On Joint Maximization in Energy and Spectral Efficiency in Cooperative Cognitive Radio Networks

Abstract

Cognitive radio networks (CRNs) look promising to mitigate the spectrum underutilization problem by providing an opportunistic communication of secondary users (SUs) over the licensed or primary user (PU) band through spectrum sensing (SS). This leads to an increase in spectral efficiency (SE) of the network. Cooperative CRN (CCRN) not only enables fast and reliable SS over the spectrum band of PU but also improves the secondary throughput by means of power saving operation of the cooperative relay (secondary) nodes. This in turn leads to an increase in the overall energy efficiency (EE) of the system. However, simultaneous maximization of EE and SE is difficult to achieve, and there exists a trade-off which demands an efficient solution for maximizing this bi-objective problem while satisfying some other goals. This chapter addresses a joint SE–EE optimization problem in a single SU and PU network under the constraints of sensing reliability, cooperative SE for primary network, and transmission power constraints. Differential evolution (DE) is explored to handle this nonlinear optimization problem and finds the optimal set of values for the sensing duration, cooperation, and transmission power of SU. EE–SE trade-off is shown through the simulation.