Adaptive scheduling for MIMO wireless networks:: Cross-layer approach and application to HSDPA

In this paper, we consider the scheduling problem in multiple-input multiple-output (MIMO) wireless networks. The main important characteristic of an optimal scheduler is to maximize throughput while servicing users in a fair manner. Herein, we formulate MIMO scheduling as a Generalized Assignment Problem (GAP) and propose a general solution for the GAP, namely, a Cross-Layer MIMO scheduler (CMS), which uses a novel Adaptive Proportional Fairness (APF) mapping approach in conjunction with a new Fast Transmit Antenna Selection (FTAS) technique, to determine the set of users to transmit to and the antenna over which the data associated to each user should be transmitted. The proposed scheduler is applied for packet transmission in High-Speed Downlink Packet Access (HSDPA), taking advantage of the use of adaptive modulation and coding while coping with the constraints on the maximum number of simultaneous codes a user equipment can support, the limited uplink signalling, and the absence of fast power control. Numerical results show that the proposed CMS provides up to 70% increase in total throughput compared to other scheduling schemes.