Senro Saito
Associate Professor
Anh T. Pham
Assistant Professor
Tongiun Huang
Assistant Lecturer
Truong Thi Dieu Linh
Visiting Researcher
|
Senro Saito Associate Professor |
Anh T. Pham Assistant Professor |
Tongiun Huang Assistant Lecturer |
Truong Thi Dieu Linh Visiting Researcher |
Current research at the Computer Communications Laboratory (CCL) encompasses
Optical communications and networking technologies, in particular, modeling, theoretical analysis and simulation of optical fiber and optical wireless access systems;
New-generation communication network research: architecture design, survivability and protection methods;
Architecture design and modeling of computer networks; and
Internetworking technologies for security & reliability sensitive applications e.g. medical and healthcare networks.
E-Learning, distributed algorithms and ubiquitous computing
We welcome undergraduate and graduate students who are interested in the research of communication networks and their applications.
Anh T. Pham, Tu A. Luu, and Ngoc T. Dang. Performance Bound for Turbo-coded 2-D FSO/CDMA Systems over Atmospheric Turbulence Channels. IEICE Trans. on Fundamentals, E93-A(12):2696-2699, December 2010.
We propose turbo-coded two-dimensional (2-D) free-space optical (FSO) CDMA systems for broadband ac- cess networks. The performance bound for the proposed system over atmospheric turbulence channels is obtained considering multiple-access interference (MAI) and receiver noise. The results show that the proposed system oers a better performance than that of previously proposed ones. Also, it has a better tolerance to the turbulence and the number of users.
Ngoc T. Dang and Anh T. Pham. Reducing the Dispersion Effects in Multiwavelength Optical CDMA Systems by Using MCM Signaling. IEEE/OSA Journal of Optical Communications and Networking, 2(11):967 974, November 2010.
We propose a novel multiwavelength optical code-division multiple-access (OCDMA) system using multicode modulation (MCM) signaling. For the multicode demodulator, we employ a maximum-likelihood detection and optical hard limiters. The work in this paper theoretically analyzes the performance of the proposed system over linear dispersive channels, while taking into account the impacts of multiple-access interference (MAI), optical-beating interference (OBI), and receiver noise. It is seen that the use of MCM can significantly relax the effects of chromatic dispersion. In addition, MAI and OBI can be effectively mitigated in the proposed system. As a result, in comparison with the conventional systems using on-off keying (OOK) modulation and pulse-position modulation (PPM), the proposed system can support a higher user bit rate and a larger number of users. Also, a lower transmitted power is required and a longer transmission length can be achieved.
Lei Jing, Zixue Cheng, and Tongjun Huang. A system for localising and searching objects to enhance self-directed practical learning. Int. Journal of Computational Science and Engineering, 5(2):165-173, 2010.
We are living in an era of knowledge explosion. The meaning of knowing has shifted from being able to remember and repeat information to being able to find and use it. Practical learning has been proved as an effective way to arouse learner CT curiosity and deepen the understanding on a given subject. To perform practical learning more effectively,supervisors are necessary to recommend proper learning material and give instructions in the learning process. Up to now, however, human beings are the only candidate to act as supervisorsin the learning process which has hindered the learner CT practical learning activity. In this paper,we propose a computing system which can substitute human beings to act as supervisors to recommend proper experimental learning contents to the learner and help the learner to accomplish the experiment process.
Tu A. Luu, Ngoc T. Dang, and Anh T. Pham. Channel Coding for 2-D FSO/CDMA Systems over Strong Atmospheric Turbulence Channels. In Proc. of the 3rd International Conference on Communications and Electronics (ICCE 2010), number Digital Object Identifier: 10.1109/ICCE.2010.5670667, pages 278-283, Nhatrang, Vietnam, August 2010. IEEE/IEICE, IEEEXplore.
We propose 2-dimensional (2-D) free-space optical (FSO) CDMA systems for broadband access networks. The performance of the proposed system is analyzed over strong atmospheric turbulence channels. To mitigate the impact of the strong atmospheric turbulence, channel coding schemes, including Reed-Solomon (R-S) and convolutional (CC) codes, are employed. In the analysis, the upper bound of bit-error rate (BER) is derived taking into account multiple access interference (MAI), optical beating interference (OBI) and receiver noise. It is shown that the channel coding schemes can help to effectively mitigate the impact of strong turbulence. Additionally, the use of channel coding enable the 2-D FSO/CDMA systems to sustain from performance degradation when the supportable number of users increases.
Ngoc T. Dang, Hien T. T. Pham, and Anh T. Pham. Novel 2-D OCDMA Systems using Multi-Code Modulation and Optical Hard-Limiters. In Proc. of the 3rd International Conference on Communications and Electronics (ICCE 2010), number Digital Object Identifier: 10.1109/ICCE.2010.5670718, pages 242-246, Nhatrang, Vietnam, August 2010. IEEE/IEICE, IEEEXplore.
A novel 2-D OCDMA system using multi-code modulation (MCM) and optical hardlimiters (OHLs) is proposed in this paper. The proposed system has abilities of simultaneously mitigating dispersion, multiple access interference (MAl), and optical beating interference (OBI). The numerical results show that the proposed system allows for low bit error rate, large number of supportable users, low required power, and high user bit-rate. For example, the system using 8-MCM can support 38 users at the user's bit rate 2.5 Gbit/s when the trausmitted power per bit is -5 dBm and the transmission length is 20 km.
Ngoc T. Dang and Anh T. Pham. Performance Enhancement of 2D OCDMA Systems using Multi-Code Modulation and Heterodyne Detection. In Proc. of the 12th International Conference on Transparent Optical Networks (ICTON 2010), number Digital Object Identifier: 10.1109/ICTON.2010.5548966, page Tu.C1.4, Munich, Germany, June 2010. IEEE Photonics, IEEEXplore.
A new modulation scheme for 2-D OCDMA systems named multi-code modulation (MCM) is proposed in this paper. The key advantage of MCM over the conventional ones is the ability of mitigating simultaneously both multiple access interference and dispersion. We also propose to combine MCM with heterodyne detection, a powerful technique to relax optical beating interference, to obtain better performance. The numerical results show that the proposed system allows for lower bit error rate, lower required power, and higher user bit rate than that of conventional ones using other modulation schemes such as on-off keying modulation, pulse amplitude modulation, and pulse position modulation.
Tu A. Luu, Ngoc T. Dang, and Anh T. Pham. Performance Analysis of Optical Atmospheric Turbo-Coded CDMA Systems with PPM Signaling. In Proc. of the 8th Asia-Pacific Symposium on Information and Telecommunication Technologies (APSITT 2010), pages 1-6, Sarawak, Malaysia, June 2010. IEEE/IEICE, IEEEXplore.
This paper proposes Turbo code for optical atmospheric 2-dimensional (2-D) CDMA systems using pulse-position modulation (PPM) signaling. The system performance is theoretically analyzed and the upper bound of bit-error rate (BER) is derived considering the impact of scintillation. The analysis also takes into account various types of interferences and noises such as multiple access interference (MAI), optical beating interference (OBI), and receiver noise. It is shown that system performance is significantly improved when Turbo codes is employed. In particular, the use of Turbo code results in a power gain of 3.5 dB at the BER = 10results in a power gain of 3.5 dB at the BER = 10?7, the supportable number of users 7, the supportable number of users is also increased.
Ngoc T. Dang (PhD student). Travel Support Grant awarded by the Research Foundation for the Electro-technology of Chubu, 2010.
Anh T. Pham, 2010.
Technical reviewer for various IEEE, OSA and IEICE journals/transactions and international conferences
Anh T. Pham, 2010.
Member, Optical Society of America (OSA), IEICE
Anh T. Pham, 2011. Election to the Senior member grade, IEEE
Zixue Cheng, Shengguo Sun, Mizuo Kansen, and Tongjun Huang. Learning Support Systems and Learning Support Methods, Patent No. 4579634, Sep 2010.
Tu A. Luu. Master thesis: On the error correction codes for 2-D FSO/CDMA systems over atmospheric turbulence channels, Graduate School of Computer Science and Engineering, September 2010.
Thesis Adviser: Anh T. Pham
Shinichi Hirasawa. Graduation thesis: Performance of FSO system with Convolutional Codes using sub-carrier PSK modulation, School of Computer Science and Engineering, March 2011.
Thesis Adviser: Anh T. Pham
Hiroki Ochi. Graduation thesis: Simulation of SAE/OCDMA systems using APD receiver, School of Computer Science and Engineering, March 2011.
Thesis Adviser: Anh T. Pham
Ngoc T. Dang. PhD thesis: Performance Evaluation and Improvement Methods for Multi-wavelength Optical Code-Division Multiple-Access Systems, Graduate School of Computer Science and Engineering, September 2010.
Thesis Adviser: Anh T. Pham
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