A Fair Subcarrier Allocation Algorithm for Cooperative Multiuser OFDM Systems with Grouped Users

Dynamic resource allocation improves the performance of multiuser OFDM systems by exploiting multiuser diversity. Cooperative diversity is a technique where multiple users share their resources to realize a spatial diversity gain through cooperation. In this paper, the problem of downlink subcarrier allocation in a cooperative multiuser system is investigated. We assume a single-cell case where the base station has perfect knowledge of subchannel gains and all the mobile users are paired in cooperative groups. The mobile users in one cooperative group relay their partner data stream which is received from base station using a time division protocol. Based on the capacity contribution from the relaying terminal, a new parameter called cooperation coefficient is introduced. Considering the cooperation among users in assigning the subcarriers, a new subcarrier allocation algorithm is proposed. The performance of the proposed algorithm is then evaluated for different values of cooperation coefficients and is shown to maintain the same level of fairness but higher data rates compared with a similar algorithm which does not consider cooperation.