In a possible attempt to seek middle ground on the issue of white space usage, Motorola has offered a two-tier scheme to allow both high-power devices (up to 36 dBm EIRP, for applications such as rural broadband or other large-area operations) and low-power (up to 10 dBm EIRP, for consumer-type devices).
Motorola presented a 43-page “white paper” to the FCC on white spaces (aka interference zones) Thursday. Broadcasters have urged a cautious approach to the use of the spectrum in unused DTV channels for fear of interference.
The white paper expands on a proposal offered by Motorola in late September, discussed by TV Technology columnist Doug Lung in his RF Report Oct. 5
Motorola’s plan for the high-power devices would include spectrum-sensing technology and use of a geolocation database to avoid interference with DTV signals. The plan would also support of the type of beacon detection technology (defined by IEEE 802.22.1) to allow higher-priority users to control white space devices in a limited area. Motorola says this would protect the signals other devices, such as wireless microphones.
Motorola says these mechanisms, which include the possibility for later adjustments to the regulations, should be sufficient to allow mobile high-power devices, not just fixed devices.
For lower-power consumer devices, Motorola said sensing and beacon technology should ensure protection of other signals. The company’s pitch would also keep the low-power devices off Channels 14-20 to provide protection for other mobile systems whose signals are harder to detect than broadcast signals.
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