Dr. Guangzhi Li Profile

Dr. Guangzhi Li

at AT&T Labs Research

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Author

Publications (6)

Proceedings Article | 19 November 2007 Paper

On IPTV network design

Guangzhi Li, Dongmei Wang

Proceedings Volume 6784, 67840V (2007) https://doi.org/10.1117/12.742888

KEYWORDS: Video, Multimedia, Failure analysis, Internet, Network architectures, Video compression, Receivers, Televisions, Copper, Switches

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Proceedings Article | 17 October 2001 Paper

Reliable optical network design

Guangzhi Li, Jennifer Yates, Dongmei Wang, Charles Kalmanek

Proceedings Volume 4585, (2001) https://doi.org/10.1117/12.445177

KEYWORDS: Optical networks, Failure analysis, Signal processing, Network architectures, Reliability, Interfaces, Prototyping, Optical design, Control systems, Standards development

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Proceedings Article | 17 October 2001 Paper

Metro/core routing information exchange in optical networks

Dongmei Wang, John Strand, Jennifer Yates, Charles Kalmanek, Guangzhi Li, Albert Greenberg

Proceedings Volume 4584, (2001) https://doi.org/10.1117/12.445144

KEYWORDS: Optical networks, Opacity, Interfaces, Network architectures, Bridges, Databases, Networks, Prototyping, Switching, Computer programming

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Proceedings Article | 9 August 2001 Paper

Fiber span failure protection in mesh optical networks

Guangzhi Li, Robert Doverspike, Charles Kalmanek

Proceedings Volume 4599, (2001) https://doi.org/10.1117/12.436053

KEYWORDS: Optical networks, Networks, Network architectures, Evolutionary algorithms, Optical design, Silicon, Wavelength division multiplexing, Optical amplifiers, Structured optical fibers, Lithium

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A major challenge of optical network design is deciding where spare capacity is needed and how much, so that interrupted traffic may be rerouted in the event of a failure. Given the optical network topology and traffic forecast, the network design needs to map the traffic forecast into optical connection demands. For each optical connection demand, two paths need to be computed, i.e., a service path and a restoration path. In most cases, optical network design mainly considers single failure. If two service paths do not share any single failure, their restoration paths can share the same capacity on any links that they have in common. In this way, the total spare capacity needed for restoration can be dramatically reduced. However, due to the layered architecture in optical networks, a pair of diverse paths in a particular layer won't necessarily be diverse when the lower layer topology is considered. For example, optical networks are typically built on top of a network of fiber spans. A single span cut in the fiber network can cause multiple link failures in the optical layer. In this paper, we investigate fiber span failure protection scenarios in mesh optical networks. Specifically, we provide an algorithm to find two fiber span disjoint paths for each demand, such that the total spare capacity allocated in the network is minimized. Another problem that arises in restoration path computation is the existence of a trap topology. In a trap topology, the pre- selected service path may not have a diverse restoration path even though two diverse paths exist in the network. For simple link-disjoint protection, the min-cost max-flow algorithm can be used to avoid this problem. For fiber span failure protection, the trap topology problem becomes complicated. We show that it is NP-hard problem to find the maximum number of fiber-span disjoint paths between two nodes. We provide two heuristic algorithms to solve this trap topology problem. We have implemented fiber span failure protection in our restoration capacity planning toolkit Cplan. We describe an application of fiber span failure protection at the end of the paper.

Proceedings Article | 5 October 2000 Paper

Wavelength assignment problem in multifiber optical tree networks

Guangzhi Li, Rahul Simha

Proceedings Volume 4213, (2000) https://doi.org/10.1117/12.402532

KEYWORDS: Optical fibers, Optical networks, Information operations, Lithium, Stars, Network architectures, Wavelength division multiplexing networks, Wavelength division multiplexing, Calcium, Computer science

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Proceedings Article | 25 August 1999 Paper

Efficient routing to reduce the cost of add-drop multiplexers in WDM optical ring networks

Guangzhi Li, Rahul Simha

Proceedings Volume 3843, (1999) https://doi.org/10.1117/12.360404

KEYWORDS: Wavelength division multiplexing, Optical networks, Multiplexers, Network architectures, Computer simulations, Computer programming, Lithium, Wavelength division multiplexing networks, Computer science, Analytical research

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Showing 5 of 6 publications

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