Rural Macrocell Path Loss Models for Millimeter Wave Wireless Communications

Abstract

Little research has been done to reliably model millimeter wave (mmWave) path loss in rural macrocell settings, yet, models have been hastily adopted without substantial empirical evidence. This paper studies past rural macrocell (RMa) path loss models and exposes concerns with the current 3rd Generation Partnership Project (3GPP) TR 38.900 (Release 14) RMa path loss models adopted from the International Telecommunications Union -Radiocommunications (ITU-R) Sector. This paper shows how the 3GPP RMa large-scale path loss models were derived for frequencies below 6 GHz, yet they are being asserted for use up to 30 GHz, even though there has not been sufficient work or published data to support their validity at frequencies above 6 GHz or in the mmWave bands. We present the background of the 3GPP RMa path loss models and their use of odd correction factors not suitable for rural scenarios, and show that the multi-frequency close-in free space reference distance (CI) path loss model is more accurate and reliable than current 3GPP and ITU-R RMa models. Using field data and simulations, we introduce a new close-in free space reference distance with height dependent path loss exponent model (CIH), that predicts rural macrocell path loss using an effective path loss exponent that is a function of base station antenna height. This work shows the CI and CIH models can be used from 500 MHz to 100 GHz for rural mmWave coverage and interference analysis, without any discontinuity at 6 GHz as exists in today's 3GPP and ITU-R RMa models.

Overview of Millimeter Wave Communications for Fifth-Generation (5G) Wireless Networks—With a Focus on Propagation Models

“…Standard bodies historically create omnidirectional path loss models with the assumption of unity gain antennas for generality. However, it is worth noting that omnidirectional path loss models will not be usable in directional antenna system analysis unless the antenna patterns and true spatial and temporal multipath channel statistics are known or properly modeled [19], [20], [29], [80], [99], [115], [116].…”

“…where χ CI σ is the shadow fading (SF) that is modeled as a zeromean Gaussian random variable with a standard deviation in dB, n is the path loss exponent (PLE) found by minimizing the error of the measured data to (2), d 3D > 1m, FSPL(f, 1 m) is the free space path loss (FSPL) at frequency f c in GHz at 1 m and is calculated by [19], [85]: where c is the speed of light, 3 × 10 8 m/s. Using (3) it is clear that (2) can be represented as given in Table IV.…”

Propagation Measurement System and Approach at 140 GHz-Moving to 6G and Above 100 GHz

“…However, little is known about radio channels above 100 GHz where there are wider unused bandwidth slots available. The immense bandwidths at mmWave and THz frequencies can enable future indoor and outdoor mobile networks as well as rural macrocell (RMa) point-to-point copper replacement over very large distances [15], [16]. For example, there is 60 GHz of spectrum in D-band (110 GHz to 170 GHz) and when allocated for high-speed wireless links, this large bandwidth has potential applications in "wireless fiber" backhaul for fixed links, indoor/WiFi access, mobile communication, precision positioning, velocity sensors, passive mmWave cameras, vehicular communication, navigation, radar, and on-body communication for health monitoring systems [17]- [19].…”

Indoor Wireless Channel Properties at Millimeter Wave and Sub-Terahertz Frequencies

“…Frequencies from 100 GHz to 3 THz are promising bands for the next generation of wireless communication systems because of the wide swaths of unused and unexplored spectrum. Availability of this new spectrum above 95 GHz will open up much needed broadband service enabling new applications for medical imaging, spectroscopy, new massively broadband IoT, sensing, communications, and wireless fiber links in rural areas [2], [10], [13]. Early work shows that weather and propagation impairments are not very different from today's mmWave all the way up to 400 GHz [1], [2], [14].…”