Wireless blankets

Aperto Networks and Ceragon Networks have developed enhanced fixed broadband wireless frequencies to tap potentially lucrative, underserved markets.

That's where the similarities end.

Aperto's suite of point-to-multipoint products targets the residential market with features that maximize spectrum re-use and overcome line-of-sight problems. Aperto's gear works best in tight cellular architectures that are taking the place of first generation wide-ranging supercells.

Ceragon uses point-to-point wireless to deliver up to 1 GHz of bandwidth to medium and high-end commercial customers who generally do not have access to wireline broadband connections from telco or cable suppliers.

“They're completely different, and they represent completely different plays in different parts of the market,” said Paul Kellett, senior director of research for Pioneer Consulting.

Aperto targets the small and medium enterprise (SME) market and some residential customers, while Ceragon is going after the larger business customers, he said.

You can't even compare the amounts of bandwidth the two companies deliver. Aperto's 20 Mb/s burst system pales in comparison to the gig being fired out by Ceragon, but “it's really apples and oranges” to make the comparison, Kellett added.

Nevertheless, both companies aim to serve untargeted audiences with relatively quick-hit solutions that require a minimal infrastructure investment.

“When we were looking at what kind of product to bring to market, we recognized that because of this increasing bandwidth [need] it would be critical to offer fiber-like speed and quality,” said Gordon Moller, Ceragon's vice president of sales and marketing.

Moller estimated that fiber serves only 3% to 4% of the roughly 800,000 large commercial customers. He's ready to jump in and help out the other 96%.

“He who gets there firstest with the mostest will win,” he predicted. “The inherent advantages of wireless lend themselves very well to competing with things like fiber.”

Ceragon is on the right track, said Kellett. “They've been a very successful company. They have a strategic relationship with Lucent and, especially in view of that relationship and in view of their past sales success, they have the opportunity to get the level of volume that will get their unit costs down,” he said.

If that happens, Ceragon's success rate will soar. That doesn't mean the company will stop expanding its bandwidth potential, Moller said, because “there is a great and growing demand for high-capacity connections.”

Ceragon developed a common platform for use in the frequency bands appropriate for metro networks, from 18 to 38 GHz, including LMDS at 28 to 31 GHz. It has outputs that connect directly to Sonet, IP and ATM networks.

“Ceragon felt that the topology should serve the service provider, not the other way around. Therefore, we wanted to develop a system that was simple to use in any of those network topologies, whether it be ring, star, mesh and so on,” Moller said.

The company advocates progressive implementation as a quick hit, quick return on investment strategy, he said.

“You have to go out and spend hundreds of millions of dollars putting in nodes for multipoint or other different technologies and then go out and grab customers,” Moller said. “We have a product that can seamlessly interconnect into the existing legacy network as well as to next generation IP networks and is really suitable for use in a cost-effective business model where customers can aggressively implement it.”

The 1 GHz system is the latest piece in a bandwidth-expanding series of offerings. The system has an input/output of a gigabit of Ethernet that is sub-aggregated down to eight fast Ethernet channels that are then trunked together over the radio link. At the other end, those eight channels are re-combined to deliver a gig of Ethernet output or to directly provision up to eight 100 Mb/s fast Ethernet ports.

“That gives the service provider options to either directly connect to something else on the access end at gigabit Ethernet speeds or to save the cost of buying another switch [and] directly provision people with discrete 100 Mb/s fast Ethernet ports,” Moller said.

The system is undergoing laboratory compatibility testing with different switches and should be in field trial deployments within the next three months, Moller said, predicting full commercial deployment within six months.

If Ceragon's strategy resembles the high-powered beam atop the Luxor casino in Las Vegas, Aperto's resembles any of the neon-decorated joints along the Vegas Strip.

“The word that comes to mind when I think of Aperto is flexibility. Their technology provides the ability to maximize quality of service based on a whole host of different parameters,” said Kellett.

“Ceragon felt that the topology should serve the service provider, not the other way around. Therefore, we wanted to develop a system that was simple to use in any of those network topologies.”
— Gordon Moller, Ceragon

Aperto's approach gives service providers the chance to chase small businesses and residential customers by using and reusing the same wireless spectrum, he said.

Most importantly, the technology “cellularizes” fixed broadband wireless networks, said Alan Menezes, Aperto's marketing vice president. Large cell sizes quickly use up bandwidth while smaller, targeted cells improve capacity limitations and actually help overcome issues like obstructed line-of-sight and non-line-of-sight.

Aperto's system operates in the 2.5, 3.5, 5.3 and 5.8 GHz frequency bands and includes base stations, subscriber units, radios and antennas. It employs an advanced TDMA interface protocol that uses a burst mode upstream and downstream and on-demand allocation of time slots and packet size, Menezes said. The Aperto system delivers up to 20 Mb/s of data in a6 MHz channel for up to 12 miles, although it will be most effective in the four- to five-mile range.

“It also supports flexible duplexing,” Menezes said.

Although later products will support frequency division duplexing (FDD), the initial product line will rely on time division duplexing (TDD) to use a single channel for upstream and downstream transmission.

“TDD allows you to adapt the bandwidth allocation between upstream and downstream depending on your traffic requirements,” he said. “This isn't possible with FDD; it's pre-fixed, and you can't change it.”

Menezes said the most important part of the product suite is its ability to optimize the subscriber connection by adjusting power and modulation schemes.

“For subscribers who have ideal conditions close to the cell tower, we use a lower power because we don't need to use higher power and create more interference for adjacent cells,” Menezes said.

The optimization scheme also uses high order modulation, minus error-correcting codes or antenna diversity in this mode.

For customers who are further out — a more challenging scenario — Aperto might use higher power, he said. “You might use a more robust modulation scheme, maybe a different antenna diversity, maybe a higher order error correcting encoding. On a burst-by-burst basis we can actually change the parameters to each subscriber,” he said.

This sort of optimization is essential as operators abandon 30- to 35-mile supercell configurations and adopt multi-cellular approaches, Menezes said.

“In many ways this competes with cable and DSL. It's also complementary to cable and DSL because in many cases people just can't get services,” he said. “We've solved some real-world problems, solved some of the interference mitigation management issues, so you can build multi-cell networks.”