Performance analysis of interference-limited cooperative systems with relay selection over independent log-normal fading channels

Closed-form expressions of the upper and lower bounds of the outage probability are derived for interference-limited dual-hop decode-and-forward and channel-state-information-assisted amplify-and-forward relay systems using three relay selection (RS) schemes [optimal source-relay link (OSRL) scheme, optimal relay-destination link (ORDL) scheme and optimal source-relay-destination link (OSRDL) scheme] over independent log-normal fading channels. Multiple interferers at both relay and destination are considered. The diversity order of the targeted cooperative system under the three different RS schemes is analysed. The analysis shows that the asymptotic relative diversity orders (ARDO) for OSRL, ORDL and OSRDL schemes are 2, 2 and (N + 1) (where N is the number of the relay candidates), respectively. Finally, the ARDO is verified by simulation results.