Protocol Coding through Reordering of User Resources, Part II: Practical Coding Strategies

TL;DR

This paper develops practical coding strategies for a secondary communication channel created by reordering user resources in a primary system, enhancing reliable communication with low-complexity devices, based on prior information-theoretic analysis.

Contribution

It introduces practical protocol coding strategies inspired by theoretical capacity analysis, improving error control in secondary channels within existing systems.

Findings

Enhanced error performance over naive strategies

Effective use of information-theoretic insights for code design

Demonstrated practical applicability of secondary channel coding

Abstract

We use the term protocol coding to denote the communication strategies in which information is encoded through the actions taken by a certain communication protocol. In this work we investigate strategies for protocol coding via combinatorial ordering of the labelled user resources (packets, channels) in an existing, primary system. This introduces a new, secondary communication channel in the existing system, which has been considered in the prior work exclusively in a steganographic context. Instead, we focus on the use of secondary channel for reliable communication with newly introduced secondary devices, that are low-complexity versions of the primary devices, capable only to decode the robustly encoded header information in the primary signals. In Part I of the work we have characterized the capacity of the secondary channel through information-theoretic analysis. In this paper we consider practical strategies for protocol coding inspired by the information-theoretic analysis. It turns out that the insights from Part I are instrumental for devising superior design of error-control codes. This is demonstrated by comparing the error performance to the "na"{\i}ve" strategy which is presumably available without carrying out the analysis in Part I. These results are clearly outlining both the conceptual novelty behind the discussed concept of secondary channel as well as its practical applicability.