OPPORTUNISTIC APPROACH TO EXPLOIT WIRELESS SPECTRUM BY USE OF COGNITIVE RADIO: A REVIEW
---
paper_title: A multipath routing survey for mobile ad-hoc networks

paper_content:

Mobile ad hoc networks (MANETs) pose particular challenges in terms of Quality of Service (QoS) and performance. This is due to the effect of numerous parameters such as; bandwidth and power constrains, delays, security issues, etc. On the there hand, the degree of freedom enables the wireless mobile nodes to enter and leave the network dynamically. The latter offers redundant paths and dynamic coverage. Particular attention is given to the multipath transmission capability as well as load balancing to have efficient routing possible for heavy multimedia traffics. In this paper, the issues of multipath routing in MANETs are surveyed and performances of such MANETs are compared to discuss the application of multipath routing and its effects on different layers to support QoS.
---
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: Cognitive networks

paper_content:

This paper presents a definition and framework for a novel type of adaptive data network: the cognitive network. In a cognitive network, the collection of elements that make up the network observes network conditions and then, using prior knowledge gained from previous interactions with the network, plans, decides and acts on this information. Cognitive networks are different from other "intelligent" communication technologies because these actions are taken with respect to the end-to-end goals of a data flow. In addition to the cognitive aspects of the network, a specification language is needed to translate the user's end-to-end goals into a form understandable by the cognitive process. The cognitive network also depends on a software adaptable network that has both an external interface accessible to the cognitive network and network status sensors. These devices are used to provide control and feedback. The paper concludes by presenting a simple case study to illustrate a cognitive network and its framework
---
paper_title: Cognitive networks

paper_content:

This paper presents a definition and framework for a novel type of adaptive data network: the cognitive network. In a cognitive network, the collection of elements that make up the network observes network conditions and then, using prior knowledge gained from previous interactions with the network, plans, decides and acts on this information. Cognitive networks are different from other "intelligent" communication technologies because these actions are taken with respect to the end-to-end goals of a data flow. In addition to the cognitive aspects of the network, a specification language is needed to translate the user's end-to-end goals into a form understandable by the cognitive process. The cognitive network also depends on a software adaptable network that has both an external interface accessible to the cognitive network and network status sensors. These devices are used to provide control and feedback. The paper concludes by presenting a simple case study to illustrate a cognitive network and its framework
---
paper_title: CRAHNs : Cognitive radio ad hoc networks

paper_content:

Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage by exploiting the existing wireless spectrum opportunistically. CR networks, equipped with the intrinsic capabilities of the cognitive radio, will provide an ultimate spectrum-aware communication paradigm in wireless communications. CR networks, however, impose unique challenges due to the high fluctuation in the available spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying spectrum availability are some of the key distinguishing factors. In this paper, intrinsic properties and current research challenges of the CRAHNs are presented. First, novel spectrum management functionalities such as spectrum sensing, spectrum sharing, and spectrum decision, and spectrum mobility are introduced from the viewpoint of a network requiring distributed coordination. A particular emphasis is given to distributed coordination between CR users through the establishment of a common control channel. Moreover, the influence of these functions on the performance of the upper layer protocols, such as the network layer, and transport layer protocols are investigated and open research issues in these areas are also outlined. Finally, a new direction called the commons model is explained, where CRAHN users may independently regulate their own operation based on pre-decided spectrum etiquette.
---
paper_title: Cognitive networks

paper_content:

This paper presents a definition and framework for a novel type of adaptive data network: the cognitive network. In a cognitive network, the collection of elements that make up the network observes network conditions and then, using prior knowledge gained from previous interactions with the network, plans, decides and acts on this information. Cognitive networks are different from other "intelligent" communication technologies because these actions are taken with respect to the end-to-end goals of a data flow. In addition to the cognitive aspects of the network, a specification language is needed to translate the user's end-to-end goals into a form understandable by the cognitive process. The cognitive network also depends on a software adaptable network that has both an external interface accessible to the cognitive network and network status sensors. These devices are used to provide control and feedback. The paper concludes by presenting a simple case study to illustrate a cognitive network and its framework
---
paper_title: CRAHNs : Cognitive radio ad hoc networks

paper_content:

Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage by exploiting the existing wireless spectrum opportunistically. CR networks, equipped with the intrinsic capabilities of the cognitive radio, will provide an ultimate spectrum-aware communication paradigm in wireless communications. CR networks, however, impose unique challenges due to the high fluctuation in the available spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying spectrum availability are some of the key distinguishing factors. In this paper, intrinsic properties and current research challenges of the CRAHNs are presented. First, novel spectrum management functionalities such as spectrum sensing, spectrum sharing, and spectrum decision, and spectrum mobility are introduced from the viewpoint of a network requiring distributed coordination. A particular emphasis is given to distributed coordination between CR users through the establishment of a common control channel. Moreover, the influence of these functions on the performance of the upper layer protocols, such as the network layer, and transport layer protocols are investigated and open research issues in these areas are also outlined. Finally, a new direction called the commons model is explained, where CRAHN users may independently regulate their own operation based on pre-decided spectrum etiquette.
---
paper_title: Emerging cognitive radio technology: Principles, challenges and opportunities

paper_content:

Due to the increasing demand for new wireless services and applications as well as the increasing number of wireless users, the available spectrum is becoming increasingly scarce. As a result, the federal communications commission (FCC) has been investigating new ways to manage the radio frequency resources. Cognitive radio (CR) technology is an innovative radio design philosophy which aims to increase spectrum utilization by exploiting unused and under-utilized spectrum in dynamically changing environments. The basic idea is to let unlicensed users use licensed frequencies, provided they can guarantee minimum interference perceived by the primary licensed users. However, allowing opportunistic use of the wireless spectrum creates new problems such as peaceful coexistence with other wireless technologies as well as understanding the influence of interference that each of these networks can create. In this article, we discuss the key CR operations and principles, and then discuss some of the main challenges and research opportunities that exist in CR-based emerging wireless networks.
---
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: CRAHNs : Cognitive radio ad hoc networks

paper_content:

Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage by exploiting the existing wireless spectrum opportunistically. CR networks, equipped with the intrinsic capabilities of the cognitive radio, will provide an ultimate spectrum-aware communication paradigm in wireless communications. CR networks, however, impose unique challenges due to the high fluctuation in the available spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying spectrum availability are some of the key distinguishing factors. In this paper, intrinsic properties and current research challenges of the CRAHNs are presented. First, novel spectrum management functionalities such as spectrum sensing, spectrum sharing, and spectrum decision, and spectrum mobility are introduced from the viewpoint of a network requiring distributed coordination. A particular emphasis is given to distributed coordination between CR users through the establishment of a common control channel. Moreover, the influence of these functions on the performance of the upper layer protocols, such as the network layer, and transport layer protocols are investigated and open research issues in these areas are also outlined. Finally, a new direction called the commons model is explained, where CRAHN users may independently regulate their own operation based on pre-decided spectrum etiquette.
---
paper_title: Software Defined Cognitive Radio Prototype toward IMT-Advanced Wireless Communication Systems

paper_content:

This paper summarizes the current status of frequency allocation plan in Japan and discusses how to create new frequency bands for the next generation mobile communication systems. Then the needs for cognitive radio are summarized such as one of the solutions, and the current situation of the research and development is also shown. Finally, some of the research results on cognitive radio in the author's institute are shown
---
paper_title: Software Defined Cognitive Radio Prototype toward IMT-Advanced Wireless Communication Systems

paper_content:

This paper summarizes the current status of frequency allocation plan in Japan and discusses how to create new frequency bands for the next generation mobile communication systems. Then the needs for cognitive radio are summarized such as one of the solutions, and the current situation of the research and development is also shown. Finally, some of the research results on cognitive radio in the author's institute are shown
---
paper_title: Emerging cognitive radio technology: Principles, challenges and opportunities

paper_content:

Due to the increasing demand for new wireless services and applications as well as the increasing number of wireless users, the available spectrum is becoming increasingly scarce. As a result, the federal communications commission (FCC) has been investigating new ways to manage the radio frequency resources. Cognitive radio (CR) technology is an innovative radio design philosophy which aims to increase spectrum utilization by exploiting unused and under-utilized spectrum in dynamically changing environments. The basic idea is to let unlicensed users use licensed frequencies, provided they can guarantee minimum interference perceived by the primary licensed users. However, allowing opportunistic use of the wireless spectrum creates new problems such as peaceful coexistence with other wireless technologies as well as understanding the influence of interference that each of these networks can create. In this article, we discuss the key CR operations and principles, and then discuss some of the main challenges and research opportunities that exist in CR-based emerging wireless networks.
---
paper_title: CRAHNs : Cognitive radio ad hoc networks

paper_content:

Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage by exploiting the existing wireless spectrum opportunistically. CR networks, equipped with the intrinsic capabilities of the cognitive radio, will provide an ultimate spectrum-aware communication paradigm in wireless communications. CR networks, however, impose unique challenges due to the high fluctuation in the available spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying spectrum availability are some of the key distinguishing factors. In this paper, intrinsic properties and current research challenges of the CRAHNs are presented. First, novel spectrum management functionalities such as spectrum sensing, spectrum sharing, and spectrum decision, and spectrum mobility are introduced from the viewpoint of a network requiring distributed coordination. A particular emphasis is given to distributed coordination between CR users through the establishment of a common control channel. Moreover, the influence of these functions on the performance of the upper layer protocols, such as the network layer, and transport layer protocols are investigated and open research issues in these areas are also outlined. Finally, a new direction called the commons model is explained, where CRAHN users may independently regulate their own operation based on pre-decided spectrum etiquette.
---

Title: OPPORTUNISTIC APPROACH TO EXPLOIT WIRELESS SPECTRUM BY USE OF COGNITIVE RADIO: A REVIEW

Section 1: INTRODUCTION
Description 1: Introduce the concept of software-defined radio (SDR) and cognitive radio (CR), their applications, objectives, and the general purpose of the paper.

Section 2: COGNITIVE RADIO (CR)
Description 2: Discuss the technology behind CR, including its key characteristics such as cognitive capability and reconfigurability.

Section 3: CR ARCHITECTURE
Description 3: Describe the architecture of cognitive radio, including the components and layers that enable its cognitive capabilities.

Section 4: PROTOTYPE SIMULATION
Description 4: Explain the prototype simulation environment developed for handling beacon signal conflicts and how it demonstrates CR’s capabilities.

Section 5: PRIMARY AND CR NETWORKS
Description 5: Define primary networks and CR networks, and outline the functionalities required for CR networks to share licensed spectrum bands.

Section 6: SPECTRUM SENSING
Description 6: Elaborate on the importance of spectrum sensing, the types of sensing required, and the functionalities such as PU detection, sensing control, and cooperation.

Section 7: SPECTRUM DECISION
Description 7: Discuss the process of spectrum decision, its relation to QoS requirements, and the steps involved in spectrum characterization and selection.

Section 8: SPECTRUM SHARING
Description 8: Illustrate the need for spectrum sharing among CR users, and describe the resource allocation and spectrum access strategies.

Section 9: SPECTRUM MOBILITY
Description 9: Explain the concept of spectrum mobility, including spectrum handoff scenarios and the structure required for cognitive radio ad hoc networks (CRAHNs).

Section 10: SOFTWARE DEFINED COGNITIVE RADIO
Description 10: Define SDCR and discuss the projects and research topics related to the development and implementation of cognitive radio technologies in various frequency bands.

Section 11: RESEARCH TOPICS OF SDCR
Description 11: Identify and elaborate on the hardware and software research topics necessary for realizing SDCR, focusing on components such as RF parts, A/D converters, and spectrum capacity estimation.

Section 12: CONCLUSION
Description 12: Summarize the findings of the paper, highlighting the significance of CR in optimizing the use of radio spectrum and the ongoing research efforts.