5G mmW Coverage
How Much Coverage Should Operators Expect?

Over the last few years, we’ve seen many papers talk about different mmWave propagation/channel models. However, one thing lacking in all of these papers is a demonstration of what coverage from a street light deployment would look like. Propagation models allow us to determine pathloss in Line of Sight (LOS), Non-Line of Sight (NLOS) & Indoor conditions.

In a street light based small cell deployment the propagation characteristics will matter, but far more critical will be the physical structures all around including things like buildings, trees, hills, and other large objects. We have done a lot of 5G mmWave network economic modeling based on 3GPP TR 38.901. From those results, it was clear that it would not be possible to guarantee coverage indoors or under Non-line of sight conditions. In cases where a coverage target exists initial deployments will need to be planned for LOS coverage and with indoor or NLOS coverage treated as a bonus.

Multiple trials and demonstrations have shown it is possible to achieve coverage at large distances using mmWave provided you have LOS. Using the assumption that LOS is required for mmWave deployments, we determine coverage from individual Street lights while taking into consideration surrounding buildings, foliage, & other nearby obstructions. For our analysis, we will use the same 2,181 street lights from our backhaul analysis titled: "Is Terragraph Backhaul Essential For 5G?".

To determine LOS from a street light, calculations are done at 1m resolution with each receiver assumed to be at a height of 1.5m. The green circle on the plot below represents the location of a street light at a turn in the road. The blue dots are points on the map from which LOS is possible to the street light.

This plot highlights a perfect example of why the traditional way of quantifying coverage is inadequate. In macro networks, we can typically assume close to uniform coverage in all directions. However, in this case, coverage is constrained by physical objects which are taller than the street light. On the eastern side, coverage is blocked by a house and trees while there is clear coverage on road on the western side. What is the coverage radius and coverage area of this site? Whatever we come up with, it is not going to be a very useful metric.

For this study, we assume the coverage radius is the max distance at which LOS from a specific site is possible. The coverage area of the site above is equal to the count of blue dots above with each blue dot representing 1 sqm of coverage. The LOS coverage for each of the 2,181 street lights were generated and analyzed. Below we share a couple more views of LOS coverage from different street lights.

In the article "Why is Terragraph mmWave Backhaul essential for 5G deployments?", we had demonstrated how to model wireless backhaul. In this study we will integrate the mmWave access model and the mmWave backhaul model to form a comprehensive end to end view of the network.

In the picture below, the red stars represent fiber locations. The green circles represent street lights with 5G small cells and Terragraph backhaul. The random colors represent the available coverage each street lights. Keep in mind this represents outdoor coverage only while indoor coverage will be significantly lower. Based on the plots below, it will be nearly impossible to offer ubiquitous coverage using mmWave bands. As these coverage plots below show, with street light deployments using 5G mmWave bands it will be nearly impossible to offer ubiquitous coverage. Operators will need to offer dual connectivity with sub 6GHz 5G/4G bands to fill in the coverage gaps.

5G Coverage Metrics

As you can see in the image above, districts 3,4,6, & 7 have the site density. The figure below shows the distribution of maximum outdoor coverage by district with the size of each violin and its shape representing the probability distribution for each district. Taking a look at district 6 we see a higher %ile of sites with less than 200m max coverage. This can likely be explained due to district 6 representing a denser part of town with higher buildings.

The figure below shows the coverage area of each site. As seen earlier District 6 tends to be on a slightly lower side.

The figure below shows the distance between sites by district. This is something we would expect to be lower in highly populated regions with lots of traffic. District 3 appears to have the lowest value here and should be investigated more for current mobile traffic usage.

These 2181 sites independently cover 32.6 Million sqm but with a lot of overlap.

The figure on top shows the number of sites with overlapping coverage on each sqm.

The total coverage area of this full network is 13.1 million square meters

This article was written to demonstrate the type of coverage to expect from 5G at mmWave along with the coverage challenges the operators will face.

The opinions expressed in this case study are based on publicly available information and do not claim to represent any companies views or strategy.