Hybrid Channel Estimation with Quantized Phase Feedback for Over-the-Air Computation

TL;DR

This paper introduces a hybrid channel estimation method for over-the-air computation that combines reciprocity and feedback techniques, optimizing phase and amplitude estimation to reduce signaling overhead.

Contribution

It proposes a novel hybrid estimation scheme with quantized phase feedback, allowing separate control of amplitude and phase accuracy, and compares two variants for improved performance.

Findings

The second scheme variant outperforms the first in simulations.

Optimal phase quantization improves estimation accuracy.

Hybrid approach reduces signaling overhead effectively.

Abstract

To reduce the signaling overhead of over-the-air computation, a hybrid channel estimation scheme is proposed, where reciprocity-based and feedback-based channel estimation are combined. In particular, the impact of quantized phase-feedback is studied while the amplitude is assumed estimated exactly. The scheme enables selecting the estimation precision of amplitude and phase separately, depending on the importance of each. Two variants of the scheme are proposed: As shown through simulations and theory, the second variant with reciprocity-based estimation of the channel phase, and optimal quantization of phase feedback, can outperform the first variant estimating the phase by feedback only.