RIS-Assisted Coverage Enhancement in Millimeter-Wave Cellular Networks

Mahyar Nemati,Jihong Park,Jinho Choi

doi:10.1109/access.2020.3031392

Mahyar Nemati, Jihong Park + Show 1 more

Open Access

https://doi.org/10.1109/access.2020.3031392

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Abstract

The use of millimeter-wave (mmWave) bandwidth is one key enabler to achieve the high data rates in the fifth-generation (5G) cellular systems. However, mmWave signals suffer from significant path loss due to high directivity and sensitivity to blockages, limiting its adoption within small-scale deployments. To enhance the coverage of mmWave communication in 5G and beyond, it is promising to deploy a large number of reconfigurable intelligent surfaces (RISs) that passively reflect mmWave signals towards desired directions. With this motivation, in this work, we study the coverage of an RIS-assisted large-scale mmWave cellular network using stochastic geometry, and derive the peak reflection power expression of an RIS and the downlink signal-to-interference ratio (SIR) coverage expression in closed forms. These analytic results clarify the effectiveness of deploying RISs in the mmWave SIR coverage enhancement, while unveiling the major role of the density ratio between active base stations (BSs) and passive RISs. Furthermore, the results show that deploying passive reflectors are as effective as equipping BSs with more active antennas in the mmWave coverage enhancement. Simulation results confirm the tightness of the closed-form expressions, corroborating our major findings based on the derived expressions.

Highlights

Millimeter-wave cellular networks are widely studied for the emerging fifth generation (5G) of mobile communication networks and beyond
In this study, we proposed a new reconfigurable intelligent surfaces (RISs)-assisted mmWave cellular network where a message is transmitted by a base stations (BSs) towards a desired user equipment (UE) though two LoS and NLoS paths
Since the UE utilizes selection diversity technique to pick the strongest signal received through the two paths, we analysed the signal-to-interference ratio (SIR) coverage performance of both paths with major emphasis on RIS and BS densities and compared its performance with a baseline model

Summary

Introduction

Millimeter-wave (mmWave) cellular networks are widely studied for the emerging fifth generation (5G) of mobile communication networks and beyond. The Asia-Pacific region is supposed to give rise to the greatest share of the total contribution of mmWave communications to the gross domestic product (GDP), i.e., $212 billion, over the period 2020 to 2034 [1]; with a compound annual growth rate of 31% in the volume of mobile data traffic [2]. These significant growths imply that within the decades, mmWave cellular networks will have significantly drawn attention to deliver much higher data-rate and capacity compared to current levels due to the availability of wider bandwidths [3]–[5].

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Discussion

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