Cross-layer MAC scheduling for multiple antenna systems

In this paper, we present a unified view of both, PHY and MAC layer visions for a multiple input multiple output (MIMO) multiple access channel. First, we evaluate the impact in terms of throughput of a MAC scheduling strategy, based on throughput maximization and compare it with a PHY scheduling strategy based on capacity maximization. Second, a MAC scheduler with QoS requirements is presented. The particularity of such a MAC scheduler is that it combines PHY level instantaneous optimization with MAC level average maximization. We present mathematical expressions to evaluate the schedulers. We also present our design as an extension of the multiuser diversity scheduler for the multi-user detector case.