April 29, 2008 9:00 AM | Permalink
by Caroline Gabriel, Weekly Features Contributing Editor

Until recently, it seemed that the US' lightly licensed 3.65GHz band, which was opened up amid high expectations in 2005, would prove a disappointment to the WiMAX community. Not only did the agenda of the WiMAX industry refocus heavily on licensed bands and fully mobile business models, but the FCC appeared to be mandating anti-interference methods (to protect satellite incumbents) that were not supported in WiMAX. Three years on, however, most of the regulatory issues have been addressed, and there is renewed interest in the potential for this spectrum to provide a low cost route to market for WiMAX operators, especially those offering fixed or nomadic services in underserved markets. Metro Wi-Fi provider Azulstar recently turned to 3.65GHz WiMAX to make the municipal broadband model work at last, and now fixed WiMAX veteran TowerStream is looking to make its first deployments of 802.16e in this band.
The 3.65GHz band is available in the US under a light licensing scheme (no fees, but operators have to sign a 'good neighbor', non-interference undertaking and register their deployments). Although it has less good propagation qualities than 2.4GHz, it is far less congested, and protected from becoming so by the licensing approach - and it has better range and penetration than the other license-exempt option, 5.8GHz. TowerStream is working with Alvarion, which last week announced that its 3.65GHz 802.16e product had been approved by the FCC.

Although TowerStream is moving from a combination of proprietary and 802.16d equipment (mainly from Aperto) to 802.16e, this is not because it plans to support mobility or cellular-style wide area deployments any time soon - but because it sees greater spectral efficiency and volume economics in the newer, fixed/mobile standard. In this it is actually in the majority of early stage WiMAX adopters - despite the headlines about mobile providers like Sprint, most early 802.16e deployments are focused on fixed home or business access in underserved markets, which should remain WiMAX' key market until 4G-style mobile broadband really takes hold. This flipflop in focus - back towards traditional broadband wireless models, with wide area mobility seen as a second stage option - has helped reawaken the interest in unlicensed or lightly licensed spectrum options for WiMAX, either to support smaller operators or in remote regions where there is little licensed spectrum yet available. This will, in turn, change the R&D agenda somewhat, especially for the traditional WiMAX suppliers like Alvarion, which have strong presence in this type of market. For instance, there is rising demand from providers to have the 64QAM option supported in the uplink in 802.16e - something that has been largely ignored before because it was seen as unnecessary for mobile deployments.

TowerStream is now testing five networks using the Alvarion base stations in Rhode Island, where it has one of its existing networks already offering its T1/E1/DSL replacement services to enterprises, but its first commercial 802.16e roll-out will be in a new market, as yet unannounced. Most of the provider's operations are in major cities such as New York, Chicago, Boston and San Francisco, where it has specialized in gaining roof rights to tall and famous buildings such as the Empire State Building.

The Alvarion base station and CPE that were authorized this month are the BreezeMAX 3650 family. This supports self-install CPE and wave two smart antenna technologies such as MIMO, and enables up to fourth order diversity to maximize capacity and coverage."

One of the reasons for interest in the 3.65GHz band is that it is close to 3.5GHz, which is allocated almost globally for broadband wireless (fixed and, in a rising number of countries, mobile too), but which is not open in the US. Agile devices for these two neighboring bands are one of the best hopes for near term, low cost equipment that is usable in much of the world, although it is unlikely that the US will ever see anything close to universal availability of 3.65GHz as it has of the entirely license-free 2.4GHz. Alvarion said the closeness to 3.5GHz shortened its time to market for 802.16e in the new band, and would allow operators, even though they are currently few in number in this spectrum, to take advantage of the volume economics of the 3.5GHz profile.