Diffusion Adaptation over Multi-Agent Networks with Wireless Link Impairments

TL;DR

This paper investigates how wireless channel impairments like fading and path-loss impact diffusion LMS algorithms in multi-agent networks and proposes adaptive strategies to maintain performance despite these challenges.

Contribution

It introduces a method to incorporate equalization and dynamic weight updates in diffusion algorithms to counteract wireless impairments without requiring channel state information.

Findings

Proper CSI monitoring and small step-sizes ensure stable performance

Equalization coefficients mitigate fading effects

Dynamic neighborhood updates adapt to changing wireless conditions

Abstract

We study the performance of diffusion least-mean-square algorithms for distributed parameter estimation in multi-agent networks when nodes exchange information over wireless communication links. Wireless channel impairments, such as fading and path-loss, adversely affect the exchanged data and cause instability and performance degradation if left unattended. To mitigate these effects, we incorporate equalization coefficients into the diffusion combination step and update the combination weights dynamically in the face of randomly changing neighborhoods due to fading conditions. When channel state information (CSI) is unavailable, we determine the equalization factors from pilot-aided channel coefficient estimates. The analysis reveals that by properly monitoring the CSI over the network and choosing sufficiently small adaptation step-sizes, the diffusion strategies are able to deliver satisfactory performance in the presence of fading and path loss.