Are millimeter waves the key to easy Internet access?
You may be familiar with Aereo, Inc., a now-defunct start-up that brought streaming TV to individuals via a “farm” of per-user micro-antennas and the Internet. Their scheme was both simple and complicated, and had modest commercial success but they were put out of business by a 2015 Supreme Court decision that their concept constituted copyright infringement and appropriation of content owned by others.
The founder and force behind Aereo, Chet Kanojia, is certainly full of ideas and energy. His latest startup, called Starry, plans to bring low-cost Internet access and simplified set-up and installation of RF those who are under-served or perhaps feel they are paying too much. The basis of the idea is to use millimeter-wave frequencies between local microcell nodes and the individual users.
There would be no need for any sort of wiring or having a cable installer visit: you (or the building owner) would just buy/lease the user-side Starry Beam box (Figure 1) with its integral phased-array antenna, and use it in conjunction with the Starry Point Wi-Fi router (Figure 2); on power up, the system would take care of everything needed for configuration and setup. At least that’s the proposition (see here). Starry Beam radios will sit on top of buildings to capture the incoming signals and transmit them to the Starry Point.
The building’s Starry Beam (Figure 1) and user’s Starry Point (Figure 2) work in a tight pairing to bring mm-wave based Internet to individual users at low cost and with simple setup – at least in theory.
Millimeter waves encompasses a broad range of lightly used wireless spectrum, generally considered to range from 30 GHz to 300 GHz, located between microwaves (1 GHz to 30 GHz) and infrared (IR) waves, with wavelength in the 1mm to 10mm range. Using mm waves is also a technical challenge, especially as you go up in frequency. In principle, there is a lot of available bandwidth – a good thing – but also a world of very tricky RF design, costly components, and unforgiving and often temperamental designs where even a shift in ambient temperature of even a few degrees can spur instabilities and erratic performance due to drifts.
The other problems are that while mm waves have wide bandwidth potential, they also have two other well-known characteristics that can be virtues or vices depending on the application. First, they are effective for unobstructed line-of-sight links, but suffer high attenuation from unavoidable obstacles such as trees, water vapor and rain, leaves, birds, insect swarms, walls, and similar. The Starry proposal therefore will need many base stations (or equivalent) on their build-out infrastructure, which means time, money, local approvals, and more. They also plan to use some sort of dynamic directional control of the beam via phased-array design, to get the best path available at any given instant.
Next: The second thing
Second, mm waves are subject to the laws of physics, of course, and the well-known free-space path-loss equation, with loss L (in dB) = 92.4 + 20log(f) + 20log(R) where R is the line-of-sight distance between transmit and receive points (in kilometers), and f is the frequency (in gigahertz). So there’s considerable loss between transmitter and receiver, with no way around that loss.
I’m interested in this type of product because and mass-market use of mm waves, such as the 77/79GHz used for automotive radar, brings lots of new ICs (silicon and other), experience, expertise, vendor support, tools, and more. The mm zone has been, to a large extent, untapped territory where only a few brave (or perhaps foolish, crazy, emboldened, or desperate) engineers hang out, and mass-market commercial devices are fairly rare (mil/aero applicaoit0nd are another story, of course).
I contacted Starry with three basic questions that engineers would want to know answers to:
What specific part of the millimeter-wave spectrum did they plan on using? (One other story I saw reported it was between 37GHz and 39GHz, but that is not confirmed, nor is the speculation of 1Gbps service.)
What is the maximum transmitting power they are planning to use?
What are the spectrum-use regulatory issues they face?
The answers I got were simple: “those are great questions, we can’t say right now, check with us later.” (There are, however, some technical details in the launch press release here.)
I wish the folks at Starry good luck; I think their intentions are good, the plans are ambitious, and the obstacles are many and deep. It will be interesting to find out more about their technical specifics, their implementation, and their success, or not. I’ll be trying to follow their progress and find out more; any advances they achieve may have benefits for other related and unrelated applications.
What are your views on the viability of mass-market, low-cost, millimeter-wave links for widespread Internet access as Starry plans, or other applications?
Bill Schweber, is an engineer, author and editor and this article first appeared on EE Times’ Planet Analog website.
Related links and articles:
News articles:
EU project takes mm-waves beyond WiGig
Infineon samples 60GHz chips for backhaul
MMICs from Microsemi expand RF semiconductor range
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