Buffer-Aware and Traffic-Dependent Packet Scheduling in Wireless OFDM Networks

Most current research on wireless packet scheduling assumes infinite buffer space and fixed packet length, which is impractical for real systems. In this paper, the authors propose a practical packet scheduling algorithm for wireless packet-switched OFDM systems, called buffer-aware and traffic-dependent (BATD) scheduler, which consists of two interactive parts: PHY-layer adaptive modulation and coding (AMC) technology on each subcarrier and MAC-layer opportunistic scheduling. Aiming at decreasing the buffer overflow probability while keeping the system throughput as large as possible, the scheduling decision is made based on the information of not only channel conditions but also buffer status as well as traffic characteristics. In addition, the scheduler is able to guarantee certain fairness among users by introducing the so-called "history service function". Simulation results show that under practical constraints of finite buffer space and variable packet length, the proposed algorithm outperforms traditional packet scheduling schemes significantly in terms of packet loss rate due to buffer overflow and the total system throughput.