—In this paper we investigate a cooperative mobile network with respect to error performance. Power allocation is applied between source and relay. The relay cooperates after having received a request from the destination which decides upon successful or non-successful transmission based on a threshold criterion. We show that with respect to the relay’s location a suitable power allocation technique can increase performance enormously. Our results reveal that a practical implementation strategy for cooperative networks first proposed in [1] can easily be adopted to cognitive networks where a relay senses its environment for feedback signals from the destination. Depending on the applied services, however, it may be beneficial to always cooperate, since this creates spatial diversity at the destination.