Effects and Implications of Beacon Collisions in Co-Located IEEE 802.15.4 Networks

Beacon-synchronized operation allows wireless networks to operate very efficiently, in particular focusing on energy requirements. It is, however, unclear, to what extend this beacon-based synchronization suffers in case of independently operating networks with overlapping communication ranges. We study the effects and implications of beacon collisions in co-located IEEE 802.15.4 networks. This protocol has become the de-facto standard in many areas of wireless communications including wireless sensor and body area networks, but also in industrial network domains. IEEE 802.15.4 defines a node synchronization strategy using beacons for achieving robust and real-time capable low energy communication. Nonetheless, collisions are inevitable as some packets, e.g., the synchronization beacons indicating the start of a new superframe, are sent without carrier sensing. Consequently, co-located networks may substantially suffer from beacon collisions. In an extensive set of simulation experiments of co-located networks, we found that the number of lost beacons is independent of the amount of superframe overlap, but is a major cause of performance degradations.