Abstract: The node moving trajectorypredicting mechanism was introduced into expected transmission count(ETX)routing metric， which worked before the ETX metrics was in operation. An auto regressive integrated moving average(ARIMA)model was developed using the historical and current location information of a node， by which the location of nodes at next time was predicted， thus the trajectory of nodes was obtained. According to the predicted results， ETX could be used for routing metric if the distance between two nodes of a link was less than the communication radius， otherwise the link was discarded. The simulation results showed that the links with high packet loss rates were selected less and the frequency of the routing interruption were reduced due to the introduction of the prediction mechanism which increased the average throughput of a network with the packet loss rate dropped.

Key words: ETX metric, ARIMA model, moving trajectory prediction, DSDV protocol, ad hoc network