Reliability through frequency diversity: why channel hopping makes sense

Wireless sensor networks (WSNs) face the challenge of en-suring end-to-end communication while operating over in-dividually unreliable wireless links. This paper addresses channel hopping, a class of frequency diverse communication protocols in which subsequent packets are sent over different frequency channels. Channel hopping combats external in-terference and persistent multipath fading, two of the main causes of failure along a communication link. This paper is, to our knowledge, the first to address the impact of channel hopping on routing. We simulate the performance of channel hopping and single channel solutions on connectivity traces gathered from a real-world officeWSN deployment. Results indicate that the most basic channel hopping pro-tocol increases connectivity along communication links, im-proving network efficiency (measured by the expected trans-mission count ETX) by 56 % and network stability (mea-sured by the average churn) by 38%. Further improvement can be achieved through the use of whitelisting – selective channel hopping over a subset of the available frequencies