Measuring Pulsed Interference in 802.11 Links

TL;DR

This paper introduces a transmitter-side method to detect and statistically characterize pulsed interference in 802.11 wireless links, enabling better management and potential capacity improvements in noisy environments.

Contribution

A novel approach for detecting and estimating the full distribution of pulsed interference affecting 802.11 links using standard hardware.

Findings

Effective detection of pulsed interference in real-world tests

Ability to recover complete probability distribution of interference intervals

Potential to optimize frame durations for improved network capacity

Abstract

Wireless 802.11 links operate in unlicensed spectrum and so must accommodate other unlicensed transmitters which generate pulsed interference. We propose a new approach for detecting the presence of pulsed interference affecting 802.11 links, and for estimating temporal statistics of this interference. This approach builds on recent work on distinguishing collision losses from noise losses in 802.11 links. When the intervals between interference pulses are i.i.d., the approach is not confined to estimating the mean and variance of these intervals but can recover the complete probability distribution. The approach is a transmitter-side technique that provides per-link information and is compatible with standard hardware. We demonstrate the effectiveness of the proposed approach using extensive experimental measurements. In addition to applications to monitoring, management and diagnostics, the fundamental information provided by our approach can potentially be used to adapt the frame durations used in a network so as to increase capacity in the presence of pulsed interference.