White Spaces Database Is Still ‘a Work in Progress’
A key tool for the new RF landscape remains underdeveloped and underutilized
One of the issues on the table at last December’s SVG Summit was the status of the White Spaces databases established in 2012 by the FCC to manage the spectrum available to White Space devices (WSDs) while protecting licensed (and, in some cases, unlicensed) users of the core: TV bands. Currently, four White Spaces database administrators are authorized by the FCC and also accept wireless-microphone registrations: Google, Key Bridge Global, LStelecom/RadioSoft, and Spectrum Bridge. (Other database administrators manage only WSDs.) FCC rules require that the databases be synchronized on a daily basis, but they are actually synchronized every few hours.
Spectrum Bridge explains its mission: “Radios authorized and operating as White Space devices (TVBDs) are required to provide their geographic location, by means of a secure internet connection, to a TV-band–database system authorized by the commission. The database will return a list of authorized channels available for operation by the TVBD for its reported location.”
However, several presenters at the Summit noted that the databases have not been kept up to date. Just as important, awareness of the need to use the databases both for protection from WSDs and as a record of wireless-microphone/IEM/intercom/IFB deployments was significantly lacking among many wireless-microphone users.
The Status Today
Six months on, not much has changed, and that may be reason for continued concern. Henry Cohen, senior RF systems design engineer, CP Communications, and a principal in wireless-intercom manufacturer Radio Active Designs, notes that the databases still contain numerous errors and omissions and that some registrations have simply disappeared. This has contributed to instances of RF interference for some registered users; however, the transient nature of events that use a large number of wireless audio channels, including sports broadcasts, means that many of those occurrences are discovered during rehearsals and run-throughs or become irrelevant once an event or its broadcast is concluded.
“The number of White Space devices is still pretty small, probably less than a few thousand,” Cohen estimates, noting that the category is at the enterprise level and last-mile deployments now and is not yet in the consumer-product realm. “Many, if not most, of those instances of interference were WSD manufacturers demonstrating experimental equipment at their own events.
“However,” he continues, “because of the state of the database, this could become more of a problem if and when White Space devices start to become more numerous.”
Companies including Microsoft and Carlson Wireless Technologies are developing products for the next generation of broadband. Carlson’s RuralConnect radio, for example, would be used as a backhaul to networks, make more open channels available, deploy quickly in difficult terrain, and use less equipment/infrastructure to provide coverage at longer distances.
WSDs rely on location-sensing in conjunction with a license-assignment database, which comprises a list of channels reserved for wireless microphones used in registered events at protected areas, such as entertainment and sports venues. Before operating, WSDs must first access the database to obtain a list of permitted channels in the area. A WSD lacking this capability can operate only under the direct control of another WSD that can access the database.
Joe Ciaudelli, director, spectrum affairs, Sennheiser, notes that no enforcement actions have yet been taken by the FCC, the agency ultimately responsible for monitoring and enforcing spectrum incursions.
“Generally,” he says, “the [FCC] acts upon receiving complaints. Luckily, there have not been any catastrophes thus far, so no major enforcement actions have been necessary. The biggest challenge for wireless-microphone coordinators has been that T-Mobile has effectively accelerated the 39-month transition period in many areas by commencing services faster than envisioned in the FCC 10-phase plan. T-Mobile has been communicating their plans by providing a regularly updated list of counties with target dates when they plan to deploy their services.”
Those regular updates have been very helpful, Ciaudelli says. However, he adds, they can be somewhat broad in their details.
“Providing [input at] a county-level rather than at a metropolitan-area–level service contour does not provide the exacting granularity that wireless-microphone operators truly require,” he explains. “Thus, the White Spaces database system should be the tool used to determine channels available for the day of operation.” It remains, he says, “very much a work in progress.”