Energy efficient cooperative spectrum sensing by MIMO sensors in Wireless Sensor Network

In this paper we address sensor selection problem for spectrum sensing in cognitive radio network. The limited sensor´s energy is an important issue which has attracted more attention in recent years. We propose an energy efficient cooperative spectrum sensing when Multi-Input Multi-Output (MIMO) sensors are used. Two decision techniques for combination of antennas signals were used in each sensor: hard decision and soft decision. The OR rule is used for hard decision and Selection Combining (SC) and Equal Gain Combining (EGC). In each combination scheme, the problem was the sensor selection so that the energy consumption was minimized while detection performance was satisfied. The problem was solved based on the standard convex optimization method. Simulation results show that significant energy saving is achieved in comparison with the networks using Single-Input Single-Output (SISO) sensors specifically in low Signal to Noise Ratio (SNR) regime. Among of all methods, EGC combining has the least energy consumption while satisfy desired detection performance.