Random Access Game in Fading Channels with Capture: Equilibria and Braess-like Paradoxes

TL;DR

This paper analyzes the equilibrium behavior of selfish nodes in a slotted ALOHA system with fading channels, revealing that more channel information can paradoxically degrade network performance under certain conditions.

Contribution

It introduces a game-theoretic analysis of heterogeneous nodes in fading channels, identifying conditions for Braess-like paradoxes in power and SINR capture models.

Findings

Braess-like paradoxes can occur when channel state information is available.

Paradoxes are analytically shown for homogeneous nodes in power capture.

Paradoxes occur in SINR capture with high capture ratio and low noise-to-signal ratio.

Abstract

The Nash equilibrium point of the transmission probabilities in a slotted ALOHA system with selfish nodes is analyzed. The system consists of a finite number of heterogeneous nodes, each trying to minimize its average transmission probability (or power investment) selfishly while meeting its average throughput demand over the shared wireless channel to a common base station (BS). We use a game-theoretic approach to analyze the network under two reception models: one is called power capture, the other is called signal to interference plus noise ratio (SINR) capture. It is shown that, in some situations, Braess-like paradoxes may occur. That is, the performance of the system may become worse instead of better when channel state information (CSI) is available at the selfish nodes. In particular, for homogeneous nodes, we analytically present that Braess-like paradoxes occur in the power capture model, and in the SINR capture model with the capture ratio larger than one and the noise to signal ratio sufficiently small.