Companies urge Industry Canada to prevent white space interference with broadcasting

Industry Canada should allow for unlicensed use of white space spectrum but must take steps to ensure it doesn't interfere with TV signals and other over-the-air transmissions, Canadian and international companies have told the department in consultation submissions. In response to the department’s request in August for public input on non-broadcasting applications for the frequency bands below 698 MHz, Google Inc., Microsoft Co., Nokia Co., Research in Motion Ltd., Rogers Communications Inc., and Shaw Communications Inc. have all called for licence-exempt uses of the white space bands that previously served as buffers between analog television broadcasting frequencies. While many of the companies argue that an effective licence-free white space regime is pivotal to the future Canadian digital economy, several noted the importance of protecting licensed services already operating on neighbouring frequencies. Rogers said it is concerned that signals from white space devices could interfere with over-the-air antenna systems, wireless microphones, and broadcast distribution head ends. “Given that millions of Canadians rely on the high quality of these services, the Department’s WSD policy will need to adequately protect these services from harmful interference caused by WSD,” the company wrote in its submission. The deadline for comments passed Nov. 4. The department received 25 submissions and posted them on its website Tuesday. As one of the country’s largest broadcast distributors, Rogers said Canada’s continued use of some analog over-the-air TV transmitters could mean the department will have to take a cautious approach to protecting those systems, which are more susceptible to interference than digital towers. This means Canada may have to apply more stringent interference guidelines than those imposed for white space devices in the U.S., where over-the-air TV signals have converted to digital. That point was reiterated in a separate submission by the Broadcasters Technical Coordinating Committee, a consultation group sponsored by Rogers and a dozen other Canadian broadcasters. “So far in Canada, the DTV transition has occurred for about 20% of the 750 licensed regular TV transmitters and there is no regulatory timetable for conversion of most of the remaining facilities,” the group said. “Should unlicensed WSD be authorized in the interim, users will need to realize that the spectrum environment in which they will operate will be less stable than is the case in the US.” To guard against such interference with traditional broadcasting systems and other licensed usage of the spectrum, the department should rely on the type of interactive databases used in the U.S. and U.K., several of the submissions said. A geographically-oriented system capable of maintaining intermittent contact with each individual new and incumbent device utilizing the frequencies, such a database would help ensure white space devices were aware of which frequencies were available—as well as which were not—in any given region or location, several companies noted. Companies also noted that such a system could also offer the flexibility of real-time updates to those frequency allocations if necessary and could help to ensure that individual white space devices do not interfere with each other’s signals. “The ability to adjust the database entries also offers the flexibility to adjust performance as deployments and experience develop,” RIM wrote in its submission. “With some extensions of database capability, the database could also be useful in controlling the interference among the white space users. Such capability will provide some reliability and quality of service for the white space users and the equipment and service providers.” Rogers also noted that it is important to ensure that any such database would not be vulnerable to attack or manipulation. “For example, hobbyists could maliciously develop methods to bypass database instructions to obtain exclusive TV channels for their private WSD use,” Rogers wrote. “The sharing of these database bypass methods via the internet could lead to widespread and rapid implementation of the tampering, rendering database control of WSD ineffective in a very short period of time.” One alternative, or potentially supplementary signal protection mechanism the department should not rely on, however, is the use of unproven spectrum sensors, a majority of companies said. At least, they said, not quite yet. Designed to continually scan spectrum frequencies to identify potential sources of interference, spectrum sensing technologies allow white space devices to hop between frequencies to avoid potential interference issues. Considered by the U.S. Federal Communications Commission (FCC) as a potential mandatory requirement for all white space devices during that country’s white space consultation process, the FCC moved away from the requirement at the last minute last September. The FCC appeared to back off the requirement due to reported problems with the technology and difficulties bridging legacy low-powered white space devices (such as low-powered wireless microphones), which do not have spectrum sensing technologies. In its call for submissions in August, Industry Canada asked for comments on whether spectrum sensing standards should be developed “when that technology has matured.” Rogers noted in its submission that spectrum sensors “have a limited ability to detect weak signals and are susceptible to false positives in detecting protected systems.” Other companies agreed. “Taking into account the current challenges and increased complexity in the implementation of reliable sensing, other approaches to protect the incumbents should be preferred,” Nokia wrote. “Sensing may later evolve to a useful took that can complement geo-location, especially in some use cases, but currently it should not be required,” Nokia, an international device manufacturer and patent-owner, added. Companies did not come to a broad consensus on regulating the power at which white space devices could operate or other device-specific technical characteristics. Google and Nokia are arguing for a flexible approach comparable to that taken in the United Kingdom, which has incorporated concepts like location-specific output power requirements and does not lump devices into specific categories with pre-determined technical limits and requirements. Rogers and Microsoft are urging the department to adopt more stringent regulations in these areas—with a nod to measures adopted by the FCC—and which Industry Canada originally proposed to do. Most companies agreed that it is important to harmonize requirements with the U.S. or another significant market to ensure that Canadian users can take advantage of products designed for use in other jurisdictions. “International harmonization of the rules is important in order to facilitate sufficient market and economies of scale which offers best benefits to the users,” Nokia wrote. nkyonka@thewirereport.ca

Companies urge Industry Canada to prevent white space interference with broadcasting

News | November 9, 2011

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