Universal Decoding for Asynchronous Slepian-Wolf Encoding

TL;DR

This paper introduces a universal decoder for asynchronous Slepian-Wolf source coding that performs as well as an optimal decoder without knowing source parameters or delay, ensuring reliable decoding.

Contribution

It proposes a universal decoder for asynchronous Slepian-Wolf coding that matches the performance of the optimal MAP decoder despite unknown parameters.

Findings

Achieves the same rate region as known-parameter decoding.

Performs asymptotically as well as the MAP decoder.

Works effectively without prior knowledge of delay or source parameters.

Abstract

We consider the problem of (almost) lossless source coding of two correlated memoryless sources using separate encoders and a joint decoder, that is, Slepian-Wolf (S-W) coding. In our setting, the encoding and decoding are asynchronous, i.e., there is a certain relative delay between the two sources. Neither the source parameters nor the relative delay are known to the encoders and the decoder. Since we assume that both encoders implement standard random binning, which does not require such knowledge anyway, the focus of this work is on the decoder. Our main contribution is in proposing a universal decoder, that independent of the unknown source parameters and the relative delay, and at the same time, is asymptotically as good as the optimal maximum a posteriori probability (MAP) decoder in the sense of the random coding error exponent achieved.Consequently, the achievable rate region is also the same as if the source parameters and the delay were known to the decoder.