Energy efficiency analysis of cooperative sensing and sharing in cognitive radio networks

This paper investigates energy consumption problem in cooperative spectrum sensing and sharing in energy-constrained Cognitive Radio Networks (CRN). With the aim of the realization of green energy-saving cognitive communications, we mainly analyze energy efficiency in the process of cooperative sensing and transmission. Robust cooperative sensing technique is presented with the consideration of sensing channel SNR and reporting channel SNR. In addition, the error rates of transmission between cooperative secondary users (SUs) are also taken into account, which are more practical than traditional cooperative sensing analysis. In spectrum sharing process, an analytical expression of transmission energy consumption and an exact closed-form expression of average BER with BPSK and MQAM modulation are derived. Based on the minimization of energy consumption, optimization algorithm is presented in order to obtain the whole average BER performance with the minimum energy consumption. Optimal cooperative SU number sets are also presented under certain transmission distance constraint. Simulation results confirm our derivation. It is indicated that the analysis of cooperative sensing and sharing provides a significant way for energy saving in CRN.