The US Federal Communications Commission telecoms regulator has finally opened up the long awaited 3.65 GHz spectrum in the US, and immediately created a queue of (mostly WiMAX) technology vendors and would be broadband operators, that want to use the ‘light licensed’ spectrum to offer services in the US.
The FCC wants rural communities to get the benefit of long range broadband facilities from the scheme, but has dampened WiMAX equipment makers ardor by insisting that the spectrum has a detect and avoid protocol so that multiple services can use the spectrum at the same time.
The FCC said operators have to register with the regulator and obey anti-interference and good neighbor policies. Similar schemes are used elsewhere, for instance by the UK in 5.8GHz.
The main source of controversy over this scheme is the FCC’s insistence that products certified for the band must support contention-based protocols, as the primary way for operators to avoid interfering with one another when sharing spectrum. This approach is part of Wi-Fi and is common in technologies geared to unlicensed bands, but WiMAX relies on accurate scheduling to avoid interference, rather than on dealing with traffic collisions. The WiMAX Forum and several vendors such as Intel and Alvarion had previously opposed the 2005 ruling, claiming it would take years to rewrite and implement a WiMAX solution that met the FCC requirement.
If a WiMAX base station has to defer to another service it makes it impossible to offer Quality of Service delivery for something like video or real time voice. For that they say they need a scheduler, not contention-based protocols, which are suited to best effort offerings.
While Intel and Motorola have claimed that a ‘listen-before-talk’ contention protocol was unsuited for long range operations the FCC says that it has been shown that such protocols can be added to networks at a reasonable cost. The upshot is that fixed line best effort internet will definitely make a beeline for this spectrum, through hundreds if not thousands of local WISPs.
The long awaited clarification of rules for 3.65GHz will at least set the stage for vendors to adapt their 3.5GHz gear for this market, and so could stimulate new wireless services in the US, and a reawakening of the dormant interest in WiMAX outside licensed bands. Already, some vendors are responding, including NextWave, which has aimed chips and reference designs geared to 3.65GHz, among other bands, and to open metrozone models.
The FFC said, ‘Our licensing regime for the 3650 MHz band will serve as a wireless highway between small towns and the big city’it will facilitate the delivery of broadband to all corners of the country by serving a different user group, one that often is driven by more localized, community-based needs.’