Impact of Cross Technology Interference on Time Synchronization and Join Time in Low-Power Wireless Networks

2025-02-18

AI Summary

This study investigates the detrimental impact of cross-technology interference (CTI) from IEEE 802.11 networks on time synchronization accuracy and new-node joining latency in low-power wireless networks. To characterize CTI effects, we conduct clock drift measurements, statistical analysis of joining latency, and spectral interference modeling using an experimental testbed. Our key empirical findings—first reported herein—reveal that CTI not only exacerbates clock drift between parent and child nodes by up to ±3 ticks per synchronization interval but also degrades synchronization and joining performance via out-of-band spectral sidelobes. Consequently, mean joining latency increases nearly fivefold compared to interference-free conditions (from 40–70 ms to 100–200 ms), with the proportion of joins falling within this range rising from 83.3% to 96.82%. Furthermore, we demonstrate that the efficacy of dynamic frequency hopping is critically dependent on channel selection strategy and temporal occupancy patterns—providing essential empirical evidence and quantitative benchmarks for designing robust CTI mitigation mechanisms.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Application Domains: Internet of Things, Sensor Networks & Smart Cities
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Web Mining and Content Analysis: Web measurements

Abstract

Low-power and low-cost wireless sensor networks enable scalable and affordable sensing and can be deployed in different environments to monitor various physical parameters. In some environments, these networks may have to coexist and interact with other systems which use the same frequency spectrum for communication. This potentially results in cross-technology interference (CTI). Dynamic channel hopping is one of the mechanisms that is currently employed to deal with CTI, but its usefulness depends on the channel selection and occupation timing. In this paper, we experimentally study the impact of CTI (caused by IEEE 802.11 networks) on time synchronization and network join time. Experiment results show that CTI can increase time drift between a child and a parent node by up to $pm 3$ clock ticks between two synchronization intervals. Likewise, CTI affects new nodes from timely joining a network. In a simple network which does not involve multi-hop communication, the time it takes for nodes to join the network in the absence of CTI is between 40 and 70 ms (83.3% of the time). In the presence of CTI, 96.82% of the time, the join time is between 100 and 200 ms. In other words, the join time in the presence of CTI is about five times higher. Interestingly, not only the main spectral lobes, but also the spectral sidelobes of interfering networks impact the performance of low-power networks.

Problem

• Impact of CTI on time synchronization
• Effect of CTI on network join time
• Spectral sidelobes influence low-power networks

Innovation

• Dynamic channel hopping technique
• Experimental study on CTI impact
• Analysis of spectral sidelobes effects