Broadband Wireless Gets To The (Multi)Point
By Fred Dawson Contributing Editor, Inter@ctive Week
March 13, 2000 7:49 AM ET
zdnet.com
Vendor assertions that this is the year when wireless broadband technology will finally take off will soon be put to the test. The lead guinea pig will be Teligent, which has a plan to ramp up wide-scale deployment of point-to-multipoint access systems starting this spring.
"Right now, that's the plan, but we won't know for sure until things get rolling," says Steve White, vice president of sales at the company's operations in Louisiana and Texas. "There's still a lot of testing going on in the vendor selection process."
Teligent, which now has high-speed wireless access operations in place in 40 major U.S. markets, is currently using point-to-multipoint transmitters on a limited basis in many of those areas, including White's territories. But until now, Teligent has relied on the more mature and technologically simpler point-to-point wireless technology, along with some wireline Digital Subscriber Line connections, to serve its small and midsized business customers.
With only 4 percent of roughly 760,000 office buildings nationwide now directly connected to fiber-optic networks, the opportunity for delivering broadband access via wireless networks remains huge, White says. "We see revenue from fixed wireless services going from $0.3 billion [$300 million] in 1999 to more than $5 billion in 2003," he says.
Shrinking Advantage
Teligent, which owns licenses for the 24-gigahertz tier that were granted before the Federal Communications Commission issued licenses for Local Multipoint Distribution Service (LMDS) at the 28-GHz level, has been touting point-to-multipoint as the key to its long-term success. Teligent sees the cost efficiencies of being able to serve multiple office buildings from a single transmitter as the linchpin to its business case.
If Teligent can proceed as planned with point-to-multipoint service launches over the next 90 days or so, it will have a shot at capturing a big share of the broadband wireless market before many of its competitors have a chance to complete the extensive preparations needed for point-to-multipoint service. Those preparations include installing all the support infrastructure, obtaining site permits and installing transmitter towers that must precede actual marketing of the point-to-multipoint services.
But Teligent's head start in the point-to-multipoint race has dwindled significantly in recent months, primarily because the service provider has not been satisfied with products being offered by point-to-multipoint suppliers. The inability of vendors to demonstrate technology that can compete with broadband wireline services also has delayed deployment of point-to-multipoint services at Winstar Communications, which holds licenses to operate broadband wireless networks in the 38-GHz to 39-GHz tier.
The biggest weakness in broadband wireless technology to date has involved plain old voice traffic. "Prior to this generation of broadband wireless access technology, the industry didn't have the technology platform it needed to deliver voice as well as data, which is what the market wants," says Cynthia Hillery, vice president of marketing at Netro, a supplier of point-to-multipoint access equipment. "Now we've stepped beyond those limitations and are seeing preparations for service launches under way worldwide, including in the U.S."
Netro now has eight commercial pilot launches and more than 30 trials of its systems in play outside the U.S. It uses Time Division Multiple Access to multiplex signals into Asynchronous Transfer Mode (ATM) cells, and a proprietary Media Access Control layer to manage time slots in a way that meets market needs for dynamic allocation of bandwidth, Hillery says. "TDMA is a hardened technology that is winning market confidence worldwide," she adds.
Hillery won't get any argument from rivals such as Newbridge Networks, which is betting on other approaches to combining TDMA and ATM to achieve the quality of service, robustness and dynamic flexibility that today's market requires for broadband services. "We have shipped over 500 base station sectors of TDMA systems globally - we're in a heck of a trajectory now," says Tony Jenkins, assistant vice president for wireless product management at Newbridge, which is to be acquired by Alcatel in a stock transaction valued at $7.1 billion.
Newbridge, which just won the contract to build out a nationwide LMDS network in Belgium for British Telecommunications' subsidiary BT Belgium, has integrated wireless broadband access into its multiplatform edge switches. That integration will support the needs of major U.S. carriers, including MCI WorldCom, Nextlink Communications and Sprint, for efficient means of operating over a mix of wireline and wireless local access links, Jenkins notes. "Dynamic bandwidth allocation and multiplatform access are realities of products being shipped today," Jenkins says. Prospective partners MCI WorldCom and Sprint both made major investments last year to secure licenses to operate Multichannel Multipoint Distribution Service (MMDS) broadband wireless networks.
Getting Real
The fact that U.S. players across the broadband wireless spectrum, from LMDS to MMDS to the 39-GHz tier, have yet to announce suppliers for commercial rollouts of point-to-multipoint systems has fueled a new wave of technology offerings from established and start-up vendors. "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 Ensemble Communications.
Ensemble had originally expected to be playing catch-up with its Adaptix air link protocol, which is slated for release this spring. But the failure of the market in general to take off has greatly improved the company's prospects, O'Neal says. "It's not a great situation for the carriers, but it's great for us," he notes.
Along with providing the mechanisms for dynamically assigning bandwidth at predetermined pricing levels, the Ensemble system can handle 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 specified 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.
Other Adaptix features include the 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 bandwidth efficiency; and adaptive modulation, which provides for the 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 O'Neal says Ensemble's system will register at about a 6 on a scale of 1 to 10 in the pricing of wireless broadband systems, he contends that the overall cost of infrastructure based on its technology will be much lower because of the flexibility the company has built into its technology. The system, which includes 64 Quadrature Amplitude Modulation (QAM) as one of the dynamically assignable modulation options, operates over any frequency tier, from 10 GHz to 43 GHz.
Perhaps nothing signals that the market is still looking for the right solutions better than the decision by Cisco Systems to jump into the broadband wireless fray using a new type of modulation technology. In an alliance with broadband chip supplier Broadcom, Cisco will use a modulation technique developed by Clarity Wireless, a company Cisco acquired four years ago.
Quadrature Phase Shift Key and, more recently, QAM have been the mainstays in broadband modulation for both wireless and wireline networks. But Cisco contends that broadband wireless operators need something better that will improve coverage by reducing line-of-sight and interference barriers, even if it means giving up the cost efficiencies associated with the mass production base for chips developed in the QPSK and QAM domains.
Initially, Cisco was uncertain about whether to make its vector orthogonal frequency division modulation (VOFDM) technology available at the very high-frequency tiers such as LMDS, but the company has decided the market need in that category merits development of product, says Steve Smith, director of marketing for broadband wireless at Cisco.
The first publicly announced user of Cisco's VOFDM is Nucentrix Broadband Networks, which holds MMDS licenses in 87 markets in Texas and several Midwestern states. Nucentrix now operates high-speed two-way data services commercially in Austin and Sherman, Texas, under development licenses issued by the FCC. It is planning to switch to the Cisco platform as quickly as possible, following a round of testing that's slated to get under way next month, according to Carroll McHenry, chief executive of Nucentrix.
"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 licensing process," McHenry says. He adds that as many as 40 of the 57 markets in which Nucentrix now operates will have two-way data services by the end of 2001.
One key to the attractiveness of Cisco's approach, McHenry says, is the fact that the VOFDM chip from Broadcom exploits Broadcom's implementation of the cable industry's Data Over Cable Service Interface Specification platform, which delivers packet voice as well as other Internet Protocol (IP) content. Moreover, the Broadcom system can be implemented on DOCSIS-based circuit cards inserted into Cisco routers, allowing carriers to add wireless links in a wireline environment without changing out the edge switching system.
Targeting Industrial Parks
Cisco's entry into the market with a DOCSIS-friendly platform comes just as the cable industry is beginning to experiment with broadband wireless as a means of reaching business customers in areas that are not well served by cable, such as industrial parks. Cisco is working with several cable operators in trials of the technology for various applications, including point-to-point back-haul between cable network headends and remote hubs, and point-to-multipoint connections to businesses, Smith says.
"We have a large customer in the cable space who's doing back-haul 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."
The unnamed operator, along with others that are testing the gear for point-to-multipoint applications, are operating over unlicensed spectrum at the 5.7-GHz tier, Smith notes. "Cable doesn't pass a lot of the strip malls and industrial parks, where there's an opportunity to generate significant new revenue from the data networking platform operators already have in place," he says.
The cable industry's interest in wireless broadband is indeed intensifying, says Richard Green, president of Cable Television Laboratories, the cable industry's key standards-setting group. Green points to the availability of ever more unlicensed and licensed spectrum and improved technology that makes serving the business community a viable option for cable operators as two key drivers for that interest. "We'll continue to monitor the technical developments closely, building on the foundation we laid in wireless when we started looking at PCS [personal communications services] several years ago," Green says.
VOFDM is one of the new over-the-air transmission technologies CableLabs is following, Green says, adding that the company actually owns patents on some of the techniques used in VOFDM. "It's a very interesting possibility, as are others we're looking at, such as ultrawideband," he says.
Ultrawide Coverage
Ultrawideband is a new technology based on the spread spectrum wireless transmission techniques that were developed for military applications. The ultrawideband approach to spread spectrum, in contrast to the more widely used Code Division Multiple Access spread spectrum approach, uses the entire frequency band to achieve very robust signal-to-noise performance rather than breaking that band into smaller channels.
Another supplier vying for network operators' attention as the FCC makes more wireless spectrum available under unlicensed and licensed categories is Lucent Technologies, with its Blast system. Lucent claims its Blast technique can increase capacity on wireless links by 10 to 20 times, while overcoming many of the interference problems that plague today's systems.
Blast employs Lucent-developed algorithms to assign specific signals to given transmission paths in the multipath dissemination of a radio wave at a specific frequency, thereby allowing reuse of the frequency many times over for the delivery of different messages to and from different users.
Cisco isn't alone in using a wireless adaptation of the cable industry's DOCSIS platform as a means of providing highly integrated multitiered classes of service in the wireless domain. Vyyo, a longtime player formerly known as Phasecom, recently introduced a point-to-multipoint system based on "DOCSIS Plus" that will operate at spectrum tiers ranging from the ultrahigh frequency transmission band up to 30 GHz, says Eric Wilson, vice president of systems management at Vyyo.
"Our architecture takes advantage of the data side access and quality-of-service management capabilities of DOCSIS, while adding enhancements to optimize the system for wireless," Wilson says. "Being DOCSIS-compatible allows us to take advantage of the inherent data and voice-over-IP capabilities."
Whether all the new techniques in play will prove successful against the options that have led the market so far remains to be seen. But it's clear that, one way or another, carriers will find a means of making point-to-multipoint services a reality in the U.S. before the year is out. For a sign of just how soon this will happen, the company to watch is Teligent. |
