TDMA scheduling in wireless sensor networks

In this thesis, we address the time slot scheduling problem that arises while utilizing time division multiple access (TDMA) as the medium access control (MAC) protocol for wireless sensor networks (WSN). We first propose two algorithms: Centralized link scheduling and channel assignment algorithm, and distributed broadcast TDMA scheduling algorithm (DB-TDMA), to solve the scheduling problem. The centralized link scheduling and channel assignment algorithm allocates receiving channels to each node and allocates time slot to each link between two nodes. Prior to link scheduling algorithm, a balanced tree formation algorithm is introduced to generate a balanced tree structured network topology. Another proposed scheduling algorithm is the distributed broadcast TDMA scheduling algorithm (DB-TDMA), that allows each node to select its own time slot based on the local two-hop neighbourhood information. Here, an option to obtain either global time framing or local time framing after .We focus on reducing the message transaction between the nodes without compromising the convergence time of the algorithm. We also present an extension to the distributed broadcasts scheduling algorithm to provide multiple time slots to some nodes. Finally, we present the performance analysis of the algorithms presented in this thesis. Our experimental results show that: 1) In centralized link scheduling and channel assignment algorithm, the schedule length decreases with the increase in number of available channels. The decrease is maximum when channel availability increases from one to two. However, the decrease in schedule length becomes -less significant when channel availability is more than two; 2) The DB-TDMA and its extension provides optimal time slot schedule with low message transactions within reasonable run time; 3) The performance of DB-TDMA is observed to better than previously proposed distributed algorithms; distributed randomized TDMA scheduling (DRAND) and deterministic distributed TDMA scheduling (DDTDMA) algorithms in terms of message actions required for scheduling