Relay-based throughput maximization in multiple antennas cognitive radio networks

Cognitive radio is a promising technology that solves the problem of spectrum scarcity. A major challenge in cognitive radio is how to increase secondary throughput without interfering the primary user transmissions. In this paper, the effect of using multiple antennas at the relay is studied, and an optimal power allocation strategy is used to maximize the secondary throughput under power constraints by simply seeking an optimum value of the relay amplification factor. The analysis of the system is performed and simulation results show that there is an optimum value of the relay amplification factor at which the secondary throughput is maximized. Compared to using single antenna, the results show that using multiple antennas at the relay network increases the maximum achievable throughput and also improves the detection capability.