Interference-Robust Non-Coherent Over-the-Air Computation for Decentralized Optimization

TL;DR

This paper introduces an interference-robust NCOTA scheme for decentralized optimization that maintains unbiased consensus estimates under external interference by using coordinated random rotations and pseudo-random pilots.

Contribution

It proposes a novel IR-NCOTA method that enhances interference robustness in non-coherent over-the-air computation for decentralized systems.

Findings

IR-NCOTA outperforms baseline NCOTA under interference conditions

The scheme preserves convergence guarantees of decentralized optimization

Numerical results show improved classification accuracy

Abstract

Non-coherent over-the-air (NCOTA) computation enables low-latency and bandwidth-efficient decentralized optimization by exploiting the average energy superposition property of wireless channels. It has recently been proposed as a powerful tool for executing consensus-based optimization algorithms in fully decentralized systems. A key advantage of NCOTA is that it enables unbiased consensus estimation without channel state information at either transmitters or receivers, requires no transmission scheduling, and scales efficiently to dense network deployments. However, NCOTA is inherently susceptible to external interference, which can bias the consensus estimate and deteriorate the convergence of the underlying decentralized optimization algorithm. In this paper, we propose a novel interference-robust (IR-)NCOTA scheme. The core idea is to apply a coordinated random rotation of the frame of reference across all nodes, and transmit a pseudo-random pilot signal, allowing to transform external interference into a circularly symmetric distribution with zero mean relative to the rotated frame. This ensures that the consensus estimates remain unbiased, preserving the convergence guarantees of the underlying optimization algorithm. Through numerical results on a classification task, it is demonstrated that IR-NCOTA exhibits superior performance over the baseline NCOTA algorithm in the presence of external interference.