One of the controversial areas of 5G development is millimeter wave. In Europe, this means frequencies such as 26 GHz and 35 GHz and in the US it’s 28 GHz and 39 GHz. These very high frequencies have very little penetrating power and so are often condemned as being of little use. A signal can easily be blocked by a wall.
Millimeter wave is attractive because the high frequencies are so unused there are a lot of them available and that means more bandwidth and in turn more throughput.
Strictly, any frequency under 30 GHz is more than a centimeter in length, so you could argue that it’s not properly a millimeter wavelength. The usual riposte to this is that one centimeter is ten millimeters so it counts. Arguing that in that case, 10 kHz is 30 million millimeters will just get you labeled at a pedant until you agree that “millimeter wave” means a very high frequency typically over 20 GHz, and everyone goes to the pub.
Down at the Maxwell’s Arms, the discussions will continue around how useful millimeter wave might be. My interest was piqued by a comment last week by Philip Marnick, group director, Spectrum at Ofcom that “26GHz is in its infancy, I have no doubt it will work but it will take time.” I sought out more information. Marnick pretty much decides what is done with radio spectrum in the U.K. and very influential in setting global policy, so having some that important air a different view to the usual “Well, millimeter is next to useless,” I looked to find someone who had actually used it.
That’s not hard because the 5G which has been rolled out by Verizon in the U.S. is at 28GHz and 39GHz. One such company is Inseego, which no-one I’ve asked has ever heard of, until I’ve said “They used to be Novatel Wireless,” and then everyone knows them. Novatel’s claim to fame is the MiFi product, a Wi-Fi hotspot that uses mobile connectivity for backhaul to connect back to the internet. All smartphones can be a hotspot but there are times when a dedicated solution works better and MiFi is close to being a generic term for the devices akin to Tannoy, Hoover or Kleenex. Indeed in India the word “Nokia” meaning mobile phone, even if it’s a Samsung.
Inseego is a useful company to ask about this, since it makes a kit relied upon by spooks as well as the mass market MiFi, which it sells through Verizon, so has real hands-on experience.
Dan Mondor, Inseego’s CEO tells me that Inseego has been surprised at just how well the millimetre wave MiFi has worked. “Even using it in a car, we have seen real-world performance has far exceeded what we expected.” He conceded that, in buildings, it doesn’t go through walls but says that when using line-of-sight it gets through the windows without losing throughput.
So what matters to make millimeter wave work is infrastructure. Inseego’s CMO Ashish Sharma adds: “If you can blanket the coverage this technology works really well.” But what’s really surprising is that it works in a car. This is after all a mobile technology. That’s down to MIMO, the technology which uses Multiple Input Multiple Output where you have large quantities of antennas, something like 30 or 40 of them. Sharma describes the throughput as “bouncy,” but giving a reliable 100Mbps and up to 2Gbs.
Launching the millimeter wave in the U.K. will take a while. Most of the interest in 5G here is in mid-band, at around 3 GHz and 5 GHz, but it’s worth remembering that it wasn’t so long ago that those frequencies were considered ludicrously high, and only suitable for point to point so it can’t be that long in the future, with improvements in transmitter and receiver sensitivity, that millimeter wave will become normal.