Scheduling fairness of real-time scheduling algorithms in wireless multimedia application

This paper investigates the fairness of different scheduling algorithms for real-time multimedia applications over wireless shared link. We evaluate the scheduling fairness, which usually concerns with packet delay or throughput in existing literatures, by jointly considering traffic packet delay, packet drop rate and throughput requirements. An analytical model based on probability, statistics and random processes is presented to derive the allocated scheduling opportunities from algorithms' priority functions. Through study of two classical real-time scheduling algorithms: Modified largest weighted delay first (MLWDF) and Exponential rule (Exp), it is found that these two algorithms provide limited scheduling fairness in typical voice and video applications. Therefore, a Modified exponential rule (MExp) is proposed to enhance the scheduling fairness by timely scheduling and optimal design of scheduling priority function. Numerical results show that the MExp outperforms the two baseline algorithms in system outage capacity and. throughput.