Two novel schemes for opportunistic multi-access

We study opportunistic multiuser communications, and propose two novel schemes to address scheduling in asymmetric channels and admission control in such systems, respectively. We first device a relay-aided multiuser diversity (RAMD) scheme, in which a user can choose to communicate with the base station either directly or using relay transmission. We show that the RAMD scheme performs significantly better than Qualcomm\´s HDR scheme. Next, we propose a traffic-aided "smooth" admission control (SAC) scheme that guarantees the quality-of-service (QoS) provisioning. Specifically, building on the weighted proportional fair (WPF) scheduling, we devise a QoS driven weight adaptation algorithm. The weights assigned to new users are increased in a guarded manner. An admission decision is made based on the measured throughput within a time-out window. Our results show that the SAC scheme works well in opportunistic communication systems.