Outage analysis of MIMO DF relay systems with partial Nth-best relay selection scheme in the presence of co-channel interference

The outage performance of dual-hop multiple-input multiple-output (MIMO) decode-and-forward (DF) relay network with partial N^th-best relay selection scheme is investigated. Both the relay and destination are subjected to multiple co-channel interference (CCI) and additive white Gaussian noise (AWGN). Transmit antenna selection with maximal ratio combining (TAS/MRC) is employed to obtain multi-antenna diversity. Exact and asymptotic expressions for the outage probability are derived, which are validated by the Monte Carlo simulations. Our results reveal that the diversity order is determined by the worse hop and directly proportional to the number of antennas at the relay. Specially, only the first hop diversity order is affected by the number of relays and the value of N. In addition, the interference deteriorates the outage performance by reducing the coding gain of the system. These results provide further insights into the practical system design.