Resource efficient cooperative wireless system
QI Li-juan · Journal of Xidian University · 2009
An adaptive cooperative wireless communication system based on quadrature signaling is proposed,in which each user can transmit its own and the partner's information simultaneously in the in-phase and quadrature components of a two-dimension modulated signal.The virtual multiple-antenna transmitter generated in this way allows each user to achieve transmit diversity in a distributed fashion,without expanding the bandwidth and boosting the transmit power.With the decode-and-forward(DF) relay channel model,a closed-form bit error rate(BER) performance expression is derived,and then the effect of different power allocation algorithms together with various inter-user and uplink channel qualities on the system performance is investigated.Simulation results show that the proposed system,with an equal power allocation algorithm,provides diversity gains and can achieve a full diversity order at high inter-user channel signal-to-noise ratios(SNRs).Furthermore,additional performance benefits can be obtained by employing an optimum power allocation algorithm.