Uplink Age of Information of Unilaterally Powered Two-way Data Exchanging Systems

TL;DR

This paper analyzes the age of information in a two-way energy-harvesting system, deriving formulas for AoI and data rate to understand the tradeoffs and performance limits of such systems.

Contribution

It provides the first closed-form expressions for uplink AoI and data rate in a unilaterally powered two-way data exchange system.

Findings

Derived closed-form average uplink AoI and data rate.

Identified the tradeoff between uplink and downlink data rates.

Illustrated the performance limits of the system.

Abstract

We consider a two-way data exchanging system where a master node transfers energy and data packets to a slave node alternatively. The slave node harvests the transferred energy and performs information transmission as long as it has sufficient energy for current block, i.e., according to the best-effort policy. We examine the freshness of the received packets at the master node in terms of age of information (AoI), which is defined as the time elapsed after the generation of the latest received packet. We derive average uplink AoI and uplink data rate as functions of downlink data rate in closed form. The obtained results illustrate the performance limit of the unilaterally powered two-way data exchanging system in terms of timeliness and efficiency. The results also specify the achievable tradeoff between the data rates of the two-way data exchanging system.