Diversity and multiplexing tradeoff bounds for cooperative diversity protocols

We consider a wireless network with multiple terminals (m≥2) as well as multiple receive antennas at the destination (N≥1) and obtain diversity multiplexing tradeoff upper bounds for some recently proposed cooperative diversity protocols. The results obtained show that irrespective of the coding scheme employed none of these protocols can yield a diversity order greater than N+m-1. Further, the tradeoff bounds indicate that the protocol yielding the best diversity order may change with the multiplexing gain. Using these bounds we propose a switching strategy that yields the best tradeoff bound which also significantly outperforms the optimal tradeoff curve for the baseline noncooperative system at all possible multiplexing gains.