Unlicensed LTE/WiFi Coexistence: Is LBT Inherently Fairer Than CSAT?

TL;DR

This paper compares unlicensed LTE access methods, CSAT and LBT, demonstrating that both can achieve similar fairness to WiFi when properly configured, with the choice driven by operator preferences.

Contribution

It provides a comparative analysis showing that both CSAT and LBT can ensure fairness, challenging the assumption that LBT is inherently fairer than CSAT.

Findings

Both approaches can provide equal fairness when optimally configured.

The choice between CSAT and LBT depends on LTE operator interests.

Regulatory and compatibility considerations influence the preferred method.

Abstract

Ensuring fair co-existence between unlicensed LTE and WiFi networks is currently of major concern to both cellular operators and WiFi providers. Two main unlicensed LTE approaches currently being discussed, namely Carrier Sense Adaptive Transmission (CSAT) and Listen Before Talk (LBT). While these mechanisms differ in their compatibility with existing LTE specifications and regulatory compliance in different countries, they also use fundamentally different approaches to access the channel. Nevertheless, we show in this article that when optimally configured both approaches are capable of providing the same level of fairness to WiFi and that the choice between CSAT and LBT is solely driven by the LTE operator's interests.