Energy-Efficient Communication in the Presence of Synchronization Errors

TL;DR

This paper introduces an energy-efficient communication scheme that tolerates synchronization errors, proving asymptotic optimality in Gaussian channels and near-optimality in general discrete channels, especially beneficial for low-SNR applications.

Contribution

It proposes a novel communication scheme that requires only loose synchronization and demonstrates its asymptotic optimality in Gaussian channels and near-optimality in general discrete channels.

Findings

Scheme is asymptotically optimal for Gaussian channels with synchronization errors.

Lack of synchronization causes negligible energy efficiency loss.

Achieves within a factor of two of the information-theoretic optimum in general channels.

Abstract

Communication systems are traditionally designed to have tight transmitter-receiver synchronization. This requirement has negligible overhead in the high-SNR regime. However, in many applications, such as wireless sensor networks, communication needs to happen primarily in the energy-efficient regime of low SNR, where requiring tight synchronization can be highly suboptimal. In this paper, we model the noisy channel with synchronization errors as an insertion/deletion/substitution channel. For this channel, we propose a new communication scheme that requires only loose transmitter-receiver synchronization. We show that the proposed scheme is asymptotically optimal for the Gaussian channel with synchronization errors in terms of energy efficiency as measured by the rate per unit energy. In the process, we also establish that the lack of synchronization causes negligible loss in energy efficiency. We further show that, for a general discrete memoryless channel with synchronization errors and a general input cost function admitting a zero-cost symbol, the rate per unit cost achieved by the proposed scheme is within a factor two of the information-theoretic optimum.