An Analytical Model for Wireless Mesh Networks with Collision-Free TDMA and Finite Queues

TL;DR

This paper presents an analytical Markov chain model for evaluating collision-free TSCH wireless mesh networks with finite queues, enabling performance assessment and comparison of scheduling algorithms like Orchestra.

Contribution

It introduces a novel interconnected Markov chain model for finite queues in TSCH networks, facilitating performance analysis of different scheduling strategies.

Findings

Model accurately predicts network performance metrics.

Traffic-aware scheduling improves throughput.

Comparison shows Orchestra's effectiveness in various scenarios.

Abstract

Wireless mesh networks are a promising technology for connecting sensors and actuators with high flexibility and low investment costs. In industrial applications, however, reliability is essential. Therefore, two time-slotted medium access methods, DSME and TSCH, were added to the IEEE 802.15.4 standard. They allow collision-free communication in multi-hop networks and provide channel hopping for mitigating external interferences. The slot schedule used in these networks is of high importance for the network performance. This paper supports the development of efficient schedules by providing an analytical model for the assessment of such schedules, focused on TSCH. A Markov chain model for the finite queue on every node is introduced that takes the slot distribution into account. The models of all nodes are interconnected to calculate network metrics such as packet delivery ratio, end-to-end delay and throughput. An evaluation compares the model with a simulation of the Orchestra schedule. The model is applied to Orchestra as well as to two simple distributed scheduling algorithms to demonstrate the importance of traffic-awareness for achieving high throughput.