科研之友
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摘要
Cognitive radio technology enables Secondary Users (SUs) to access the frequency channels licensed to Primary Users. In this paper, we propose a novel dynamic multichannel access scheme for cognitive radio systems, which are based on a multichannel variation of a p-persistent Carrier Sensing Multiple Access scheme. To optimize the system-wide performance, the proposed scheme exploits different gains of frequency channels due to frequency-selective fading. With the proposed scheme, SUs share frequency channels in a fully distributed way, without any explicit control information exchange. To design the proposed scheme, we formulate the whole system as a "channel access game," according to game-theoretic framework. In the channel access game, the utility function should reflect the system-wide performance. We derive closed-form performance measures by modelling the system as a continuous time Markov chain, and use them to construct a proper utility function. Then, each SU independently decides its own channel access strategy (i.e., the distribution of the random backoff time) which optimizes the utility function. The simulation results show that the proposed scheme promotes SUs to compete and cooperate with each other to a suitable level and, as a result, performs well in all range of SU population.
- 出版日期2013-5
