An analytical study of the Primary User activity pattern effect on the performance of cooperative opportunistic networks

Dynamic Spectrum access (DSA) is a promising solution to solve the spectrum scarcity problem by allowing unlicensed user (a.k.a Secondary User (SU)) to access the licensed spectrum in a way that does not harm the spectrum owner (a.k.a Primary User (PU)). The SU's performance can be further enhanced by utilizing cooperative transmission via an intermediate relay instead of using direct transmission. In this paper, we study the effect of the PU activity pattern on the performance of SU in cooperative opportunistic network. The interaction between the primary and secondary transmissions are modeled using discrete time Markov chain in cooperative and non-cooperative secondary transmissions modes. By using this model, we quantify the effect of the PU transmission pattern on the SU transmission performance. The results show that the cooperative transmission has a superior performance over the direct transmission. Moreover, the gap in the performance increases as the PU channel utilization level increases and/or the PU packets become more discontinuous.