Optimal design for dynamic spectrum access in cognitive radio networks under Rayleigh fading
Hyeon Je Cho, Ganguk Hwang · Journal of Industrial and Management Optimization · 2012
We consider a time slotted cognitive radio network under Rayleighfading where multiple secondary users (SUs) contend for spectrumusage over available primary users' channels. Weanalyze the performance of a channel access policy where each SU stochasticallydetermines whether to access a wireless channel or not based on agiven access probability. In the analysis, we focus on the queueing performance ofan arbitrary SU with the channel access policy.To improve the queueing performance of SUs, theaccess probability in our channel access policy is adapted to theknowledge on the wireless channel information, e.g., the number of available channels andthe nonfading probability of channels.It is then important to obtain the optimalaccess probabilities from the queueing performance perspective. In this paper we consider three scenarios. In the first scenario,all SUs have full information on wireless channel status andfading channel conditions. In the second scenario, all SUs havethe information on wireless channel status but do not know theirfading channel conditions, and in the last scenario all SUs do nothave any information on wireless channel status and conditions. Foreach scenario we analyze the queueing performance of anarbitrary SU and show how to obtain the optimal accessprobabilities with the help of the effective bandwidth theory.From our analysis we provide an insight on how to design an optimalchannel access policy in each scenario. We also show how the optimal channel accesspolicies in three scenarios are related with each other. Numericalresults are provided to validate our analysis. In addition, weinvestigate the performance behaviors of the optimal channel access policies.