Liang Li – Curriculum Vitae of Dr.-Ing. Liang Li

Place of
birth
Marital
status
11/2006 -
05/2012
10/2002 -
11/2006
Personal Information
Taiyuan, China
Married
Education
Liang Li
Curriculum Vitae of Dr.-Ing. Liang Li
Doctorate in the Communication Systems Group, TU Darmstadt, Germany
Note: Very Good
Dissertation: “Transmit and Multiuser Diversity Techniques in Wireless Communications”
Submission of the dissertation: 07/02/2012
Referee: Prof. Dr.-Ing. Marius Pesavento
Co-referee: Prof. Dr. Constantinos B. Papadias
Date of oral examination: 02/05/2012
Diploma in Electrical Engineering and Information Technology, TU Darmstadt, Germany
Overall classification: Very Good
Studienarbeit Note: 1.0 (Very Good)
Diplomarbeit
(Final thesis)
09/2001 -
10/2002
09/2000 -
10/2001
Thesis: “Comparison of Transmit Antenna Selection Techniques in MIMO Communication
Systems with Low Rate Channel State Feedback”
Advisor: Prof. Dr. Alex Gershman
Note: 1.0 (Very Good)
Thesis: “Advanced Methods for Antenna Selection in MIMO Communications”
Advisor: Prof. Dr. Alex Gershman
Intensive German course, Tongji University, Shanghai, China
Study in Electrical Engineering, Tongji University, Shanghai, China
S3|19 3 Rundeturmstr. 12 – 64283 Darmstadt
T +49 6151 16-75306 • B lli@nt.tu-darmstadt.de 1/5

11/2006 -
now
08/2010 -
09/2010
07/2005 -
11/2006
11/2004 -
09/2006
Professional Experience
Research and teaching assistant in the Communication Systems Group at TU Darmstadt
Tutorial for lecture “Information Theory I ” (WS2010/2011)
Lecture Information Theory I (WS2012/2013)
Research visit at ECIT, Queen’s University Belfast, UK
Internship & Working student at HBM GmbH, Darmstadt, Germany
Student research and teaching assistant in the Power System Control Laboratories,
High Voltage Laboratories, and the Group of Microwave Engineering at TU Darmstadt
Academic Awards
05/2011 2010 Chinese Government Award for Outstanding Self-financed Students Abroad
2001 - 2002 Outstanding Student Award, Tongji Universität, Shanghai, China
Research Interests
MIMO Communications with Limited Feedback
The performance of multiple-antenna communication systems critically depend on
the amount of channel state information (CSI) available at the transmitter. Limited
feedback is a methodology for obtaining and exploiting CSI at the transmitter. Specifically,
it uses a finite rate feedback to convey the quantized CSI from the receiver to
the transmitter. My research in this area deals with the important questions such as
what kind of information should be submitted to the transmitter and what is the optimal
transmission strategy in this case. I have partially addressed this problem in both
point-to-point and multiuser systems and analytically studied the symbol error rate
performance. Future work in this area includes design of high-performance precoding
techniques and feedback-based dynamic scheduling schemes.
Multiuser Diversity
Current growing demand on delay-tolerant high-rate data services has motivated the
application of multiuser diversity in practical communication systems. In a multiuser
wireless system, the antennas of different users are often located sufficiently far apart
such that channels of different users experience space-selective fading. By scheduling
users under the most advantageous channel condition, the overall system performance
can be greatly enhanced. This kind of performance improvement is generally referred
to as multiuser diversity. My work on this topic is aimed at quantifying the maximal
multiuser diversity gain and designing practical communication schemes to achieve
the promised performance gain.
Cognitive Radio
Cognitive radio is an emerging field in wireless communication aimed at increasing the
current inefficient spectrum usage. While the benefits of cognitive radio are intuitively
appealing, many important questions regarding its theoretical limits and practical
implementation remain open. My research on cognitive radio focuses on pursuing its
information theoretical limit and designing feasible schemes to realize its practical
implementation.
S3|19 3 Rundeturmstr. 12 – 64283 Darmstadt
T +49 6151 16-75306 • B lli@nt.tu-darmstadt.de 2/5

5/2009 -
5/2012
11/2011 -
01/2012
Cooperative Communications
Cooperative communications can be achieved by relaying signals using antennas belonging
to different nodes. Recently, cooperative communications have drawn considerable
attention in the field of wireless communication. My work in this area includes
analyzing the performance gain provided by cooperative diversity, investigating the
application of cooperative communication in future wireless systems and designing
advanced techniques to enable the reliable cooperative communication.
Physical Layer Security
Security in wireless communications is an important issue. Currently used techniques
including Public-key/private-key cryptography, frequency hopping, and CDMA may
become vulnerable in the future as they are based either on the assumption of limited
computational power or the assumption of limited knowledge at the eavesdropper.
For instance, public-key schemes provide security based on the hardness of some mathematical
problems like factoring (Rivest-Shamir-Adleman algorithm) and discrete
logarithms (Diffie-Hellman algorithm) while private-key cryptography relies on absolutely
secure links for key exchange. The existing physical layer techniques such as
frequency hopping and CDMA assume that the hopping sequences or the chip codes
are unknown at the eavesdropper. With the appearing of quantum computers in the
future, current computationally infeasible problems may become easily solvable. On
the other hand, it is generally impossible to establish an absolutely secure link to
exchange information like private keys, hopping sequences, or chip codes. Therefore,
new concepts to provide future physical layer security are currently appealing. Information
theoretic security is an emerging concept to provide physical layer security.
The key idea of information theoretic security is to create better effective channel
to the desired receiver than to any potential eavesdropper such that the signals can
only be successively decoded at the desired receiver but not at any other undesired
receiver. My research in this area targets at the following two objectives: 1) Quantifying
the secrecy capacity of different communication channels such as wireless fading
channels and wireless relay channels. 2) Investigating practical signal processing and
communication techniques to provide the physical layer security.
Academic Activities and Projects
Participated Research Projects
Cognitive Radio Oriented Wireless Networks (CROWN)
Representation of TU Darmstadt at several consortium meetings held in London 2009,
Athens 2010, and Barcelona 2011. CROWN is funded under FET-Open scheme within
the Seventh Framework Programme (FP7), consisting of six partners from UK,
Germany, France and Greece, working towards the realistic implementation of cognitive
radios for better, more spectrally and financially efficient wireless communications.
http://www.fp7-crown.eu/
Proposal writing for EU STREP proposal “Flexible spectrum Usage via collaborative
Sensing tEchniques (FUSE)”
S3|19 3 Rundeturmstr. 12 – 64283 Darmstadt
T +49 6151 16-75306 • B lli@nt.tu-darmstadt.de 3/5

The goal of the FUSE proposal is to develop and demonstrate database aided localized
and distributed collaborative sensing techniques for hierarchical radio access networks
that enable efficient spectrum access and interference coordination. The participants
of this proposal are Queen’s University Belfast, TU Darmstadt, Intel Mobile Communications
from France, Huawei Technologies Sweden, Athens Information Technology,
Qinetiq Limited, Eurecom, Trinity College Dublin and Portugal Telecom Inovacao Sa.
The Principal Investigator at TU Darmstadt is Prof. Marius Pesavento.
Invited Talks and Tutorials
10/2011 Invited talk in panel session “Cognitive Radio Networks: Challenges, Opportunities
and the Role of Spatial Dimension”. The 4th International Conference on Cognitive
Radio and Advanced Spectrum Management (CogART 2011), October 26-29, 2011,
Barcelona, Spain.
Yuefeng
Qian
Reviewer of the Following Journals
IEEE Transactions on Wireless Communications
IEEE Signal Processing Letters
IEEE Transactions on Signal Processing
IEEE Transactions on Communications
IEEE Transactions on Vehicular Technology
EURASIP Journal on Wireless Communications and Networking
International Journal of Electronics and Communications
Journal of Communications and Networks
Supervised Bachelor, Master und Diploma Theses
Feedback Optimization in Multiuser Downlink Channels
Qichao Li CQI Estimation for MIMO Transmission in the Presence of Receiver Impairments
(external)
Yin Zhu Optimal Downlink Beamforming in OFDM Systems
Philemon
Ivan Derwin
Symbol Error Rate Analysis in Multiuser Underlay Cognitive Radio System
Jun Ma Symbol Error Rate of Underlay Cognitive Radio System
Peng Jin The Application of Game Theory to the OFDM Based Cognitive Radio Systems
Javier
Chiquero
Applying Game Theory for Spectrum Sharing in Cognitive Radio
Language Skills
Chinesisch Native language
Deutsch Fluent
Englisch Fluent
Publications
Dissertation
Transmit and Multiuser Diversity Techniques in Wireless Communications
Date of submission: 07/02/2012.
S3|19 3 Rundeturmstr. 12 – 64283 Darmstadt
T +49 6151 16-75306 • B lli@nt.tu-darmstadt.de 4/5

Journal Papers
L. Li, S. A. Vorobyov, and A. B. Gershman, “Transmit antenna selection based strategies
in MIMO communication systems with low-rate channel state feedback”, IEEE
Transactions on Wireless Communications, vol. 8, no. 4, pp. 1660-1666, April 2009.
L. Li, M. Pesavento, and A. B. Gershman, “Downlink opportunistic scheduling with
low-rate channel state feedback: Error rate analysis and optimization of the feedback
parameters”,IEEE Transactions on Communications, vol. 58, no. 10, pp. 2871-2880,
October 2010.
Conference Papers
L. Li, S. A. Vorobyov, and A. B. Gershman, “Adaptive resource allocation in MIMO
communication systems using low rate channel state feedback”, Proceedings of the
IEEE Workshop on Signal Processing Advances in Wireless Communications (SPA-
WC’07), pp. 1-5, Helsinki, Finland, June 2007.
L. Li and A. B. Gershman, “Downlink opportunistic scheduling with low-rate channel
state feedback: Error rate analysis and optimization of the feedback parameters”,
Proceedings of the IEEE Workshop on Signal Processing Advances in Wireless Communications
(SPAWC’08), pp. 356-360, Recife, Brazil, July 2008.
L. Li, M. Pesavento, and A. B. Gershman, “On ergodic sum capacity of underlay
cognitive broadcast channels”, Proceedings of the IEEE Workshop on Personal Indoor
and Mobile Radio Communications (PIMRC 2010), pp. 2710-2714, Istanbul, Turkey,
September 2010.
L. Li, F. A. Khan, M. Pesavento, and T. Ratnarajah, “Power allocation and beamforming
in overlay cognitive radio systems”, Proceedings of the Vehicular Technology
Conference (VTC 2011), pp. 1-5, Spring, Budapest, Hungary, May 2011.
L. Li, and M. Pesavento, “The Sum Capacity of Underlay Cognitive Broadcast Channel”,
Proceedings of the International ICST Conference on Cognitive Radio Oriented
Wireless Networks and Communications (CROWNCOM 2011), pp. 390-394, Osaka,
Japan, May-June 2011.
L. Li, P. I. Derwin, and M. Pesavento, “Symbol Error Rate Analysis in Multiuser
Underlay Cognitive Radio Systems”, Proceedings of the IEEE Workshop on Personal
Indoor and Mobile Radio Communications (PIMRC 2011), pp. 681-684, Toronto,
Canada, September 2011.
L. Li and M. Pesavento, “Link Reliability of Underlay Cognitive Radio: Symbol Error
Rate Analysis and Optimal Power Allocation”, Proceedings of the International
Conference on Cognitive Radio and Advanced Spectrum Management (CogART 2011),
invited, Barcelona, Spain, October 2011.
L. Li and M. Pesavento, “A Game Theoretical Approach for Spectrum Sharing in
Cognitive Radio Systems with Payoff Perturbations”, Proceedings of the 17th International
OFDM Workshop (InOWo 2012), pp. 59-63, Essen, Germany, August 2012.
S3|19 3 Rundeturmstr. 12 – 64283 Darmstadt
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