Frequency hopping in IEEE 802.15.4 to mitigate IEEE 802.11 interference and fading

In this paper, we investigate the issues of initialization and deployment of wireless sensor networks (WSNs) under IEEE 802.11b/g interference and fading channels using frequency hopping (FH). We propose an FH algorithm for WSNs, which is implemented and tested with a pair of nodes employing IPv6 over low power wireless personal area networks (6LoWPAN) standard. The merits and demerits of the proposed FH scheme in WSNs are studied under strong IEEE 802.11b/g interference and frequency selective fading channels. We compare the performance results of the proposed FH scheme with those obtained by single-channel radio in WSNs, and show that FH maintains very reliable data rates in the presence of adverse conditions where the single-channel radio fails. We determine a minimum center frequency offset of channels between IEEE 802.15.4 and IEEE 802.11b/g-based networks, which guarantees the error free network operation of IEEE 802.15.4 using a single channel. We design a second FH procedure comprising only four free channels (15, 20, 25, and 26) of IEEE 802.15.4 standard, and show that in the presence of nearby IEEE 802.11b/g interference, the IEEE 802.15.4 data rate using this method is always 98% and more.