Dr. Wing-Kin (Ken) Ma

Associate Professor

Department of Electronic Engineering

The Chinese University of Hong Kong


Office: Room 323, Ho Sin Hang Engineering Building

Tel.: +852 3943 4350    Fax: +852 2603 5558

E-mail: wkma AT ee.cuhk.edu.hk


Bio Sketch

Wing-Kin Ma was born in Hong Kong. After obtaining his B.Eng. degree in electrical and electronic engineering (with first class honours)  from the University of Portsmouth, U.K., in 1995, he returned to Hong Kong pursuing postgraduate studies at the Chinese University of Hong Kong (CUHK). He received his M.Phil. and Ph.D. degrees, both in electronic engineering, CUHK, in 1997 and 2001, respectively.

He is currently an Associate Professor in the Department of Electronic Engineering, CUHK. He was with the Department of Electrical Engineering and the Institute of Communications Engineering, National Tsing Hua University, Taiwan, as an Assistant Professor from Aug. 2005 to Aug. 2007. Prior to becoming a faculty, he held various research positions at McMaster University, Canada, CUHK, Hong Kong, and the University of Melbourne, Australia.

His research interests are in signal processing (SP) and communications, with a recent emphasis on optimization;  MIMO communication and interference management techniques; and blind signal processing theory and applications to speech separation, image separation and hyperspectral unmixing.

Dr. Ma received British Telecom Research and Technology Prize at the University of Portsmouth in 1995. His Ph.D. thesis was commended to be "of very high quality and well deserved honorary mentioning" by the Faculty of Engineering, CUHK in 2001. He has served or currently serves as Associate Editor of IEEE Transactions on Signal Processing (2007-2011), IEEE Signal Processing Letters (2009-2012) and Signal Processing (2013-Present); Guest Editor of the IEEE Signal Processing Magazine, Special Issue on "Convex Optimization for Signal Processing" in May 2010, and IEEE Journal on Selected Areas of Communications, special issue on "Signal Processing Techniques for Wireless Physical Layer Security" in Sep 2013; and Lead Guest Editor of the IEEE Signal Processing Magazine, Special Issue on "Signal and Image Processing in Hyperspectral Remote Sensing" in Jan 2014. He is a member of the SPTM Technical Committee and SPCOM Technical Committee, IEEE Signal Processing Society. He was a tutorial speaker in EUSIPCO 2011,  STATOS 2013, and ICASSP 2014.

Research and Ongoing Projects

Check out my full publication list for my old and recent work.

Also check Google Scholar or Researcher ID for my publication information (they seem to do a better job than my home-compiled publication list!).

Here are some of the topics I am currently pursuing:

For these projects there are vacancies for postgraduate scholarships leading to M.Phil. or Ph.D. degree. For suitable Ph.D. holders, research positions might be considered. If you think you are highly motivated and have strong interest in signal processing and communications research, send me an email to discuss the opportunities. Note that according to various surveys, CUHK has good international and regional (Asia) rankings.

And here is a sample of my favorite publications, done with good friends, colleagues and/or students (or student-turned friends).


  1. Z.-Q. Luo, W.-K. Ma, A. M.-C. So, Y. Ye, and S. Zhang, "Semidefinite relaxation of quadratic optimization problems," IEEE Signal Processing Magazine, vol. 27, no. 3, pp. 20-34, May 2010 [PDF] [Tutorial Slides, MIIS2012] (Received 2015 IEEE Signal Processing Magazine Best Paper Award).

  2. W.-K. Ma, J. M. Bioucas-Dias, T.-H. Chan, N. Gillis, P. Gader, A. Plaza, A. Ambikapathi and C.-Y. Chi, "A signal processing perspective on hyperspectral unmixing," IEEE Signal Processing Magazine, vol. 31, no. 1, pp. 67-81, Jan 2014. [PDF] [Talk Slides at KTH, 2015] [Talk Slides at Chinese WHISPERS, 2015].

MIMO Detection

  1. W.-K. Ma, T.N. Davidson, K.M. Wong, Z.Q. Luo and P.C. Ching, "Quasi-maximum-likelihood multiuser detection using semi-definite relaxation with application to synchronous CDMA," IIEEE Transactions on Signal Processing, vol. 50, no. 4, pp. 912-922, Apr. 2002. [PS]

  2. W.-K. Ma, "Blind ML detection of orthogonal space-time block codes: Identifiability and code construction," IEEE Transactions on Signal Processing, vol. 55, no. 7, pp. 3312-3324, July 2007. [PDF] [Talk Slides]

  3. W.-K. Ma, C.-C. Su, J. Jaldén, T.-H. Chang, and C.-Y. Chi, "The equivalence of semidefinite relaxation MIMO detectors for higher-order QAM," IEEE Journal of Selected Topics of Signal Processing, vol. 3, no. 6, pp. 1038-1052, Dec 2009. [PDF]

MIMO Transceiver Designs and Optimization

  1. X. Wu, W.-K. Ma, and A. M.-C. So, "Physical-layer multicasting by stochastic transmit beamforming and Alamouti space-time coding," IEEE Transactions on Signal Processing, vol. 61, no. 17, pp. 4230-4245, Sep 2013. [ArXiv] [Companion Technical Report] [Talk Slides, MIIS2012]

  2. K.-Y. Wang, A. M.-C. So, T.-H. Chang, W.-K. Ma, and C.-Y. Chi, "Outage constrained robust transmit optimization for multiuser MISO downlinks: Tractable approximations by conic optimization," IEEE Transactions on Signal Processing, vol. 62, no. 21, pp. 5690-5705, Nov. 2014. [PDF] [Companion Technical Report]

  3. W.-K. Ma, J. Pan, A. M.-C. So, and T.-H. Chang, "Unraveling the rank-one solution mystery of robust MISO downlink transmit optimization: A verifiable sufficient condition via a new duality result," IEEE Transactions on Signal Processing, vol. 65, no. 7, pp. 1909-1924, Apr. 2017. [ArXiv] [Talk Slides, ICCOPT2016]

Blind Separation and Structured Matrix Factorization

  1. T.-H. Chan, W.-K. Ma, C-.Y. Chi, and Y. Wang, "A convex analysis framework for blind separation of non-negative sources," IEEE Transactions on Signal Processing, vol. 56, no. 10, pp. 5120-5134, Oct. 2008. [PDF] [Talk Slides]

  2. C.-H. Lin, W.-K. Ma, W.-C. Li, C.-Y. Chi, and A. Ambikapathi, "Identifiability of the simplex volume minimization criterion for blind hyperspectral unmixing: The no pure-pixel case," IEEE Transactions on Geoscience and Remote Sensing, vol. 53, no. 10, pp. 5530-5546, Oct. 2015. [ArXiv]

Target Tracking

  1. B.-N. Vo and W.-K. Ma, "The Gaussian mixture probability hypothesis density filter," IEEE Trans. Signal Process., vol. 54, no. 11, 4091-4104, Nov. 2006. [PDF]


I should also mention the following names; without these great collaborators, the research results above might not have been possible.

News & Updates

March 2017: more than 1000 citations for our semidefinite relaxation overview paper in IEEE Signal Processing Magazine.


May 2016: The paper

B.-N. Vo and W.-K. Ma, "The Gaussian mixture probability hypothesis density filter," IEEE Trans. Signal Process., vol. 54, no. 11, 4091-4104, Nov. 2006. [PDF]

has reached one thousand citations in Scholar Google!


Mar 2016: 2015 IEEE Signal Processing Magazine Best Paper Award for the following paper

Z.-Q. Luo, W.-K. Ma, A. M.-C. So, Y. Ye, and S. Zhang, "Semidefinite relaxation of quadratic optimization problems," IEEE Signal Processing Magazine, vol. 27, no. 3, pp. 20-34, May 2010 [PDF] [Tutorial Slides, MIIS2012]

Some photos in the opening ceremony in ICASSP 2016.

Dec 2015: Xiaoxiao Wu won the Postgraduate Research Output Award 2014. See here. Congrats. Xiaoxiao!

Aug 2015: check out some of our recent publications:

J. Pan, W.-K. Ma, X. Xia, and Y. Tian, "WMMSE-based multiuser MIMO beamforming: A practice-oriented design and LTE system performance evaluation," in Proc. SPAWC 2015, Stockholm, Sweden, Jun. 2015. [PDF]

W.-K. Ma, C.-H. Lin, W.-C. Li, and C.-Y. Chi, "When can the minimum volume enclosing simplex identify the endmembers correctly when there is no pure pixel?" in Proc. WHISPERS 2015, Tokyo, Japan, Jun. 2015. [PDF]

Mar 2015: the annual awards presentation ceremony day, the CUHK engineering faculty, where I received his Research Excellence Award 2013-2014.

Mar 2015: an update of our manuscript, with MATLAB demo:

X. Fu, W.-K. Ma, T.-H. Chan, and J. M. Bioucas-Dias, "Self-dictionary sparse regression for hyperspectral unmixing: Greedy pursuit and pure pixel search are related," to appear in IEEE Journal of Selected Topics in Signal Processing, Sep. 2015. [ArXiv] [MATLAB code]

Feb 2015: Check out this manuscript, recently accepted by IEEE Transactions on Signal Processing:

X. Fu, W.-K. Ma, K. Huang, and N. D. Sidiropoulos, "Blind separation of quasi-stationary sources: Exploiting convex geometry in covariance domain," accepted for publication in IEEE Transactions on Signal Processing, Jan. 2015. Submitted Apr. 2014, revised Aug. 2014. [PDF] [MATLAB code]

The paper describes a novel way to tackle the classical problem of blind source separation using quasi-stationarity. In particular, we establish a link between quasi-stationary blind separation and convex geometry, which were considered two different contexts previously. From such a link, we introduce convex geometry-based algorithms for quasi-stationary blind separation, which show a different flavor from many existing quasi-stationary blind separation frameworks. Numerical experiments suggest that the convex geometry-based algorithms work well (see "SPA", "Pro-SPA" and "VolMin-AO" below).


Old News: Check out the news archive for past news. Some old stuff I am not that willing to remove:

June 2014: I gave a talk at the University of of Electronic Science and Technology of China (UESTC) (电子科技大学), Chengdu. Left: Qiang Li, who was my Ph.D. student and now an Associate Professor at UESTC. Right: Jiaxian Pan, also my Ph.D. student. Jiaxian got his Ph.D. just a few months ago, and he together with me are now working on some exciting research project on MIMO communications.

May 2014: Xiao Fu received a 3rd Prize in the ICASSP 2014 Best Student Paper Awards. ICASSP is is the largest and most prestigious conference in signal processing. The work, titled "Blind Spectra Separation and Direction Finding for Cognitive Radio Using Temporal Correlation-domain ESPRIT," was carried out during his overseas exchange last summer at the University of Minnesota, where Prof. Nikos Sidiropoulos is the host.


Left: Xiao Fu and his labmate Jiaxian Pan (who also received an ICASSP Best Student Award in 2011). Right: Me, Xiao Fu, and Prof. Sidiropoulos.

May 2014: Anthony So (at SEEM CUHK) and I gave a tutorial in ICASSP 2014. The tutorial, titled "Semidefinite Relaxation: From Theory to Applications to Latest Advances," describes a very powerful class of methods in signal processing - namely, semidefinite relaxation - which finds numerous applications and has significant impacts on key research topics such as MIMO detection, transmit beamforming and interference management, and sensor network localization. See [PDF] [Tutorial Slides, MIIS2012].

Dec 2012: My students, Ka-Kit Lee and Hoi-To Wai, won Outstanding Tutor Award.

July 2012: I gave a tutorial and was a speaker in MIIS2012, held in Xi'An, China.

June 2011: Our paper, entitled "robust endmember extraction using worst-case simplex volume maximization", won a Best Paper Award in WHISPERS 2011.

May 2011: Jiaxian Pan, my Ph.D. student, won an ICASSP 2011 Best Student Paper Award. ICASSP is one of the most prestigious conferences in SP, and the largest. The paper is entitled "a Lagrangian dual relaxation approach to ML MIMO detection: reinterpreting regularized Lattice decoding".


Last update: May 2016.