Research on a Markov Chain Based CSMA/CA Communication Mechanism of Wireless Sensor Network for High-Speed Railway Catenary

The catenary is the key subsystem of a high-speed railway (HSR), and the wireless sensors network (WSN) used for catenary monitoring is very important for the safe operation and maintenance of HSR. In order to ensure the real-time and reliable performance of key sensor nodes, an improved Markov chain-based CSMA/CA communication mechanism was proposed. A Markov model for this mechanism was built based on a multipriority scheme. Then, the Markov model was used to analyze the accessing probability, channel occupancy, and transmission success rate of nodes with different priorities, and its feasibility was verified. Finally, a test platform for the WSNs of HSR catenary was established, and the intrinsic relationship between the backoff exponent (BE) and the number of backoffs (NBs) in CSMA/CA, failure probability, and average delay and throughput was studied. The experimental results showed that this mechanism achieved service differentiation, improved the communication quality of key sensor nodes, reduced the overall network delay, increased the throughput, and provided a favorable foundation for improving the performance of HSR catenary WSNs.