Information and Power Transfer by Energy Harvesting Transmitters over a Fading Multiple Access Channel with Minimum Rate Constraints

TL;DR

This paper characterizes the fundamental limits of simultaneous wireless information and power transfer over fading multiple access channels, considering minimum rate constraints and analyzing practical receiver architectures.

Contribution

It introduces the minimum-rate capacity region for SWIPT with minimum rate guarantees and compares the performance of time switching and power splitting receivers.

Findings

Power splitting receivers offer larger capacity regions than time switching.

Minimum-rate capacity regions are derived for different receiver architectures.

The study highlights the trade-offs between complexity and capacity in SWIPT systems.

Abstract

We consider the problem of Simultaneous Wireless Information and Power Transfer (SWIPT) over a fading multiple access channel with additive Gaussian noise. The transmitters as well as the receiver harvest energy from ambient sources. We assume that the transmitters have two classes of data to send, viz. delay sensitive and delay tolerant data. Each transmitter sends the delay sensitive data at a certain minimum rate irrespective of the channel conditions (fading states). In addition, if the channel conditions are good, the delay tolerant data is sent. {Along with data, the transmitters also transfer power to aid the receiver in meeting its energy requirements.} In this setting, we characterize the \textit{minimum-rate capacity region} which provides the fundamental limit of transferring information and power simultaneously with minimum rate guarantees. Owing to the limitations of current technology, these limits might not be achievable in practice. Among the practical receiver structures proposed for SWIPT in literature, two popular architectures are the \textit{time switching} and \textit{power splitting} receivers. For each of these architectures, we derive the minimum-rate capacity regions. We show that power splitting receivers although more complex, provide a larger capacity region.