There has been a lot of regulatory activity since the FCC adopted its revised White Spaces rules in 2010, but not much marketplace activity. The FCC allows unlicensed low power transmitters to operate on “White Spaces”—TV band frequencies that are not being used by TV stations or other licensed transmitters.
The FCC Rules prescribe two general operational methods for TV Band devices (TVBDs) to prevent interference. They can sense their location, connect to a database and report their location, and the database will tell them which TV channels are available. Or they can analyze the signals they receive, and determine which channels are available. But the FCC’s spectrum sensing requirements are very stringent, so all the activity up to now has been with geo-location/database devices.
The databases must contain the locations of all TV stations, because the rules prohibit operation of TVBDs within certain distances from TV transmitters. But they also must contain locations of other protected services, such as licensed wireless microphones, land mobile systems that operate on TV channels 14-20 in some areas, and off-air TV receive sites. For example, cable TV system sites that receive TV signals off-air are protected.
Numerous companies have applied to the FCC for approval as database administrators. To date, two have been approved, Spectrum Bridge and Telcordia. Others undergoing the approval process include Google and Key Bridge. In addition, the FCC itself is operating a registration database for venues where large numbers of unlicensed wireless microphones operate. These might include sports arenas, theaters and churches.
As of late September 2013, four companies have received FCC authorizations to sell TVBDs. The normal FCC equipment authorization process for radio transmitters requires the manufacturer to make measurements of parameters such as transmitter power, occupied bandwidth and out-of-band emissions, and to submit those measurements to the FCC or an FCC-designated test lab for review. But there is nothing normal about approval for these TVBDs. Not only must the radio parameters be measured, but the process for interacting with the database must be specified and tested. And then product samples must be submitted to the FCC Labs, where FCC engineers do their own testing.
The four companies with approved TVBDs are Koos Technical Services (KTS), Adaptrum, Redline Communications and Meld Technology. All of the devices so far approved are “fixed” as opposed to portable, and require installation by a professional installer.
KTS TVBDs support a data rate of 3.1 Mbit/sec in a 6 MHz TV channel, with a range of up to 2 miles. Longer range, up to 10 miles, can be achieved with a lower data rate. Some applications, according to KTS, include perimeter security, environmental sensor monitoring and closed circuit TV. KTS also sells higher-power radios that operate on licensed frequencies.
Adaptrum has announced a commercial trial of its TVBD in Nottoway County, Va., to demonstrate how this technology can help bring broadband service to underserved populations.
The Adaptrum device can achieve data rates as high as 12 Mbps, depending on modulation and distance (i.e., received signal strength).
Adaptrum envisions portable TVBDs built into tablets and smart phones, in the same way that Wi-Fi transmitters are now deployed.
Redline sells a number of point-topoint microwave products to cell phone companies for cell site backhaul and to other industrial customers such as oilfield operations networks. The Redline TVBD uses OFDM technology and time division duplexing for a two-way link.
Redline claims it can operate at speeds of up to 100 Mbps over distances as great as 20 miles, and at slower speeds can reach distances up to 35 miles.
Meld Technology makes products for broadcasting ATSC video and audio signals. The Meld TVBD is intended for use indoors, within a store or shopping mall. It could, for example, broadcast a TV program to all the TV floor models on display at a Best Buy store. It could be used to transmit digital signage information.
The range is 360 to 1,000 feet.
The Meld product will be used indoors where GPS reception might be unreliable. So Meld had to ask the FCC for a rule waiver to employ other procedures. The FCC imposed the following conditions: The Meld devices must be professionally installed on a fixed mounted rack, and the geographic coordinates must not be changeable by the user; they may only be used indoors within retail stores and not offered for sale to the general public; and they must contact the Spectrum Bridge database at least once every 30 minutes to obtain an updated list of available channels.
Other waivers have been granted, as well. For example, cable TV receive sites are protected out to a distance of 80 km from a TV station transmitter. But Comcast received a waiver to protect sites 85 and 88 km out. And Allegiance Communications, a small Midwest cable company, received a waiver for a Kansas site that is nearly 180 km from the TV transmitter.
In summary, rollout has been slow. Is this the next Wi-Fi? It’s way too soon to tell.[See also: FCC OKs Adaptrum + Google white space combo]