Joint Phy and Mac Optimization for Wireless Scheduling

This dissertation studies wireless scheduling by jointly optimizing the physical (PHY) layer and the medium-access-control (MAC) layer. It consists of the following three main thrusts. In the first thrust, rate optimization for multicast communications at the medium access control (MAC) layer is studied. For Threshold-T based multicast policies, the transmission rates are optimized to maximize the throughput in stable networks and in saturated networks, respectively. To ensure multicast reliability when no retransmission is required at the MAC layer, transport layer erasure coding is used for reliability enhancement. The second thrust focuses on distributed opportunistic scheduling (DOS) for throughput maximization in wireless ad hoc networks based on random access. In such networks, DOS involves a process of joint channel probing and distributed scheduling. The desired tradeoff, between the throughput gain from better channel conditions and the cost for further channel probing, boils down to judiciously choosing the optimal stopping policy for channel probing. First, the collision model is assumed for random access, and the optimal scheduling policy is characterized from two perspectives: 1) For the network-centric case, it is shown that the optimal DOS is a pure threshold policy. 2) For the user-centric case, the problem of threshold selection is treated as a non-cooperative game, and the existence and the uniqueness of Nash equilibrium is explored. Since there is an efficiency loss at the Nash equilibrium, a pricing-based scheme is proposed to mitigate the loss. The study on distributed opportunistic scheduling is also generalized to the network models with multiple-input-multiple-output (MIMO) links and imperfect channel estimation. Next, DOS under the PHY-interference model is characterized. Different from the