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WiMAX Forum 'clarifies' stance on 3G killer
|30 января 2008|
The WiMAX Forum has denied reports that it is planning a version of the WiMAX standard that would compete more directly with 3G and 4G cellular network technologies.
The industry body denied statements that the Forum is working on an FDD version of WiMAX alongside the TDD version, which is less of a threat to 3G technologies.
“Contrary to any of the unofficial statements made recently, the WiMAX Forum has not made any Board-approved policy or determination of when FDD mobile WiMAX system or certification profiles will be created,” said Ron Resnick, president and chairman of the WiMAX Forum, according to WiMAX Day. Although the Forum is exploring FDD profiles, there has been no decision yet whether to propose an FDD version of the WiMAX standard approved by international telecoms body, the ITU.
Most WiMAX profiles use TDD, sending and receiving data using time slots on one channel, while FDD uses separate channels to send and receive.
However, Paul Senior, chief technology officer of Airspan Networks, "clarified" rather than denied the reports. His company is apparently planning to move attitude on FDD, although the WiMAX Forum will be moving more slowly than he implied.
When Senior spoke of "a WiMAX FDD profile in six months," he was speaking for Airspan, not the Forum, and meant the profile would be stable enough then for Airspan to start building products: “As a WiMAX vendor we can’t develop equipment until a system profile is available. Work in the WiMAX Forum on an FDD system profile for mobile WiMAX is underway and I estimate that it will take about another six months before a vendor like Airspan can start work on developing products – without a risk that things would change significantly,” he told WiMAX Day.
In fact Airspan expects FDD mobile WiMAX products late in 2009, and WiMAX proponents believe they will be important in competing with other technologies in more parts of the radio more spectrum - even though it may be possible to boost TDD's chances by giving it more spectrum than the small amount envisaged in the European band plan proposed by the European body CEPT.
The UK regulator Ofcom prefers to offer spectrum on a "technology neutral" basis so it can be used by any appropriate technology, but the 2.6GHz band will have TDD and FDD services, allocated in other European countries, so licence holders in the UK must follow suit, to allow common products which can roam between countries.
However, Ofcom has suggested increasing the TDD section of spectrum is at the centre of the band, which is straddled by pairs of FDD channels. The CEPT plan puts a buffer of 50kHZ of TDD in the middle of the band, in spectrum which simply couldn't be used by FDD. Each pair of FDD channels has to be separated by 120kHz, and the whole band is only 190kHz wide, necessitating the 70-50-70 split.
It would be possible to change this division in TDD's favour, says Ofcom, making the TDD chunk larger, and perhaps moving to 50-90-50 or further. This would keep the FDD channels widely spaced, and give plenty of common FDD spectrum with the rest of Europe.