Parallel multiplexing scheduling in DAS with partial channel state information

Transmit diversity (TD) is an efficient method to yield channel capacity in single-user multi-antenna system. In this paper, we first analyze scheduling based on TD in multi-user distributed antenna systems (DAS). We show that average throughput of the system grows with the total number of remote access units (RAUs) in DAS. However, when the total number of RAUs is constant, TD has little improvement to average throughput. Then, parallel multiplexing scheduling (PMS) is proposed based on multi-user multiplexing in spatial domain to improve average throughput of DAS. In PMS, multiple users are selected to transmit simultaneously at each slot rather than only one user occupies all channel resources in scheduling based on TD. Thus PMS achieves a better performance than scheduling based on TD does. Finally, an optimized PMS (OPMS) scheme is presented, in which all users are classified as multiple scheduling user groups (SUGs), and then parallel scheduling is implemented among the SUGs. OPMS inherits all characteristics of PMS but only partial channel state information (CSI) is fed back to base station (BS).