Japan’s National Institute of Information and Communications Technology says it has developed “the world’s first Wi-Fi prototype” for TV band white spaces based on IEEE’s 802.11af draft specification.
It works in the 470-710 MHz spectrum band — U.S. TV channels 14 through Ch 50. The OFDM PHY mode can take a single 6 MHz TV channel and operate with transmission power of 20 dBm (100mW).
Cognitive radio chips are used by the two major white space standards groups; IEEE 802.11af and IEEE 802.22. The maximum possible data rate per 6-MHz channel ranges from 18 to 22 Mbits/s. The 802.22 spec was originally designed for fixed rural use, operating on 6 MHz wide channels. The 802.11af standard can aggregate channels into 5, 10, and 20 MHz bandwidths for both mobile and fixed devices.
IEEE 802.11af TG was formed in 2009 under the IEEE 802.11 WG. The target is to define modifications to both the 802.11 PHY and MAC layers to meet the legal requirements for channel access and coexistence in unused television frequencies.
Last month, the IEEE 802.11af Task Group released its first stable draft standard. The resulting prototype verifies the physical and medium-access control layer design of the draft specification, NICT said. The prototype works with a white-space database developed by NICT.
The prototype also works with a Registered Location Secure Server—defined in the 802.11af draft standard—to avoid interference with other white-space users (wireless mics, for example).
TV frequencies can penetrate walls and multiple 6 MHz TV channels can be ganged together to make it more competitive with 20 MHz WiFi channels.
“We are now working on the next revision to implement the full physical specification and new features come along with the regulatory updates,” they said. “We are also looking for the opportunities for technical transfer.” NICT expects the IEEE 802.11af standard to be completed by 2014.
Large cellular providers may buy up most of this spectrum. Where television channels are not auctioned off (primarily in rural areas), unlicensed White Space radios may enable WiFi-like connectivity. The FCC will implement 6MHz “guard bands” to protect revered group owners.
The trickle down economics of telecom monopolies and media consolidation will long endure if White Space competition can be killed off by Congressional leadership.
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