Relay and antenna selection for cooperative communication

This thesis investigates the effectiveness of relay selection and antenna selection for cooperative wireless communication networks. Analytical expressions are derived for the outage probability and error rates, followed by verification through computer simulation. First, two relay selection schemes are considered. A new relay selection scheme is proposed (Distributed switch-and-examine combining with threshold-based relaying; DSEC-T) and lower bounds of the outage probability and symbol error rate are derived assuming Rayleigh fading channels. Then the performance improvements that can be achieved by partial relay selection in mixed Rayleigh and Rician fading environment are investigated by deriving expressions for the outage probability and bit error rate. Both relay selection schemes considerably decrease the outage probability and error rates while reducing the system complexity. Next the performance of a dual-hop multiple antenna relay network is investigated when the relay is subject to interference. In this network, the source and the destination consist of multiple antennas while the number of antennas at the relay is limited to one. Transmit antenna selection at the source is coupled with maximal ratio combining, equal gain combining or selection combining at the destination. The outage probability of this network is investigated assuming Rayleigh fading channels. In dual-hop systems, it is shown that the impact of interference can be lowered by increasing the number of antennas at the source and the destination. Finally the performance of a fixed relay (infrastructure relay) network is analyzed. In this network, the relay consists of two receive antennas and performs switch-and-stay combining with threshold-based relaying. Lower bounds of the outage probability and symbol error rate for a range of modulation schemes are derived assuming Rayleigh fading channels. It is found that, the switch-and-stay antenna selection scheme considerably reduces the outage probability and symbol error rate while maintaining the complexity at a tractable level