# Coexistence of Age and Throughput Optimizing Networks: A Game Theoretic Approach

## TL;DR

This paper models the coexistence of age and throughput optimizing networks sharing wireless spectrum as a repeated game, deriving equilibrium strategies that reveal how these networks can coexist efficiently.

## Contribution

It introduces a game-theoretic framework for analyzing coexistence of age and throughput optimizing networks, deriving Nash equilibria and studying their evolution over time.

## Key findings

- Sharing spectrum with an AON is more favorable for a TON than sharing with another TON.
- AON's equilibrium strategy involves occasional refraining from transmission, enabling free access for the TON.
- Equilibrium strategies evolve over time, affecting the networks' average payoffs.

## Abstract

Real-time monitoring applications have Internet-of-Things (IoT) devices sense and communicate information (status updates) to a monitoring facility. Such applications desire the status updates available at the monitor to be fresh and would like to minimize the age of delivered updates. Networks of such devices may share wireless spectrum with WiFi networks. Often, they use a CSMA/CA based medium access similar to WiFi. However, unlike them, a WiFi network would like to provide high throughputs for its users. We model the coexistence of such networks as a repeated game with two players, an age optimizing network (AON) and a throughput optimizing network (TON), where an AON aims to minimize the age of updates and a TON seeks to maximize throughput. We define the stage game, parameterized by the average age of the AON at the beginning of the stage, and derive its mixed strategy Nash equilibrium (MSNE). We study the evolution of the equilibrium strategies over time, when players play the MSNE in each stage, and the resulting average discounted payoffs of the networks. It turns out that it is more favorable for a TON to share spectrum with an AON in comparison to sharing with another TON. The key to this lies in the MSNE strategy of the AON that occasionally refrains all its nodes from transmitting during a stage. Such stages allow the TON competition free access to the medium.