The Benefit of Decoder-Provided Pilots in Highly Dynamic Channels
2026-05-01 • Information Theory
Information Theory
AI summaryⓘ
The authors describe a new way to improve communication over channels that change quickly by using decoded messages themselves as training signals to better understand the channel. This method doesn't need repeated back-and-forth adjustments, making it faster and suitable for situations where speed is important. They also show that their approach works with many types of coding and modulation, making it widely applicable. Simulations indicate that their technique helps improve accuracy, especially in challenging conditions where signals fade quickly.
channel estimationforward error correctiondecoder-provided pilotstime-varying channelsnon-iterative methodsmodulationcoding theoryfast-fading channelssoft-output decodingerror correction
Authors
Duschia Bodet, Muriel Médard, Muralidhar Rangaswamy, Ken Duffy
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.