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FCC Places 2.3 GHz Wireless Communications Service on Agenda

At its upcoming monthly meeting on May 20, the FCC will address the issue of whether its proposed rules will adequately protect satellite digital audio radio system (SDARS) subscribers from interference from mobile WCS devices.

The commission's agenda for the May 20 FCC Open Meeting [PDF] includes the WCS-SDARS Report and Order--"A Report and Order that enables robust mobile broadband use of 25 MHz of spectrum in the 2.3 GHz Wireless Communications Service (WCS) band while protecting neighboring incumbent operations." As previously reported, the FCC claims the proposed rules will adequately protect satellite digital audio radio system (SDARS) subscribers from interference from mobile WCS devices. SiriusXM Radio, which operates in the SDARS band, disagrees.

An article on, Sirius XM Delivers Strong Notice to the FCC describes an independent technical analysis of potential interference to satellite radio listeners.

Sirius XM Radio submitted a study prepared by Dr. Theodore S. Rappaport of the Tellsite Corporation. Rappaport is the William and Bettye Nowlin Chair in Engineering at the University of Texas at Austin, and the founding director of the Wireless Networking and Communications Group at the UT Austin campus.

The study, according to Satwaves, "proves beyond any doubt, that the FCC Staff proposal will cause 'crippling interference' to the Satellite Radio service, and 'a decrease in availability that renders the service commercially unacceptable by broadcast consumer standards."

The study, Technical Analysis of the Impact of Adjacent Service Interference to the Sirius XM Satellite Digital Audio Radio Services (SDARS) and available from the FCC ECFS, indicates that other broadcasters have much greater protection from adjacent channel services than what proposed by the FCC for SDARS.

Engineers will be interested in the analysis of the causes of adjacent band interference, including out-of-band emissions from the adjacent transmitter, receiver overload, and spurious signals generated by intermodulation. The proposed relaxation of out-of-band emissions and power limits from WCS transmitters is highlighted as a major source of interference. The study notes that while SDARS receivers were designed based on FCC rules adopted 13 years ago, they still perform better than today's common broadcast receiver types.

Broadcasters may be tempted to ignore SiriusXM Radio's concerns, as SDARS is a competitor to terrestrial broadcasting. However, there should be concern that the FCC is willing to relax current interference standards to promote broadband, even if it would cause significant harmful interference to reception of satellite radio and threaten its continued existence, as claimed in the SiriusXM study.

Will the FCC take the same approach when it comes to operation of wireless devices in the TV broadcast band?

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.