WiMAX & satcomms square off over spectrum

06 Jul 2007
00:00

Satellite players are calling on their brethren to be more proactive in educating government regulators on the interference issues generated by broadband wireless access (BWA) technologies like WiMAX that seek to use extended C-band frequencies.

As regulators start making plans to issue BWA licenses, WiMAX vendors have been lobbying market by market to reassign to 56% of frequencies below 5 GHz for BWA licenses, particularly in the 3.4- to 3.7-GHz extended C-band range used by satellite operators, to give them extra capacity.

The problem, says AsiaSat general manager of engineering Barry Turner, is simple: WiMAX and satellite TV cannot co-exist in the C-band.

"There is no disagreement on this," Turner says. "Everyone from the ITU to the WiMAX Forum knows that if you deploy WiMAX base stations anywhere in the C-band, you will generate enough interference to block out TV signals."

Turner also says that technical solutions proposed by the ITU's IMT-2000 group (which covers WiMAX) - such as exclusion zones and minimum distances between base stations and earth stations - simply won't work.

Consequently, he says, "regulators have to decide who gets to use C-band - WiMAX or satellite. Someone has to lose."

And time is getting short. Regulators in Australia, India, Indonesia, Malaysia, the Philippines, Singapore, Taiwan and Thailand are already examining the issue, while this year's World Radio Conference is expected to issue a decision on C-band. Turner worries that the WRC could decide that sharing C-band is acceptable if it's limited to specific countries.

BWA and WiMAX proponents have argued to regulators that extended C-band is often underutilized by satellite operators, and that there's no harm in reallocating some of it for wireless broadband. There's also the attraction of more revenue for the government from the resulting license allocations, and the prestige of enabling "4G" services early in the game.

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