Distributed Approach for Power and Rate Allocation to Secondary Users in Cognitive Radio Networks
ABSTRACT We consider a multichannel cognitive radio network where multiple secondary users (SUs) share a single channel and where multiple channels are simultaneously used by a single SU to satisfy their rate requirements. We attempt to evaluate the optimal power and rate distribution choices that each SU has to make to maintain their quality of service (QoS). Our measures for QoS include bit error rate (BER) and minimum rate requirement. We design a QoS-constrained bi-objective optimization problem with the objective of minimizing transmit power and maximizing rate. Unlike prior efforts, we transform the BER constraint into a convex constraint to guarantee optimality of the resulting solution. Our interest in this paper is to develop a user-based distributed approach to solve the optimization problem and compare the solution with the centralized approach. We employ dual decomposition theory to derive three different formulations of the distributed problem. Simulation results demonstrate that optimal transmit power follows the “reverse water filling” process and that rate allocation follows signal-to-interference-plus-noise ratio (SINR). We show that the solutions from the distributed formulations follow the centralized solution.
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ABSTRACT: Cognitive radio (CR) networks have attracted many attentions recently, while the security issues are not fully studied yet. In this paper, we propose a new and powerful network layer attack, routing-toward-primary-user (RPU) attack in CR networks. In this attack, malicious nodes intentionally route a large amount of packets toward the primary users (PUs), aiming to cause interference to the PUs and to increase delay in the data transmission among the secondary users. In the RPU attack, it is difficult to detect the malicious nodes since the malicious nodes may claim that those nodes, to which they forward the packets, behave dishonestly and cause problems in the data transmission. To defend against this attack without introducing high complexity, we develop a defense strategy using belief propagation. First, an initial route is found from the source to the destination. Each node keeps a table recording the feedbacks from the other nodes on the route, exchanges feedback information and computes beliefs. Finally, the source node can detect the malicious nodes based on the final belief values. Simulation results show that the proposed defense strategy against the RPU attack is effective and efficient in terms of significant reduction in the delay and interference caused by the RPU attack.IEEE Transactions on Mobile Computing 09/2013; 12(9):1750-1760. DOI:10.1109/TMC.2012.137 · 2.91 Impact Factor
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ABSTRACT: This article proposes a joint power control, rate adaptation and channel selection strategy for Cognitive Radio Networks (CRNs) operating over vacant TV bands, also known as TV Bands Devices (TVBDs). To exploit the abundance of vacant channels available at the disposal of these devices, we combine the well-studied power and rate adaptation strategies with adaptive channel selection. The combined strategy maximizes the achievable throughput while guaranteeing a desired level of performance, i.e., error and outage probabilities. It also reduces the chances of causing or being subject to harmful interference to/from other co-channel users. Furthermore, to waive the processing complexity resulting from the frequent channel switching, we propose an alternative strategy that switches the operating channel only when the operating channel fails to support the least supportable data rate. For the two strategies, we derive closed form expressions for the average data rates and transmission powers. The accuracy of the derived results as well as the performance gains achieved are verified using intensive numerical and simulations results.Global Communications Conference (GLOBECOM), 2012 IEEE; 01/2012
Conference Paper: A survey on security in Cognitive Radio networks[Show abstract] [Hide abstract]
ABSTRACT: Cognitive radio (CR) has been introduced to accommodate the steady increment in the spectrum demand. In CR networks, unlicensed users, which are referred to as secondary users (SUs), are allowed to dynamically access the frequency bands when licensed users which are referred to as primary users (PUs) are inactive. One important technical area that has received little attention to date in the cognitive radio system is wireless security. New classes of security threats and challenges have been introduced in the cognitive radio systems, and providing strong security may prove to be the most difficult aspect of making cognitive radio a long-term commercially-viable concept. This paper addresses the main challenges, security attacks and their mitigation techniques in cognitive radio networks. The attacks showed are organized based on the protocol layer that an attack is operating on.2014 6th International Conference on Computer Science and Information Technology (CSIT); 03/2014