Diversity-Multiplexing Tradeoff in Cooperative Multiple Access Channels

Cooperative transmission schemes can offer benefits in terms of diversity and multiplexing gain compared with conventional direct transmission by forming a virtual antenna array. In this paper, a spectrally efficient strategy is proposed for cooperative multiple access channels in a centralized communication environment with N users. With help of superposition coding, the deteriorating effect of cooperative communication on the data rate is effectively suppressed since relaying transmission does not consume extra channel use. By carefully categorizing the outage events, the diversity-multiplexing tradeoff can be obtained, which shows that the proposed strategy can achieve optimal tradeoff for multiplexing gains 0 les r les 1 whereas the compared cooperative scheme is only optimal for 0 les r les 1/N.