Relay vs. User Cooperation in Multiaccess Networks

The performance of user-cooperation in a multiaccess network is compared to that of using a wireless relay. Using the total transmit and processing power consumed at all nodes as a cost metric, the outage probabilities achieved by dynamic decode-and-forward (DDF) and amplify-and-forward (AF) are compared for the two networks. A high SNR outage analysis in conjunction with area-averaged numerical simulations is used to show that user and relay cooperation can achieve a maximum diversity of K and 2 respectively for a K-user multiaccess network under both DDF and AF. However, by accounting for the energy costs of cooperation it is shown that relay cooperation is more energy efficient than user cooperation, i.e., it achieves coding (SNR) gains that override the diversity advantage of the latter.