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数据网络技术论文报告. Routing in Ad Hoc Networks: A Case for Long Hops Martin Haenggi and Daniele Puccinelli University of Notre Dame Reporter : juan yang. Background.
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数据网络技术论文报告 Routing in Ad Hoc Networks: A Case for Long Hops Martin Haenggi and Daniele Puccinelli University of Notre Dame Reporter:juan yang
Background • For multi-hop wireless networks, a fundamental question is whether it is advantageous to route over many short hops (short-hop routing) or over a smaller number of longer hops (long-hop routing) • While,short-hop routing has gained a lot of support, and its proponents mainly produce two arguments: • reduced energy consumption • higher signal-to-interference ratios
Questions of short-hop routing • Reduced energy consumption neglects • delay • end-to-end reliability • bias power consumption • Higher signal-to-interference ratios does not consider • the total duration of multi-hop communication and delay • the inherent loss
Solution For many networks, long-hop routing is in every aspect a very competitive strategy In this article authorsshed more light on these issues by listing 18 reasons why short-hop routing is not as beneficial as it seems to be.
Reasons listed Interference、the end-to-end reliability、Shannon capacity、Channel coding、Total energy consumption、Path efficiency、Sleep modes、Cooperation、Routing overhead and Routing maintenance、Link longevity in mobile environments、Traffic accumulation and energy balanced、Variance in hop length in random networks、Bounded attenuation、Opportunistic transmission、Percolation and connectivity in random networks、Delay variance、Multipath routing、Multicast advantage
The end-to-end reliability The smaller the number of hops, the less likely this is to happen.
Total energy consumption reducing the output power does very little to save energy, and the receive power consumption is as high as the transmit power consumption.
Link longevity in mobile environments As can be seen in the ratio column, the short links suffer significantly more if the link length is increased by the same amount.
A 10-Node Experiment • The setup of network: • 10 MicaZ motes • 40 packets/min • over a duration of 24 h • a certain amount of fading • routing algorithm • a matric consisting of a weighted sum • Sleep modes • MAC scheme is standard CSMA/CA)
A 10-Node Experiment • Results • a packet loss of about 14 percent • Routes: 9.4 percent were single-hop 87.7 percent were two-hop 2.5 percent three-hop 0.4 percent four-hop (or more)
Results • some nodes are used as relays much more frequently than others • the depletion curves look quite similar
Comparison with short-hop routing Packets reach the BS about four times faster the network lives at least twice as long, most likely much longer. This significant gain is achieved by an algorithm that exploits sleep modes, favors long hops with favorable fading state, Aiming at energy balancing. Requiring less maintenance and are more robust to node failures In a multisource setting, would alleviate the problem of traffic accumulation around the BS.
Conclusion 18 reasons listed indicate that routing over many short hops is not as clear cut as is often assumed Routing as far as possible is a very competitive strategy in many cases