Flexible-Schedule-Based TDMA Protocols for Supporting Fault-Tolerance, On-Demand TDMA Slot Transfer, and Peer-to-Peer Communication in Wireless Sensor Networks

T his thesis addresses the problem of developing protocols for wireless sensor networks that are energy-efficient, have predictable performance, and are able to adapt to topology changes and different communication (traffic) requirements. In wireless sensor networks, nodes work under severe resource constraints: limited battery power, limited communication bandwidth, limited computing power, and limited memory. Energy-efficiency and effective collision avoidance have been the primary goals of protocols designed for sensor networks. Other attributes are normally secondary. As new sophisticated applications of sensor networks emerge, the users of wireless sensor networks need end-to-end guarantees on data delivery such as predictable throughput for gathered data, fair access to the network for all data gathering nodes, and robust selfhealing of the network when sensor nodes join or leave the network, and when communication conditions change. In practice, however, it has proved difficult to achieve these guarantees because of the severe resource constraints of sensor nodes and the hostile environments in which they must operate. This thesis develops a scheduled protocol (time division multiple access, TDMA) called flexible-schedule-based TDMA Protocol (FlexiTP), to address the problem of providing end-to-end guarantees on data delivery, whilst also respecting severe resource constraints of wireless sensor networks. FlexiTP achieves this balance through a distributed, synchronised, and loose slot structure in which sensor nodes can build, modify, or extend their schedules based on their local information. In FlexiTP, it is not necessary to predetermine the number of slots required for a network. FlexiTP’s local repair scheme allows