User Cooperation Through Network Coding

Most user cooperation protocols work in a timesharing manner, where each user transmits its own message and relays for the other at different segments of a time slot. We develop a new scheme to send these messages simultaneously using network coding. We show that network coding is more tolerant to poor inter-user channels than time-sharing, and achieves a better overall performance. We generalize the scheme to a multi-user, multi-slot cooperation framework. Under this framework, we show that the network coding scheme reaps a better diversity order and provides a better effective inter-user channel than time-sharing schemes.