The Research Of ETX Metric Routing Protocol Based On Location Prediction In Ad Hoc Network

The Ad Hoc network is a wireless multihop autonomous systerm, which is centerless and self-organized. It is specialized for the dynamic topology and limited resources of the mobile node. So far, many protocols have been proposed on the topic. However, the complexity of wireless link makes the protocol hardly acquire the actual condition of the physical link. As a result, route metric is proposed to choose the best link. Now, the metric algorithm mainly includes ETX ETT WCETT and so on.The ETX of a link is the predicted number of data transmissions required to send a packet over that link, including retransmissions. The ETX of a route is the sum of the ETX for each link in the route. Each node broadcasts link probes at an average period. The two nodes of a link remember the probes they received to calculate the link delivery rate, which is used to calculate the ETX metric. This paper describes the implementation of the protocol using ETX in NS2. The link measurement at a certain frequence and a fixed period, as ETX used, can only reflect the loss rate of the network in the past period. The ETX value is a simple statistics of the loss rate which isn’t able to reflect real status of the network. In order to slove this problem, this paper proposes an ARIMA based location prediction mechanism on the basis of ETX implementation. This mechanism acts before the ETX metric taking effect and it can predict the node’s position during next interval. In this way, we can judge that whether the nodes will still be in each other’s communication coverage during next interval. Thus, the predicted result will act as the pre-condition of the ETX metric.This paper describes the implementation of location prediction based ETX(L-ETX) as a route metric for DSDV in NS2. And then compare the performance of DSDV based on L-ETX and DSDV with the changing node’s speed and packet sending rate. The simulation result shows that DSDV based on L-ETX reduces the loss rate and route failures. The throughput is also improved.