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 |
Associate Professor |
Assistant Professor |
- Optical communication technology, in particular, modeling,
theoretical analysis and simulation of multiple access optical systems;
- Architecture design and modeling of computer networks; and
- Internetworking technologies for security & reliability sensitive applications
e.g. medical and healthcare networks.
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Current research at the Computer Communications Laboratory (CCL) encompasses
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Refereed Journal Papers
| [pham-01:2008] |
Ngoc T. Dang, Anh T. Pham, and Shigaku Tei. Impact of GVD on the
Performance of 2-D WH/TS OCDMA Systems using Heterodyne Detection
Receiver. IEICE Trans. on. Fundamentals of Electronics, Communications
and Computer Sciences, E92-A(4):1182–1191, April 2009. |
| In this paper, a novel model of Gaussian pulse propagation in optical fiber is proposed
to comprehensively analyze the impact of Group Velocity Dispersion (GVD) on the
performance of two-dimensional wavelength hopping/time spreading optical code division
multiple access (2-D WH/TS OCDMA) systems. In addition, many noise and
interferences, including multiple access interference (MAI), optical beating interference
(OBI), and receiver’s noise are included in the analysis. Besides, we propose to use
the heterodyne detection receiver so that the receiver’s sensitivity can be improved.
Analytical results show that, under the impact of GVD, the number of supportable
users is extremely decreased and the maximum transmission length (i.e. the length at
which BER <= 10−9 can be maintained) is remarkably shortened in the case of normal
single mode fiber (ITU-T G.652) is used. The main factor that limits the system
performance is time skewing. In addition, we show how the impact of GVD is relieved
by dispersion-shifted fiber (ITU-T G.653). For example, a system with 32 × 1 Gbit/s
users can achieve a maximum transmission length of 111 km when transmitted optical
power per bit is -5 dBm |
Refereed Proceeding Papers
| [pham-02:2008] |
Ngoc T. Dang and Anh T. Pham. Impact of Four Wave Mixing on
2-D OCDM Systems. In IEEE Photonics Society Summer Topicals Meeting
(SUM’09), pages CD–ROM, Newport, CA, USA, July 2009. IEEE, Photonics
Society. |
|
This paper theoretically analyzed the impact of FWM on 2-D OCDM system performance
considering various noises, interferences, and system’s parameters. Specifically,
the impact on the operational power range, power penalty is quantitatively analyzed
and discussed |
|
| [pham-03:2008] |
Ngoc T. Dang and Anh T. Pham. Modeling the Impact of GVD on
the Performance of 2-D WH/TS OCDMA Systems. In The 14th Asia Pacific
Conference on Communications, pages CD–ROM, Tokyo, Japan, Oct. 2008.
IEEE/IEICE. |
| In this paper, a modified model of Gaussian pulse propagation in optical fiber is proposed
to comprehensively analyze the performance degradation of spectral amplitude
encoding (SAE) optical code division multiple access (OCDMA) systems due to group
velocity dispersion (GVD). The analytical results show that the number of supportable
users is decreased and the maximum transmission length (i.e. the length at which
BER <= 10−9 can be maintained) is shortened under the impact of GVD. For example,
a system with 31 × 1 Gbit/s users and wavelength interval of 1.0 nm has a maximum
transmission length of 16 km when transmitted power per bit is 0 dBm. Although,
the impact of GVD is reduced when wavelength interval is decreased to 0.4 nm, it is
still relatively strong. A power penalty of up to 8 dB is seen in the SAE/OCDMA
system with the transmission length of 33 km. In addition, we propose a method to
combat the impact of GVD, which can increase the maximum transmission length of
SAE/OCDMA systems |
|
| [pham-04:2008] |
Ngoc T. Dang and Anh T. Pham. Modeling the Impact of GVD on the
Performance of 2-D WH/TS OCDMA Systems. In IEEE Region 10 Technical
Conference (TENCON’08), pages CD–ROM, Hyderabad, India, Nov. 2008.
IEEE Region 10. |
| In this paper, a novel model of Gaussian pulse propagation in optical fiber is proposed
to comprehensively analyze the impact of Group Velocity Dispersion (GVD) on the
performance of two-dimensional wavelength hopping/time spreading optical code division
multiple access (2-D WH/TS OCDMA) systems. In addition, many noise and
interferences, including multiple access interference (MAI), optical beating interference
(OBI), and receiverpsilas noise are included in the analysis. Besides, we propose
to use the heterodyne detection receiver so that the receiverpsilas sensitivity can be
improved. Analytical results show that, under the impact of GVD, the number of
supportable users is extremely decreased and the maximum transmission length is remarkably
shortened when the normal single mode fiber is used. The main factor that
limits the system performance is time skewing. In addition, we show how the impact of
GVD is relieved by dispersion-shifted fiber. For example, a system with 32 × 1 Gbit/s
users can achieve a maximum transmission length of 111 km when transmitted optical
power per bit is -5 dBm |
Unrefereed Papers
| [pham-05:2008] |
Ngoc T. Dang and Anh T. Pham. Performance Analysis of 2-D OCDM
Systems under the impact of Four Wave Mixing (FWM) Phenomenon. In IEICE
Technical Report, pages B–8–32, Ehime University, Matsuyama, Ehime, Japan,
Mar 2009. IEICE. |
|
We theoretically analyze the performance of 2-dimensional (2-D) OCDM systems under
the impact of Four Wave Mixing (FWM) phenomenon. Other interferences and noises
such as multiple access interference (MAI), optical beating interference (OBI), and receiver’s
noise are also included in the analysis |
|
| [pham-06:2008] |
Anh T. Pham and Ngoc T. Dang. Modelling the Impact of GVD on
the Performance of 2-D WH/TS OCDMA Systems. In IEICE Technical Report,
pages 7–14, Chitose Institute of Science and Technology, Hokkaido, Japan, June
2008. IEICE OCS2008-11. |
|
This report proposes a novel model of Gaussian pulse propagation in optical fiber to
comprehensively analyze the impact of Group Velocity Dispersion (GVD) on the performance
of two-dimensional wavelength hopping/ time spreading optical code division
multiple access (2-D WH/TS OCDMA) systems. In addition, many noise and interferences,
including multiple access interference (MAI), optical beating interference (OBI),
and receiver’s noise are included in the analysis. Besides, we propose to use the heterodyne
detection receiver so that the receiver’s sensitivity can be improved. Analytical
results show that, under the impact of GVD, the number of supportable users is extremely
decreased and the maximum transmission length (i.e. the length at which BER
<= 10−9 can be maintained) is remarkably shortened; and it is found that the main factor
that limits the system performance is time skewing |
Grants
| [pham-07:2008] |
Anh T. Pham. Grants-in-Aid (Grant No. 18760278) for Encouragement
of Young Scientists, awarded by the Japan Society for Promotion of Science,
2006-2008. |
Academic Activities
| [pham-08:2008] |
Anh T. Pham, 2005-2008. Member of the Technical Committee on Telecommunications, IASTED |
| [pham-09:2008] |
Anh T. Pham, 2008. Technical reviewer for various IEEE, IEICE journals/transactions & international conferences |
| [pham-10:2008] |
Anh T. Pham, 2009. Program Vice Chair, The 4th International Conference on Frontier of Computer Science and Technology (FCST 2009) |
Ph.D, Master and Bachelor Theses
| [pham-11:2008] |
Watahiki Michinori. Graduation Thesis: Performance Analysis of Atmospheric
SAE/Optical CDMA Systems, University of Aizu, 2008. Thesis Advisor: Anh T. Pham |
| [pham-12:2008] |
Nakau Yousuke. Graduation Thesis: Monte-Carlo Simulation of 2-D
Optical CDMA Systems, University of Aizu, 2008. Thesis Advisor: Anh T. Pham |
| [pham-13:2008] |
Kiyohashi Kenji. Graduation Thesis: Performance Improvement of Two-
Dimensional Optical CDMA Systems using Reed-Solomon Codes, University of
Aizu, 2008. Thesis Advisor: Anh T. Pham and A. Kara, |
| [pham-14:2008] |
Suzuki Satoshi. Graduation Thesis: SAE/OCDMA Networks using
Random Access Protocol, University of Aizu, 2008. Thesis Advisor: Anh T. Pham |
| [pham-15:2008] |
Shihomi Sato. Master Thesis: Dynamic Routing using Layer-2 VPN
over IPsec NAT-T, University of Aizu, 2008. Thesis Advisor: Anh T. Pham and A. Kara, |
