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A high-throughput path metric for multi-hop wireless routing
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2003
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EngineeringWireless RoutingHigh-throughput PathEdge ComputingExpected Transmission CountNetwork RoutingComputer EngineeringRoutingNetwork AnalysisDsr Routing ProtocolsNetwork PerformanceDelay-tolerant NetworkingMulti-hop RoutingMulti-hop Wireless NetworksRouting Protocol
In multi‑hop wireless networks, routing based on minimum hop‑count often yields poor throughput because it ignores link loss, asymmetry, and interference, leading to suboptimal path selection. The study proposes the expected transmission count (ETX) metric to identify high‑throughput paths in multi‑hop wireless networks. ETX is defined as the expected total number of packet transmissions, accounting for link loss ratios, directional asymmetry, and interference, and is implemented in the DSDV and DSR routing protocols. Test‑bed measurements on a 29‑node 802.11b network show that ETX significantly outperforms minimum hop‑count, with throughput gains of two‑fold or more on longer paths.
This paper presents the expected transmission count metric (ETX), which finds high-throughput paths on multi-hop wireless networks. ETX minimizes the expected total number of packet transmissions (including retransmissions) required to successfully deliver a packet to the ultimate destination. The ETX metric incorporates the effects of link loss ratios, asymmetry in the loss ratios between the two directions of each link, and interference among the successive links of a path. In contrast, the minimum hop-count metric chooses arbitrarily among the different paths of the same minimum length, regardless of the often large differences in throughput among those paths, and ignoring the possibility that a longer path might offer higher throughput.This paper describes the design and implementation of ETX as a metric for the DSDV and DSR routing protocols, as well as modifications to DSDV and DSR which allow them to use ETX. Measurements taken from a 29-node 802.11b test-bed demonstrate the poor performance of minimum hop-count, illustrate the causes of that poor performance, and confirm that ETX improves performance. For long paths the throughput improvement is often a factor of two or more, suggesting that ETX will become more useful as networks grow larger and paths become longer.