Bandwidth Recycling in IEEE 802.16 Networks

IEEE 802.16 standard was designed to support the bandwidth demanding applications with quality of service (QoS). Bandwidth is reserved for each application to ensure the QoS. For variable bit rate (VBR) applications, however, it is difficult for the subscriber stations (SSs) to predict the amount of incoming data. To ensure the QoS guaranteed services, the SS may reserve bandwidth more than the amount of its transmitting data. As a result, the reserved bandwidth may not be fully utilized all the time. In this paper, we propose a scheme, named Bandwidth Recycling, to recycle the unused bandwidth without changing the existing bandwidth reservation. The idea of our scheme is to allow other SSs to utilize the unused bandwidth when it is available. Thus, not only the same QoS guaranteed services can be provided but also the system throughput can be improved. Mathematical analysis and simulation are used to evaluate the proposed scheme. Simulation and analysis results confirm that our proposed scheme can recycle 35 percent of unused bandwidth on average. By analyzing factors affecting the recycling performance, three scheduling algorithms are proposed to improve the overall throughput. The simulation results show that our proposed algorithm can further improve the overall throughput by 40 percent when the network is in the steady state.