parts of Sacramento as optimal testing environments and is focused on developing a fixed network, which carries fewer challenges for mmWave deployment than a mobile network. However, even in these optimized circumstances it is clear that scaling this solution to provide more coverage would be a time- and cost-intensive endeavor requiring a massive infrastructure build-out.
Google also performed a preliminary study for the Defense Innovation Board to ascertain the approximate capital expenditure (capex) and base station counts needed for mmWave deployments, using 425 MHz of spectrum at 28 GHz (a mmWave configuration standard for current U.S. 5G trials), compared to 250 MHz of spectrum in the 3.4 GHz band (a sub-6 configuration, standard for Chinese 5G trials and deployment). This equipment was deployed on 72,735 existing macrocell towers and rooftops (the easiest choice for deployment) and was found to provide mmWave coverage to only 11.6% of the U.S. population at cell edge speeds of 100 Mbps, with 3.9% coverage at 1 gigabit. For sub-6, the same tower sites covered 57.4% of the population at 100 Mbps, and 21.2% of the population at 1 Gbps. The study used high-resolution geospatial data that included shadowing from foliage structures, but did not take into account shadowing from the human body or a vehicle, which realistically would exist in a deployed environment and even further disrupt connectivity for mmWave networks.
Most operators are looking at deploying mmWave 5G sites on utility poles, given the poles’ ease of accessibility and abundance. Using a database of utility poles in the United States, the study indicated that it would require approximately 13 million pole-mounted 28-GHz base stations and $400B dollars in capex to deliver 100 Mbps edge rate at 28 GHz to 72% of the U.S. population, and up to 1 Gbps to approximately 55% of the U.S. population. Figures 1 and 2 below show the difference in “splat” (propagation) between 28 GHz (mmWave) and 3.4 Ghz (sub-6) deployments on the same pole height in a relatively flat part of Los Angeles (blue represents 100 Mbps speed, red represents 1 Gbps speed):
Figure 1: “Splat” chart with mmWave propagation |
Figure 2: “Splat” chart with sub-6 propagation |
