The University of British Columbia

We analyze the performance of a fully decentralized (FD) transmit power allocation (TPA) scheme for relay-assisted cognitive-radio (CR) systems. In particular, we assume that the frequency band chosen by the CR relay network for unlicensed spectrum usage overlaps with an active primary narrowband link. The considered FD-TPA scheme maximizes the signal-to-noise-plus-interference ratio at the destination node of the CR network according to a best-effort strategy, while limiting the interference experienced by the primary receiver. Numerical performance results show substantial improvements compared to non-cooperative transmission. Moreover, the performance of the FD-TPA scheme is close to that of the optimal centralized power allocation solution.