Distributed Function Computation in Asymmetric Communication Scenarios

TL;DR

This paper introduces an optimal interactive communication protocol for distributed function computation in asymmetric scenarios, reducing communication for lossy functions compared to traditional source coding.

Contribution

It generalizes distributed source coding to function computation, providing a constructive, optimal protocol and rate-region analysis for asymmetric communication.

Findings

Lossy functions require fewer bits than DSC for computation.

Lossless functions need as many bits as DSC.

The protocol is optimal and applicable to any function.

Abstract

We consider the distributed function computation problem in asymmetric communication scenarios, where the sink computes some deterministic function of the data split among N correlated informants. The distributed function computation problem is addressed as a generalization of distributed source coding (DSC) problem. We are mainly interested in minimizing the number of informant bits required, in the worst-case, to allow the sink to exactly compute the function. We provide a constructive solution for this in terms of an interactive communication protocol and prove its optimality. The proposed protocol also allows us to compute the worst-case achievable rate-region for the computation of any function. We define two classes of functions: lossy and lossless. We show that, in general, the lossy functions can be computed at the sink with fewer number of informant bits than the DSC problem, while computation of the lossless functions requires as many informant bits as the DSC problem.