802.11a/b/g多模無線網狀網路之系統最佳化分析

Abstract

The wireless mesh network (WMN) is designed as an economical solution for last-mile broadband Internet access. Some commercial applications have emerged, such as “community wireless networks”. These WMNs offer increased reliability, coverage and reduced infrastructure costs over their single-hop counterpart, namely wireless LANs. Providing broadband access to Internet is their major objective. Equipping mesh nodes with multiple radios can further improves the network capacity by transmitting over multiple radios simultaneously using orthogonal channels. Efficient channel assignment and routing are essential to capture the benefits of them. However, most previous studies only focus on heuristic approaches. In this thesis, our objective is to investigate the capacity region of 802.11 based multi-radio multi-channel wireless mesh networks for network designers to plan network deployment. First, we present a network model which captures the characteristics of 802.11 MAC mechanism and 802.11 a/b/g multi-mode radio, including RTS/CTS/DATA/ACK handshake, wireless interference, adaptive data rates, orthogonal channels, multi-mode radios, and evaluate the performance. Then, we formulate the problem as a linear programing (LP) in wireless mesh networks with 802.11 a/b/g multi-mode radios. And we evaluate the performance in the three different topologies to analyze the affects of each parameter. Finally, we extend our formulation and discuss the impact of gateway placement, wired bandwidth limitation and fairness schemes on the performance of wireless mesh networks. Our work can be used for planning of wireless mesh networks with respect to the performance trade-offs of different important deployment parameters.