Work begins next month on one of the IEEE s most important, and most politically charged, projects, to devise an intelligent air interface (cognitive radio), that can tap into unused television frequencies, reports Rethink Research.
This will be the standard for fixed wireless systems that use cognitive radio techniques to switch automatically to a clear area of the band, and to avoid interfering with other occupying devices.
The IEEE is particularly focused on systems for the underused US television spectrum between 54MHz and 862MHz, which is being vacated (reluctantly) as broadcasters move to digital. The FCC proposes to open up 300MHz of this UHF/VHF spectrum as its first major test of software defined or cognitive radios. It would permit fixed access systems transmitting up to 1W in power and portable devices up to 100mW.
Vendors don’t want UHF networking to be entirely reliant on GPS or a centralized Web service like the FCC envisions, explains Information Week. The IEEE is lobbying to allow an alternative based on smart radio, which would mean APs or clients that automatically scan for unused frequencies to determine which can be used as their own.
The FCC database could give 802.22 too little bandwidth, because not everything that’s been licensed is actually used. Smart 802.22 may take too much, because a device’s measurements can only cover signal strength at a single point in space and time. The final 802.22 may need to use both methods, say industry observers.
The FCC requires that 802.11a radios using the mid (5.4 GHz band) detect radar signals and avoid interfering with them. Startup Adaptix announced the launch of a broadband wireless product line (point-to-multipoint, non-line-of-sight, last-mile access and backhaul solutions) that is said to use SDR and is based on 802.16e.
This year, the 802.22 group was designated to develop a standard. The 802.16 faction argued that cognitive radio work should be under its tent, rather than in a separate group, but was defeated. So the quest to turn 802.22 into a real 700 Mhz alternative is underway.
WiMAX is flexible in its channel sizes and can use the 6MHz width of the TV channels. Below 900MHz, range could be three times that in 2.4GHz, reducing the number of base stations required well below 3G s requirements, making mobile WiMAX clouds an even stronger proposition against cellular. Both in licensed and unlicensed modes.
The first focus of the 802.22 effort, reports the Rethink report, is on rural fixed wireless access. “This is ideal spectrum for deploying regional networks to provide broadband service in sparsely populated areas,” said Carl Stevenson, interim chair of the new group, in a statement. Our goal is to equal or exceed the quality of DSL or cable modem services, and to be able to provide that service in areas where wireline service is economically infeasible, due to the distance between potential users. In fixed networks, 802.22-based technologies could achieve 40 kilometer range and complement local Wi-Fi and 802.16 backhaul, he said.
The 802.22 leaders, apparently, don’t want their work too closely identified with 802.16 (WiMax). But, in the view of Rethink Research, it would be a serious blow to the vision that the FCC is putting forward, if the cognitive radio work becomes bogged down in politics and radio turf wars.
Related DailyWireless articles include McCain’s 700 MHz Bill, IEEE Cat Fight on TV, Roger That WiMan, Selling Out DTV, Public Safety Vrs the Broadcasters, Multicasting, and U.S. Gets MobileTV via DVB-H.
The official 802.22 Press Release (Word doc) is available, after the jump, in html:
