| Summary: | 碩士 === 長庚大學 === 電機工程研究所 === 91 === An ad hoc network is composed of a collection of mobile nodes with no fixed infrastructure or central administration. And each mobile node acts as a router. In IEEE 802.11b standard, it supports four different data rate: 1, 2, 5.5, and 11 Mb/sec. Each level of data rate is coded in different modulation schemes. According to the characteristic of modulation scheme, a higher level modulation scheme requires higher signal to noise ratio (SNR). In general, the SNR value decreases when transmission distance becomes larger. And this characteristic forms a multi-range wireless networks for multi-rate transmission. But, all the existing multicast routing protocols only use fixed data rate (e.g., 1 or 2 Mb/sec) to transfer data. If we can take advantage of higher data rate to transfer data, we can reduce the time spent for transferring data. And then, there will be more channel resource time been released. At the same time, we can also obtain less end-to-end delay. In this paper, we propose an efficient multi-rate/multi-range multicast routing protocol (M3RP). It constructs a multicast tree with multiple data rates that has lower network channel resource consumption and smaller end-to-end delay from the multicast source to the multicast receivers. Simulation results show that M3RP performs much better in high traffic load than conventional minimum-hops approach with fixed data rate.
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