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3.6 GHz: VoIP or Not?

The new 3650-3700 Mhz band, recently opened up by the FCC, has (apparently) some restrictions for WiMax that could limit its utilitity for voice backhaul.

This article from Broadband Wireless World indicates difficulties with the contention-based protocol required in the new band:

Some of the more pointed talk at the Broadband Wireless World show held last week came in the “Perspectives on the Industry” panel discussion that followed the Keynote Address by Fujitsu’s Keith Horn.
The panel, moderated by Tim Downs, editor of BWB magazine, included George Wu, director of wireless solutions at Fujitsu, Dr. Reza Ahy, CEO at Aperto Networks, Mitch Vine, director of strategic marketing at Redline Communications and Dr. Ron Marquardt, director of alternative last-mile products at Covad Communications.
What follows are some of the highlights from this discussion. One big bombshell delivered during the talk was the general discontent expressed concerning the Federal Communications Commission’s (FCC’s) recent decision on the 3.65 GHz band. Despite the FCC’s wish that opening the 3.65 GHz band to fixed wireless would provide more spectrum for WiMAX applications, the FCC’s rules on the use of a contention-based protocol in the band will make this difficult to achieve, according to panelists.
Tim Downs: How will 3.5 GHz WiMAX trials and network deployments in Europe affect the U.S. market?
Mitch Vine: The FCC is trying to do something different with the 3.6 GHz band i.e., high-speed access for rural development, supporting the WISP community. Unfortunately, the products that are certified [for that band] have to use a contention-based protocol. This requirement disqualifies WiMAX as it is defined today. WiMAX was designed as a scheduler, as opposed to Wi-Fi, which deals with [traffic] collisions. It will take years to rewrite and implement a WiMAX solution that meets the [FCC's] requirement.
Reza Ahy: Seventy percent of our [Aperto's] sales are in the 3.5 GHz spectrum. We believe there should have been amendments [to the FCC's 3.65 GHz rules] to reflect where the WiMAX industry is today. Carrier-class services need to be predictable. With a contention-based protocol, an SLA [service level agreement] is not possible. We need help from the FCC on the 3.65 spectrum to make it competitive in the U.S. market.

The FCC’s March 10, 2005 Press Release (pdf) states:

The Commission also provided an opportunity for the introduction at 3650 MHz of a variety of new wireless broadband technologies, such as Wi-Max, into the band. Under the Commission s approach, there is no limit on the number of licenses that can be granted, and each licensee will be authorized to operate on a shared basis with other licensees on all 50 megahertz of the band, subject to restrictions in geographic areas occupied by grandfathered Fixed Satellite Service (FSS) and Federal Government stations.
Licensees will also be required to register all system base stations electronically with the Commission. Base station registration will enable licensees to locate each other s operations and will facilitate protection of grandfathered stations from interference. This type of licensing and registration will enable the Commission to monitor the use of this spectrum as new technologies and services develop.

The WiMAX Forum believes global harmonization can be achieved in the following spectrum bands:

License-Exempt 5 GHz: Because license-exempt spectrum is free to use, this band is a key to enabling grassroots deployments in underserved, low population density rural and remote markets.
Licensed 3.5 GHz: In these bands, the focus of the WiMAX Forum will be to minimize unnecessary technical and regulatory requirements that might constrain BWA usage models and overall market development.
Licensed 2.5 GHz: Though already allocated in the U.S., Mexico, Brazil and some Southeast Asian countries, the WiMAX Forum is participating in ongoing global efforts to make this band available in other countries.

Broadband Wireless Magazine also has an article on VoIP in Broadband Wireless.

airBand Communications began rolling out its VoIP service last year. They plans to migrate VoIP onto its wireless network in mid-2006. The WISP connects business customers in metro Dallas, Houston and Phoenix using 5.8 GHz unlicensed spectrum, using 18 GHz and 23 GHz licensed spectrum for its larger customers. The company currently delivers VoIP service to 300 of its 1,600 business customers located in all of its markets.
NextWeb teamed with CommPartners to deliver VoIP service to early customers.
U.S. Wireless Online plans to roll out VoIP to customers in tier 2 cities in 11 states by the end of the second quarter. They use Aperto gear for the backhaul.
Speakeasy plans to launch its broadband wireless network in Seattle next month. Their WiMAX plans call for simultaneous VoIP and data services.
Clearwire plans to offer VoIP services in the near future, although Clearwire has blocked Vonage. Clearwire signed an agreement with Bell Canada under which Bell Canada will provide VoIP systems and services for Clearwire.

Originally regulation free, VoIP is now under new management at the FCC. The FCC plans to require VoIP providers to provide 911 support, although how mobile users will be located is not exactly clear.

WISP Centric has details on 3.650 GHz. Related DailyWireless stories include; Broadband World Wrap, Navini Offers 3.5 GHz PC Card, 3.5 GHz: Licensed or Un?, and The FCC Opens the 3650MHz band.