Coverage-optimized downlink scheduling design for wireless systems with multiple antennas

It is well-known that wireless scheduling algorithm could exploit multi-user diversity to enhance the network capacity of wireless systems. However, the advantage of scheduling with respect to network coverage is a relatively unexplored topic and it is the focus of this paper to study optimal scheduler design with respect to network coverage. We consider a wireless system with an access point or base station equipped with n_T transmit antennas as well as K mobiles with single receive antenna. We first extend the conventional concept of coverage and proposed a utility-based coverage. We consider two examples of coverage utility functions, namely the network centric utility and the user centric utility. Based on the generalized concept of network coverage, we propose a systematic framework based on information theoretical approach and formulate the scheduling design as a mixed concave and combinatorial optimization problem. As a result, we found that multi-user selection diversity, spatial multiplexing and spatial diversity due to the n_T antennas are the major factors contributing to network coverage gain. Due to the huge search space, the complexity of the optimal algorithm is enormous. We consider a genetic-based scheduler design, which offers a reasonable complexity-performance tradeoff