Annual Review 2011 > Division of Computer Engineering

Computer Communications Laboratory

Anh T. Pham

Assistant Professor

Cong-Thang Truong

Assistant Professor

Tongiun Huang

Assistant Lecturer

In the AY2011, the Computer Communications Laboratory (CCL) has three faculty members, two visiting scholars and 14 research students. Our research and education focus on the areas of computer networks, multimedia communications and networks, optical communications and networking technologies, communication engineering, and ubiquitous computing & its applications. Especially, we encompass following topics:

  1. Multimedia communications and networks: Visual media, video streaming, Image/video processing, video streaming, content adaptation, MPEG/JVT/ITU-T Standardization.

  2. Computer networks: Internet of Things, smart town, smart grid; Inter-networking technologies for security & reliability sensitive applications e.g. medical and healthcare networks.

  3. Optical communications and networks: Optical fiber, optical wireless comm., systems design and performance analysis; Enabling technologies and techniques for broadband Fiber to the Home (FTTH), Fiber in the Home (FITH) networks; Optical network architecture, network protection, survivable and green optical networks.

  4. Communication engineering: System modeling and performance analysis, Modulation techniques and channel coding, Code acquisition and synchronization techniques in spread spectrum systems, Cognitive radio, cooperative communications

  5. E-Learning, distributed algorithms and ubiquitous computing

We always welcome undergraduate and graduate students who are interested in the above mentioned research. For further information, visit our website at

Refereed Journal Papers


Anh T. Pham and Ngoc T. Dang. Performance Enhancement of 2-D Optical CDMA Systems using MCM Signaling and Heterodyne Detection Receiver. Wiley's Transactions on Emerging Telecommunications Technologies, page DOI: 10.1002/ett.2512, Feb 2012.

We propose 2-D optical code-division multiple-access systems using multi-code modulation signalling and heterodyne detection receiver. The proposed system's performance is theoretically analysed and compared with conventional ones using onoff keying, pulseamplitude modulation and pulseposition modulation. The numerical results show that the proposed system outperforms the conventional ones in terms of required transmitted power, the number of supportable users and spectral efficiency.


Ngoc T. Dang and Anh T. Pham. Performance analysis of 2-D OCDMA systems using novel multi-code pulse-position modulation. IET Communications, pages Accepted, to appear, 2012.

Previous works show that pulse-position modulation (PPM) is an effective signaling method for mitigating multiple-access interference (MAI), and hence is able to increase the number of users in 2-D OCDMA systems. However, in order to achieve high bit-rates, 2-D OCDMA systems using PPM signaling require very high transmitted power due to the negative impact of dispersion. In this paper, we propose a novel modulation technique of multi-code pulse-position modulation (MCPPM), which is the combination of the PPM and multi-code modulation (MCM). As the proposed technique inherits advantages from both MCM (in mitigating the dispersion) and PPM, 2-D OCDMA systems using MCPPM signaling are able to support higher user bit-rates for a larger number of users at low transmitted powers. Our numerical results show that 2-D OCDMA systems using 4-4-MCPPM can support 60 users with 5 Gbps per user at the transmitted power of -7 dBm. The power gain in this case is 11 dB compared to 2-D OCDMA systems using 4-PPM signaling. The proposed systems using 4-2-MCPPM can support as many as 36 users with the bit-rate of 10 Gbps per user and transmitted power is -2 dBm.


Truong Cong Thang, Q.-D. Ho, J. W. Kang, and Anh T. Pham. Adaptive Streaming of Audiovisual Content using MPEG DASH. IEEE Trans. Consumer Electronics, 58(1):78-85, Feb. 2012.

HTTP streaming has become a cost effective means for multimedia delivery nowadays. In this paper, we study the use of MPEG DASH standard to stream audiovisual content. We first describe a novel estimation method for connection throughput. Then, employing the extensibility feature of DASH syntax, we present a systematic method for selecting the best audio and video alternatives given the estimated throughput. The experiments show that our solution is stable to short-term fluctuations while responding quickly to large fluctuations.

Refereed Proceedings Papers


Ngoc T. Dang, Hien T. T. Pham, and Anh T. Pham. Novel Multi-code Pulse Position Modulation for Performance Improvement of 2-D OCDMA Systems. In Proc. IEEE 17th Asia Pacific Conference on Communications (APCC2011), DOI: 10.1109/APCC.2011.6152767, pages 96-101, Kota Kinabalu, Malaysia, October 2011. IEEEXplore.

In OCDMA systems, pulse position modulation (PPM) and multi-code modulation (MCM) have been proven as efficient methods for respectively mitigating multiple access interference (MAI) and dispersion. In this paper, we propose to combine PPM and MCM to create a novel modulation scheme, multi-code pulse position modulation (MCPPM). We then theoretically analyze the performance of the 2D OCDMA system using MCPPM over a linear dispersive channel, while taking into account the negative impact of MAI, optical-beating interference (OBI), and receiver noise. It is seen that the use of MCPPM can simultaneously relax the effects of MAI, OBI, and dispersion. As a result, in comparison to the conventional systems using PPM and MCM, the one using MCPPM can support a higher user bit rate and a larger number of users. Also, a lower transmitted power can be achieved.


Ngoc T. Dang, Hien T. Nguyen, Hien T. T. Pham, Ban T. Nguyen, and Anh T. Pham. A Novel Scheme of 2-D Optical Code Label for Core GMPLS Networks. In Proc. of the 2011 International Conferences on Advanced Technologies for Communications (ATC 2011), DOI: 10.1109/ATC.2011.6027453, pages 144-147, Danang, Vietnam, August 2011. IEEEXplore.

The standard core GMPLS networks consist of two layers, Fiber Switch Capable (FSC) and Wavelength Switch Capable (LSC). To extend the core switch capacity, code switch capable (CSC) layer has been added. The CSC layer, however, induces the complexity of the networks. In this paper, we propose a novel scheme of twodimensional (2-D) optical code label for core GMPLS networks. In our proposal, the LSC layer and CSC layer are combined into one, i.e., 2-D CSC layer. The complexity of the GMPLS networks is therefore reduced while the core switch capacity is still enhanced. In addition, to the mitigate multiple-access interference (MAI), we propose to use optical hard-limiters (OHLs) at the core switches. Numerical results show that the throughput is increased significantly and able to reach the peak value.


Anh T. Pham, Truong C. Thang, S. Guo, and Z. Cheng. Performance Bounds for Turbo-coded SC-PSK/FSO Communications over Strong Turbulence Channels (invited paper). In Proc. of the 2011 International Conferences on Advanced Technologies for Communications (ATC 2011), DOI: 10.1109/ATC.2011.6027457, pages 161-164, Danang, Vietnam, August 2011. IEEEXplore.

This paper comprehensively investigates the performance of the Turbo-coded free space optical (FSO) system using subcarrier phase shift keying (SC-PSK) signaling. We obtain theoretical bounds for the system's bit-error rate (BER) and channel capacity over the gamma-gamma strong turbulence channels in both uncoded and Turbo-coded cases. We quantitatively show that the BER and channel capacity are considerably affected by the strong turbulence. In Turbo-coded systems, a coding gain of about 4 dB and 5the strong turbulence regime.


Deze Zeng, Song Guo, Zixue Cheng, and Anh T. Pham. IF-THEN in the Internet of Things. In Proc. of IEEE 3rd International Conference on Awareness Science and Technology (IEEE iCAST 2011), DOI: 10.1109/ICAwST.2011.6163180, pages 503-507, Dalian, China, September 2011. IEEEXplore.

With the advent of Internet of Things (IoT), more and more smart things automatically engage in people's daily life by various means as they are becoming capable of computation and communication. Both challenges and opportunities are posed. To exploit the potential of IoT, different concepts from various points of view have been explored. One of the IoT developing trend is so-called Ambient Intelligence (AI), which refers to things that are sensitive and responsive to the presence of other things and people. The things shall be aware of ambient environments (e.g., other things or people) and take actions accordingly. However, complicated configuration of AI hinders the popularity of IoT. To tackle this problem, we advocate applying the highly abstract concept of IF-THEN as the front-end of AI in IoT. To realize such a concept, we present a preliminary design in this paper, including issues of the architecture design, the uniformly understandable language and function assembly.


Anh T. Pham, Tu A. Luu, and Cong T. Truong. On the Channel Capacity of Two-dimensional FSO/CDMA Systems Over Atmospheric Turbulence Channels. In Proc. of IEEE Globecom 2011, the Workshop on Optical Wireless Communications, pages 838-842, Houston, TX, USA, December 2011. IEEEXplore.

We quantitatively study the performance limits of two-dimensional (2-D) free-space optical code-division multiple-access (FSO/CDMA) systems over weak and strong atmospheric turbulence channels. The theoretical bounds for channel capacity are derived taking into account multiple-access interference (MAI), optical beating interference (OBI) and receiver noise. Forward error correction (FEC) codes are employed to mitigate the impact of turbulence. We find that the impact of atmospheric turbulence on the channel capacity limit is severe, especially when the turbulence is strong. The channel capacity limit is decreased as much as 16% when turbulence variance oe2s = 0:6178.


Linh D. Truong and Anh T. Pham. A Model for Designing Survivable Mesh Optical Access Networks. In Proc. of the 2011 International Conferences on Advanced Technologies for Communications (ATC 2011), DOI: 10.1109/ATC.2011.6027456, pages 156-160, Danang, Vietnam, 2011. IEEEXplore.

In this paper, we propose to use mesh topology for PON based access network in order to strengthen its survivable ability. We propose also an exact model for designing survivable mesh PON with objective of minimizing fiber miles. A greedy heuristic for designing survivable PON is also proposed.


L. Jing, K. Yamagishi, J. Wang, Y. Zhou, T. Huang, and Z. Cheng. A Unified Method for Multiple Home Appliances Control through Static Finger Gestures. In Proc. of SAINT2011(Symposium on Applications and the Internet), pages 82-90. IEEE-CS/IPSJ, IEEE Computer Society Press, July 2011.

In this paper, a one-for-all gesture-based remote control system is proposed by which consumers can control different appliances in a nature and unified way.


Truong Cong Thang, Jung Won Kang, and Anh T. Pham. Qualityguided Adaptivity for Audiovisual Content Streaming by MPEG DASH. In Proc. of the 2012 IEEE International Conference on Consumer Electronics, pages 13-16, 2012.

HTTP streaming has become a cost effective means for multimedia delivery nowadays. In this paper, we study the use of MPEG DASH standard to stream audiovisual content. Our focus is on a systematic approach for selecting the best audio and video alternatives. For that purpose, we extend the current standard syntax with quality related information.


Truong Cong Thang, J. W. Kang, and Anh T. Pham. StandardCompliant Content Adaptation in IPTV Systems. In Proc. of the 2011 International Conferences on Advanced Technologies for Communications (ATC 2011), pages 66-69, 2011.

IPTV, which is based on the universal IP infrastructure, has the inherent nature of heterogeneity in terms of contents, networks, terminals, and users. An important solution to cope with such heterogeneity is content adaptation. This paper reviews the standardization issues related to content adaptation in IPTV standards. We first describe the basic architecture of content adaptation and its integration into the ITU-T IPTV architecture. Then typical methods of content adaptation in practical IPTV systems are discussed in detail. Especially, we highlight the standard metadata tools that are potential to support adaptation methods within ITU-T IPTV architecture. Some recent developments in other standard bodies are also discussed.


Truong Cong Thang, Anh T. Pham, Zixue Cheng, and Nam Pham Ngoc. Towards a Full-duplex Emergency Alert System based on IPTV Platform. In Proc. of IEEE 3rd International Conference on Awareness Science and Technology (IEEE iCAST 2011), pages 536-539, 2011.

Recently, IPTV has become a convergent infrastructure for entertainment and communications services in our daily life. An IPTV set-top-box is now an important device in the Internet-of-things of each home. It is expected that this infrastructure would be suitable for emergency alert systems (EAS), especially in disaster and health-care scenarios. In this paper, we first review the recent developments to support emergency scenarios, including related IPTV standards and research in smart home. Then we propose an architecture for full-duplex emergency alert services based on IPTV platform. In order to maintain a very high availability of service, the key features of the architecture include the redundancy of devices and network connections and the scalability of data.



Anh T. Pham (main researcher). Cross layer optimization for Adhoc and Multihop networks, 2012-2014. Grant-in-aid by Vietnam National Foundation for Science and Technology Development, PI: Dr. Ha Duyen Trung (Hanoi University of Science and Technology)

Academic Activities


Anh T. Pham, 2011-2012.

Technical reviewer for various IEEE, OSA and IEICE journals, transactions and international conferences.


Anh T. Pham, 2001-2012.

Senior member grade (2011 class), IEEE, Communications, Photonics societies


Anh T. Pham, 2012.

Member of the International Steering Committee, Chair of the Optical Communications and Network Session, The 4th International Conference on Communications and Electronics (ICCE2012)


Anh T. Pham, 2002-2012.

Member, IEICE


Anh T. Pham, 2012.

Member of TPC, The International Symposium on Embedded Multicore System-onChip (MCSoC-12)


Anh T. Pham, 2012.

Member of TPC, IIAI International Conference on Advanced Applied Informatics (IIAI AAI 2012)


Anh T. Pham, 2012.

Member of TPC, 25th International Conference on Computer Applications in Industry and Engineering (CAINE 2012)


Anh T. Pham, 2005-2012.

Member, Optical Society of America


Anh T. Pham, 2012.

Member of TPC, 2012 IEEE Symposium on Wireless Technology & Applications (ISWTA 2012)


Anh T. Pham, 2012.

Member of TPC, The 3rd International Symposium on Information and Communication Technology (SoICT 2012)



Shengguo Sun Tongjun Huang Zixue Cheng (Shigaku Tei), Mizuo Kansen. Automatic Support Systems and Antomatic Support Methods, Sep. 2011.

Ph.D., Master and Graduation Theses


Masato Sato. A Support System for Learning Java Programming Structures Based on Templates. Graduation thesis, School of Computer Science and Engineering, 2012.

Thesis Adviser: T. Huang


Moemi Takeuchi. Teaching Support System to Provide Samples of Java Programming Exercises. Graduation thesis, School of Computer Science and Engineering, 2012.

Thesis Adviser: T. Huang