A Novel Relay Assisted Cooperative Transmission Protocol for Wireless Multiple Access Systems

In this paper, we propose a novel spectrally efficient cooperative transmission protocol for multiple access scenarios. Different to some existing cooperative multiple access schemes, the proposed scheme can exploit the availability of relays as an extra dimension to increase reception robustness. By carefully scheduling the multiple sources and relays’ transmission, a source with a poor connection to the destination can have higher priority to obtain better help from relays. As a result, the full diversity gain can be achievable for each user although only a fraction of the all relays is scheduled to help him. An achievable diversity-multiplexing tradeoff (DMT) is developed for the proposed transmission protocol to assist performance evaluation. With a large number of relays, the DMT achieved by the proposed scheme can approximate the optimal multiple-input single-input upper bound. Both analytical and numerical results show that the proposed protocol can outperform comparative schemes in most conditions.