Google’s 2.5 GHz Experimental License Application Raises Eyebrows

Several Web news outlets have reported about Google’s application for an experimental license to use some 2.5 GHz BRS/EBS spectrum in Mountain View, Calif., Location.

I used the FCC Office of Engineering and Technology’s Experimental Licensing System Generic Search to pull up the Google application and found that it’s still pending, so a call sign hasn't been granted.

There is surprisingly little technical data in the application. The FCC had to ask for more specific information before it would consider the application, and while there’s a list of transmitting equipment, manufacturers and model numbers are listed as “confidential.” In adding up the entries, it seems that perhaps as many as 60 transmitters are planned. Google said the equipment is not capable of station identification, pursuant to FCC Rules Section 5.115.

Directional antennas are proposed, but no patterns were attached to the application and the orientations are not specified. The application specifies operation in the 2524-2546 MHz band with power levels between 60 mW and 76.83 watts ERP. Use of the 2567-2625 MHz band is requested at the same power levels.

What I found surprising was the 20M0F9W emission designator. Google specified F9W. This was a popular emission type for “Twinstream” BAS fixed links until the FCC stopped accepting it. Using the tables in Section 2.201 of the FCC rules to decode the designator, it’s a 20 MHz-wide composite signal using frequency modulation with “one or more channels containing quantized or digital information, together with one or more channels containing analogue information.” The final “W” indicates a combination of information types is transmitted, which could include data transmission, telephony, television and even telegraphy and facsimile. D7W or W7D are more commonly used for digital transmissions.

In response to the FCC’s request for more information on the ERP and bandwidth on the different transmitter model, Google supplied data on the two proposed base station transmitters and four of the five mobile unit models– information was not available from the vendor for the fifth experimental model.

The FCC also raised concern that Google didn't indicate it had permission from the EBS/BRS licensees in this band to use this spectrum. The company responded by stating: “Google understands that a grant will be conditioned on coordination with affected licensees, and is engaged in discussions to satisfy that obligation.”

For a less technical overview of the Google application as well as some suggestions on what Google might be planning to do with it, see Phil Goldstein’s article Google wants to experiment with wireless networks using Clearwire spectrum at

Doug Lung

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.