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All-optical networks have been proposed to eliminate expensive optical-to-electrical or electrical-to-optical conversions and to remove potential capacity bottlenecks of electronic
switching. Apart from significant cost reduction and bandwidth increase, all-optical switching is protocol
transparent to upper layers and, therefore, facilitates future deployment of new technologies. To handle increasing dynamic traffic requirements in all-optical networks, much attention has been paid recently to the agility and intelligent control of all-optical networks, with which dynamic traffic requirements will be fulfilled with rapid bandwidth allocation at appropriate granularities. Currently, wavelength division multiplexing (WDM) has been considered as an efficient data transport mechanism for all-optical networks. However, as per-wavelength speed moves to 40 Gbps and beyond, WDM may lead to lower channel utilization when certain applications or traffic flows do not need the full bandwidth of a wavelength. To address this issue, a proposed approach is to further divide a wavelength channel into sub-channels by applying time-division multiplexing (TDM) on top of WDM to form WDM/TDM all-optical networks.
My research focuses on the agile and intelligent control of dynamic traffic in metro all-optical networks. Ring topology is considered to enhance network survivability and a distributed control scheme is applied to decrease the degree of coordination among nodes. In order to accommodate dynamic connection requests with flexible bandwidth requirements in WDM/TDM networks, some distributed bandwidth allocation approaches have been proposed with the objective of minimizing network blocking probability. By incorporating the dynamic programming technique, introducing the concept of residual wavelengths and residual timeslots, or combining the existing wavelength assignment heuristics into the wavelength and timeslot assignment schemes, these bandwidth allocation approaches are compared via simulation on the aspects of global information gain, stale link state impact, and signaling and reservation efficiency. An analytical blocking model has been presented for single fiber all-optical ring networks
to facilitate future investigation on the impacts of following factors on the blocking probability, including network traffic load, number of node in the network, number of wavelengths per fiber and number of timeslots per frame
Future work will still focus on the dynamic traffic control issues in agile all-optical networks: study network survivability via connection protection and restoration, borrow concepts and rules from biology and apply into next generation network architectures, and analyze reconfigurable module control in an experimental environment.
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Wei Yang, Sofia A. Paredes and Trevor J. Hall
"A study of fast flexible bandwidth assignment methods and their blocking probabilities for metro agile all-optical ring networks"
in Proc. of IEEE International Conference on Communications, 2007, pp. 2418 – 2423, June 2007
Wei Yang, Sofia A. Paredes and Trevor J. Hall
"The impact of stale information on the blocking performance of dynamic routing, wavelength and timeslot assignment schemes for bandwidth on demand in metro agile all-optical ring networks"
to appear in Proc. of Photonic North 2007, June 2007
Wei Yang and Trevor J. Hall
"Distributed dynamic routing, wavelength and timeslot assignment for bandwidth on demand in agile all-optical networks"
in Proc. of Canadian Conference on Electrical and Computer Engineering, pp. 136 – 139, May 2006
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