Browsing by Author "Chang, Chien-Ping"

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A strictly nonblocking network based on nonblocking 4 x 4 optical switches
(2012-01-01)
Lee, Chi-Ping
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Chang, Chien-Ping
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Deng, Jiun-Shiou
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Li, Min-Hao
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Lu, Ming-Feng
Recently, the demand for communication has been growing rapidly. Hence, optical multistage network technologies are more appreciated nowadays. A double-layer network is a strictly nonblocking network, and it has the lowest system insertion loss of non-dilated networks. A Benes network is a rearrangeably nonblocking network, and it has the same system insertion loss as a double-layer network. We have proposed the use of modified polarization selection elements (PSEs). The system insertion loss, number of drivers, and number of required components of a double-layer network could be reduced if it is constructed with modified PSEs. A nonblocking 4 x 4 optical switch with two stages of polarization selective elements has been presented in our previous study. Based on this nonblocking 4 x 4 optical switch, we propose a strictly nonblocking network structure which features even lower system insertion loss than those of a double-layer network and a Benes network. The signal-to-noise ratio of the proposed network structure is a constant, and is higher than the constraint, although it is lower than that of the double-layer network. The number of major components of the proposed network is less than that of a double-layer network and larger than that of a Benes network, since a Benes network is rearrangeably nonblocking. We also offer a routing algorithm for the new proposed network; the time complexity of the routing algorithm is O(1). (C) 2011 Elsevier B.V. All rights reserved.
Components Reduction of Double-Layer Networks with Holographic Optical Switches
(2009)
Deng, Jiun-Shiou
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Lee, Chi-Ping
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Chang, Chien-Ping
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Lu, Ming-Feng
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Huang, Yang-Tung
Combining the unique features of the double-layer network and holographic optical switches not only reduces the volume of the whole system, eliminates all interconnection lines and crossovers significantly, reduces the number of drivers from N-2/4+2Nlog(2)N-2N to 2Nlog(2)N, but also the system insertion loss can also be minimized. After rearranging the channels allocation, the number of electro-optic halfwave plates can be significantly decreased from 2N(2)-2N to 2Nlog(2)N.
Dummy-Based Schemes for Protecting Movement Trajectories
(2012-03-01)
Lei, Po-Ruey
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Peng, Wen-Chih
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Su, Ing-Jiunn
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Chang, Chien-Ping
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資訊工程學系
Dummy-based anonymization techniques for protecting the location privacy of mobile users have appeared in the literature. By generating dummies that move in human-like trajectories, this approach shows that the location privacy of mobile users can be preserved. However, the trajectories of mobile users can still be exposed by monitoring the long-term movement patterns of users. We argue that, once the trajectory of a user is identified, the locations of the user are exposed. Thus, it is critical to protect the movement trajectories of mobile users in order to preserve user location privacy. We propose two schemes that generate consistent movement patterns in the long run. Guided by three parameters in a user specified privacy profile, namely, short-term disclosure, long-term disclosure and distance deviation, the proposed schemes derive movement trajectories for dummies. The experimental results show that our proposed schemes are more effective than existing works in protecting movement trajectories.
Multicast Network with MMI-based Optical Switches on Active Splitter/Active Combiner Structure
(2009)
Lee, Chi-Ping
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Deng, Jiun-Shiou
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Lu, Ming-Feng
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Chang, Chien-Ping
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Huang, Yang-Tung
Multicast communications have become more and more important recently, especially in their applications in multimedia communication, quality of service (QoS), video conferencing, and distance education. In a point-to-point (PTP) optical communication system, how to provide multicast services is an essential issue. There are some advantages of active splitter/active combiner (AS/AC) networks, such as strictly nonblocking, simpler routing algorithm, lower system-insertion-loss, zero differential loss, and better signal-to-noise characteristics. The active multimode interference (MM!) coupler can provide splitting/combining operations with low loss and good balancing. It has been demonstrated that the AS/AC network constructed by active MMI switching devices can implement the multicast and PTP communications simultaneously. In this study, we offer two multicast algorithms, parallel multicast, and tunable multicast, on AS/AC network. The parallel multicast algorithm is suitable when there are multi requests arriving at the same tame. The tunable multicast algorithm is suitable for balancing the output signals\' power.