Multi-channel TDMA Scheduling in Wireless Sensor Networks.

In wireless sensor networks (WSNs) that use TDMA-based scheduled channel access, spatial re-use of time-slots is possible among a non-conflicting set of nodes. In this way, data gathering delays can be reduced and aggregate network throughput can be increased. Besides spatial re-use, available multiple channels, which is already an available feature in some sensor node platforms, can be utilized to increase concurrency and minimize the number of time-slots required for a round of communication. In this paper, we propose TDMA-based scheduling algorithms for multi-channel wireless sensor networks. By redefining the conflicts in a multi-channel environment, we extend two existing single-channel TDMA scheduling algorithms into multi-channel structure. We also present two channel assignment schemes (called NCA and LCA) appropriate to use with the extended multi-channel scheduling algorithms. We evaluate our proposed schemes by extensive simulation experiments and compare them with other single-channel and multichannel algorithms from literature. The results show that in large networks our proposed algorithms can provide better performance, more concurrency, and up to 50% less delay compared to other methods.