An Enhanced Analytical Model and Performance Evaluation of the IEEE 802.15.4e TSCH CA

Abstract

The Time Slotted Channel Hopping (TSCH) mechanism is created in the IEEE 802.15.4e amendment, to meet the need of Industrial Wireless Sensor Networks. It combines time slotted access and channel hopping with deterministic behavior. The mechanism offers two types of links: dedicated links and shared links. In order to reduce the probability of repeated collisions in shared links, the mechanism implemented a retransmission backoff algorithm, named TSCH Collision Avoidance (TSCH CA). In this article, we develop a two dimensional Markov chain model for the IEEE 802.15.4e TSCH CA mechanism, we take into account the deterministic behavior of this mechanism. In order to evaluate its performances, we estimate the stationary distribution of this chain. Then, we derive theoretical expressions of: collision probability, data packet loss rate, reliability, energy consumption, throughput, delay and jitter. Then, we analyze the impact of the number of devices sharing the link for a fixed network size under different traffic conditions. Finally, the accuracy of our theoretical analysis is validated by Monte Carlo simulation. It is shown that the performances of the IEEE 802.15.4e TSCH parameters are strongly related to the number of devices sharing the link.