Resource Slicing in Virtual Wireless Networks: A Survey
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paper_title: Software-Defined and Virtualized Future Mobile and Wireless Networks: A Survey

paper_content:

With the proliferation of mobile demands and increasingly multifarious services and applications, mobile Internet has been an irreversible trend. Unfortunately, the current mobile and wireless network (MWN) faces a series of pressing challenges caused by the inherent design. In this paper, we extend two latest and promising innovations of Internet, software-defined networking and network virtualization, to mobile and wireless scenarios. We first describe the challenges and expectations of MWN, and analyze the opportunities provided by the software-defined wireless network (SDWN) and wireless network virtualization (WNV). Then, this paper focuses on SDWN and WNV by presenting the main ideas, advantages, ongoing researches and key technologies, and open issues respectively. Moreover, we interpret that these two technologies highly complement each other, and further investigate efficient joint design between them. This paper confirms that SDWN and WNV may efficiently address the crucial challenges of MWN and significantly benefit the future mobile and wireless network.
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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.
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paper_title: Mobile Network Resource Sharing Options: Performance Comparisons

paper_content:

Resource sharing among mobile network operators is a promising way to tackle growing data demand by increasing capacity and reducing costs of network infrastructure deployment and operation. In this work, we evaluate sharing options that range from simple approaches that are feasible in the near-term on traditional infrastructure to complex methods that require specialized/virtualized infrastructure. We build a simulation testbed supporting two geographically overlapped 4G LTE macro cellular networks and model the sharing architecture/process between the network operators. We compare Capacity Sharing (CS) and Spectrum Sharing (SS) on traditional infrastructure and Virtualized Spectrum Sharing (VSS) and Virtualized PRB Sharing (VPS) on virtualized infrastructure under light, moderate and heavy user loading scenarios in collocated and noncollocated E-UTRAN deployment topologies. We also study these sharing options in conservative and aggressive sharing participation modes. Based on simulation results, we conclude that CS, a generalization of traditional roaming, is the best performing and simplest option, SS is least effective and that VSS and VPS perform better than spectrum sharing with added complexity.
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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.
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paper_title: Wireless Network Virtualization: A Survey, Some Research Issues and Challenges

paper_content:

Since wireless network virtualization enables abstraction and sharing of infrastructure and radio spectrum resources, the overall expenses of wireless network deployment and operation can be reduced significantly. Moreover, wireless network virtualization can provide easier migration to newer products or technologies by isolating part of the network. Despite the potential vision of wireless network virtualization, several significant research challenges remain to be addressed before widespread deployment of wireless network virtualization, including isolation, control signaling, resource discovery and allocation, mobility management, network management and operation, and security as well as non-technical issues such as governance regulations, etc. In this paper, we provide a brief survey on some of the works that have already been done to achieve wireless network virtualization, and discuss some research issues and challenges. We identify several important aspects of wireless network virtualization: overview, motivations, framework, performance metrics, enabling technologies, and challenges. Finally, we explore some broader perspectives in realizing wireless network virtualization.
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paper_title: Programming Software-Defined wireless networks

paper_content:

Programming a mobile network requires to account for multiple complex operations, such as allocating radio resources and monitoring interference. Nevertheless, the current Software-Defined Networking ecosystem provides little support for mobile networks in term of radio data-plane abstractions, controllers, and programming primitives. Starting from the consideration that WiFi is becoming an integral part of the 5G architecture, we present a set of programming abstractions modeling three fundamental aspects of a WiFi network, namely state management of wireless clients, resource provisioning, and network state collection. The proposed abstractions hide away the implementation details of the underlying wireless technology providing programmers with expressive tools to control the state of the network. We also describe a proof-of-concept implementation of a Software-Defined Radio Access Network controller for WiFi networks and a Python-based Software Development Kit leveraging the proposed abstractions. The resulting platform can be effectively leveraged in order to implement typical control tasks such as mobility management and traffic engineering as well as applications and services such as multicast video delivery and/or dynamic content caching.
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paper_title: SoftCell: scalable and flexible cellular core network architecture

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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.
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paper_title: Building Programmable Wireless Networks: An Architectural Survey

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In recent times, there is increasing consensus that the traditional Internet architecture needs to be evolved for it to sustain unstinted growth and innovation. A major reason for the perceived architectural ossification is the lack of the ability to program the network as a system. This situation has resulted partly from historical decisions in the original Internet design which emphasized decentralized network operations through colocated data and control planes on each network device. The situation for wireless networks is no different resulting in a lot of complexity and a plethora of largely incompatible wireless technologies. With traditional architectures providing limited support for programmability, there is a broad realization in the wireless community that future programmable wireless networks would require significant architectural innovations. In this paper, we will present an unified overview of the programmability solutions that have been proposed at the device and the network level. In particular, we will discuss software-defined radio (SDR), cognitive radio (CR), programmable MAC processor, and programmable routers as device-level programmability solutions, and software-defined networking (SDN), cognitive wireless networking (CWN), virtualizable wireless networking (VWN) and cloud-based wireless networking (CbWN) as network-level programmability solutions. We provide both a self-contained exposition of these topics as well as a broad survey of the application of these trends in modern wireless networks.
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paper_title: Software-Defined and Virtualized Future Mobile and Wireless Networks: A Survey

paper_content:

With the proliferation of mobile demands and increasingly multifarious services and applications, mobile Internet has been an irreversible trend. Unfortunately, the current mobile and wireless network (MWN) faces a series of pressing challenges caused by the inherent design. In this paper, we extend two latest and promising innovations of Internet, software-defined networking and network virtualization, to mobile and wireless scenarios. We first describe the challenges and expectations of MWN, and analyze the opportunities provided by the software-defined wireless network (SDWN) and wireless network virtualization (WNV). Then, this paper focuses on SDWN and WNV by presenting the main ideas, advantages, ongoing researches and key technologies, and open issues respectively. Moreover, we interpret that these two technologies highly complement each other, and further investigate efficient joint design between them. This paper confirms that SDWN and WNV may efficiently address the crucial challenges of MWN and significantly benefit the future mobile and wireless network.
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paper_title: Can the Production Network Be the Testbed?

paper_content:

A persistent problem in computer network research is validation. When deciding how to evaluate a new feature or bug fix, a researcher or operator must trade-off realism (in terms of scale, actual user traffic, real equipment) and cost (larger scale costs more money, real user traffic likely requires downtime, and real equipment requires vendor adoption which can take years). Building a realistic testbed is hard because "real" networking takes place on closed, commercial switches and routers with special purpose hardware. But if we build our testbed from software switches, they run several orders of magnitude slower. Even if we build a realistic network testbed, it is hard to scale, because it is special purpose and is in addition to the regular network. It needs its own location, support and dedicated links. For a testbed to have global reach takes investment beyond the reach of most researchers. ::: ::: In this paper, we describe a way to build a testbed that is embedded in--and thus grows with--the network. The technique--embodied in our first prototype, FlowVisor--slices the network hardware by placing a layer between the control plane and the data plane. We demonstrate that FlowVisor slices our own production network, with legacy protocols running in their own protected slice, alongside experiments created by researchers. The basic idea is that if unmodified hardware supports some basic primitives (in our prototype, Open-Flow, but others are possible), then a worldwide testbed can ride on the coat-tails of deployments, at no extra expense. Further, we evaluate the performance impact and describe how FlowVisor is deployed at seven other campuses as part of a wider evaluation platform.
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paper_title: Towards programmable enterprise WLANS with Odin

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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.
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paper_title: A Survey on Software-Defined Network and OpenFlow: From Concept to Implementation

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Software-defined network (SDN) has become one of the most important architectures for the management of largescale complex networks, which may require repolicing or reconfigurations from time to time. SDN achieves easy repolicing by decoupling the control plane from data plane. Thus, the network routers/switches just simply forward packets by following the flow table rules set by the control plane. Currently, OpenFlow is the most popular SDN protocol/standard and has a set of design specifications. Although SDN/OpenFlow is a relatively new area, it has attracted much attention from both academia and industry. In this paper, we will conduct a comprehensive survey of the important topics in SDN/OpenFlow implementation, including the basic concept, applications, language abstraction, controller, virtualization, quality of service, security, and its integration with wireless and optical networks. We will compare the pros and cons of different schemes and discuss the future research trends in this exciting area. This survey can help both industry and academia R&D people to understand the latest progress of SDN/OpenFlow designs.
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paper_title: Towards a scalable and near-sighted control plane architecture for WiFi SDNs

paper_content:

Not much is known today about how to reap the SDN benefits in WiFi networks-a critical use case given the increasing importance of WiFi networks. This paper presents AeroFlux, a scalable software-defined wireless network, that supports large enterprise and carrier WiFi deployments with low-latency programmatic control of fine-grained WiFi-specific transmission settings. This is achieved through AeroFlux's hierarchical design. We report on an early prototype implementation and evaluation, showing that AeroFlux can significantly reduce control plane traffic.
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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.
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paper_title: Programmatic orchestration of WiFi networks

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With wireless technologies becoming prevalent at the last hop, today's network operators need to manage WiFi access networks in unison with their wired counterparts. However, the non-uniformity of feature sets in existing solutions and the lack of programmability makes this a challenging task. This paper proposes Odin, an SDN-based solution to bridge this gap. With Odin, we make the following contributions: (i) Light Virtual Access Points (LVAPs), a novel programming abstraction for addressing the IEEE 802.11 protocol stack complexity, (ii) a design and implementation for a software-defined WiFi network architecture based on LVAPs, and (iii) a prototype implementation on top of commodity access point hardware without modifications to the IEEE 802.11 client, making it practical for today's deployments. To highlight the effectiveness of the approach we demonstrate six WiFi network services on top of Odin including load-balancing, mobility management, jammer detection, automatic channel-selection, energy management, and guest policy enforcement. To further foster the development of our framework, the Odin prototype is made publicly available.
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paper_title: AeroFlux: A Near-Sighted Controller Architecture for Software-Defined Wireless Networks

paper_content:

Applying the concept of SDN to WiFi networks is challenging, since wireless networks feature many peculiarities and knobs that often do not exist in wired networks: obviously, WiFi communicates over a shared medium, with all its implications, e.g., higher packet loss and hidden or exposed terminals. Moreover, wireless links can be operated in a number of different regimes, e.g., transmission rate and power settings can be adjusted, RTS/CTS mechanisms can be used. Indeed, due to the non-stationary characteristic of the wireless channel, permanently adjusting settings such as transmission rate and power is crucial for the performance of WiFi networks and brings significant benefits in the service quality, e.g., through reducing the packet loss probability. Today’s rate and power control is mainly done on the WiFi device itself. But it is rarely optimized to the application-layer demands and their diverse traffic requirements, e.g., their individual sensitivity to packet loss or jitter. Therefore, if SDN for wireless can provide mechanisms to control the WiFi-specific transmission settings on a per-slice, per-client, and per-flow level, traffic and application-aware optimizations are feasible. This however requires that controllers frequently collect link characteristics and, accordingly, adjust transmission settings in a timely manner. As a reference, the standard rate control mechanism in the Linux kernel adjusts the transmission rate on a wireless link based on transmission success probability statistics every 100 ms. Leaving rate control (and power control accordingly) to a centralized controller comes with a risk of overloading the control plane, or of adding too much latency, while there is limited benefit in maintaining these statistics globally. For instance, the coherence time (also a function of the client mobility) can easily exceed the expected time of the successful transmission of multiple data frames [2], rendering optimized control difficult. In this paper, we suggest a 2-tiered approach for the design of a wireless SDN control plane. Our design, called AeroFlux, handles frequent, localized events close to where they originate, i.e., close to the data plane, by relying on NearSighted Controllers (NSC) [3, 4, 7]. Global events, which require a broader picture of the network’s state, are handled by the Global Controller (GC). More specifically, GC takes care of network functions that require global visibility, such as mobility management and load balancing, whereas NSCs control per-client or per-flow transmission settings such as rate and power based on transmission status feedback information exported by the Access Points (AP), which include the rates for best throughput and best transmission probability. Put differently, we enable the global controller to offload latency-critical or high-load tasks from the tier-1 control plane to the NSCs. This reduces the load on the GC and lowers the latency of critical control plane operations. As a result, with AeroFlux, we realize a scalable wireless SDN architecture which can support large enterprise and carrier WiFi deployments with low-latency programmatic control of fine-grained WiFi-specific transmission settings. The AeroFlux design introduces a set of new trade-offs and optimization opportunities which allow for advancements in the use of the shared wireless medium, and, as a result, in the user’s quality of experience. For instance, our prototype’s perflow control allows application-aware service differentiation by prioritizing multimedia streams (§2). Another key feature of AeroFlux is that it does not require modifications to today’s hardware and works on top of commodity WiFi equipment. 1 The AeroFlux Architecture AeroFlux uses a 2-tiered control plane: the Global Control plane GC and the Near-Sighted Control plane NSC. Figure 1 depicts the high level interactions of the architecture’s building blocks. The GC is logically centralized, e.g., a set of redundant controllers deployed in data centers, whereas the NSCs are located closer to where they are needed, e.g., close to the wireless APs. On the APs runs a Radio Agent (RA), which hosts the Light Virtual Access Points (LVAPs) [6] that abstract the specifics of the 802.11 protocol, such as association and authentication state. Furthermore, LVAPs store per-client OpenFlow and WiFi Datapath Transmission (WDTX) rules. In the following, we describe the different elements in more detail. Global Controller (GC): The global controller handles events which are not time-critical [7] or events belonging to inherently global tasks [4]. Examples include: authentication, wide-area mobility management, global policy verification (including loop-free forwarding sets), client load balancing, and applications for intrusion detection or network monitoring. In addition, the global controller is best suited to man-
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paper_title: Cloud-RAN: Innovative radio access network architecture

paper_content:

Recent penetration of SDR (Software defined radio) technology into mobile systems of new generation as well as increasing throughput demands in radio access network (RAN) are main development engines of new paradigm in radio access network world, better known as Cloud-Radio Access Network (C-RAN). This inovative architecture whose main proponent among telecom companies is China Mobile, should significantly decrease bussiness costs of Telcos, mainly on the long term basis, and also enable higher resource utilization as well as faster and more flexibile development of radio access networks following the IT concept of Cloud Computing. Although the architecture itself, applied to this field, is quite revolutionary compared to the present one, its realization would be based on optimal combination of existing technologies that would have to be adjusted to system requirements of, mainly, LTE and LTE advanced systems. Even though theoretically, reviewed architecture provides a number of improvements, for its wider acceptance and implementation, certain problems must be solved due to the current capabilities of SDR technology and optical infrastructure. This paper will present brief overview of pros and cons of this architecture as well as an estimate of further progress in this field. This paper will present a new overview of all known techniques to realize a system capable to support a C-RAN network. We explored all the external factors that affect the radio access network and we made our own conclusions.
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paper_title: CloudMAC — An OpenFlow based architecture for 802.11 MAC layer processing in the cloud

paper_content:

IEEE 802.11 WLANs are a very important technology to provide high speed wireless Internet access. Especially at airports, university campuses or in city centers, WLAN coverage is becoming ubiquitous leading to a deployment of hundreds or thousands of Access Points (AP). Managing and configuring such large WLAN deployments is a challenge. Current WLAN management protocols such as CAPWAP are hard to extend with new functionality. In this paper, we present CloudMAC, a novel architecture for enterprise or carrier grade WLAN systems. By partially offloading the MAC layer processing to virtual machines provided by cloud services and by integrating our architecture with OpenFlow, a software defined networking approach, we achieve a new level of flexibility and reconfigurability. In Cloud-MAC APs just forward MAC frames between virtual APs and IEEE 802.11 stations. The processing of MAC layer frames as well as the creation of management frames is handled at the virtual APs while the binding between the virtual APs and the physical APs is managed using OpenFlow. The testbed evaluation shows that CloudMAC achieves similar performance as normal WLANs, but allows novel services to be implemented easily in high level programming languages. The paper presents a case study which shows that dynamically switching off APs to save energy can be performed seamlessly with CloudMAC, while a traditional WLAN architecture causes large interruptions for users.
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paper_title: NFV: State of the Art, Challenges and Implementation in Next Generation Mobile Networks (vEPC)

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As mobile network users look forward to the connectivity speeds of 5G networks, service providers are facing challenges in complying with connectivity demands without substantial financial investments. Network function virtualization (NFV) is introduced as a new methodology that offers a way out of this bottleneck. NFV is poised to change the core structure of telecommunications infrastructure to be more cost-efficient. In this article, we introduce an NFV framework, and discuss the challenges and requirements of its use in mobile networks. In particular, an NFV framework in the virtual environment is proposed. Moreover, in order to reduce signaling traffic and achieve better performance, this article proposes a criterion to bundle multiple functions of a virtualized evolved packet core in a single physical device or a group of adjacent devices. The analysis shows that the proposed grouping can reduce the network control traffic by 70 percent.
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paper_title: Network Function Virtualization: State-of-the-art and Research Challenges

paper_content:

Network function virtualization (NFV) has drawn significant attention from both industry and academia as an important shift in telecommunication service provisioning. By decoupling network functions (NFs) from the physical devices on which they run, NFV has the potential to lead to significant reductions in operating expenses (OPEX) and capital expenses (CAPEX) and facilitate the deployment of new services with increased agility and faster time-to-value. The NFV paradigm is still in its infancy and there is a large spectrum of opportunities for the research community to develop new architectures, systems and applications, and to evaluate alternatives and trade-offs in developing technologies for its successful deployment. In this paper, after discussing NFV and its relationship with complementary fields of software defined networking (SDN) and cloud computing, we survey the state-of-the-art in NFV, and identify promising research directions in this area. We also overview key NFV projects, standardization efforts, early implementations, use cases, and commercial products.
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paper_title: Wireless Network Virtualization: A Survey, Some Research Issues and Challenges

paper_content:

Since wireless network virtualization enables abstraction and sharing of infrastructure and radio spectrum resources, the overall expenses of wireless network deployment and operation can be reduced significantly. Moreover, wireless network virtualization can provide easier migration to newer products or technologies by isolating part of the network. Despite the potential vision of wireless network virtualization, several significant research challenges remain to be addressed before widespread deployment of wireless network virtualization, including isolation, control signaling, resource discovery and allocation, mobility management, network management and operation, and security as well as non-technical issues such as governance regulations, etc. In this paper, we provide a brief survey on some of the works that have already been done to achieve wireless network virtualization, and discuss some research issues and challenges. We identify several important aspects of wireless network virtualization: overview, motivations, framework, performance metrics, enabling technologies, and challenges. Finally, we explore some broader perspectives in realizing wireless network virtualization.
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paper_title: Virtualization of Multi-Cell 802.11 Networks: Association and Airtime Control

paper_content:

This paper investigates the virtualization and optimization of a multi-cell WLAN. We consider the station (STA)-access point (AP) association and airtime control for virtualized 802.11 networks to provide service customization and fairness across multiple internet service providers (ISPs) sharing the common physical infrastructure and network capacity. More specifically, an optimization problem is formulated on the STAs transmission probabilities to maximize the overall network throughput, while providing airtime usage guarantees for the ISPs. Subsequently, an algorithm to reach the optimal solution is developed by applying monomial approximation and geometric programming iteratively. Based on the proposed three-dimensional Markov-chain model of the enhanced distributed channel access (EDCA) protocol, the detailed implementation of the optimal transmission probability is also discussed. The accuracy of the proposed Markov-chain model and the performance of the developed association and airtime control scheme are evaluated through numerical results.
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paper_title: Current trends and perspectives in wireless virtualization

paper_content:

The objective of this paper is to survey and compare recent works in the field of wireless virtualization in order to identify potential applications, common trends and future research directions. First, this paper briefly summarizes different wireless virtualization architectures as well as both enabling and enabled technologies related to wireless virtualization. Then, this paper proposes a wireless virtualization classification based on the type of virtualized resources and the depth of slicing. The three main perspectives identified are data and flow-based perspective, protocol-based perspective and spectrum-based perspective. A hypothetical ecosystem scenario of a future virtualized wireless infrastructure in which these perspectives coexist is explored. Finally, the challenges and requirements of a sustainable wireless virtualization framework are discussed.
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paper_title: Future Mobile Communications: Lte Optimization and Mobile Network Virtualization

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The key to a successful future mobile communication system lies in the design of its radio scheduler. One of the key challenges of the radio scheduler is how to provide the right balance between Quality of Service (QoS) guarantees and the overall system performance. Yasir Zaki proposes innovative solutions for the design of the Long Term Evolution (LTE) radio scheduler and presents several LTE radio scheduler analytical models that can be used as efficient tools for radio dimensioning. The author also introduces a novel wireless network virtualization framework and highlights the potential gains of using this framework for the future network operators. This framework enables the operators to share their resources and reduce their cost, thus achieving a better overall system performance and radio resource utilization.
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paper_title: Resource allocation for broadband networks

paper_content:

The author suggests the use of congestion measures at the packet level, the burst level, and the call level to evaluate congestion for integrated traffic. These measures result from the fact that communication terminals can often be characterized in terms of call level, burst level, and packet level statistics. They can be used for the purpose of bandwidth allocation at these levels, virtually emulating the functions of circuit switching, fast circuit switching, and fast packet switching, respectively. Various methodologies are described for evaluating blocking probabilities at these levels. The analysis sheds light on traffic engineering issues such as appropriate link load, traffic integration, trunk group and switch sizing, and bandwidth reservation criteria for bursty services. >
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paper_title: NVS: A Substrate for Virtualizing Wireless Resources in Cellular Networks

paper_content:

This paper describes the design and implementation of a network virtualization substrate (NVS ) for effective virtualization of wireless resources in cellular networks. Virtualization fosters the realization of several interesting deployment scenarios such as customized virtual networks, virtual services, and wide-area corporate networks, with diverse performance objectives. In virtualizing a base station's uplink and downlink resources into slices, \ssr NVS meets three key requirements-isolation, customization, and efficient resource utilization-using two novel features: 1) NVS introduces a provably optimal slice scheduler that allows existence of slices with bandwidth-based and resource-based reservations simultaneously; and 2) NVS includes a generic framework for efficiently enabling customized flow scheduling within the base station on a per-slice basis. Through a prototype implementation and detailed evaluation on a WiMAX testbed, we demonstrate the efficacy of \ssr NVS. For instance, we show for both downlink and uplink directions that \ssr NVS can run different flow schedulers in different slices, run different slices simultaneously with different types of reservations, and perform slice-specific application optimizations for providing customized services.
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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.
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paper_title: Resource allocation and cross-layer control in wireless networks

paper_content:

Information flow in a telecommunication network is accomplished through the interaction of mechanisms at various design layers with the end goal of supporting the information exchange needs of the applications. In wireless networks in particular, the different layers interact in a nontrivial manner in order to support information transfer. In this text we will present abstract models that capture the cross-layer interaction from the physical to transport layer in wireless network architectures including cellular, ad-hoc and sensor networks as well as hybrid wireless-wireline. The model allows for arbitrary network topologies as well as traffic forwarding modes, including datagrams and virtual circuits. Furthermore the time varying nature of a wireless network, due either to fading channels or to changing connectivity due to mobility, is adequately captured in our model to allow for state dependent network control policies. Quantitative performance measures that capture the quality of service requirements in these systems depending on the supported applications are discussed, including throughput maximization, energy consumption minimization, rate utility function maximization as well as general performance functionals. Cross-layer control algorithms with optimal or suboptimal performance with respect to the above measures are presented and analyzed. A detailed exposition of the related analysis and design techniques is provided.
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paper_title: LTE Wireless Network Virtualization: Dynamic Slicing via Flexible Scheduling

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The successful virtualization of wireless access networks is strongly affected by the way in which radio resources are managed. The Infrastructure Provider (InP) is required to deploy efficient and flexible scheduling techniques to dynamically allocate the resources for the users associated with different Service Providers (SPs). Service contracts with different SPs and fairness among their users are crucial to the success of the virtualization scheme deployed by the InP. In this paper we develop an efficient resource allocation scheme to allocate the radio resource blocks in LTE networks. The scheme keeps track of the service contracts with the SPs and also the fairness requirements between cell-center users and cell-edge users. Also the scheme allows the flexible definition of fairness requirements for different SPs. The performance of the proposed schemes is evaluated and the results show that the proposed low-complexity scheme is very efficient in terms of computation time and its performance in terms of sum rate is close to the results due to the relaxed solution and coordinate search algorithm.
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paper_title: Investigation of Network Virtualization and Load Balancing Techniques in LTE Networks

paper_content:

Mobile Network Virtualization (NV) is an emerging technique which has drawn increasingly research attention. Network Virtualization enables multiple network operators to share a common infrastructure (including core network, transport network and access network) so as to reduce the investment capital while improving the overall performance at the same time. This is achieved by exploring the multiplexing gain. Similarly, Load Balancing (LB) is a well-known mechanism used in mobile networks to offload excessive traffic from high-load cells (hot spots) to low-load ones within one network operator. This paper aims at investigating the potential gain of applying NV in LTE (Long Term Evolution) networks and compares it with the LB scheme gain. In this paper, we propose an LTE virtualization framework (that enables spectrum sharing) and a dynamic load balancing scheme for multi-eNB and multi-VO (Virtual Operator) systems. We compare the performance gain of both schemes for different applications, e.g. VoIP, video, HTTP and FTP. We also investigate the parameterization of both schemes, e.g. sharing intervals, LB intervals and safety margins, in order to find the optimal parameter settings. The presented results show that the LTE networks can benefit from both NV and LB techniques.
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paper_title: NVS: A Substrate for Virtualizing Wireless Resources in Cellular Networks

paper_content:

This paper describes the design and implementation of a network virtualization substrate (NVS ) for effective virtualization of wireless resources in cellular networks. Virtualization fosters the realization of several interesting deployment scenarios such as customized virtual networks, virtual services, and wide-area corporate networks, with diverse performance objectives. In virtualizing a base station's uplink and downlink resources into slices, \ssr NVS meets three key requirements-isolation, customization, and efficient resource utilization-using two novel features: 1) NVS introduces a provably optimal slice scheduler that allows existence of slices with bandwidth-based and resource-based reservations simultaneously; and 2) NVS includes a generic framework for efficiently enabling customized flow scheduling within the base station on a per-slice basis. Through a prototype implementation and detailed evaluation on a WiMAX testbed, we demonstrate the efficacy of \ssr NVS. For instance, we show for both downlink and uplink directions that \ssr NVS can run different flow schedulers in different slices, run different slices simultaneously with different types of reservations, and perform slice-specific application optimizations for providing customized services.
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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.
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paper_title: CellSlice: Cellular wireless resource slicing for active RAN sharing

paper_content:

We present the design and implementation of Cell-Slice, a novel system for slicing wireless resources in a cellular network for effective Radio Access Network (RAN) sharing. CellSlice is a gateway-level solution that achieves the slicing without modifying the basestations' MAC schedulers, thereby significantly reducing the barrier for its adoption. Achieving slicing with a gateway-level solution is challenging, however, since resource scheduling decisions occur at the basestations at fine timescales, and these decisions are not visible at the gateways. In the uplink direction, CellSlice overcomes the challenge by indirectly constraining the uplink scheduler's decisions using a simple feedback-based adaptation algorithm. For downlink, we build on the technique used by NVS, a native basestation virtualization solution, and show that effective downlink slicing can be easily achieved without modifying basestation schedulers. We instantiate a prototype of CellSlice on a Picochip WiMAX testbed. Through both prototype evaluation and simulations, we demonstrate that CellSlice's performance for both remote uplink and remote downlink slicing is close to that of NVS. CellSlice's design is access-technology independent, and hence can be equally applicable to LTE, LTE-Advanced and WiMAX networks.
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paper_title: A Dynamic Embedding Algorithm for Wireless Network Virtualization

paper_content:

Wireless network virtualization enables multiple virtual wireless networks to coexist on shared physical infrastructure. However, one of the main challenges is the problem of assigning the physical resources to virtual networks in an efficient manner. Although some work has been done on solving the embedding problem for wireless networks, few solutions are applicable to dynamic networks with changing traffic patterns. In this paper we propose a dynamic greedy embedding algorithm for wireless virtualization. Virtual networks can be re-embedded dynamically using this algorithm, enabling increased resource usage and lower rejection rates. We compare the dynamic greedy algorithm to a static embedding algorithm and also to its dynamic version. We show that the dynamic algorithms provide increased performance to previous methods using simulated traffic. In addition we formulate the embedding problem with multiple priority levels for the static and dynamic case.
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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.
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paper_title: Karnaugh-map like online embedding algorithm of wireless virtualization

paper_content:

Wireless virtualization enables multiple concurrent wireless networks running on a shared wireless substrate to support different services (e.g. multimedia, VoIP). A fundamental challenge in wireless virtualization is how to efficiently assign wireless resource to virtual networks (VNs), i.e. embedding problem. However, so far there are few research results related to the embedding problems of wireless virtualization. This paper focuses on two important goals: (1) the embedding algorithm should handle online virtual network requests; (2) an efficient embedding algorithm is needed. Inspired from karnaugh-map, we present a karnaugh-map-like online embedding algorithm of wireless virtualization, which includes: online scheduling method and karnaugh-map-like embedding algorithm. Evaluation results show that our algorithm has better performance. To the best of authors' knowledge, it is not only the first detailed algorithm on embedding problem of wireless virtualization, but also the first algorithm handling the online requests of wireless virtualization.
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paper_title: VNTS: A Virtual Network Traffic Shaper for Air Time Fairness in 802.16e Systems

paper_content:

The 802.16e standard for broadband wireless access mandates the presence of QoS classes, but does not specify guidelines for the scheduler implementation or mechanisms to ensure air time fairness. Our study demonstrates the feasibility of controlling downlink airtime fairness for slices while running above a proprietary WiMAX basestation (BS) scheduler. We design and implement a virtualized infrastructure that allows users to obtain at least an allocated percentage of BS resources in the presence of saturation and link degradation. Using Kernel virtual machines for creating slices and Click modular router for implementing the virtual network traffic shaping engine we show that it is possible to adaptively control slice usage for downlink traffic on a WiMAX Basestation. The fairness index and coupling coefficient show an improvement of up to 42%, and 73% with preliminary indoor walking mobility experiments. Outdoor vehicular measurements show an improvement of up to 27%, and 70% with the fairness index and coupling coefficient respectively
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paper_title: CellSlice: Cellular wireless resource slicing for active RAN sharing

paper_content:

We present the design and implementation of Cell-Slice, a novel system for slicing wireless resources in a cellular network for effective Radio Access Network (RAN) sharing. CellSlice is a gateway-level solution that achieves the slicing without modifying the basestations' MAC schedulers, thereby significantly reducing the barrier for its adoption. Achieving slicing with a gateway-level solution is challenging, however, since resource scheduling decisions occur at the basestations at fine timescales, and these decisions are not visible at the gateways. In the uplink direction, CellSlice overcomes the challenge by indirectly constraining the uplink scheduler's decisions using a simple feedback-based adaptation algorithm. For downlink, we build on the technique used by NVS, a native basestation virtualization solution, and show that effective downlink slicing can be easily achieved without modifying basestation schedulers. We instantiate a prototype of CellSlice on a Picochip WiMAX testbed. Through both prototype evaluation and simulations, we demonstrate that CellSlice's performance for both remote uplink and remote downlink slicing is close to that of NVS. CellSlice's design is access-technology independent, and hence can be equally applicable to LTE, LTE-Advanced and WiMAX networks.
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paper_title: ViFi: Virtualizing WLAN using Commodity Hardware

paper_content:

We consider an architecture in which the same WiFi infrastructure can be dynamically shared among multiple operators. Our system, ViFi, virtualizes WLAN resources, allowing for controlled sharing of both the uplink and downlink bandwidth. ViFi operates with stock 802.11 clients, and can be implemented entirely as a software add-on for commodity 802.11 APs. ViFi puts users (customers) of different operators in separate groups, each creating a virtual WLAN. ViFi guarantees proportional fair share of channel access time at group level, and isolates traffic between groups. The key technical contribution of ViFi is a useful form of virtualization without requiring changes to the underlying WiFi protocol.
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paper_title: Virtualization of Multi-Cell 802.11 Networks: Association and Airtime Control

paper_content:

This paper investigates the virtualization and optimization of a multi-cell WLAN. We consider the station (STA)-access point (AP) association and airtime control for virtualized 802.11 networks to provide service customization and fairness across multiple internet service providers (ISPs) sharing the common physical infrastructure and network capacity. More specifically, an optimization problem is formulated on the STAs transmission probabilities to maximize the overall network throughput, while providing airtime usage guarantees for the ISPs. Subsequently, an algorithm to reach the optimal solution is developed by applying monomial approximation and geometric programming iteratively. Based on the proposed three-dimensional Markov-chain model of the enhanced distributed channel access (EDCA) protocol, the detailed implementation of the optimal transmission probability is also discussed. The accuracy of the proposed Markov-chain model and the performance of the developed association and airtime control scheme are evaluated through numerical results.
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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.
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paper_title: Providing Throughput and Fairness Guarantees in Virtualized WLANs through Control Theory

paper_content:

With the increasing demand for mobile Internet access, WLAN virtualization is becoming a promising solution for sharing wireless infrastructure among multiple service providers. Unfortunately, few mechanisms have been devised to tackle this problem and the existing approaches fail in optimizing the limited bandwidth and providing virtual networks with fairness guarantees. In this paper, we propose a novel algorithm based on control theory to configure the virtual WLANs with the goal of ensuring fairness in the resource distribution, while maximizing the total throughput. Our algorithm works by adapting the contention window configuration of each virtual WLAN to the channel activity in order to ensure optimal operation. We conduct a control-theoretic analysis of our system to appropriately design the parameters of the controller and prove system stability, and undertake an extensive simulation study to show that our proposal optimizes performance under different types of traffic. The results show that the mechanism provides a fair resource distribution independent of the number of stations and their level of activity, and is able to react promptly to changes in the network conditions while ensuring stable operation.
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paper_title: Airtime-based resource control in wireless LANs for wireless network virtualization

paper_content:

Wireless network virtualization is needed to build a virtual network over wireless and wired networks, which enables a rapid deployment of novel mobile services or novel mobile network architectures on a shared infrastructure. This paper proposes an airtime-based resource control technique for wireless network virtualization, in which wireless network resources are allocated among competing virtual networks while keeping their programmability. A WLAN system adopting the proposed technique is developed by enhancing an IEEE 802.11e EDCA (Enhanced Distributed Channel Access) MAC (Media Access Control) mechanism. The operation of the resource control technique is demonstrated by a simulation and the performance of airtime usage and throughput are investigated. It is shown that technique can successfully control the wireless network resource allocations with a target ratio even under conditions when the WLAN system suffers interferences.
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paper_title: SplitAP: Leveraging Wireless Network Virtualization for Flexible Sharing of WLANs

paper_content:

Providing air-time guarantees across a group of clients forms a fundamental building block in sharing an access point (AP) across different virtual network providers. Though this problem has a relatively simple solution for downlink group scheduling through traffic engineering at the AP, solving this problem for uplink (UL) traffic presents a challenge for fair sharing of wireless hotspots. Among other issues, the mechanism for uplink traffic control has to scale across a large user base, and provide flexible operation irrespective of the client channel conditions and network loads. In this study, we propose the SplitAP architecture that address the problem of sharing uplink airtime across groups of users by extending the idea of network virtualization. Our architecture allows us to deploy different algorithms for enforcing UL airtime fairness across client groups. In this study, we will highlight the design features of the SplitAP architecture, and present results from evaluation on a prototype deployed with: (1) LPFC and (2) LPFC+, two algorithms for controlling UL group fairness. Performance comparisons on the ORBIT testbed show that the proposed algorithms are capable of providing group air-time fairness across wireless clients irrespective of the network volume, and traffic type. The algorithms show up to 40% improvement with a modified Jain fairness index.
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paper_title: Space Versus Time Separation for Wireless Virtualization on an Indoor Grid

paper_content:

The decreasing cost of wireless hardware and ever increasing number of wireless testbeds has led to a shift in the protocol evaluation paradigm from simulations towards emulation. In addition, with a large number of users demanding experimental resources and lack of space and time for deploying more hardware, fair resource sharing among independent co-existing experiments is important. We study the proposed approaches to wireless virtualization with a focus on schemes conserving wireless channels rather than nodes. Our detailed comparison reveals that while experiments sharing a channel by space separation achieve better efficiency than those relying on time separation of a channel, the isolation between experiments in both cases is comparable. We propose and implement a policy manager to alleviate the isolation problem and suggest scenarios in which either of the schemes would provide a suitable virtualization solution.
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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.
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paper_title: Supporting Integrated MAC and PHY Software Development for the USRP SDR

paper_content:

Software Defined Radios (SDR) offer great runtime flexibility both at the physical and MAC layer. This makes them an attractive platform for the development of cognitive radios that can adapt to changes in channel conditions, traffic load, and user requirements. However, to realize this goal, we need a software framework that supports both MAC protocol and PHY layer development in an integrated fashion. In this paper we report on our experience in using two different software frameworks for integrated PHY-MAC development for SDRs: GNU Radio, which was originally designed to support PHY layer development, and Click, a framework for protocol development. We also discuss a number of broader system considerations, such as what functionality should be offloaded to the SDR device.
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paper_title: Building Programmable Wireless Networks: An Architectural Survey

paper_content:

In recent times, there is increasing consensus that the traditional Internet architecture needs to be evolved for it to sustain unstinted growth and innovation. A major reason for the perceived architectural ossification is the lack of the ability to program the network as a system. This situation has resulted partly from historical decisions in the original Internet design which emphasized decentralized network operations through colocated data and control planes on each network device. The situation for wireless networks is no different resulting in a lot of complexity and a plethora of largely incompatible wireless technologies. With traditional architectures providing limited support for programmability, there is a broad realization in the wireless community that future programmable wireless networks would require significant architectural innovations. In this paper, we will present an unified overview of the programmability solutions that have been proposed at the device and the network level. In particular, we will discuss software-defined radio (SDR), cognitive radio (CR), programmable MAC processor, and programmable routers as device-level programmability solutions, and software-defined networking (SDN), cognitive wireless networking (CWN), virtualizable wireless networking (VWN) and cloud-based wireless networking (CbWN) as network-level programmability solutions. We provide both a self-contained exposition of these topics as well as a broad survey of the application of these trends in modern wireless networks.
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paper_title: TAISC: A cross-platform MAC protocol compiler and execution engine

paper_content:

Abstract MAC protocols significantly impact wireless performance metrics such as throughput, energy consumption and reliability. Although the choice of the optimal MAC protocol depends on time-varying criteria such as the current application requirements and the current environmental conditions, MAC protocols cannot be upgraded after deployment since their implementations are typically written in low level, hardware specific code which is hard to reuse on other hardware platforms. To remedy this shortcoming, this paper introduces TAISC, Time Annotated Instruction Set Computer, a framework for hardware independent MAC protocol development and management. The solution presented in this paper allows describing MAC protocols in a platform independent language, followed by a straightforward compilation step, yielding dedicated binary code, optimized for specific radio chips. The compiled code is as efficient in terms of memory footprint as custom-written protocols for specific devices. To enable time-critical operation, the TAISC compiler adds exact time annotations to every instruction of the optimized binary code. As a result, the TAISC approach can be used for energy-efficient cross-platform MAC protocol design, while achieving up to 97% of the theoretical throughput at an overhead of only 20 µs per instruction.
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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.
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paper_title: Current trends and perspectives in wireless virtualization

paper_content:

The objective of this paper is to survey and compare recent works in the field of wireless virtualization in order to identify potential applications, common trends and future research directions. First, this paper briefly summarizes different wireless virtualization architectures as well as both enabling and enabled technologies related to wireless virtualization. Then, this paper proposes a wireless virtualization classification based on the type of virtualized resources and the depth of slicing. The three main perspectives identified are data and flow-based perspective, protocol-based perspective and spectrum-based perspective. A hypothetical ecosystem scenario of a future virtualized wireless infrastructure in which these perspectives coexist is explored. Finally, the challenges and requirements of a sustainable wireless virtualization framework are discussed.
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paper_title: Wireless network virtualization

paper_content:

Virtualization of wired networks and end computing systems has become one of the leading trends in networked ICT systems. In contrast relatively little virtualization has occurred in infrastructure based wireless networks, but the idea of virtualizing wireless access is gaining attention as it has the potential to improve spectrum utilization and perhaps create new services. In this paper we survey the state of the current research in virtualizing wireless networks. We define and describe possible architectures, the issues, hurdles and trends towards implementation of wireless network virtualization.
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paper_title: Towards a scalable and near-sighted control plane architecture for WiFi SDNs

paper_content:

Not much is known today about how to reap the SDN benefits in WiFi networks-a critical use case given the increasing importance of WiFi networks. This paper presents AeroFlux, a scalable software-defined wireless network, that supports large enterprise and carrier WiFi deployments with low-latency programmatic control of fine-grained WiFi-specific transmission settings. This is achieved through AeroFlux's hierarchical design. We report on an early prototype implementation and evaluation, showing that AeroFlux can significantly reduce control plane traffic.
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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.
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Title: Resource Slicing in Virtual Wireless Networks: A Survey

Section 1: INTRODUCTION
Description 1: Introduce the major concerns of wireless networks, the concept of Wireless Network Virtualization (WNV), and outline the focus of the survey on wireless resource slicing, its challenges, and existing techniques.

Section 2: RELATED CONCEPTS
Description 2: Describe three enablers of wireless slicing: Wireless Network Virtualization (WNV), Software Defined Networking (SDN), and Network Function Virtualization (NFV), and review existing works on these topics.

Section 3: Wireless Network Virtualization
Description 3: Detail the concept, goals, and challenges of Wireless Network Virtualization (WNV) as an enabler for slicing wireless networks.

Section 4: Software Defined Networking
Description 4: Explain the concept of SDN, its implications for wireless slicing, and review relevant literature on SDN tools and frameworks.

Section 5: Network Function Virtualization
Description 5: Describe NFV, its role as an enabler for wireless slicing, and review pertinent research efforts.

Section 6: THE SLICING APPROACH
Description 6: Define the concept of slicing in network virtualization and introduce the motivations for slicing a wireless network.

Section 7: PROBLEM DESCRIPTION
Description 7: Identify and detail the problems of resource allocation and isolation in wireless slicing, including a brief introduction to medium access techniques.

Section 8: Medium Access Techniques
Description 8: Provide an overview of medium access control methods in LTE and IEEE 802.11 standards to contextualize the challenges in wireless slicing.

Section 9: Resource Allocation
Description 9: Discuss the complexities of assigning resources to different slices in wireless networks, including potential models and mechanisms for resource allocation.

Section 10: Isolation
Description 10: Discuss the isolation problem in wireless slicing, highlighting the challenges of maintaining slice specifications over time.

Section 11: EXISTING APPROACHES FOR WIRELESS SLICING
Description 11: Review existing mechanisms proposed for wireless slicing, focusing on solutions for LTE, WiMAX, and IEEE 802.11 technologies.

Section 12: Research Challenges
Description 12: Explore the remaining challenges and open research directions in wireless resource slicing, such as isolation in random access networks, technology-agnostic solutions, dynamics, time constraints, real deployments, user mobility, and more.

Section 13: CONCLUSION
Description 13: Summarize the survey, highlighting the integral role of slicing in wireless network virtualization and the challenges that remain to be addressed.