Department of Electronic Engineering, CityU HK


Dr. Derek PAO
B.Sc.(Eng) HKU, M.Comp.Sc., Ph.D. Concordia, MIEEE

Associate Professor

Room: G6514 Tel: (852) 3442-8607 Fax: (852)3442-0562 Email:
Dr. Pao received his B.Sc.(Eng.) degree in Electrical Engineering from the University of Hong Kong in 1984. After working for RCL Semiconductors Ltd. as an Integrated Circuits Design Engineer for one-and-a-half years, he pursued higher education at the Concordia University, Montreal, Canada, where he obtained his master and Ph.D. degrees, both in Computer Science, in 1987 and 1991, respectively. Before joining the City University of Hong Kong in 1992, he was an Assistant Professor of Computer Science at the Concordia University.


  • Hardware architectures for network processing
  • Hardware architectures for intrusion detection and virus scanning
  • Named data networking


    Weiwen Yu, Derek Pao, "Hardware accelerator for FIB lookup in Named Data Networking", Microprocessors and Microsystems: Embedded Hardware Design, 2019.

    Weiwen Yu, Srinivas Sivakumar, Derek Pao, "Pseudo-TCAM: SRAM-based architecture for packet classification in one memory access", IEEE Networking Letters, June 2019.

    Xing Wang, Derek Pao, "Memory-based architecture for multi-character Aho-Corasick string matching", IEEE Trans. on VLSI Systems, Vol. 26, No. 1, pp. 143-154, 2018.

    Weiwen Yu, Derek Pao, "Hardware accelerator to speed up packet processing in NDN router", Computer Communications, Vol 91-92, pp. 109-119, 2016.

    Nga Lam Or, Xing Wang, Derek Pao, "Memory-based hardware architectures to detect ClamAV virus signatures with restricted regular expression features", IEEE Trans. on Computers, Vol. 65, Issue 4, pp. 1225-1238, 2016.

    Xing Wang, Nga Lam Or, Ziyan Lu, Derek Pao, "Hardware accelerator to detect multi-segment virus patterns", The Computer Journal, Vol. 58, No. 10, pp. 2443-2460, 2015.

    Derek Pao, Ziyan Lu, "A multi-pipeline architecture for high-speed packet classification", Computer Communications, Vol. 54, pp. 84-96, 2014.

    Derek Pao, Ziyan Lu, Y H Poon, "IP address lookup using bit-shuffled trie", Computer Communications, Vol. 47, pp. 51-64, 2014.

    Derek Pao, Nga Lam Or, Ray C C Cheung, "A memory-based NFA regular expression match engine for signature-based intrusion detection", Computer Communications, Vol. 36, pp. 1255-1267, 2013. (MX-NFA setup for regexes shown in Fig. 12)

    Derek Pao, Xing Wang, "Multi-stride string searching for high-speed content inspection", The Computer Journal, Vol. 55, No. 10, pp. 1216-1231, 2012.

    Derek Pao, Xing Wang, Xiaoran Wang, Cong Cao and Yuesheng Zhu, "String searching engine for virus scanning", IEEE Trans. on Computers, Vol. 60, No. 11, pp. 1596-1609, 2011.

    Derek Pao, W. Lin, B. Liu, "A memory-efficient pipelined implementation of the Aho-Corasick string-matching algorithm", ACM Trans. on Architecture and Code Optimization, Vol. 7, Issue 2, Article 10, 2010. (Notes on the construction of the lookup tables)

    Derek Pao, W. Lin, B. Liu, "Pipelined architecture for multi-string matching", IEEE Computer Architecture Letters, Vol. 7, No. 2, pp. 33-36, 2008.

    Derek Pao, P. Zhou, B. Liu, X. Zhang, "Enhanced prefix inclusion coding filter-encoding algorithm for packet classification with ternary content addressable memory", IET Computers and Digital Techniques, Vol. 1, Issue 5, pp. 572-580, 2007.

    Derek Pao, C. Liu, "Parallel tree search: an algorithmic approach for multi-field packet classification", Computer Communications, Vol. 30, Issue 2, pp. 302-314, 2007.

    Y. K. Li, Derek Pao, "Address lookup algoirthms for IPv6", IEE Proc-Communications, Vol. 153, No. 6, pp. 909-918, 2006.

    Derek Pao, Y. K. Li, P. Zhou, "Efficient packet classification using TCAMs", Computer Networks, Vol. 50, Issue 18, pp. 3523-3535, 2006.

    K. S. Lau, Derek Pao, "Collision avoidance and recovery for multicast communications in ad hoc networks", IEICE Trans. Communications, Vol. E88B, No. 7, pp. 2937-2943, 2005.

    Derek Pao, "On-demand packet discard scheme for TCP over ATM-UBR service", IEE Proc-Communications, Vol. 151, No. 3, pp. 190-196, 2004.

    Derek Pao, Y. K. Li, "Enabling incremental updates to LC-trie for efficient management of IP forwarding tables", IEEE Communications Letters, Vol. 7, Issue 5, pp. 245-247, 2003.

    Derek Pao, C. Liu, A. Wu, L. Yeung, K. S. Chan, "Efficient hardware architecture for fast IP address lookup", IEE Proc-Computers and Digital Techniques, Vol. 150, No. 1, pp. 43-52, 2003.

    Derek Pao, "Scheduling multicast traffic in input-buffered ATM switch", Computer Communications, Vol. 24, No. 15-16, pp. 1607-1617, 2001.

    Derek Pao, S. P. Lam, A. S. Fong, "Parallel implementation of simulated annealing using transaction processing", IEE Proc-Computers and Digital Techniques, Vol. 146, No. 2, pp. 107-113, 1999.

    Derek Pao, S. P. Lam, "Cell scheduling for ATM switch with delay sensitive and loss sensitive traffic", Computer Communications, Vol. 21, No. 13, pp. 1153-1164, 1998.

    Derek Pao, S. P. Lam, "Look-ahead reservation based scheduling for input-output buffered ATM switch", IEE Proc-Communications, Vol. 145, No. 4, pp. 234-240, 1998.

    Derek Pao, M. C. Sun, M. Lam, "An approximate string matching algorithm for on-line Chinese character recognition", Image and Vision Computing, Vol. 15, No. 9, pp. 695-703, 1997.

    Derek Pao, S. C. Leung, "Space division approach to implement shared buffer in ATM switch", Computer Communications, Vol. 20, No. 1, pp. 29-37, 1997.

    Derek Pao, H. F. Li, R. Jayakumar, "A decomposable parameter space for the detection of ellipses", Pattern Recognition Letters, Vol. 14, No. 12, pp. 951-958, 1993.

    Derek Pao, H. F. Li, R. Jayakumar, "Shapes recognition using the straight line Hough transform: theory and generalization", IEEE Trans. on Pattern Analysis and Machine Intelligence, Vol. 14, No. 11, pp. 1076-1089, 1992.

    H. F. Li, Derek Pao, R. Jayakumar, "Improvements and systolic implementation of the Hough transformation for straight line detection", Pattern Recognition, Vol. 22, No. 6, pp. 697-706, 1989.