Big Bear Networks' 'Photronic Signal Processing' Technology Automatically Corrects for Fiber-Optic Impairments.

Business Editors/High-Tech Writers

MILPITAS, Calif.--(BUSINESS WIRE)--May 20, 2002

Tight Coupling of Electronics, Optics and DSP 

Boosts System Design Margin For Equipment Makers,

Leads to Reduced Carrier Expenditures

Big Bear Networks has introduced Photronic Signal Processing (PSP), a new technology that overcomes signal-degrading fiber impairments, enabling telecom carriers to deploy longer and faster fiber-optic links with minimum capital and operational expenditure.

Applicable to next-generation 10- and 40-gigabit-per-second optical system products, PSP combines low-cost electronics and digital signal processing (DSP) to automatically correct for common fiber impairments -- a task which previously required expensive components and equipment as well as time-intensive manual intervention by carriers. By improving equipment vendors' system design margins, PSP has the potential to significantly reduce carriers costs in both the metro/regional and multi-wavelength long-haul markets.

PSP is the foundation for a line of highly integrated electrical-optical interface solutions that Big Bear will bring to market starting later this year in the form of 10-gigabit subassemblies and transponders for long-haul applications; 40-gigabit transponders for cross-office, metro core/inter-office facility and regional networks; and 40-gigabit subassemblies optimized for long-haul transmission. The products will be deployed in equipment such as DWDM transmission systems, IP/MPLS routers and switches, SONET/SDH cross-connects and add/drop multiplexers, and optical cross-connects.

Addressing the Fiber Impairments that Degrade Signal Quality

PSP technology, for which Big Bear has submitted numerous patent applications, effectively addresses the fiber impairments that degrade signal quality. Two common impairments that become more damaging as bit rates rise are chromatic dispersion and polarization mode dispersion (PMD), in which different wavelengths or polarizations of a light pulse travel at different speeds, spreading and distorting the pulse and causing signal-detection errors at the receiver. PSP also addresses other inter-symbol interference (ISI) effects, such as transmitter and receiver patterning and self-phase modulation, further boosting system margin.

"As systems move toward higher speeds and greater transmission distances, they become far more vulnerable to fiber impairments," said Laura Adams, Big Bear co-founder and vice president of product management. "The effects of chromatic dispersion are 256 times more severe at 40G than at 2.5G, and the effects of PMD are 16 times more severe. With PMD in particular, the older the fiber, the worse the dispersion characteristics. This raises a barrier to deployment of high-speed systems on a significant portion of the installed fiber base."

In the past, chromatic dispersion has been addressed with costly dispersion-compensator fiber modules that require manual installation by highly trained personnel and allocation of system margin by the network designer for the remaining residual dispersion penalty. The expense of correcting for PMD effects is even more dramatic; carriers typically must design network links with closely spaced electro-optic regenerators which can convert and retransmit signals but which drive up system cost considerably. The potential use of emerging optical compensators to mitigate PMD effects will fall short of carrier expectations in terms of cost, power and solution footprint, limiting the applicability of such products.

Embedded Intelligence Leads to Improved System Design Margin, Carrier Profitability

Big Bear's PSP technology applies the signal processing and conditioning techniques commonly used in wireline applications to the electrical/optical interface, traditionally considered a "dumb" element of the system. Embedded intelligence in the interface provides continuous active monitoring of the data stream, measuring the quality of received data and using a DSP-controlled feedback system to provide dynamic compensation. Through the application of specifically targeted silicon gates, PSP intelligently optimizes the complex performance interactions between electronics, optics and the fiber-optic channel. Because impairments are corrected for automatically, network providers need not perform the costly characterization of their fiber infrastructure typically required to assess penalties and impairments of their fiber links.

In the long haul, this impairment compensation permits increased span lengths and eliminates costly line regenerators. In the metro network, it provides additional link margin, obviating the need for operator intervention to meticulously test and deploy optical links, and thus helping providers maintain competitive service rates. In both environments, it provides the ability to dynamically and automatically control the dispersion compensation elements.

"In a 10G long-haul network," said Adams, "PSP's adaptive compensation intelligence eliminates regeneration stages and automatically recovers system margin normally lost to coarse external line conditioners. This translates into significantly reduced operational and capital expenses for carriers. Looking out to 40G, adaptive compensation technology becomes essential to enable system vendors to economically achieve such speeds beyond the central office."

About Big Bear Networks

Big Bear Networks, founded in June 2000 with an initial core team from Lucent Technologies, Nortel Networks and Texas Instruments, currently has 70 employees. The company has raised $60 million in two rounds of private funding; investors include Accel Partners, Austin Ventures, Menlo Ventures, Oak Investment Partners and Sequoia Capital. Big Bear is located at 1591 McCarthy Blvd., Milpitas, CA 95035. For more information, call 408/434-3400 or visit the Big Bear Networks web site at www.bigbearnetworks.com.