A Study on Channel Sharing for Congestion Control in WSN MAC Protocols

Congestion control in Wireless Sensor Networks (WSNs) has been an area of interest for researchers for ensuring timely delivery of data. A number of Multi-channel MAC protocols have been proposed which guarantee parallel and collision free transmissions. This article proposes to evaluate an existing congestion control scheme that was developed for multi-channel WSN MAC protocols dealing with traffic of different priorities. The existing scheme proposed prioritized channel sharing mechanism for nodes based on the Received Signal Strength (RSS) of each priority. The authors analyze the performance of the proposed scheme by comparing it with other channel sharing mechanisms. Four cases of hybrid channel sharing mechanisms, namely complete partitioning, complete sharing, partial sharing and prioritized sharing have been studied in this work for 2 traffic priorities. The authors have modeled the schemes for WSN applications where each node may have traffic of different priorities. Major objective of the article is to facilitate the high-priority traffic, while efficiently maintaining the network utilization through reducing the number of idle channels. The analytical model has been developed using 2-dimensional Continuous Time Markov Chains (CTMC), and MATLAB has been used for the implementation. Complete sharing and Prioritized sharing are found to be the most efficient channel sharing schemes based on the network utilization and total throughput.