| Wireless Mesh Network (WMN), a static multi-hop wireless network that connecting routers and terminal devices with wireless links, is a type of broadband wireless access systems. WMN is a combination of WLAN and mobile Ad hoc network with the characteristics of reliability, self-organization and self-healing. In recent years, multimedia applications become more and more popular, and WMN are widely used in commercial environments. Therefore, it is crucial for WMN to support Quality-of-Service (QoS). However, some distinct characteristics of WMN, such as the multi-hop, distribution, self-organization and mobility, significantly impact the performance, and make it very difficult to provide effective QoS guarantee. Since MAC protocol is in charge of allocating wireless channel, design a efficient MAC protocols for WMN are gaining significant attention.Based on the analysis of conceptions, architectures, key technologies and the existing MAC protocols of WMNs, this thesis focuses on multi-channel MAC protocols design of WMN. Firstly, a single-channel MAC protocol 802.11 DCF is introduced, then DCA, MMAC and SSCH in single-transceiver multi-channel MAC protocols, as well as MUP, DCA and PCAM in multi-radio MAC protocols are described. After comparing the performances of each protocol, summarizing their merits and drawbacks, this thesis propose a new multi-channel priority MAC protocol (MPMAC) which enables hosts to dynamically negotiate channels so that multiple communications can take place in the same region simultaneously, each in different channel. Also, our protocol can guarantee flows with high priority access channel preferentially. Through our elaborate analysis and simulation, we can prove our approach can increase the throughput and decrease the delay greatly comparing to IEEE 802.11 and MMAC. |
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