Didn't see this posted/discussed anywhere. Bernard? <A> "Ensemble touts three adaptive layers for LMDS architectures -- Startup's scheme could boost broadband radio"
from techweb.com
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San Diego - The Local Multipoint Distribution Service (LMDS) market has needed fresh ideas to link multipoint broadband radio to standard wireline Internet Protocol networks. Startup Ensemble Communications Inc. has finished prototypes of a system that uses adaptive protocols at the physical, media-access and network layers, giving broadband radio the flexibility it may need for wide deployment.
Ensemble was founded by executives in San Diego and Israel with experience in wireless protocols, leveraging expertise ranging from wireless local loops and wireless LANs to the gamut of digital cellular and PCS systems. The company pulled in large venture names like Institutional Venture Partners in two rounds of financing that snared $20 million, and brought former Texas Instruments/Bosch marketing executive Carlton O'Neal to the company in late 1998 to jump-start promotional efforts as vice president of marketing and sales.
Ensemble's decision to use a time-division duplexed physical radio layer was given some external validity in February, when its erstwhile competitor Wavtrace Inc. (Bellevue, Wash.) announced it would offer LMDS systems based on TDD physical layers (see Feb. 15, page 1). Ensemble chief executive Rami Hadar said TDD is only a small part of the company's story. Ensemble is aiming at flexible use of frequency bands and modulation methods to make its systems as compatible as possible with the bursty nature of IP traffic.
Ensemble also is placing heavy emphasis on getting its basestations directly integrated with wireline central-office equipment, including routers and broadband switches. The company is working with ADC Telecommunications Inc. to interface its systems directly to ADC's CellWorx ATM/TDM product. Hadar said more OEM deals with router and access-equipment makers are coming.
"We see most of our competitors as being solely RF experts," Hadar said, "but we have designed our systems with the assumption that integration with wireline IP services is critical to the success of LMDS."
Adaptive algorithms not only allow Ensemble to offer more quality-of-service bandwidth shaping and rate adaptivity but also reduces the company's cost of deployment. Optimizing products for the U.S. LMDS A and B bands, the Canadian LMCS services, and other global variants of LMDS can be accomplished merely by changing the RF front end. No channels are assigned specifically for upstream and downstream channels, so symmetricity and asymmetricity of access can be adjusted as easily as the rate-adaptive versions of wireline digital-subscriber-line services. It also means that radios can be manufactured more cost-effectively, Hadar said.
O'Neal said that an adaptive version of TDD is only the first step in Ensemble's adaptivity advantage. On the MAC layer, the company has developed an adaptive version of time-division multiple access, which allows the radio service to be optimized for variable-frame packet service, while also supporting continuous-bit-rate service for voice and other low-latency traffic. This will be combined with statistical multiplexing to support IP differentiated services and ATM available-bit-rate services.
"We use a mix of contention and non-contention algorithms, using a back-off method for packet services and using time-slotting where it's appropriate," O'Neal said. "We think of our MAC as enabling a protocol-agnostic wireless bus."
The modem itself can use a variety of modulation methods appropriate to the quality of the RF link, scaling automatically from quadrature phase-shift keying to quadrature amplitude modulation with constellations of 16 or 64 points. The channel does not have to be preconfigured as QAM-16 or QAM-64. Instead, data frames are broken up into 800 information elements, each dynamically assigned its own modulation method.
Ensemble designed a 500,000-gate chip to handle all modulation and MAC-layer functions. It worked with Remec Inc., here, for design of all front-end RF analog functions such as power amp and low-noise amp.
Ensemble has prototypes of customer-premises equipment, antennas and
basestation gear working in its labs now, and will initiate local trials in the San Diego area this spring. First public demos are planned for the Supercomm show in Atlanta in June, with customer beta trials later in the summer.
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and fwiw, expected last mile Interop session next week:
planner.interop.com |
