WETX: A weighted expected transmission routing metric for diversity in wireless sensor networks

The expected number of transmission (ETX) metric represents the link quality for links in Wireless Sensor Networks (WSNs) that can vary for different radios. To adapt to these differences, radio diversity is a recent explored solution for wireless sensor networks. In this paper, we show that in a multi radio environment it is not enough to only choose a next hop based on link qualities as with the popular ETX metric. In such an environment, the cost of transmission and reception is radio specific, which needs to be considered when making a routing decision. Instead, we propose a scheme that explores the diversity in ETX over radios and therefore enables a node to choose an energy efficient link by considering a new metric WETX, for weighted ETX. We show by both analysis and simulation that our proposal can improve the energy consumption in a network and extend the network lifetime with up of 60%.