Study on superframe adjustment for cluster tree in wireless sensor networks

The personal area network (PAN) coordinator periodically transmits beacon frames to coordinator nodes as well as the coordinator nodes periodically transmit beacon frames to device nodes in the cluster tree topology of IEEE 802.15.4. The challenge in cluster tree network is the collisions between beacons or even between beacon and data frames, which degrades the network performance. In order to improve the collisions, this paper proposes the superframe adjustment and beacon transmission scheme (SABTS) by assigning the accurate values of beacon order and superframe order for PAN coordinator, cluster coordinators and device nodes, and deciding the precise time for beacon transmission of PAN and coordinator nodes. A Markov chain model for cluster tree network is developed with taking into account packet retransmission, acknowledgement, and defer transmission. Both analytical and simulation results present that SABTS performs better than IEEE 802.15.4 standard in terms of the probability of successful transmission, network goodput, and energy consumption.