Capacity of the Energy Harvesting Gaussian MAC

TL;DR

This paper analyzes the capacity of an energy harvesting Gaussian multiple access channel with finite batteries, providing bounds that differ by a constant and showing sum-capacity approaches that of a standard AWGN MAC as user count increases.

Contribution

It characterizes the capacity region of energy harvesting MACs and introduces bounds with a constant gap, revealing asymptotic capacity equivalence to standard AWGN MACs.

Findings

Sum-capacity approaches standard AWGN MAC as number of users grows

Inner and outer bounds differ by a constant gap

Capacity region characterized as n-letter mutual information rate

Abstract

We consider an energy harvesting multiple access channel (MAC) where the transmitters are powered by an exogenous stochastic energy harvesting process and equipped with finite batteries. We characterize the capacity region of this channel as n-letter mutual information rate and develop inner and outer bounds that differ by a constant gap. An interesting conclusion that emerges from our results is that the sum-capacity approaches that of a standard AWGN MAC (with only an average constraint on the transmitted power), as the number of users in the MAC becomes large.