Age-Energy Tradeoff in Fading Channels with Packet-Based Transmissions

TL;DR

This paper investigates the optimal balance between age of information and energy consumption in packet-based wireless systems over fading channels, proposing a new policy to improve both metrics.

Contribution

It introduces a novel optimal power allocation policy for minimizing age and energy use in fading channels, formulated via a constrained Markov decision process.

Findings

The proposed policy outperforms benchmark schemes in simulations.

Age can be reduced at higher energy costs, showing a clear tradeoff.

Optimal policy improves energy efficiency and age simultaneously.

Abstract

The optimal transmission strategy to minimize the weighted combination of age of information (AoI) and total energy consumption is studied in this paper. It is assumed that the status update information is obtained and transmitted at fixed rate over a Rayleigh fading channel in a packet-based wireless communication system. A maximum transmission round on each packet is enforced to guarantee certain reliability of the update packets. Given fixed average transmission power, the age-energy tradeoff can be formulated as a constrained Markov decision process (CMDP) problem considering the sensing power consumption as well. Employing the Lagrangian relaxation, the CMDP problem is transformed into a Markov decision process (MDP) problem. An algorithm is proposed to obtain the optimal power allocation policy. Through simulation results, it is shown that both age and energy efficiency can be improved by the proposed optimal policy compared with two benchmark schemes. Also, age can be effectively reduced at the expense of higher energy cost, and more emphasis on energy consumption leads to higher average age at the same energy efficiency. Overall, the tradeoff between average age and energy efficiency is identified.