper_content:

We present Odin, an SDN framework to introduce programmability in enterprise wireless local area networks (WLANs). Enterprise WLANs need to support a wide range of services and functionalities. This includes authentication, authorization and accounting, policy, mobility and interference management, and load balancing. WLANs also exhibit unique challenges. In particular, access point (AP) association decisions are not made by the infrastructure, but by clients. In addition, the association state machine combined with the broadcast nature of the wireless medium requires keeping track of a large amount of state changes. To this end, Odin builds on a light virtual AP abstraction that greatly simplifies client management. Odin does not require any client side modifications and its design supports WPA2 Enterprise. With Odin, a network operator can implement enterprise WLAN services as network applications. A prototype implementation demonstrates Odin's feasibility.
---
paper_title: Blueprint for introducing innovation into wireless mobile networks

paper_content:

In the past couple of years we've seen quite a change in the wireless industry: Handsets have become mobile computers running user-contributed applications on (potentially) open operating systems. It seems we are on a path towards a more open ecosystem; one that has been previously closed and proprietary. The biggest winners are the users, who will have more choice among competing, innovative ideas. The same cannot be said for the wireless network infrastructure, which remains closed and (mostly) proprietary, and where innovation is bogged down by a glacial standards process. Yet as users, we are surrounded by abundant wireless capacity and multiple wireless networks (WiFi and cellular), with most of the capacity off-limits to us. It seems industry has little incentive to change, preferring to hold onto control as long as possible, keeping an inefficient and closed system in place. This paper is a "call to arms" to the research community to help move the network forward on a path to greater openness. We envision a world in which users can move freely between any wireless infrastructure, while providing payment to infrastructure owners, encouraging continued investment. We think the best path to get there is to separate the network service from the underlying physical infrastructure, and allow rapid innovation of network services, contributed by researchers, network operators, equipment vendors and third party developers. We propose to build and deploy an open - but backward compatible - wireless network infrastructure that can be easily deployed on college campuses worldwide. Through virtualization, we allow researchers to experiment with new network services directly in their production network.
---
paper_title: SoftRAN: software defined radio access network

paper_content:

An important piece of the cellular network infrastructure is the radio access network (RAN) that provides wide-area wireless connectivity to mobile devices. The fundamental problem the RAN solves is figuring out how best to use and manage limited spectrum to achieve this connectivity. In a dense wireless deployment with mobile nodes and limited spectrum, it becomes a difficult task to allocate radio resources, implement handovers, manage interference, balance load between cells, etc. We argue that LTE's current distributed control plane is suboptimal in achieving the above objective. We propose SoftRAN, a fundamental rethink of the radio access layer. SoftRAN is a software defined centralized control plane for radio access networks that abstracts all base stations in a local geographical area as a virtual big-base station comprised of a central controller and radio elements (individual physical base stations). In defining such an architecture, we create a framework through which a local geographical network can effectively perform load balancing and interference management, as well as maximize throughput, global utility, or any other objective.
---
paper_title: SoftCell: scalable and flexible cellular core network architecture

paper_content:

Cellular core networks suffer from inflexible and expensive equipment, as well as from complex control-plane protocols. To address these challenges, we present SoftCell, a scalable architecture that supports fine-grained policies for mobile devices in cellular core networks, using commodity switches and servers. SoftCell enables operators to realize high-level service policies that direct traffic through sequences of middleboxes based on subscriber attributes and applications. To minimize the size of the forwarding tables, SoftCell aggregates traffic along multiple dimensions---the service policy, the base station, and the mobile device---at different switches in the network. Since most traffic originates from mobile devices, SoftCell performs fine-grained packet classification at the access switches, next to the base stations, where software switches can easily handle the state and bandwidth requirements. SoftCell guarantees that packets belonging to the same connection traverse the same sequence of middleboxes in both directions, even in the presence of mobility. We demonstrate that SoftCell improves the scalability and flexibility of cellular core networks by analyzing real LTE workloads, performing micro-benchmarks on our prototype controller as well as large-scale simulations.
---
paper_title: Toward Software-Defined Cellular Networks

paper_content:

Existing cellular networks suffer from inflexible and expensive equipment, complex control-plane protocols, and vendor-specific configuration interfaces. In this position paper, we argue that software defined networking (SDN) can simplify the design and management of cellular data networks, while enabling new services. However, supporting many subscribers, frequent mobility, fine-grained measurement and control, and real-time adaptation introduces new scalability challenges that future SDN architectures should address. As a first step, we propose extensions to controller platforms, switches, and base stations to enable controller applications to (i) express high-level policies based on subscriber attributes, rather than addresses and locations, (ii) apply real-time, fine-grained control through local agents on the switches, (iii)perform deep packet inspection and header compression on packets, and (iv)remotely manage shares of base-station resources.
---
paper_title: Sensor OpenFlow: Enabling Software-Defined Wireless Sensor Networks

paper_content:

While it has been a belief for over a decade that wireless sensor networks (WSN) are application-specific, we argue that it can lead to resource underutilization and counter-productivity. We also identify two other main problems with WSN: rigidity to policy changes and difficulty to manage. In this paper, we take a radical, yet backward and peer compatible, approach to tackle these problems inherent to WSN. We propose a Software-Defined WSN architecture and address key technical challenges for its core component, Sensor OpenFlow. This work represents the first effort that synergizes software-defined networking and WSN.
---
paper_title: Software Defined Wireless Networks: Unbridling SDNs

paper_content:

The {\it software defined networking} (SDN) paradigm promises to dramatically simplify network configuration and resource management. Such features are extremely valuable to network operators and therefore, the industrial (besides the academic) research and development community is paying increasing attention to SDN. Although wireless equipment manufacturers are increasing their involvement in SDN-related activities, to date there is not a clear and comprehensive understanding of what are the opportunities offered by SDN in most common networking scenarios involving wireless infrastructure less communications and how SDN concepts should be adapted to suit the characteristics of wireless and mobile communications. This paper is a first attempt to fill this gap as it aims at analyzing how SDN can be beneficial in wireless infrastructure less networking environments with special emphasis on wireless personal area networks (WPAN). Furthermore, a possible approach (called \emph{SDWN}) for such environments is presented and some design guidelines are provided.
---
paper_title: A knowledge plane for the internet

paper_content:

We propose a new objective for network research: to build a fundamentally different sort of network that can assemble itself given high level instructions, reassemble itself as requirements change, automatically discover when something goes wrong, and automatically fix a detected problem or explain why it cannot do so.We further argue that to achieve this goal, it is not sufficient to improve incrementally on the techniques and algorithms we know today. Instead, we propose a new construct, the Knowledge Plane, a pervasive system within the network that builds and maintains high-level models of what the network is supposed to do, in order to provide services and advice to other elements of the network. The knowledge plane is novel in its reliance on the tools of AI and cognitive systems. We argue that cognitive techniques, rather than traditional algorithmic approaches, are best suited to meeting the uncertainties and complexity of our objective.
---
paper_title: Cognitive radio: brain-empowered wireless communications

paper_content:

Cognitive radio is viewed as a novel approach for improving the utilization of a precious natural resource: the radio electromagnetic spectrum. The cognitive radio, built on a software-defined radio, is defined as an intelligent wireless communication system that is aware of its environment and uses the methodology of understanding-by-building to learn from the environment and adapt to statistical variations in the input stimuli, with two primary objectives in mind: /spl middot/ highly reliable communication whenever and wherever needed; /spl middot/ efficient utilization of the radio spectrum. Following the discussion of interference temperature as a new metric for the quantification and management of interference, the paper addresses three fundamental cognitive tasks. 1) Radio-scene analysis. 2) Channel-state estimation and predictive modeling. 3) Transmit-power control and dynamic spectrum management. This work also discusses the emergent behavior of cognitive radio.
---
paper_title: Artificial Intelligence Based Cognitive Routing for Cognitive Radio Networks

paper_content:

Cognitive radio networks (CRNs) are networks of nodes equipped with cognitive radios that can optimize performance by adapting to network conditions. While cognitive radio networks (CRN) are envisioned as intelligent networks, relatively little research has focused on the network level functionality of CRNs. Although various routing protocols, incorporating varying degrees of adaptiveness, have been proposed for CRNs, it is imperative for the long term success of CRNs that the design of cognitive routing protocols be pursued by the research community. Cognitive routing protocols are envisioned as routing protocols that fully and seamless incorporate AI-based techniques into their design. In this paper, we provide a self-contained tutorial on various AI and machine-learning techniques that have been, or can be, used for developing cognitive routing protocols. We also survey the application of various classes of AI techniques to CRNs in general, and to the problem of routing in particular. We discuss various decision making techniques and learning techniques from AI and document their current and potential applications to the problem of routing in CRNs. We also highlight the various inference, reasoning, modeling, and learning sub tasks that a cognitive routing protocol must solve. Finally, open research issues and future directions of work are identified.
---
paper_title: A Survey of Artificial Intelligence for Cognitive Radios

paper_content:

Cognitive radio (CR) is an enabling technology for numerous new capabilities such as dynamic spectrum access, spectrum markets, and self-organizing networks. To realize this diverse set of applications, CR researchers leverage a variety of artificial intelligence (AI) techniques. To help researchers better understand the practical implications of AI to their CR designs, this paper reviews several CR implementations that used the following AI techniques: artificial neural networks (ANNs), metaheuristic algorithms, hidden Markov models (HMMs), rule-based systems, ontology-based systems (OBSs), and case-based systems (CBSs). Factors that influence the choice of AI techniques, such as responsiveness, complexity, security, robustness, and stability, are discussed. To provide readers with a more concrete understanding, these factors are illustrated in an extended discussion of two CR designs.
---
paper_title: Trends in the development of communication networks: Cognitive networks

paper_content:

One of the main challenges already faced by communication networks is the efficient management of increasing complexity. The recently proposed concept of cognitive network appears as a candidate that can address this issue. In this paper, we survey the existing research work on cognitive networks, as well as related and enabling techniques and technologies. We start with identifying the most recent research trends in communication networks and classifying them according to the approach taken towards the traditional layered architecture. In the analysis we focus on two related trends: cross-layer design and cognitive networks. We classify the cognitive networks related work in that mainly concerned with knowledge representation and that predominantly dealing with the cognition loop. We discuss the existing definitions of cognitive networks and, with respect to those, position our understanding of the concept. Next, we provide a summary of artificial intelligence techniques that are potentially suitable for the development of cognitive networks, and map them to the corresponding states of the cognition loop. We summarize and compare seven architectural proposals that comply with the requirements for a cognitive network. We discuss their relative merits and identify some future research challenges before we conclude with an overview of standardization efforts.
---
paper_title: Cognitive Networks: Towards Self-Aware Networks

paper_content:

Contributors. Foreword 1. Foreword 2. Preface. Acknowledgements. Introduction. Chapter 1: Biologically Inspired Networking. Chapter 2: The Role of Autonomic Networking in Cognitive Networks. Chapter 3: Adaptive Networks. Chapter 4: Self-Managing Networks. Chapter 5: Machine Learning for Cognitive Networks: Technology Assessment and Research Challenges. Chapter 6: Cross-Layer Design and Optimization in Wireless Networks. Chapter 7: Cognitive Radio Architecture. Chapter 8: The Wisdom of Crowds: Cognitive Ad hoc Networks. Chapter 9: Distributed Learning and Reasoning in Cognitive Networks: Methods and Design Decisions. Chapter 10: The Semantic Side of Cognitive Radio. Chapter 11: Security Issues in Cognitive Radio Networks. Chapter 12: Intrusion Detection in Cognitive Networks. Chapter 13: Erasure Tolerant Coding for Cognitive Radios. Index.
---
paper_title: CogNet: an architectural foundation for experimental cognitive radio networks within the future internet

paper_content:

This paper describes a framework for research on architectural tradeoffs and protocol designs for cognitive radio networks at both the local network and the global internetwork levels. Several key architectural issues for cognitive radio networks are discussed, including control and management protocols, support for collaborative PHY, dynamic spectrum coordination, flexible MAC layer protocols, ad hoc group formation and cross-layer adaptation. The overall goal of this work is the design and validation of the control/management and data interfaces between cognitive radio nodes in a local network, and also between cognitive radio networks and the global Internet. Protocol design and implementation based on this framework will result in the CogNet architecture, a prototype open-source cognitive radio protocol stack. Experimental evaluations on emerging cognitive radio platforms are planned for future work, first in a wireless local-area radio network scenario using wireless testbeds such as ORBIT, and later as part of several end-to-end experiments using a wide-area network testbed such as PlanetLab (and GENI in the future).
---
paper_title: Cognitive Radio Rides on the Cloud

paper_content:

Cognitive Radio (CR) is capable of adaptive learning and reconfiguration, promising consistent communications performance for C4ISR1 systems even in dynamic and hostile battlefield environments. As such, the vision of Network-Centric Operations becomes feasible. However, enabling adaptation and learning in CRs may require both storing a vast volume of data and processing it fast. Because a CR usually has limited computing and storage capacity determined by its size and battery, it may not be able to achieve its full capability. The cloud2 can provide its computing and storage utility for CRs to overcome such challenges. On the other hand, the cloud can also store and process enormous amounts of data needed by C4ISR systems. However, today's wireless technologies have difficulty moving various types of data reliably and promptly in the battlefields. CR networks promise reliable and timely data communications for accessing the cloud. Overall, connecting CRs and the cloud overcomes the performance bottlenecks of each. This paper explores opportunities of this confluence and describes our prototype system.
---
paper_title: Cooperative spectrum sensing in TV White Spaces: When Cognitive Radio meets Cloud

paper_content:

A Cognitive Radio Cloud Network (CRCN) in TV White Spaces (TVWS) is proposed in this paper. Under the infrastructure of CRCN, cooperative spectrum sensing (SS) and resource scheduling in TVWS can be efficiently implemented making use of the scalability and the vast storage and computing capacity of the Cloud. Based on the sensing reports collected on the Cognitive Radio Cloud (CRC) from distributed secondary users (SUs), we study and implement a sparse Bayesian learning (SBL) algorithm for cooperative SS in TVWS using Microsoft's Windows Azure Cloud platform. A database for the estimated locations and spectrum power profiles of the primary users are established on CRC with Microsoft's SQL Azure. Moreover to enhance the performance of the SBL-based SS on CRC, a hierarchical parallelization method is also implemented with Microsoft's dotNet 4.0 in a MapReduce-like programming model. Based on our simulation studies, a proper programming model and partitioning of the sensing data play crucial roles to the performance of the SBL-based SS on the Cloud.
---
paper_title: Virtual radio: a framework for configurable radio networks

paper_content:

Network virtualization has recently been proposed for the development of large scale experimental networks, but also as design principle for a Future Internet. In this paper we describe the background to network virtualization and extend this concept into the wireless domain, which we denote as radio virtualization. With radio virtualization different virtual radio networks can operate on top of a common shared infrastructure and share the same radio resources. We present how this radio resource sharing can be performed efficiently without interference between the different virtual radio networks. Further we discuss how radio transmission functionality can be configured. Radio virtualization provides flexibility in the design and deployment of new wireless networking concepts. It allows customization of radio networks for dedicated networking services at reduced deployment costs.
---
paper_title: A survey of mobile cloud computing: architecture, applications, and approaches

paper_content:

Together with an explosive growth of the mobile applications and emerging of cloud computing concept, mobile cloud computing (MCC) has been introduced to be a potential technology for mobile services. MCC integrates the cloud computing into the mobile environment and overcomes obstacles related to the performance (e.g., battery life, storage, and bandwidth), environment (e.g., heterogeneity, scalability, and availability), and security (e.g., reliability and privacy) discussed in mobile computing. This paper gives a survey of MCC, which helps general readers have an overview of the MCC including the definition, architecture, and applications. The issues, existing solutions, and approaches are presented. In addition, the future research directions of MCC are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
---
paper_title: Cognitive Radio Rides on the Cloud

paper_content:

Cognitive Radio (CR) is capable of adaptive learning and reconfiguration, promising consistent communications performance for C4ISR1 systems even in dynamic and hostile battlefield environments. As such, the vision of Network-Centric Operations becomes feasible. However, enabling adaptation and learning in CRs may require both storing a vast volume of data and processing it fast. Because a CR usually has limited computing and storage capacity determined by its size and battery, it may not be able to achieve its full capability. The cloud2 can provide its computing and storage utility for CRs to overcome such challenges. On the other hand, the cloud can also store and process enormous amounts of data needed by C4ISR systems. However, today's wireless technologies have difficulty moving various types of data reliably and promptly in the battlefields. CR networks promise reliable and timely data communications for accessing the cloud. Overall, connecting CRs and the cloud overcomes the performance bottlenecks of each. This paper explores opportunities of this confluence and describes our prototype system.
---
paper_title: MPAP: virtualization architecture for heterogenous wireless APs

paper_content:

This demonstration shows a novel virtualization architecture, called Multi-Purpose Access Point (MPAP), which can virtualize multiple heterogenous wireless standards based on software radio. The basic idea is to deploy a wide-band radio front-end to receive wireless signals from all wireless standards sharing the same spectrum band, and use separate software base-bands to demodulate information stream for each wireless standard. Based on software radio, MPAP consolidates multiple wireless devices into single hardware platform, and allows them to share the same general-purpose computing resource. Different software base-bands can easily communicate and coordinate with one another. Thus, it also provides better coexistence among heterogenous wireless standards. As an example, we demonstrate to use non-contiguous OFDM in 802.11g PHY to avoid the mutual interference with narrow-band ZigBee communication.
---
paper_title: CloudMAC: towards software defined WLANs

paper_content:

Traditional enterprise WLAN management systems are hard to extend and require powerful access points (APs). In this paper we introduce and evaluate CloudMAC, an architecture for enterprise WLANs in which MAC frames are generated and processed on virtual APs hosted in a datacenter. The APs only need to forward MAC frames. The APs and the servers are connected via an OpenFlow-enabled network, which allows to control where and how MAC frames are transmitted.
---
paper_title: Virtual WiFi: bring virtualization from wired to wireless

paper_content:

As virtualization trend is moving towards "client virtualization", wireless virtualization remains to be one of the technology gaps that haven't been addressed satisfactorily. Today's approaches are mainly developed for wired network, and are not suitable for virtualizing wireless network interface due to the fundamental differences between wireless and wired LAN devices that we will elaborate in this paper. We propose a wireless LAN virtualization approach named virtual WiFi that addresses the technology gap. With our proposed solution, the full wireless LAN functionalities are supported inside virtual machines; each virtual machine can establish its own connection with self-supplied credentials; and multiple separate wireless LAN connections are supported through one physical wireless LAN network interface. We designed and implemented a prototype for our proposed virtual WiFi approach, and conducted detailed performance study. Our results show that with conventional virtualization overhead mitigation mechanisms, our proposed approach can support fully functional wireless functions inside VM, and achieve close to native performance of Wireless LAN with moderately increased CPU utilization.
---
paper_title: A Survey of Network Virtualization

paper_content:

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet architecture are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. By introducing a plurality of heterogeneous network architectures cohabiting on a shared physical substrate, network virtualization promotes innovations and diversified applications. In this paper, we survey the existing technologies and a wide array of past and state-of-the-art projects on network virtualization followed by a discussion of major challenges in this area.
---
paper_title: Wireless Going in the Cloud: A Promising Concept or Just Marketing Hype?

paper_content:

Cloud computing is a computing service paradigm which attracts increasing attention from academia and industry. In this paper we investigate the use of the terms cloud and cloud computing in the wireless communications and networking domain. We identify four distinct usages of the term cloud in this context and analyze their meaning and relevance to the cloud computing concept. For one of these meanings (which we term Wireless Networking Functionality as a Service) we provide more extensive descriptions of commercial services and proposed architectural designs that illustrate this concept and discuss their advantages and technical challenges. We conclude that the introduction of certain cloud computing ideas in the field of wireless telecommunications and networking not only has the potential to bring along some of the generic advantages of cloud computing but, in some cases, can offer added benefits that are wireless domain specific.
---
paper_title: Wireless network cloud: architecture and system requirements

paper_content:

With the growth of the mobile communication network, from second-generation to third-generation or fourth-generation networks, technologists in the mobile industry continue to consider advanced wireless network architectures that have the potential to reduce networking costs and provide increased flexibility with respect to network features. In this paper, we propose the wireless network cloud (WNC), a wireless system architecture for a wireless access network. This system makes use of emerging cloud-computing technology and various technologies involved with wireless infrastructure, such as software radio technology and remote radio head technology. Based on open information technology architecture, the WNC provides all the necessary transmission and processing resources for a wireless access network operating in a cloud mode. Note that it is useful to separate the hardware and software for different wireless standards and various services and business models, as well as to meet the new system requirements for emerging wireless technologies, such as collaborative processing at different scales of network use. We analyze several important system challenges involving computational requirements of virtual base stations, I/O throughput, and timing networks for synchronization. Based on current information technologies, we make several suggestions with respect to future system design.
---
paper_title: Wireless virtualization on commodity 802.11 hardware

paper_content:

In this paper we describe specific challenges in virtualizing a wireless network and multiple strategies to address them. Among different possible wireless virtualization strategies, our current work in this domain is focussed on a Time-Division Multiplexing (TDM) approach. Hence, we we present our experiences in the design and implementation of such TDM-based wireless virtualization. Our wireless virtualization system is specifically targeted for multiplexing experiments on a large-scale 802.11 wireless testbed facility.
---
paper_title: A Framework of Better Deployment for WLAN Access Point Using Virtualization Technique

paper_content:

Wireless network is common in the indoor and outdoor. One of the important problem is the better deployment of the access point for designing and constructing an efficient wireless network. Therefore, there are researches to determine the better deployment of access point. However, the considerations to fulfill the better deployment seem to be lacking in these researches. To keep the efficient wireless network, framework of better deployment for access point is necessity. Thus, we proposed Virtual Access Point(VAP) to be used for the better deployment of access point. VAP is a logical access point constructed by virtualization technique and independently keeps the configuration of wireless network in physical access point. VAP moves to another physical access point with executing live migration.
---
paper_title: Enable flexible spectrum access with spectrum virtualization

paper_content:

Enabling flexible spectrum access (FSA) in existing wireless networks is challenging due to the limited spectrum programmability - the ability to change spectrum properties of a signal to match an arbitrary frequency allocation. This paper argues that spectrum programmability can be separated from general wireless physical layer (PHY) modulation. Therefore, we can support flexible spectrum programmability by inserting a new spectrum virtualization layer (SVL) directly below traditional wireless PHY, and enable FSA for wireless networks without changing their PHY designs. SVL provides a virtual baseband abstraction to wireless PHY, which is static, contiguous, with a desirable width defined by the PHY. At the sender side, SVL reshapes the modulated baseband signals into waveform that matches the dynamically allocated physical frequency bands - which can be of different width, or non-contiguous - while keeping the modulated information unchanged. At the receiver side, SVL performs the inverse reshaping operation that collects the waveform from each physical band, and reconstructs the original modulated signals for PHY. All these reshaping operations are performed at the signal level and therefore SVL is agnostic and transparent to upper PHY. We have implemented a prototype of SVL on a software radio platform, and tested it with various wireless PHYs. Our experiments show SVL is flexible and effective to support FSA in existing wireless networks.
---
paper_title: A knowledge plane for the internet

paper_content:

We propose a new objective for network research: to build a fundamentally different sort of network that can assemble itself given high level instructions, reassemble itself as requirements change, automatically discover when something goes wrong, and automatically fix a detected problem or explain why it cannot do so.We further argue that to achieve this goal, it is not sufficient to improve incrementally on the techniques and algorithms we know today. Instead, we propose a new construct, the Knowledge Plane, a pervasive system within the network that builds and maintains high-level models of what the network is supposed to do, in order to provide services and advice to other elements of the network. The knowledge plane is novel in its reliance on the tools of AI and cognitive systems. We argue that cognitive techniques, rather than traditional algorithmic approaches, are best suited to meeting the uncertainties and complexity of our objective.
---
paper_title: 1 Languages for Software-Defined Networks

paper_content:

Modern computer networks perform a bewildering array of tasks, from routing and traffic monitoring, to access control and server load balancing. However, managing these networks is unnecessarily complicated and error-prone, due to a heterogeneous mix of devices (e.g., routers, switches, firewalls, and middleboxes) with closed and proprietary configuration interfaces. Softwaredefined networks are poised to change this by offering a clean and open interface between networking devices and the software that controls them. In particular, many commercial switches support the OpenFlow protocol, and a number of campus, data center, and backbone networks have deployed the new technology. However, while SDNs make it possible to program the network, they does not make it easy. Today's OpenFlow controllers offer low-level APIs that mimic the underlying switch hardware. To reach SDNs full potential, we need to identify the right higher-level abstractions for creating (and composing) applications. In the Frenetic project, we are designing simple and intuitive abstractions for programming the three main stages of network management: monitoring network traffic, specifying and composing packet forwarding policies, and updating policies in a consistent way. Overall, these abstractions make it dramatically easier for programmers to write and reason about SDN applications.
---
paper_title: The Internet of Things: A survey

paper_content:

This paper addresses the Internet of Things. Main enabling factor of this promising paradigm is the integration of several technologies and communications solutions. Identification and tracking technologies, wired and wireless sensor and actuator networks, enhanced communication protocols (shared with the Next Generation Internet), and distributed intelligence for smart objects are just the most relevant. As one can easily imagine, any serious contribution to the advance of the Internet of Things must necessarily be the result of synergetic activities conducted in different fields of knowledge, such as telecommunications, informatics, electronics and social science. In such a complex scenario, this survey is directed to those who want to approach this complex discipline and contribute to its development. Different visions of this Internet of Things paradigm are reported and enabling technologies reviewed. What emerges is that still major issues shall be faced by the research community. The most relevant among them are addressed in details.
---

Title: Building Programmable Wireless Networks: An Architectural Survey

Section 1: INTRODUCTION
Description 1: In this section, introduce the importance and widespread deployment of wireless networks and discuss the need for flexible architectural support. Define key concepts like data planes and control planes, and describe the motivations behind programmable wireless networks.

Section 2: PROGRAMMABLE NETWORKING ARCHITECTURES
Description 2: This section should cover the historical context and development of programmable networking architectures. Discuss major approaches like the OpenSig Approach and the Active Networking Approach, as well as virtualization and SDN technologies.

Section 3: BUILDING BLOCKS FOR PROGRAMMABLE WIRELESS NETWORKING
Description 3: Detail the various techniques and hardware architectures used in programmable wireless networks, such as Software Defined Radios (SDR), Cognitive Radios (CR), MAC Programmable Wireless Devices, and Programmable Routers.

Section 4: THREE DOMINANT TRENDS IN PROGRAMMABLE WIRELESS NETWORKING
Description 4: Provide an in-depth overview of the three key trends shaping programmable wireless networking: Software Defined Wireless Networks (SWNs), Cognitive Wireless Networks (CWNs), and Virtualizable Wireless Networks (VWNs). Discuss various projects and applications under each trend.

Section 5: OPEN RESEARCH ISSUES AND CHALLENGES
Description 5: Highlight the current research challenges and issues faced in the development and deployment of programmable wireless networks. Discuss areas such as Software Defined Cognitive Wireless Networks, development of wireless-specific network APIs, integration with cloud technologies, the wireless Internet of Things, and balancing centralized and distributed paradigms.

Section 6: CONCLUSIONS
Description 6: Summarize the insights provided in the paper, emphasizing the potential of programmable wireless networks. Discuss the synergy between different programmable networking techniques and propose future directions for research and implementation.