Dynamic performance analysis of IEEE 802.15.4 networks under intermittent Wi-Fi interference

A ZigBee (802.15.4) lighting network is potentially vulnerable to interference by other wireless technologies that operate in the same Industrial, Scientific and Medical (ISM) frequency band, such as Wi-Fi (802.11). Therefore the study of coexistence between IEEE 802.15.4 and IEEE 802.11/Wi-Fi is becoming more relevant than ever. In this area, literature approaches to the co-existence issue currently fall into two main categories: experimental or simulation results and analytical models which are either asymptotic (e.g., using Bianchi's assumption) and/or stationary. In contrast, in this paper we present an analytical framework in which a comprehensive study of the dynamic influence of Wi-Fi interference on ZigBee networks of arbitrary size becomes possible. We first present an application of mean field approximation to an intractable Markov model of ZigBee networks. We use this modeling approach to investigate the effect of the Wi-Fi traffic pattern on the ZigBee network performance. By taking this dynamic interaction into account, we notice major performance differences depending on the type of traffic. It also reveals that even light traffic patterns, that offer long gaps of inactivity, can hamper the ZigBee performance significantly more than previously reported Wi-Fi coexistence studies suggest.