The Benefit of Decoder-Provided Pilots in Highly Dynamic Channels

TL;DR

This paper introduces a non-iterative, decoder-provided pilots method for highly dynamic channels, improving channel estimation and data transmission without increasing latency, applicable to various communication systems.

Contribution

It proposes a novel decoder-provided pilots approach that enhances channel estimation in dynamic environments, being non-iterative and compatible with any forward error correction system.

Findings

Decoder-provided pilots significantly improve performance in fast-fading channels.

Soft-output coding across frequency further enhances performance.

Short codes can outperform long codes of the same rate in highly dynamic channels.

Abstract

Communications in highly dynamic channels relying on training-based channel estimation experience a trade-off between increasing channel measurement accuracy by sending more frequent training sequences and increasing data rate by sending fewer training sequences. Simultaneously, most communication systems use forward error correction to enable error detection and correction at the receiver. This paper presents decoder-provided pilots for time-varying channels by using decoded codewords as training sequences to update the channel estimate at the receiver. In contrast to approaches such as data-aided channel estimation, decision-feedback equalization, joint channel estimation and error correction, and turbo equalization, the decoder-provided pilots approach is non-iterative, which is ideal for low-latency requirements in highly dynamic scenarios. Furthermore, it is modulation-, code-, and decoder-agnostic, meaning it can be implemented on top of virtually any communication system that uses forward error correction. From an information-theoretic perspective, we derive the fundamental limits of decoder-provided pilots' ability to simultaneously sense the channel and transmit data. Simulation results demonstrate that decoder-provided pilots significantly improve performance, that when coding across frequency, soft-output can further enhance performance, and that when coding across time, short codes can outperform long codes of the same rate in fast-fading channels.