Cross-layer Downlink Scheduling of Multi-user Multi-Antenna Systems with Heterogeneous Delay Constraints

Cross-layer design for multi-antenna system has been shown to offer high spectral efficiency for multiuser system due to the multi-user diversity and the spatial multiplexing in wireless fading channels. Yet, most of the existing works assumed homogeneous user type (pure delay-insensitive data application). The effect of source statistics, queueing delay and application level requirements were completely ignored. In this paper, we shall propose an analytical cross layer design framework for multi-user multi-antenna systems for wireless multimedia applications with heterogeneous delay requirements. To take delay sensitive users into consideration, we shall utilize both queueing theory and information theory to model the system dynamics. A novel cross layer scheduler is designed to exploit the spatial multiplexing gain as well as the multi-user selection diversity gain, and at the same time maintain the delay constraints of the delay sensitive users. Simulation results indicate that the proposed scheduling design provides desirable delay performance and high throughput gain compared to other heuristic schemes