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Hopping the gap

Fri, 03/31/2000 - 7:00pm
Staff

... part II

Newbridge, which just won the contract for buildout of a nationwide LMDS network in Belgium by British Telecom subsidiary BT Belgium, has taken pains to integrate wireless broadband access capabilities into its multi-platform edge switches to support the needs of major U.S. carriers like MCI Worldcom, Sprint and NextLink Communications for efficient means of operating over a mix of wireline and wireless local access links, Jenkins notes. "Dynamic bandwidth allocation and multi-platform access are realities of product being shipped today," he says.

But the fact that Teligent, MCI, Sprint, NextLink and a host of other U.S. players in the wireless broadband space from MMDS (multichannel multipoint distribution service) at 2.5 GHz through LMDS (local multipoint distribution service) all the way to the 39 GHz tier have yet to announce suppliers for commercial rollouts of PMP systems has fueled a new wave of technology solutions from established and startup vendors who believe new approaches are needed if carriers hope to meet market demand. "The air links available up until now have not been sufficiently flexible to support the pricing and usage models that you need to compete in the real world," says Carlton O'Neal, vice president of marketing at San Diego-based startup Ensemble Communications Inc.

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Ensemble had originally expected that its product release in the second quarter of this year would put it in a catch-up mode against providers of previous generation equipment, but the failure of that equipment to take off and the resulting slow pace of wireless broadband rollouts has greatly improved Ensemble's prospects, O'Neal says. "It's not a great situation for the carriers, but it's great for us," he adds.

Along with providing the mechanisms for dynamically assigning bandwidth at pre-set pricing levels, the Ensemble system provides support for bursting large quantities of data on top of the guaranteed service a given customer has signed up for, O'Neal explains. Because such bursts can be accommodated via unused portions of a given channel stream at any given moment, this means that operators can assure customers they'll have added bandwidth available when they need it, while maximizing the number of customers served by any one channel.

O'Neal says other features of the Ensemble Adaptix air link protocol include use of adaptive time division duplexing, which allows variable rates of data to flow in both directions over a single channel; adaptive TDMA, which supports variable packet lengths to maximize burst rate bandwidth efficiency; and adaptive modulation, which provides for delivery of signals over the highest level of modulation that's feasible at a given moment in the fluctuating atmospheric environment of the transmission path.

While Ensemble's system will register at about a six on a scale of one-to-10 in the pricing of wireless broadband systems, the overall cost of infrastructure based on its technology versus other systems will be much lower, owing to the flexibilities the company has built into the technology, O'Neal says. The system, which includes 64 QAM as one of the dynamically assignable modulation options, operates over any frequency tiers between 10 GHz and 43 GHz.

TDD is also a mainstay of the system developed by Wavtrace Inc., which was just awarded patents for its version of the technology. TDD, by accommodating shifts in bandwidth needs in either direction within a single carrier channel, more efficiently uses bandwidth than FDD (frequency division duplex) systems, where separate channels are used for the downstream and upstream segments of the link, says Bob Foster, CTO at Wavtrace.

"In an FDD system, you have dynamic bandwidth allocations that occur in each direction, which means that, if you're not using all of the bandwidth in the return channel, for example, you can't capture that bandwidth for bursts in the downstream," Foster says. The capacity gain for TDD over FDD can be anywhere from 22 percent in a symmetrical system to 45 percent in a more typical asymmetrical system, assuming normal packet flows as measured at various test sites, he notes.

Nextlink Communications, the holder of the lion's share of LMDS coverage nationwide, has chosen Wavtrace along with three other vendors, including Ericsson, SpectraPoint Wireless and Digital Microwave, for system testing prior to deploying PMP systems across its operating territories. But the carrier, which also operates wireline networks in its LMDS markets, has yet to signal it is ready to move to commercial deployments with any of these vendors.

Ready for primetime?

Along with Nextlink, one of the key carriers to watch for signs that PMP technology is indeed ready for primetime is Teligent Inc., the holder of DEMS (digital electronic messaging system) licenses at 24 GHz nationwide. Teligent, too, has been testing PMP equipment and even offering services on a limited basis over PMP systems in many of its U.S. markets, with plans to go to widescale use of the technology sometime in this quarter.

"Right now, that's the plan, but we won't know for sure until things get rolling," says Steve White, vice president of sales for the company's operations in Texas and Louisiana. "There's still a lot of testing going on in the vendor selection process."

Teligent, with high-speed wireless access operations now in place in 40 major U.S. markets, has primarily relied on the more mature and technologically simpler point-to-point wireless technology along with some DSL connectivity to support an aggressive push into the small and mid-size business market that began in mid '98. With only four percent of some 760,000 office buildings nationwide now connected to fiber, the opportunity for delivering broadband access via wireless networks remains huge, White says. "We see revenues from fixed wireless services going from $0.3 billion in '99 to more than $5 billion in 2003," he adds.

Joining these giants as bellwethers for market readiness of PMP technology is the MMDS operator Nucentrix Broadband Networks Inc., the financially reorganized successor to Heartland Wireless Communications that controls licenses in 87 midwestern and Texas markets. Nucentrix, now operating high-speed two-way data services commercially in Austin and Sherman, Texas under development licenses issued by the FCC, is planning to switch to the Cisco VOFDM platform as quickly as possible following a round of testing that's slated to get underway this month, says Nucentrix CEO Carroll McHenry.

"Our plan is to be able to deploy on a wide scale by the fourth quarter, but that's highly dependent on the outcome of the trials and the timing of the FCC (two-way MMDS) licensing process," McHenry says, noting that some 40 of 57 currently operating markets should be operational with two-way data services by the end of 2001. "In the short- to medium-term, we're targeting the SoHo (small office/home office) and small business markets, but we expect to expand into the residential market with these services, including voice, as equipment volume goes up and prices come down," he says.

The Cisco system offers a much more viable approach to offering interactive services over MMDS than current generation platforms, McHenry adds. He cites the new orthogonal modulation system and the multipath signal integration technique of the VODFM platform as key differentiators, along with the fact that the system can be implemented on DOCSIS-based circuit cards inserted into Cisco routers.

At least one cable company has begun to use the VOFDM system as well, says Steve Smith, director of marketing for wireless broadband products at Cisco. "We have a large customer in the cable space who's doing backhaul to cable headends using our point-to-point system," Smith says. "They're using it over a 15-mile link where the costs of using fiber would be much higher."

Getting the message

Clearly, the cable industry would do well to keep its eyes on the likes of Nextlink, Teligent and Nucentrix, who, if they decide to move forward with deployments, will convey a message that could ultimately mean billions of new dollars in revenues for the cable industry. Don't be surprised if some cable operators choose not to ignore that message.

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