In this paper, we investigate the outage and error performances of a full duplex relaying cooperative system in a multicell environment, considering the possibility of co‐channel interference from the users located in the nearby cells. The decode‐and‐forward cooperative strategy is assumed at the relay. Throughout the analysis, we consider all the channels to be independent but not necessarily identically distributed as generalised Nakagami‐m fading. We find an accurate closed‐form expression of outage probability and average symbol error rate for integer values of fading parameter m. The analysis considers symmetric M‐ary phase shift keying modulation scheme with equal energy constellation. Copyright © 2014 John Wiley & Sons, Ltd.