Outage analysis for uplink mobile-to-mobile cooperation

We consider the uplink transmission over Rayleigh fading channels of two mobiles cooperating to send their information to a base station. We propose a cooperative transmission scheme, derive its achievable rate region and analyze its outage performance. By dividing each transmission block into 3 phases with variable durations, the two mobiles partially exchange their information in the first two phases, then cooperatively transmit to the base station in the third phase. Assuming full CSI at the receivers and limited CSI at the transmitters, we formulate the common and individual outage probabilities for the proposed cooperative scheme. Numerical results show that, in spite of additional outages at the mobiles, cooperation reduces the overall outage probability and achieves the full diversity order of 2, which makes mobile-to-mobile cooperation appealing for next generation cellular systems.