# Age of Information Scaling in Large Networks with Hierarchical Cooperation

## TL;DR

This paper introduces a hierarchical cooperation scheme for large networks that significantly reduces the age of information, achieving an asymptotic logarithmic scaling with network size, which is a new record.

## Contribution

It proposes a novel three-phase hierarchical cooperation scheme with mega update packets that improves age scaling in large networks with multiple source-destination pairs.

## Key findings

- Achieves an average age scaling of O(log n) as network size grows.
- Introduces a hierarchical cooperation scheme with multiple levels.
- Demonstrates the scheme's optimality among status update systems.

## Abstract

Given $n$ randomly located source-destination (S-D) pairs on a fixed area network that want to communicate with each other, we study the age of information with a particular focus on its scaling as the network size $n$ grows. We propose a three-phase transmission scheme that utilizes \textit{hierarchical cooperation} between users along with \textit{mega update packets} and show that an average age scaling of $O(n^{\alpha(h)}\log n)$ per-user is achievable where $h$ denotes the number of hierarchy levels and $\alpha(h) = \frac{1}{3\cdot2^h+1}$ which tends to $0$ as $h$ increases such that asymptotically average age scaling of the proposed scheme is $O(\log n)$. To the best of our knowledge, this is the best average age scaling result in a status update system with multiple S-D pairs.