Uplink Interference Mitigation Techniques for Coexistence of 5G mmWave Users with Incumbents at 70 and 80 GHz

TL;DR

This paper analyzes the coexistence of 5G mmWave users with incumbent fixed stations at 70 and 80 GHz, proposing interference modeling and mitigation techniques to enable effective spectrum sharing.

Contribution

It develops a detailed interference framework and proposes passive mitigation strategies for 5G coexistence with incumbents in millimeter wave bands.

Findings

Most fixed stations experience interference below the noise floor.

Propagation losses and deployment geometry aid coexistence.

Passive mitigation techniques effectively protect fixed stations.

Abstract

The millimeter wave spectra at 71-76GHz (70GHz) and 81-86GHz (80GHz) have the potential to endow fifth-generation new radio (5G-NR) with mobile connectivity at gigabit rates. However, a pressing issue is the presence of incumbent systems in these bands, which are primarily point-to-point fixed stations (FSs). In this paper, we first identify the key properties of incumbents by parsing databases of existing stations in major cities to devise several modeling guidelines and characterize their deployment geometry and antenna specifications. Second, we develop a detailed uplink interference framework to compute the aggregate interference from outdoor 5G-NR users into FSs. We then present several case studies in dense populated areas, using actual incumbent databases and building layouts. Our simulation results demonstrate promising 5G coexistence at 70GHz and 80GHz as the majority of FSs experience interference well below the noise floor thanks to the propagation losses in these bands and the deployment geometry of the incumbent and 5G systems. For the few FSs that may incur higher interference, we propose several passive interference mitigation techniques such as angular-based exclusion zones and spatial power control. Simulation results show that the techniques can effectively protect FSs, without tangible degradation of the 5G coverage.