Cross-Layer Scheduling for Multiuser Downlink Transmissions with Opportunistic Relaying

Joint channel-aware and queue-aware scheduling has been studied widely for direct downlink transmission in cellular networks. In this paper, we combine this cross-layer scheduling concept with opportunistic relaying for slotted multiuser packet transmissions. Cooperative relaying can bring additional degree of freedom, resulting in the system performance improvement in terms of throughput and fairness. Specifically, we propose two scheduling algorithms for selecting the destination user and its assistant user based on the instantaneous channel information and buffer status. Through simulation, we show that the proposed algorithms expand the system stable load region and reduce the average delay while improving the fairness among users with heterogeneous channel conditions compared to conventional schemes.