New report clarifies issues surrounding terrestrial use of satellite spectrum

A new report recently released by Industry Canada puts to rest interference issues surrounding the implementation of an ancillary terrestrial component (ATC) using L-band satellite spectrum. Prepared by COMTEK Associates, the 154-page document analyzes an application by Mobile Satellite Ventures LP (MSV) and related comments submitted by Inmarsat Ventures PLC and Transport Canada regarding the deployment of a terrestrial in-fill network that would improve coverage in urban areas of the country. Last October, the department launched a consultation on using mobile satellite spectrum in a terrestrial environment following the application by MSV (DGTP-009-01; RoW, Nov. 13/01). In its application, MSV indicated that potential interference issues could be mitigated. But Inmarsat responded that values used by MSV were incorrect and that interference from the terrestrial network would be unacceptable. The department contracted COMTEK to dispel the apparent inconsistent interference calculations by both companies. In its report, entitled Use of Mobile Satellite Spectrum to Provide Complementary Terrestrial Mobile Service to Improve Satellite Coverage, COMTEK states that both Inmarsat and MSV attempted to cloud some of the issues by either using too low or too high risk calculation factors. In the report, the engineering firm presents the facts using more standardized figures and by reviewing the many parameters, such as power output to subscriber distribution to shielding. (For the purposes of this article, however, Report on Wireless limits its analysis to inter-system interference.) COMTEK indicates that MSV’s attempt to use the six per cent level of interference as a benchmark is outdated and is routinely surpassed today due to the close spacing of satellites. "Consequently, the theme of frequency coordination efforts today is not whether or not a new entry can meet (the six per cent) criterion … but rather how to make accommodation for a new satellite entry without incurring an inordinate amount of system interference," COMTEK writes in its report. "In our view, it is certain, however, that ATC interference contribution is not as trivial as depicted by MSV, nor is it as horrendous as depicted by Inmarsat," COMTEK concludes. Competitive landscape likely to change in future COMTEK notes that prior to analyzing potential interference problems with the deployment of an ATC, it had to make certain presumptions about the competitive landscape. The company assumed that there would be four MSS operators implementing a terrestrial in-fill network: MSV in Canada and the United States (two separate companies due to current restrictions on foreign ownership of telecoms), ICO Global and Inmarsat. While MSV and ICO’s inclusion in the list is not a surprise since the two companies have applied to use satellite spectrum in a terrestrial environment, Inmarsat’s inclusion is. In its comments to Industry Canada, Inmarsat had expressly noted that its business is viable as is and doesn’t need to implement an ATC to be successful. COMTEK believes otherwise. Among the many reasons it provides, the company states: "ATC enhancement, by virtue of extending the service reach to more densely populated areas (suburban, urban), will create the necessary inertia to provide a ubiquitous service with returns necessary to continue and expand operations and services. ATC operation will reuse the same MSS spectrum with no effect on the available L-band spectrum and no undue interference on other MSS operations." While the engineering firm notes that the whole debate could become moot if government regulators find there are still major compatibility problems, a favourable conclusion would have a dramatic effect on the competitive landscape. "Under this scenario, we find it hard to visualize a future for stand-alone MSS operations in North America," states the report. "Specifically, a future without Inmarsat as an active user of ATC is highly unlikely."

New report clarifies issues surrounding terrestrial use of satellite spectrum

News | November 25, 2002

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