Demand-Based Spectrum Trading for Opportunistic Secondary Networks With Probabilistic Channel Access Mechanism

In this paper, we consider the spectrum trading problem in dynamic spectrum access networks. The trading process takes place between one opportunistic secondary network, which tries to satisfy its Secondary Users (SUs) throughput demand, and multiple Primary Users (PUs). The secondary network coordinator distributes the SUs over the PUs' channels and assigns a certain access time for every SU to satisfy its demand for the lowest cost paid to the PUs. We propose a secondary probabilistic access mechanism to control the SUs access to the free spectrum. In this mechanism, the coordinator controls the channel access probability of each SU and thus the amount of time shares it receives. To calculate the required access probabilities, we propose a novel probabilistic channel model that captures the interaction between the SUs and the PU using discrete-time Markov chain. We model the spectrum trading under the proposed access mechanisms as optimization problems. The results show the superiority of using variable access probability channel access mechanism over the equal access mechanism in terms of cost and throughput.