TV White Space Update

I believe TV White Space, while unlicensed, is a perfect example of a way to test out new spectrum management technologies beyond the lab and out in the real world to make sure it works the way it should, to improve it, and to demonstrate it could be used effectively not only for white space applications, but for other types of spectrum management as well.

We recently completed a white paper about the new TV White Space unlicensed spectrum. This spectrum lies between the assigned TV channels in each area of the country and the FCC has authorized some test and beta networks to help discover what is needed to finalize the rules. TV White Space can only be used for unlicensed broadband where there are gaps in spectrum between TV stations in a given area, and we are not only talking about major broadcast stations, but college, university, and religious stations as well.

Further, in many major metro areas, some of this white space is already being used for land mobile radio systems such as fire and police, and other portions are being used for wireless microphones, although the FCC has ordered that all of these be turned off by this past June. Practically speaking, many wireless microphones are used by small organizations and others who don’t even know what portion of the spectrum their mics are working in and have probably not even read the FCC mandate. But what this basically means is that in the top 20+ U.S. markets there is limited available spectrum for high-power TV White Space use, though there is available spectrum for low-power use for mobile TV White Space devices. There is plentiful high-power and low-power spectrum in the smaller urban areas, and of course, in rural America.

White space spectrum, where available, is located from TV channels 2 through 51, and the rules mandate two different power levels for operation depending on the portion of the spectrum and how many channels of white space are available (each TV channel occupies 6 MHz of spectrum). Generally speaking, it takes 3 unused sequential channels to be able to use high-power systems. The power limits and the fact that these frequencies are lower in the RF spectrum band than our existing Wi-Fi unlicensed allocations means that TV White Space systems can be used over longer distances than Wi-Fi (2-3 miles per cell site and even farther in point-to-point applications). The cost of the devices is expected to be on a par with today’s Wi-Fi devices, and it appears as though the air link will be 802.11 (the Wi-Fi standard), which will enable Wi-Fi vendors to build these devices and introduce them into the market quickly.

White space systems will NOT be mobile in nature, that is, they won’t compete with wide-area broadband systems for true mobility. They will be more like Wi-Fi that is nomadic in nature, providing broadband services to fixed and portable devices. Data speeds will be in the multi-megabit per system range and there will be many different types of systems (see below).

The FCC is trying to finalize the rules for TV White Space and one of the requirements is that the systems be smart enough to be able to operate on empty TV channels and that the devices or the network that controls the devices is smart enough to know which channels are available in any given area. To this end, there are two different approaches being taken by those deploying experimental systems.

One proposed method of tracking what channels may be used in a given area is to build “smarts” into each device or, in today’s parlance, to provide cognitive radios that can scan the spectrum and find the open channels on which to operate. The competing method of determining the proper channels is to employ master databases that are populated with all of the needed information and do not, therefore, require the same level of smarts in each radio. Systems using both types of technology have been deployed, but in our estimation, there are more advantages to the second system using intelligent databases.

The first advantage for consumers is that the cost of the devices will be lower since systems that are deployed using intelligent database technology will not require that each radio be truly “smart.” The second is that those that want to build wireless ISP systems to offer broadband to areas where there is no broadband available today can build these systems and subscribe to the database service to ensure that their systems will meet the FCC’s requirements to not cause interference to TV receivers. There are a number of companies that have or are in the process of deploying systems using both of these technologies and this will enable the FCC to find out if one or both of these methods of interference control is suitable for the systems.

TV White Space systems will be relatively inexpensive and can be used for a number of different forms of broadband communications. They can be built where there is no real return on investment for wide-area wireless networks and where distance rules out the use of Wi-Fi access points. (Wi-Fi muni networks were all the rage a few years ago, but most have gone dark because of ongoing interference issues and because they turned out not to be economical to build and maintain.)

We will see TV White Space systems deployed to provide point-to-point broadband services for video cameras, machine-to-machine devices, and broadband to the home and office. We believe that most of the white space systems developed for broadband to the home will end up being a mixture of white space to the home or office, received by a device that will translate the white space signal into Wi-Fi, which will provide access into the buildings. Some within the TV White Space community believe that white space wireless modems will be built into notebooks and even smartphones over time, but the first deployments will be designed to take advantage of the fact that Wi-Fi is already embedded into most computing and wireless devices.

White space systems will also be used as true last-mile or last-several-mile systems in order to extend broadband coverage where it has been too expensive to deploy. For example, a town that sits a couple of miles from a major highway and has no access to broadband might find that since there is fiber along the highway, a white space point-to-point system can be used to complete the link between the town and the fiber, and then distribute signals within the town using a combination of white space and Wi-Fi technology.

Because this spectrum is available as unlicensed spectrum, there is no cost involved in obtaining the spectrum for use, and if the equipment costs are as reasonable as they appear they will be, the availability of this spectrum could mean a rebirth of local wireless Internet providers as well as the ability for cameras and other devices to be deployed where it had not been economically feasible. One interesting use of TV White Space systems might be on a university campus to provide additional camera feeds, and to provide broadband to each building on campus without the need or expense of running wires or fiber to each building.

TV White Space opportunities will be plentiful in many portions of the country where economics of broadband deployment have not worked before, but not in the top 50 or so metro areas. One advantage for wireless ISPs is that in many cases they won’t have to compete with three or more existing broadband services providers, and while the total available market might be smaller than in metro areas, with less competition, the return on investment could prove sizable.

There is another aspect to the deployment of TV White Space systems that could have a positive impact on the way we manage other spectrum resources. As you know, spectrum is a finite resource and while new technologies are helping us use it more efficiently, the technology being developed for TV White Space systems—intelligent networks with database technology—can be used for other portions of spectrum, perhaps even licensed spectrum, to assist those who need to be able to share spectrum with others and minimize interference issues.

I believe TV White Space, while unlicensed, is a perfect example of a way to test out new spectrum management technologies beyond the lab and out in the real world to make sure it works the way it should, to improve it, and to demonstrate it could be used effectively not only for white space applications, but for other types of spectrum management as well. I have felt for many years that we need to have more flexibility to test new technologies for wireless in real-world situations before deploying them into systems where if they don’t work correctly they could do more harm than good.

TV White Space is an interesting area to watch. It not only offers opportunities to provide broadband access where we have not had it before, it also has the potential to bring new and proven tools to other portions of the spectrum moving forward.

Andrew M. Seybold

Downloadable PDF of white paper: Intelligent Spectrum Management White Paper