無線系統實驗室 Wireless System Lab (ED900/913B)

Wireless Network Lab, NCTU, Taiwan

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無線系統實驗室

Wireless System Lab (ED900/913B)

Li-Chun Wang ( 王蒞君 )

Department of Communications Engineering National Chiao Tung University

Hsinchu,[email protected]

http://cmbsd.cm.nctu.edu.tw/~lichun

mailto:[email protected]


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3C Tradeoff in Wireless

The 3C (Capacity, Cost, Cwality) Tradeoff

The more things changes, the more remain the same (Alphonse Karr, 1808)

High Capacity

Good Quality Low Cost


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What is the fundamental issue for wireless communications?

Spectrum Efficiency


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Missions

建立學生對『無線通訊』的系統整體概念。研發『 Cross-Layer Design 』的關鍵技術

包括『無線通訊實體層』和『無線資源管理』技術。

實驗室的座右銘學生為本，創意至上。 Think Big ! Think Different ! Think Simple!


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個人學歷 1982~1986 國立交通大學控制工程系學士 1986~1988 國立台灣大學電機研究所碩士 1992~1995 美國喬治亞理工學院碩士

Georgia Institute of Technology, Master of Science

1995~1996 美國喬治亞理工學院博士Georgia Institute of Technology, Ph. D.

博士論文 : Channel Modeling and Architecture Design for Cellular-Based Personal Communications


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個人經歷1990/07~1992/08 交通部電信研究所

傳輸研究室, 助理研究員1995/01~1995/06 Nortel, BNR, Dallas, TX, Co-Op

1996/07~2000/01 AT&T Labs-Research, Holmdel, NJ Wireless Communication Research

Department, Senior Member of Technical Staff

2000/02~2000/08 清華大學電機工程系助理教授2000/08~迄今交通大學電信工程系副教授2002/01~迄今 NCTU Cisco Academy Training

Center, Cisco Certified Academy Instructor


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專業領域 - 無線系統技術著重無線系統中之跨階層適應技術 (Cross-layer Link Adaptation and Protocol Design) 、無線資源管理 (Radio Resource Management)技術 : MIMO無線系統 ; MIMO 超寬頻無線電系統 (Ultra-Wide Band, UWB)

Wireless Mesh Network Cross-Layer Link Adaptation Techniques

Advanced CDMA之無線資源管理技術 : Cooperative Cognitive Radio


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Professional Services

Journal/Special Issue Editor: Associate Editor, IEEE Transaction on Wireless

Communications, 2001 ~ 2005 Associate Editor, International Journal of Sensor

Networks (2005 ~ now) Associate Editor, International Journal on

Wireless Mobile Computing (2005 ~ now) Guest Editor, Special Issue on

Radio Resource Management and Protocol Engineering in Future IEEE Broadband Networks for IEEE Wireless Communications Magazine, 2006

Guest Editor, Special Issue on "Mobile Computing and Networking” of IEEE Journal on Selected Areas in Communications, Vol. 23, No. 6, June 2005.

http://cmbsd.cm.nctu.edu.tw/~lichun/IEEEWireless/wcom-mag-cfp.pdf

http://cmbsd.cm.nctu.edu.tw/~lichun/IEEEWireless/wcom-mag-cfp.pdf


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Honors

1997 IEEE Vehicular Technology Society Jack Neubauer Memorial Award for the Best Paper of the Year on the Subject of Vehicular Technology Systems.

傑出畢業生陳瓊璋 (95 年博士畢 )

中華電信研究所經理 96 年傑出青年工程師元智大學助理教授 (to be official on 97) 龍騰論文獎

張志文 (96 年博士畢 ) 成大電機助理教授

陳磊 (93 碩士畢 ) 中國工程師傑出論文獎

謝昆瑾 (92 碩士畢 ) 國科會碩士論文獎


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研究理念與過程研究最先進理論

率先提出 MIMO Scheduling 系統中之 Soft Coverage 觀念，建立 MIMO Scheduling 系統正確的研究方向及新的研究領域，預期對未來 Multiuser MIMO Systems 將有重要貢獻。

率先研究整合 MIMO 與 UWB 兩技術之間的 Performance Tradeoff Analysis Model ，提醒學術界避免往不正確的方向繼續發展。

與國際接軌積極參與重要國際會議每年均有論文發表於 ICC 或

Globecom 等 Flagship International Conference 。在國際會議上給 Tutorial Course ， IEEE VTC 2003

Spring ， IEEE VTC 2007 Spring and Fall, IEEE PIMRC 。

受邀至國外知名大學及研究單位，包括美國 Caltech 、 University of Florida 、 WINLAB 、 Bell Labs 、香港大學、和香港科技大學演講，讓研究成果被世界頂尖學者知道並接受他們的考驗，進一步建立學術交流機會。


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People

博士後研究員黃建華、鍾文敬 (report on 2008) 。

博士陳銘賓、劉維正、王中瑋、葉俥榮、 Samer

Talat 。碩士

盧盈志、黃偉賢、蘇文山、陳政敏、陳皓、嚴語麟、 Diego Ballesteros 。

專題王文新、楊峻民、蔣明虔。


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Current Research

Cognitive Radio （感知無線電） Sponsor: 國科會 (2005.8~2008.7) Subjects:

Cognitive MAC Protocol （陳銘賓） Concurrent Transmission MAC Protocol （王中瑋） QoS-based Cognitive Scheduling (Samer Talat)

Ultra-Wide Band (UWB) Sponsor: 國科會 (2004.8~2007.7) Subject:

MIMO-UWB MIMO Ad Hoc Channels Space-Time-Frequency Coding （劉維正 )


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Current Research

Intelligent Transport System Sponsor: 教育部卓越計劃　（ 2006.3~2009.2) Subject:

Vehicular Network （黃建華 ) Wireless Mesh Network （黃建華 )

Network-Coordination for Multi-Cell OFDM System Sponsor: 工研院 (2007.1 ~ 2007.12) Joint base station coordination and user

scheduling （葉俥榮 ) 　


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New Project

Cooperative Cognitive Radio Network Sponsor: 國科會 (2007.8~2010.7) Subject:

Cooperative Sensing and Robust Topology Control techniques

Cooperative Cognitive MAC Protocol Multiplexing-based Cooperative Multi-hop systems


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Multiuser Scheduling for MIMO Wireless Networks


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Background on MIMO Techniques

Independent parallel transmit and receive antenna pair

MIMO antenna techniques boost channel capacity enhance link reliability reject strong interference

Tx … Rx…

Nt Nr


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Major Challenges for MIMO Techniques

•Difficulties to simultaneously leverage the benefits of diversity and multiplexing

e.g. diversity-multiplexing tradeoff (huge capacity gain may come at a price of reduced link reliability)

implementation complexity


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Diversity-Multiplexing Tradeoff

Diversity -> improve link reliability by replicas

Multuplexing -> enhance data rate by multiplexing

Tx Rx

a

a

a

a

Tx Rx

a

b

a+b

b+aba

a a

ba

subchannel interference canceling is required


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Background on Scheduling Techniques

Through periodically selecting the best user to serve, the system performance is improved by exploiting multiuser diversity or cooperative diversity.

Ordered Statistics is the fundamental mathematical techniques for analyzing the scheduling wireless systems.

1 2 3 4 5 6 7 8 9

user 1

1 2 3 4 5 6 7 8 9

user 1user 2user 3


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A Multiuser MIMO Scheduling System

• Perfect SNR estimation and noiseless feedback

• Hk=[ hij(k) ], each hij

(k) is subject to Nakagami fading

• The BS selects the target user with highest effective SNR


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0 1 2 3 4 5 6 7 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

i and

i

CD

FK=30, N=3

1

1

~

~

2

3

Effect of SWNSF Scheduling on λmin

SWNSF scheduling enhances the output SNR of the weakest

subchannel

λ3 > λ2 >λ1

3

21


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Effect of SWNSF Scheduling on Coverage

MS

MIMO + RR Scheduling

MS

MIMO + SWNSF Scheduling (“soft” coverage depends on K)1 5 10 15 20 25 30

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Number of users K

Nor

mal

ized

cov

erag

e ra

dius N=3

N=2


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Coverage Extension & Capacity Improvement

number of antennas

number of users


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PublicationsScheduling for MIMO Systems1. Chiung-Jang Chen and Li-Chun Wang, “A Unified Capacity Analysis

for Wireless Systems with Joint Multiuser Scheduling and Antenna Diversity in Nakagami Fading Channels,” IEEE Trans. on Communications, vol. 54, No. 3, pp. 469~478, Mar. 2006.

2. Chiung-Jang Chen and Li-Chun Wang, "Enhancing Coverage and Capacity for Multiuser MIMO Systems by Utilizing Scheduling, " IEEE Trans. on Wireless Communications, Vol. 5, No. 5, pp. 1148-1157, May 2006.

3. Chiung-Jang Chen and Li-Chun Wang, "Impacts of Radio Channel Characteristics, Heterogenous Traffic Intensity and Near-Far Effect on Rate Adaptive Scheduling Algorithms," IEEE Trans. on Vehicular Technology, Vol. 55, No. 5, pp. 1544~1554, Sep. 2006

4. Chiung-Jang Chen and Li-Chun Wang, “Performance Analysis of Scheduling in Multiuser MIMO Systems with Zero-Forcing Receivers,” IEEE Journal of Selected Area in Communication, July 2007 .

5. Li-Chun Wang and Chu-Jung Yeh, “Comparison of Scalar Feedback Mechanisms in MIMO Scheduling Systems,” Wireless Personal Mulitmedia (WPMC), pp. 1172-1176, Sep. 2005.

6. Li-Chun Wang and Chu-Jung Yeh,“On the Performance of Zero-Forcing Beamforming for MIMO Broadcast Systems,” 2007 IEEE AP-S International Symposium on Antennas and Propagation in Honolulu, Hawaii, USA, June 2007


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MIMO Ultra-Wideband 7. Li-Chun Wang, Wei-Cheng Liu, and Kuan-Jiin Shieh, “On the

performance of using multiple transmit and receive antennas in pulse based ultra-wideband systems,” IEEE Transactions on Wireless Communications, vol. 4, no. 6, pp. 2738-2750, Nov. 2005.

8. Wei-Cheng Liu and Li-Chun Wang, “Performance analysis of pulse based ultra-wideband systems in the highly frequency selective fading channel with cluster property,” VTC2006-Spring.

Wireless Mesh Network:9. Jane-Hwa Huang, Li-Chun Wang, and Chung-Ju Chang, “Coverage

and Capacity of A Wireless Mesh Network”, IEEE International Conference on Wireless Networks, Communications and Mobile Computing, pp. 458~463, June 2005.

10. Jane-Hwa Huang, Li-Chun Wang, and Chung-Ju Chang, “Deployment Strategies of Access Points for Outdoor Wireless Local Area Networks,” IEEE VTC 2005, pp. 2949~2953, May 2005.

11. Jane-Hwa Huang, Li-Chun Wang, and Chung-Ju Chang, “Coverage Enhancement for a Multi-channel Ring-based Wireless Mesh Network with Guaranteed Throughput and Delay,” IEEE ICC 2006.


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Advanced CDMA Systems 11. Li-Chun Wang and Chih-Wen Chang, “On the Performance of

Multicarrier DS-CDMA with Imperfect Power Control and Variable Spreading Factors,” IEEE Journal on Selected Areas in Communications, Special issue on Advances in Multicarrier CDMA, Vol. 24, No. 6, pp. 1154-1166, June 2006.

12. Li-Chun Wang and Chih-Wen Chang, “Probability of false power control command in CDMA systems subject to measurement errors,” IEEE Communications Letters, vol. 9, no. 4, pp. 298-300, Apr. 2005.

13. Ching-Yu Liao, Li-Chun Wang and Chung-Ju Chang, "Comparison of Downlink Power Allocation Mechanisms in Soft Handoff for the WCDMA System with Heterogeneous Cell Structures," ACM/Kluwer Wireless Network, pp. 593-605, Nov. 2005 (EI, SCI:1.17)

14. Chih-Min Chao, Yu-Chee Tseng, Li-Chun Wang, “Reducing Internal and External Fragmentations of OVSF Codes in WCDMA Systems with Multiple Codes,” IEEE Trans. on Wireless Communications, Vol. 4, No. 4, pp. 1516~1526, July 2005 (EI,SCI: 1.232)


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Advanced CDMA Systems 16. Chih-Min Chao, Yu-Chee Tseng, Li-Chun Wang, “Dynamic

Bandwidth Allocation for Multimedia Traffic with Rate Guarantee and Fair Access in WCDMA Systems," IEEE Trans. on Mobile Computing, Vol. 4, No. 5, pp. 420~429, Sep./Oct. 2005

17. Li-Chun Wang, Shi-Yen Huang, and Yu-Chee Tseng, "Interference Analysis and Resource Allocation for TDD-CDMA Systems to Support Asymmetric Services by Using Directional Antennas," IEEE Trans. on Vehicular Technology, Vol. 54, No. 3, pp. 1056-1069, May 2005

18. Li-Chun Wang, Ming-Chi Chen and Yi-Cheng Chen, "A Cross-layer Cost-function Based Rate Adaptation Mechanism for the WCDMA System with Multi-class Services by Transport Format Selection," Wireless Communications and Mobile Computing (Wiley Inter Science), Vol. 5, No. 4, pp. 397 ~406, July 2005.

19. Li-Chun Wang and Chih-Wen Chang, “An interference avoidance code assignment strategy for MC-DS-CDMA with TF-domain Spreading,” accepted by IEEE International Conference on Communications 2006.


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Fast HARQ for HSDPA20. Li-Chun Wang and Chih-Wen Chang, “Gap Processing Time Analysis

for Stall Avoidance Mechanisms for High Speed Downlink Packet Access with Parallel HARQ Schemes,” IEEE Trans. on Mobile

Computing, Vol. 5, No. 11, pp. 1591 -1605, Nov. 2006. 21. Li-Chun Wang, Chih-Wen Chang, and Chung-Ju Chang, “On the

Performance of Indicator-based Stall Avoidance for High-Speed Downlink Packet Access Systems,” IEEE Trans. on Vehicular Technology, Vol. 55, No. 2, pp. 691 ~703, March 2006.

Cross-Layer Protocol Design for WLAN and Sensor Network22. L. C. Wang and C. H. Lee, “A TCP-physical cross-layer congestion

control mechanism for the multirate WCDMA system using explicit rate change notification," IEEE International Conference on Advanced Information Networking and Application, vol. 2, pp. 449-452, Mar 2005.

23. Li-Chun Wang, Chung-Wei Wang, and Chuan-Ming Liu, “Adaptive Contention Window-based Cluster Head Election Algorithms for Wireless Sensor Networks,” appeared in the VTC'05 Fall.

24. Li-Chun Wang, Hung-Hsi Chen, and Anderson Chen, “Optimal Channel Search Time for Handoff in the IEEE 802.11 WLANs”, to appear in VTC2006-Spring.

25. Li-Chun Wang, Kuang-Nan Yen, and Anderson Chen, “Joint Rate and Power Adaptation for Wireless Local Area Networks in Nakagami Fading Channels,” to appear in IEEE WCNC, Apr. 2006

Documents

無線系統實驗室 Wireless System Lab (ED900/913B)