Quality of Service Supports in Multihop Wireless Local Area Networks

• Main Authors: Ming-Hung Tao, 陶明宏
• Other Authors: Sheng-Tzong Cheng
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/98351986722441982568

博士 === 國立成功大學 === 資訊工程學系碩博士班 === 95 === Since the demand for the wireless transmission of real-time services has been growing significantly in recent years, Quality of Service (QoS) becomes a very important issue in the design of network protocols. However, it is not trivial to design a good Medium Access Control (MAC) protocol which provides real-time services large amounts of bandwidth and also supports multihop transmission, since wireless channel suffers much interference and unpredictable problems. In this dissertation, we analyze the performance of the existing wireless MAC protocols, and propose a framework which provides QoS supports and multihop transmission ability for Wireless Local Area Networks (WLANs). This framework consists of a centralized scheduling-based MAC protocol, a multihop mechanism, and a delay-sensitive fair queueing model. The scheduling-based MAC protocol contains a slot-scheduling algorithm and a QoS enhanced admission control algorithm. The slot-scheduling algorithm is designed to efficiently utilize the network bandwidth and fairly schedule the transmission for various services while the QoS-enhanced admission control algorithm is designed to manage resources and guarantee the QoS requirements of services. The multihop mechanism that eliminates the restriction on single-hop transmission for centralized MAC protocols and alleviates the hidden terminal problem can be adapted to various protocols and network topologies. Moreover, to ensure that the services in relay stations meet their QoS requirements, the delay-sensitive fair queueing model is proposed for highly variant multihop WLANs. This queueing model slows down the growth of queue length for real-time services, still maintains the property of fairness, and guarantees the throughputs of stations. This dissertation also provides experimental and analytical models for the proposed protocols, mechanisms and algorithms. With these models, the correctness and feasibility of our framework can be verified. Based on the achievements in this dissertation, the QoS issue in the multihop WLAN can be easily addressed.