Television (TV) White Space consists of unoccupied channels in the very high frequency (VHF) and ultra high frequency (UHF) bands. Federal Communications Commission (FCC) regulations have made this spectrum available to unlicensed radio devices operating under specific rules. Commercial products operating in this spectrum have recently become available. This report presents the results of testing TV White Space for utility communications network applications.
The TV White Space (TVWS) spectrum is “prime real estate” in terms of utility communications. The VHF and UHF frequency range provides longer range than higher microwave frequencies. The 6 MHz wide TV channel supports broadband data communications, compared to the narrow voice channels that are historically allocated for utilities in the VHF and UHF bands. Standards addressing TVWS are completed or in the development process, including Institute of Electrical and Electronics Engineers (IEEE) 802.22, IEEE 802.11af, IEEE 802.19.1, and IEEE 802.15.4m. Equipment vendors have conducted some tests and trials, but none focus specifically on utility and smart grid applications.
Utility and smart grid communications applications have a unique set of requirements. TV White Spaces present an interesting opportunity, but there are many questions to be answered before utilities can engage in their own pilot programs. The results of this testing will provide information that can become a valuable asset to utilities considering the use of TV White Space in their future communications systems.
To determine the availability and applicability of TV White space for utility communications.
To determine, where available, what performance characteristics the TV White Space system offers.
To determine the place TV White Space communications have in a utility’s communications infrastructure.
The research focused on the performance characteristics and reliability of radio links operating in the TV White Space spectrum. Testing was conducted in two geographic areas, Overland Park, Kansas, and Knoxville, Tennessee. TV White Space is usually not available in larger urban areas (because all channels are occupied), so testing in suburban settings was anticipated to provide a realistic assessment of the types of environments that could potentially be used by utilities.
In each licensed location, a fixed base station was used. Testing of terminal devices was conducted at various distances between base station and terminals. System performance was measured in different terrains and environments.
The scope of this Technical Innovation (TI) project was limited to testing using products from one vendor. A relative performance comparison between products was not the intention of the project. Rather, it was to evaluate the spectrum and technology in a general sense.
The throughput and latency (100s of Kbps, around 100s mS ping) are adequate for many utility applications. The 4 W EIRP power limit is relatively low in the context of commercial wireless equipment. Although it is higher than is allowed in unlicensed bands such as 2.4 GHz and 915 MHz, it is still a significant factor in the system’s range. The range was 3 to 5 km under the conditions tested. When the antenna is installed on a tower, distances of greater than 10 km appear to be possible (based on simulation).
Applications, Value, and Use
Channel availability is the biggest concern for utility deployment of TV White Space technology. The channel availability is fairly good today, except in large cities. Initial analysis indicates that channel availability may be quite limited after the 600 MHz auctions in 2016, except in very rural areas. Given the current rules and constraints, and the current plans for auctioning the channels in the 600 MHz band, it seems unlikely that TV White Space will become a widely adopted utility telecommunication solution. Although it is not a universal solution, it could still represent a viable option in some areas.