A variable-length burst scheduling algorithm (VLBS) for downlink traffic in IEEE 802.16m OFDMA systems

In IEEE 802.16m networks, each frame is divided into eight advanced air interface (AAI) subframes, composed of Logical Resource Units (LRUs). According to stations´ requirements, advanced base stations (ABSs) allocate bursts constructed by contiguous LRUs to stations. If ABSs can not efficiently schedule and allocate bursts, bandwidth resource will be wasted in or among bursts. Such these problems are called internal fragmentation and external fragmentation in this paper. In this study, this paper formulates a downlink burst allocation problem, considering both internal fragmentation (IF) and external fragmentation (EF), and then proposes a variable-length burst scheduling algorithm, called VLBS, to determine the position and the number of required LRUs of each burst in the downlink (DL) AAI subframe, subject to minimizing the bandwidth wastage. Moreover, VLBS also tries to allocate bursts across several AAI subframes so that the bandwidth wastage can further be decreased. Simulation results show that VLBS outperforms other related approaches in the network throughput, service ratio, and the bandwidth utilization ratio.