Optimum power allocation in cooperative networks

Abstract

Abstract — Cooperation among network users provides trans-mit diversity in cases where wireless transmitters, due to size and power limitation, cannot support multiple antennas. We consider cooperation between M users, where each user achieves space-time diversity by using other users ’ antennas as relays. Cooperation among users has been shown to achieve impressive gains as compared to a non-cooperative system while maintaining the same information rate, transmit power, and bandwidth [1], [2], [3], [4]. This paper formulates an optimum power allocation scheme appropriate for a cooperative network using transparent relaying. It will be shown that the proposed allocation scheme significantly outperforms the equal power allocation scheme, e.g., by up to 7 dB at a bit error rate of 10−3. The results presented here may serve as bounds for the performance assessment of sub-optimal (but practical) algorithms. I.