An analysis on decentralized adaptive MAC protocols for Cognitive Radio networks

The scarcity of bandwidth in the radio spectrum has become more vital since the demand for more and more wireless applications has increased. Most of the spectrum bands have been allocated although many studies have shown that these bands are significantly underutilized most of the time. The problem of unavailability of spectrum and inefficiency in its utilization has been smartly addressed by the Cognitive Radio (CR) Technology which is an opportunistic network that senses the environment, observes the network changes, and then using knowledge gained from the prior interaction with the network, makes intelligent decisions by dynamically adapting their transmission characteristics. In this paper some of the decentralized adaptive MAC protocols for CR networks have been critically analyzed and a novel adaptive MAC protocol for CR networks, DNG-MAC which is decentralized and non-global in nature, has been proposed. The results show the DNG-MAC out performs other CR MAC protocols in terms of time and energy efficiency

Implementation and Analysis of Adaptive Spectrum Sensing

The electromagnetic spectrum is a finite resource that has become increasingly crowded as the day-to-day operation of the world has become increasingly reliant on wireless devices. With the growing deployment of the Internet-of-Things (IoT), 5G Networks, and broadband internet systems, the available spectrum for radar applications has been reduced and instances of interference across all device types have increased. To mitigate this problem going forward, devices need to be better able to intelligently access the spectrum based on the presence of other users. A cognitive radio or radar system functions by using adaptive spectrum sensing to detect existing users in the frequency band and adapt to use ’open’ spectrum bands. To ensure the predictable performance of the system and systems that it shares spectrum with, it must detect new users and adapt without interrupting its operation or interfering with the other users. Because modern communications networks can update their spectrum utilization on a sub-millisecond timescale, the critical detection and adaption phase must operate in real-time. This work presents an implementation of a fast spectrum sensing (FSS) algo- rithm deployed on the field-programmable gate array (FPGA) of an Ettus USRP software-defined radio. This implementation allows for microsecond scale updates of the environment’s spectrum availability. Unfortunately, this FSS algorithm is limited by its knowledge of the spectrum, which is ever-changing. To help improve the system’s dynamic performance a new adaptive detection algorithm is proposed to replace the static threshold of the first implementation. The new detection algo- rithm is a constant false alarm rate (CFAR) inspired detector which allows a cogni- tive sensor to work in a dynamic environment without a-priori information about the spectrum. Combining the FSS algorithm with dynamic signal detection allows the cognitive radio system to adapt to the ever-changing environment without requiring extensive ’listen before talk’ periods before operation

Regulatory and Policy Implications of Emerging Technologies to Spectrum Management

This paper provides an overview of the policy implications of technological developments, and how these technologies can accommodate an increased level of market competition. It is based on the work carried out in the SPORT VIEWS (Spectrum Policies and Radio Technologies Viable In Emerging Wireless Societies) research project for the European Commission (FP6)spectrum, new radio technologies, UWB, SDR, cognitive radio, Telecommunications, regulation, Networks, Interconnection

Multiband Spectrum Access: Great Promises for Future Cognitive Radio Networks

Cognitive radio has been widely considered as one of the prominent solutions to tackle the spectrum scarcity. While the majority of existing research has focused on single-band cognitive radio, multiband cognitive radio represents great promises towards implementing efficient cognitive networks compared to single-based networks. Multiband cognitive radio networks (MB-CRNs) are expected to significantly enhance the network's throughput and provide better channel maintenance by reducing handoff frequency. Nevertheless, the wideband front-end and the multiband spectrum access impose a number of challenges yet to overcome. This paper provides an in-depth analysis on the recent advancements in multiband spectrum sensing techniques, their limitations, and possible future directions to improve them. We study cooperative communications for MB-CRNs to tackle a fundamental limit on diversity and sampling. We also investigate several limits and tradeoffs of various design parameters for MB-CRNs. In addition, we explore the key MB-CRNs performance metrics that differ from the conventional metrics used for single-band based networks.Comment: 22 pages, 13 figures; published in the Proceedings of the IEEE Journal, Special Issue on Future Radio Spectrum Access, March 201

Survey of Spectrum Sharing for Inter-Technology Coexistence

Increasing capacity demands in emerging wireless technologies are expected to be met by network densification and spectrum bands open to multiple technologies. These will, in turn, increase the level of interference and also result in more complex inter-technology interactions, which will need to be managed through spectrum sharing mechanisms. Consequently, novel spectrum sharing mechanisms should be designed to allow spectrum access for multiple technologies, while efficiently utilizing the spectrum resources overall. Importantly, it is not trivial to design such efficient mechanisms, not only due to technical aspects, but also due to regulatory and business model constraints. In this survey we address spectrum sharing mechanisms for wireless inter-technology coexistence by means of a technology circle that incorporates in a unified, system-level view the technical and non-technical aspects. We thus systematically explore the spectrum sharing design space consisting of parameters at different layers. Using this framework, we present a literature review on inter-technology coexistence with a focus on wireless technologies with equal spectrum access rights, i.e. (i) primary/primary, (ii) secondary/secondary, and (iii) technologies operating in a spectrum commons. Moreover, we reflect on our literature review to identify possible spectrum sharing design solutions and performance evaluation approaches useful for future coexistence cases. Finally, we discuss spectrum sharing design challenges and suggest future research directions