Single-radio point-to-point delivers 311 Mbits/s
By Patrick Mannion
EE Times
(02/20/01, 5:38 p.m. EST)
SAN JOSE, Calif. — DMC Stratex Networks has set a new benchmark for single-radio, point-to-point wireless communications with the release of its 311-Mbit/second Altium 311 line for wireless 2x OC-3 and ATM data transmission. An extension of the company's 155-Mbit/s line, the Altium 311 operates in the 38-GHz band. It will be unveiled at the Broadband Wireless World Forum 2001 in San Francisco this week.
"Typically, competing systems will double capacity by simply adding extra hardware to meet the demand," said Stuart Little, director of marketing for DMC (San Jose, Calif.). "We, on the other hand, have completely redesigned our modem chip set with an advanced modulation scheme to enable the higher rates with a single radio."
Little was referring to the company's Vantex modem chip set effort, which condenses "a large amount" of on-board circuitry to two chips. The chip set uses forward error correction and adaptive equalization to improve throughput while allowing software programmability of the quadrature amplitude modulation scheme from 4 to 256 QAM. This gives rates between 4 and 311 Mbits/s.
"We are the only ones capable of 256-level QAM," said Little. [Bernard: These guys and about a dozen others have made this same claim over the years. What's the real scoop here? That nobody can do it reliably at any reasonable distance in a real deployment, but they can all demonstrate it under ideal conditions?]
"While the initial versions will be static, programmable versions are next, as are 622-Mbit/s systems in the near future."
DMC is playing as a pure-play transport provider in the line-of-sight, point-to-point wireless area with a range of 4 to 5 km. While its solution would seem to compete with wireless optical products, Little does not see much in common with optical. "We're not affected by infrared radiation, weather or fog, and we have a much greater range," he said. "Optical systems are limited to 500 to 600 yards."
Priced at $70,000 per nonprotected link, the system is due to be released this summer. |
