High-band, millimeter wave 5G is shaping up as the Usain Bolt of wireless: Insanely fast over 200 meters or less, not so hot over long distances.

Millimeter wave (mmWave), typically at 28GHz or 39GHz, is bringing an entire new swathe of high-band spectrum to the wireless services sector. The bands have previously been used, in limited fixed wireless and microwave backhaul applications, but multi-antenna arrays (MIMO) and beamforming technology has made it possible for the very narrow waves -- that can be attenuated by weather conditions, foliage, and building material -- to be used for blazing-fast consumer services.

More evidence of this emerged this week as AT&T Inc. (NYSE: T) revealed some of its fixed wireless 5G results, reporting speeds of 1 Gbit/s or even faster at 150 meters (492 feet) to 275 meters (900 feet). (See AT&T 5G Tests Go Gaga for Gigabit.)

Verizon Communications Inc. (NYSE: VZ), meanwhile, clocked gigabit downloads at up to 2,000 feet (609 meters) in its tests earlier this year. Of course, millimeter wave signals can be blocked by low-energy glass, concrete, and foliage in these wireless-to-the-home scenarios. (See Verizon Says 'Up to 5' Fixed 5G Markets Will Go Live in 2H18 and Nokia Bell Labs & Verizon Stretch Fixed 5G to the Home.)

Earlier this year, the consensus from multiple people I spoke to at Mobile World Congress in Barcelona was that mobile 5G on millimeter wave would have a range of 100 meters to 200 meters, or 328 feet to 656 feet.

There are ways to add more range to high-band spectrum 5G services, notably by using the 5G standard in low- or mid-band spectrum as a coverage layer. But while this will increase coverage range, it could decrease overall average upload and download speeds. I haven't seen results from 600MHz or 2.5GHz 5G tests yet in order to get a handle on the differences.

SK Telecom (Nasdaq: SKM), meanwhile, plans to use 28GHz signal repeaters to double the range of the mobile 5G radios it is rolling out in South Korea. (See SK Telecom Plans to Extend 5G Range With Repeater.)

What is most likely for initial 28GHz deployments in the US, however, is a greatly increased deployment of mmWave small cells to fill in major coverage gaps. With a 28GHz spectrum in the US expected in November 2018, it is no wonder that the Federal Communications Commission (FCC) has moved aggressively to relax federal regulations on small cell deployments. (See FCC Trims Small Cell Reviews, AT&T Cheers.)

The average length of a city block in Mahnattan is about 900 feet. This suggests that a mobile 5G small cell may need to be deployed every city block in NYC. This is bound to lead to many, many more health and aesthetic questions from residents as 5G moves from hype to reality in 2018 and beyond.

— Dan Jones, Mobile Editor, Light Reading