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12/09/2008FCC White Spaces Decision: Opportunities, but a Few Questions
On November 13 the FCC released its long-awaited decision establishing rules for unlicensed usage of unoccupied television broadcast spectrum, also known as the “TV white space.” The decision undoubtedly will lead to new spectrum opportunities for public and private entities interested in providing wireless services, particularly broadband access. Yet, much work remains to be done before unlicensed usage of the TV white space becomes a reality. Interested parties should obtain a copy of the FCC’s decision (http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-08-260A1.doc) and monitor the FCC’s activities closely in the coming months. With certain limitations, the FCC’s new rules permit use of both fixed and portable unlicensed devices in the TV white space. Due to the spectrum’s superior propagation characteristics, the FCC envisions that fixed usage may include wide-area wireless broadband networks and other long range applications (e.g., backhaul). Possible portable devices include, for example, laptop computers, PDAs, wireless in-home networks, home video/theater equipment, wireless cash registers, and wireless headphones. All devices may used TV channels 21-51, except channel 37. Channels 2 and 5-20 are reserved for fixed devices exclusively; however, channels 14-20 will be unavailable in certain metropolitan areas where they are used for land mobile services. In all cases, an unlicensed device may not use a channel occupied by an analog or digital full power or low power (LPTV) station; Offshore Radiotelephone Service (which uses channels 15-17 in the Gulf region) and Broadcast Auxiliary Services (for example, wireless microphones and wireless assist video devices). To avoid potential interference, fixed devices may not use channels that are immediately adjacent to channels occupied by television stations. Portable devices may use such adjacent channels, but at a lower power limit. Fixed and portable devices must be equipped with certain capabilities that permit them to identify where open TV channels are available. Specifically, all devices (except for ‘client” portable devices that are controlled by another fixed or portable device) must have geo-location capabilities and the ability to access an Internet-based database that lists where TV channels are already in use. The devices also must be able to identify their own locations within 50 meters. The FCC has established a procedure by which it may authorize use of devices that avoid interference through spectrum sensing capabiliies rather than the geo-location/database approach. Power limits for fixed devices are those that generally apply to many outdoor unlicensed facilities, i.e. maximum power of 1 watt, with a maximum EIRP of 4 watts. Fixed antennas must be no more than 30 meters above ground level. The maximum permitted power level for portable devices is 100 milliwatts, but is reduced to 40 milliwatts when the device is operating within the service are of a television station operating on an immediately adjacent channel. The above only scratches the surface of the various complexities in the FCC’s new rules, all of which are discussed in greater detail in the FCC’s decision. There are, however, some near-term issues of note: No matter how you slice it, it’s still unlicensed spectrum. Unlicensed operation means no interference protection for the unlicensed device, and an obligation to cease operation when causing interference to an unlicensed facility. Wireless operators should examine this issue carefully before investing significant resources in TV white space operation, particularly if emergency or other time-critical services are contemplated. Exactly how much white space is out there? No one really knows right now, and thus potential users of the white space should not make any broad assumptions about where they can operate. More information will become available once the FCC selects the entity that will operate the database. At this time, however, it I not clear when the FCC will begin the selection process, or when the database will be up and running. There is some indication that the FCC would like to have the database in operation by the DTV transition deadline (February 17, 2009), but that may not be realistic. Who is making the devices, and where can I get one? TV white space devices cannot be made available commercially until they are certified by the FCC. However, industry and the FCC must complete certain tasks before the certification process can even begin (for example, an industry standards body will need to develop standards for how fixed devices will transmit identifying information (e.g., the geographical coordinates of the location where the device is operating). Accordingly, it is too early to predict when a significant number of white space devices will clear the certification process and make their way to the shelves of local retailers. What types of unlicensed white space services are feasible under the power and antenna limitations in the FCC’s rules? Wireless operators should have a good working knowledge of the Commission’s Part 15 rules for unlicensed devices, and how they apply in the TV white space. Note that while those rules do give operators some leeway in expanding the range of their signals by using narrower beamwidths, such operation may not be technically feasible for certain wireless services. Again, those interested in operating in the TV white space should stay abreast of the FCC’s activities and consult with their engineers and/or legal counsel for further clarification of how the new rules work, and what opportunities may become available as those rules are implemented over time.
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