Dense Urban Outdoor-Indoor Coverage from 3.5 to 28 GHz

TL;DR

This paper analyzes outdoor and indoor coverage in urban environments across 3.5 to 28 GHz, highlighting the impact of building materials and proposing models to optimize network deployment for high data rates.

Contribution

It introduces models for urban outdoor-indoor coverage at mmWave frequencies and evaluates their implications for network planning and performance.

Findings

At 28 GHz, 90% outdoor users achieve over 250 Mbps with 1 W transmit power.

Indoor users face a 15% outage rate at 28 GHz under certain building penetration conditions.

At 3.5 GHz, high data rates are achievable indoors with sufficient bandwidth and transmit power.

Abstract

In the US, people spend 87% of their time indoors and have an average of four connected devices per person (in 2020). As such, providing indoor coverage has always been a challenge but becomes even more difficult as carrier frequencies increase to mmWave and beyond. This paper investigates the outdoor and outdoor-indoor coverage of an urban network comparing globally standardized building penetration models and implementing models to corresponding scenarios. The glass used in windows of buildings in the grid plays a pivotal role in determining the outdoor-to-indoor propagation loss. For 28 GHz with 1 W/polarization transmit power in the urban street grid, the downlink data rates for 90% of outdoor users are estimated at over 250 Mbps. In contrast, 15% of indoor users are estimated to be in outage, with SNR $<-$3 dB when base stations are 400 m apart with one-fifth of the buildings imposing high penetration loss ($\sim$ 35 dB). At 3.5 GHz, base stations may achieve over 250 Mbps for 90% indoor users if 400 MHz bandwidth with 100 W/polarization transmit power is available. The methods and models presented can be used to facilitate decisions regarding the density and transmit power required to provide high data rates to majority users in urban centers.