5G propagation is known to be affected by trees, especially at millimeter wave (mmWave) frequencies. However, many telecom providers’ propagation models don’t take vegetation into account. This could be a problem for the rollout of the 5G network.
At a glance:
- mmWave frequency bands are impacted by trees and vegetation
- We compared 5G propagation models with and without the presence of vegetation
- Find out how much of an impact trees and vegetation have on 5G propagation
- Learn why trees and plants affect wave propagation
Telecom providers are currently going through a period of rapid change as they expand their 5G wireless networks. Statistics from Ericsson show consumer demand is high (there are already ~1 billion consumer 5G subscriptions worldwide), and we’re seeing uptake in countries around the world.
Unlike previous generations of wireless communication system, 5G – and particularly mmWave 5G – requires more cells to be installed close to where people use the services. This is because the high frequency of mmWave 5G attenuates (loses strength) over much shorter distances.
To plan out their 5G wireless networks, telcos use maps to decide where to place base stations in order to achieve the most efficient 5G propagation (transmission). The problem, however, is that many are using maps that don’t contain all the information they need to accurately predict wave propagation – including the location of obstacles such as trees.
To illustrate this issue, we conducted a comparative study of 5G propagation in Barcelona using 3D maps. We compared 5G path loss modeling in a map that contained trees, versus another one where trees weren’t included.
Let’s learn more about this issue, then explore the results of our study.
The issue of vegetation and other obstacles in 5G propagation
Trees and other forms of vegetation are an invaluable part of the urban landscape. They make cities more attractive, offer shade and cooling, and they absorb air pollution. And most people really appreciate their presence. But for 5G propagation, vegetation is an issue.
A recent study in the US showed that, on average, a single tree causes a mmWave propagation loss of 35.3 decibels (it varies by tree species, foliage, crown size, age, and other factors). A single tree can significantly attenuate mmWave propagation, and so larger numbers of trees (a small wood, a few trees planted on a row, or on a roundabout…) have an even greater effect.
The extremely high-frequency signals of 5G often cannot pass through the wood. What is more, water stored in the trunk and leaves of trees also impacts radio frequency and makes it much less effective.
Recommended reading: mmWave 5G will disappoint without better planning
Propagation models with and without vegetation included
Over the past decade, 3D maps have become widely used for planning cellular networks in dense urban areas – particularly in places with high-rise buildings. These maps accurately model each building, the terrain, transportation networks, and other infrastructure.
With 5G however, the frequencies are higher than ever, ranging from 3.6 GHz — 3.8 GHz, and 26 GHz — 28 GHz. At these frequencies, any obstacle in the line of sight between the transmitter and the receiver will have a huge impact on the signal’s propagation. This means that even trees are highly attenuating to the signal (standard values around 1dB / meter at 26 GHz).
The following study compares predictions of 5G propagation with and without 3D trees being taken into account. This area counts five macro sites (antenna height = 30 meters) that we selected in Barcelona.