# Risk-Informed Interference Assessment for Shared Spectrum Bands: A Wi-Fi/LTE Coexistence Case Study

## TL;DR

This paper introduces a risk-informed interference assessment method for Wi-Fi and LTE coexistence in the 5 GHz band, demonstrating its effectiveness through simulations and providing insights for spectrum regulation and engineering.

## Contribution

First application of risk assessment to Wi-Fi/LTE spectrum sharing, offering a comprehensive quantification of interference impact and practical insights for coexistence.

## Key findings

- Risk of LTE interfering with Wi-Fi is negligible in typical 5 GHz band scenarios.
- Wi-Fi coexists better with itself in dense deployments and better with LTE in sparse deployments.
- Listen-before-talk reduces interference in dense LTE deployments.

## Abstract

Interference evaluation is crucial when deciding whether and how wireless technologies should operate. In this paper we demonstrate the benefit of risk-informed interference assessment to aid spectrum regulators in making decisions, and to readily convey engineering insight. Our contributions are: we apply, for the first time, risk assessment to a problem of inter-technology spectrum sharing, i.e. Wi-Fi/LTE in the 5 GHz unlicensed band, and we demonstrate that this method comprehensively quantifies the interference impact. We perform simulations with our newly publicly-available tool and we consider throughput degradation and fairness metrics to assess the risk for different network densities, numbers of channels, and deployment scenarios. Our results show that no regulatory intervention is needed to ensure harmonious technical Wi-Fi/LTE coexistence: for the typically large number of channels available in the 5 GHz band, the risk for Wi-Fi from LTE is negligible, rendering policy and engineering concerns largely moot. As an engineering insight, Wi-Fi coexists better with itself in dense, but better with LTE, in sparse deployments. Also, both main LTE-in-unlicensed variants coexist well with Wi-Fi in general. For LTE intra-technology inter-operator coexistence, both variants typically coexist well in the 5 GHz band, but for dense deployments, implementing listen-before-talk causes less interference.