Optimized Quantized Feedback in a Multiuser System Employing CDF Based Scheduling

In this paper, we show that optimizing the feedback strategy in a limited feedback multiuser system can significantly improve system performance. Herein, we consider a limited feedback multiuser system, in which the fairness among users are guaranteed by the application of the cumulative distribution function (CDF) based scheduling technique. As the users are diverse in types, priorities and channel statistics, adjusting feedback strategy as well as dynamically distributing feedback resources among the users helps the system to exploit multiuser diversity gain. The system performance optimization is formulated in which we consider feedback as a resource to optimize. Then, the optimization is decoupled into two sub-problems, namely optimization of quantizers and allocation of feedback bits for the users. Optimizing feedback usage is shown to be significantly beneficial, both analytically and with the help of simulation results. Finally, in order to address the practical aspect, we propose an algorithm to efficiently solve these two sub-problems in an optimal manner followed by a low complexity sub-optimal approach which offers good tradeoff between complexity and performance.