# Age-Optimal Power Control for Status Update Systems with Packet Based Transmissions

## TL;DR

This paper develops an age-optimal power control strategy for status update systems with fixed-rate packet transmissions, minimizing the average age of information under power constraints.

## Contribution

It introduces a closed-form average AoI expression and proposes a stochastic optimization algorithm for power control to minimize AoI.

## Key findings

- Power is allocated more after multiple failures in low-power regimes.
- The proposed power control reduces average AoI compared to constant power.
- On-off power control achieves satisfactory performance.

## Abstract

This paper investigates the average age of information (AoI) minimization in status update systems in which the update packets are transmitted with fixed rate. It is assumed that the source avoids queue-induced delay by generating and sending a new status update packet in each time slot. Assuming that the transmit power can be adapted based on the number of successive NACKs (negative acknowledgements) received, a closed-form expression for the average AoI is derived considering transmissions over block fading channel models. An optimization problem for minimizing the average AoI under average power constraints is formulated and a stochastic optimization algorithm for obtaining a feasible solution is proposed. Numerical results on the proposed power control policy show that more power is preferred to be allocated to packets after a certain number of failure packets in the low-power regime and the proposed power control reduces the average AoI compared to the constant power policy. An alternative on-off power control policy is also proposed and shown to achieve satisfactory performance.