UTILITY BASED CHANNEL AWARE MIMO DOWNLINK SCHEDULING IN IEEE 802.16 BROADBAND WIRELESS SYSTEM

One of the basic approaches for providing the QoS guarantees in IEEE 802.16 is the uplink and downlink scheduling at the base station (BS). To maximize usage of available resources and take advantage of the varying channel condition at the subscriber stations (SSs), adaptive and dynamic scheduling techniques are typically used. In this paper, we propose a new adaptive resource allocation and scheduling scheme for real-time downlink traffic in a single cell MIMO-based IEEE 802.16 broadband wireless system. Our scheme is a cross-layer approach, which improves system performance in terms of increasing system throughput and provides better quality of service for users in terms of reducing Head of Line (HOL) packet delays. We use a utility based framework to provide the link between physical and data link layers. In this architecture a new utility function is used that accounts for channel conditions, and users requirements. To improve throughput, adaptive modulation and coding (AMC) at the physical layer is used. We provide simulation results comparing our proposal with different schemes. The simulation results illustrate the superiority of our scheme for different channel conditions and different numbers of active users in the system in addition to its ability to serve multiple traffic classes providing good differentiation to traffic with lower maximum allowed delay.