Single handedly Microsoft is planning to trigger the use of TV White spaces in the US, after more than 7 years of research, the creation of one of a handful of effective spectrum maps to go inside such systems, and experience it has gained in White Spaces deployments, mostly across Africa.
Microsoft, along with Google, initiated the idea of TV White Spaces in around 2010, and put in preparatory work in the 2 or 3 years before that. The concern at the time were the threats to Net Neutrality, which Google especially saw as a potential block on its future.
This week Brad Smith, Microsoft’s chief legal officer gave a speech and put out the contents as a blog post, saying that Microsoft is creating a Rural Airband Initiative and will invest in partnerships with telecommunications companies to create 12 projects in 12 states over the next 12 months to connect 2 million people. It produced figures which said that 34 million people in the US do not have access to the internet, and that 23.4 million of these were because they lived in rural areas.
The hope is clear cut. If Microsoft leads and gets others investing – both communication operators and local governments – this will make it worthwhile for the White Spaces 802.11af protocol to be put onto future WiFi chips. This is one of a handful of White Spaces protocols worked out by the IEEE, which under the right conditions, using up to 256 QAM OFDM signaling, and multiple MIMO streams, can deliver as much as 400 Mbps shared across all base station users.
The PHY layer in 802.11af is based on the same scheme used in 802.11ac, the most recent WiFi version. But because the propagation path loss is far smaller in the UHF and VHF bands and because the FCC has allowed them to be operated at far higher EIRP levels, the range can be as far as ten miles. If there is more than one channel of TV signals not being used for broadcast, this allows up to four channels to be bonded and if you add 4 x 4 MIMO and MU-MIMO, as has already been launched in 802.11ac wave two, you reach 400 Mbps by leveraging higher modulation schemes and channel aggregation. If the major chip companies see that there will be a market for these devices Microsoft believes low cost 802.11af-based devices would begin to enter the US market in about 24 months and it cites work it has done with Mediatek, for example on a tri-band 5 GHz, 2.4 GHz, and TV white spaces prototype based on the 802.11af Wi-Fi used in a trial in Scotland, in 2015.
Microsoft made it clear that it was not getting into the telecoms business and it wants to act mostly as a stimulant for change.
It has commissioned a white paper from the Boston Consulting Group, which it says shows that there are numerous ways of bringing broadband to rural America, saying that in a population of under 2 people per square mile it’s cheapest to use satellite, between 2 and 200 people per square mile white spaces are the answer and that above 200 people per square mile wireless broadband is best. The entire US rural population in that 2 to 200 population density sweet-spot, could be reached for something just over $10 billion, says Microsoft. Given that it says it will fund projects that reach 10% of those people, it looks like it is plowing in well over $1 billion into this project, perhaps as much as $2 billion – although it clearly is looking for other contributors to match its funding.
The aim is to reach those 23.4 million US rural inhabitants with broadband inside 5 years, at a speed of 25 Mbps or more. The Boston Consulting Group paper makes it clear that this would cost $65 billion using FTTH or $45 billion using satellite only, and between $25 billion and 40 billion using 4G or 5G fixed wireless.
Microsoft said it would also offer digital skills training for people of all ages as part of this initiative and that it will open up 39 of its patents on a royalty free basis to stimulate others to join in. It also called for the FCC to do its bit, asking for at least three channels below 700 MHz to be made available for wireless use on an unlicensed basis in every market in the country, with additional TV white spaces available in smaller markets and rural areas.
Microsoft says it has considerable experience with White Spaces spectrum, having deployed 20 TV white spaces projects in 17 countries that have served 185,000 users.
When White spaces were first discussed Rethink did a report on them in 2012, and at that time many of the functions that will now be taken up by LPWANs were expected to be placed on White Spaces networks including M2M, V2V communication, eHealth and Smart City applications. Now its role is seen as being mostly for rural consumer broadband, including streaming of video.