Google, Microsoft keep pushing for unlicensed use of 600 MHz band

Google (NASDAQ: GOOG) and Microsoft (NASDAQ: MSFT) are keeping up the pressure as they lobby the FCC to include technical rules enabling the use of unlicensed devices in the 600 MHz broadcast TV spectrum that will be auctioned next year.

According to an ex parte filing, on Sept. 17 and Sept. 18, several Google and Microsoft representatives made the rounds at the FCC, speaking with numerous FCC leaders and staffers, including Commissioner Jessica Rosenworcel; Julius Knapp, chief of the Office of Engineering and Technology; Gary Epstein, chair of the Incentive Auction Task Force; and John Leibovitz, deputy bureau chief of the Wireless Telecommunications Bureau.

Google and Microsoft are trying to convince the FCC to adopt technical rules that would permit the creation of three TV white space (TVWS) channels in the 600 MHz band. Though the ex parte letter specifies three "801.11af" channels, it apparently actually refers to the IEEE's 802.11af standard, which provides a mechanism for adding TV white-space services to IEEE 802.11 WLAN devices and supports operations in unused TV channels in the VHF and UHF bands.

Google and Microsoft suggested that the FCC should enable the operation of Mode 1 and 2 personal/portable unlicensed devices in the duplex gap, lower guard band, and on channel 37. In addition, they ask that spectrum databases for the 600 MHz band be allowed "to determine unlicensed device operation based on the device's location-accuracy capabilities so that devices with better accuracy can operate in appropriate locations, rather than preserving the current rule, which mandates that all devices establish location within +/- 50 meters."

The companies also asked the commission to permit unlicensed systems to determine areas where devices  may operate in the broadcast band by using both the database and sensing approach, plus let Mode 1 and 2 personal/portable unlicensed devices operate below channel 21.

Further, they suggested the commission let databases use the Longley-Rice propagation model to calculate interference protection for broadcast operations. That model "is based on electromagnetic theory and on statistical analyses of both terrain features and radio measurements" and "predicts the median attenuation of a radio signal as a function of distance and the variability of the signal in time and in space," according to the Institute for Telecommunication Sciences (ITS).

At its open meeting on Sept. 30, the FCC will consider a Notice of Proposed Rulemaking to revise rules for unlicensed operations in the TV bands and new 600 MHz Band, including fixed and personal/portable white space devices and unlicensed microphones. "The proposed changes and new rules are intended to allow more robust and spectrally efficient unlicensed operations without increasing the risk of harmful interference to other users," according to the commission.

The FCC will also consider a separate Notice of Proposed Rulemaking "to address the needs of wireless microphone users, while recognizing that they must share spectrum with other wireless uses in an increasingly crowded spectral environment."

In its Report and Order regarding the 600 MHz band plan, issued in May 2014, the FCC included "technically reasonable" guard bands--including a uniform duplex gap of 11 MHz to separate uplink and downlink spectrum--which can be used for unlicensed services nationwide. In addition, unlicensed devices would be able to use 6 MHz at channel 37 in locations where the channel is not already in use, "subject to the development of technical rules to prevent harmful interference" to the incumbent Wireless Medical Telemetry Service and Radio Astronomy Service, the commission said at the time.

The FCC said it expects there will be at least one channel not assigned to a TV station in all areas at the end of the repacking process, and this "naturally occurring" TV white-space channel will be allocated for shared use by unlicensed devices as well as wireless microphones. Further, any other unused TV channels following the incentive auction will be available for unlicensed devices as well as wireless microphone use.

For more:
- see this FCC filing

Related articles:
Google revamps its TV white-space database system ahead of 600 MHz auction
Google, others applaud FCC's plan for 600 MHz unlicensed spectrum
Rumor: FCC preparing to set aside channel 37, other 600 MHz spectrum for unlicensed use