The Department
The Modulation and Coding Department is primarily focused on algorithms development and proof-of-concept prototyping of advanced digital communication systems.

Empowered by over seventy research and development staff, we have strong competencies in the following areas:

• Forward error correction coding - This includes the commonly adopted convolution code and Viterbi decoder design for high throughput communication systems, and the advanced low-density parity check (LDPC) code, turbo convolutional code, turbo product code, etc
• Orthogonal frequency division multiplexing (OFDM) - Our expertise covers complete system specification, advanced transceiver algorithms design, and prototype development
• Multiple-Input Multiple-Output (MIMO) - Our expertise covers concept development, system specification, advanced transceiver algorithms design, architecture and prototype development. We have also developed full-capacity and full-diversity achieving precoding scheme, and low-complexity decoding scheme to achieve maximum-likelihood-approaching performance for MIMO-OFDM systems
• Modem algorithms - We have robust low-complexity CRB-approaching front-end algorithms for timing synchronization, carrier frequency offset estimation based on preambles and pilot signals
• Iterative turbo processing - We have developed algorithms for iterative equalization for space-time coded systems, Bayesian turbo receiver for MIMO-OFDM systems. We are also working on turbo receiver algorithms to address the synchronization performance in low SNR regions
• Multiple access and joint detection - We have a long track record on multiple access and joint detection for third generation wideband code division multiple access (CDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems for WiMAX and 3GPP Long Term Evolution (LTE). With the current focus on LTE, we are developing enabling technologies for multiuser MIMO systems
• Cognitive Channel Sensing - To optimize spectrum usage through dynamic spectrum sharing, we are developing various cognitive channel sensing schemes, e.g., the eigenvalue based channel sensing, the covariance based detection of signals, etc. We are also developing methods and devices for allocating frequency ranges in a cognitive network.
• Resource allocation and link adaptation - To fully utilize the scarce radio resource, optimal resource allocation and link adaptation is one very important element in the complete system and network design. We have developed information-theoretic approaches for link adaptation in MIMO-OFDM systems, and resource allocation scheme for OFDMA systems. Based on these solutions, we will work on multiuser scheduling and resource allocation for multiuser multi-carrier MIMO systems.

Our staff are actively involved in the following programmes:

• Towards Gigabit Personal Connectivity Programme
• Power-aware Wireless Sensor Network for Tracking and Monitoring Programme
• High Speed Marine Mesh Networks Programme

Within these programmes, the enabling technologies developed by our staff can be applied to many next generation communication systems:

• High throughput wireless local area network based on IEEE 802.11n
• Ultra-wideband wireless personal area network based on WiMedia
• 3GPP Long Term Evolution
• Wireless Regional Area Network based on IEEE 802.22
• Wireless sensor networks
• Wireline communication systems
• WiMAX systems, including IEEE 802.16d, IEEE 802.16e, IEEE 802.16m etc
• Next generation wireless local area network system beyond IEEE 802.11n

The Department is also spending efforts to look into some fundamental problems in communication system design, with some highlighted examples in the following:

• Scalable precoding schemes for multiuser/single user MIMO systems
• Multiuser resource optimization and scheduling using combined information theory + queuing theory approaches
• Joint forward error correction coding and network coding for wireless networks
• Game theoretic approach for dynamic spectrum sharing
• Distributed signal processing for sensor networks

Infrastructure-wise, the Department is equipped with high performance workstations, and design tools for system level design and verification, FPGA prototyping and ASIC design. It also has a quick prototyping platform based on MATLAB SIMULINK and structure ASIC, which is useful for validating the research outcomes in real-time.

Besides the matlab to FPGA design flow, we have also established design flow based on Synopsys Cocentric System Studio, and SystemC.

• Z. Lei, F. Chin, and Y. C. Liang, "Method for Selecting Switched Orthogonal Beams for Downlink Diversity Transmission", SG 107008, US 6,850,741
• C. K. Ho, P. He, and S. Sun, "Method and Apparatus for Frequency Offset Estimation and System Utilizing same", SG 106807, US 7,046,744
• Z. Lei, Y. Wu, C. K. Ho, S. Sun, P. He, and Y. Li, "Receiver having a signal reconstruction section for noise reduction, system and method thereof", SG 110642
• P. Fung, and C. K. Ho, "Method and system for determining a frequency offset"
• P. Fung, "Method for determining a residual frequency offset, communication system, method for transmitting a message, transmitter, method for processing a method and receiver"
• Z. Lei, Y. Dai, and S. Sun, "Method and system for determining a signal vector and computer program element"
• Y. Wu, C. K. Ho, S. Sun, and Z. Lei, "Method for transmitting a digital data stream, transmitter, method for receiving a digital data stream and receiver"
• F. Chin, X. Peng, "Method and system for detecting code sequences in Ultra Wideband Systems"
• F. Chin and Y. S. Kwok, "A method for constructing ternary code sequences in Impulse Radio"
• C. Xu, et. .al., "Method of Fast Chase Decoding Algorithm for Turbo Product Codes"

Selected Publications

• C. Yuen, Y. L. Guan, T. T. Tjhung, "Quasi-Orthogonal STBC with Minimum Decoding Complexity", IEEE Trans. Wireless Comms., Volume:4, Issue:5, Sept. 2005, Page(s): 2089 - 2094
• C. Yuen, Y. L. Guan, T. T. Tjhung, "Single-Symbol-Decodable Differential Space-Time Modulation Based on QO-STBC", IEEE Trans. Wireless Comms., Volume:5, Dec 2006, Pages: 3329-3335
• S. H. Wong, Xiaoming Peng, Francois Chin, AS Madhukumar, "Performance Analysis of an Over-Sampling Multi-channel Equalization for a Multi-Band UWB System," IEEE Transactions on Wireless Communications, 2006
• R. Zhang, Y.C. Liang, R. Narasimhan, and J. M. Cioffi, "Approaching MIMO-OFDM capacity with per antenna power and rate feedback," to appear in IEEE Journal on Selected Areas in Communications, special issue on MIMO transceiver optimizations, September 2007
• Chin Keong Ho, Z. D. Lei, Sumei Sun, and Yan Wu, "Iterative detection for pre-transformed OFDM by subcarrier reconstruction", IEEE Transactions on Signal Processing, Vol. 53, No. 8, Part 1, Aug. 2005, pp. 2842-2854
• Yan Wu, Sumei Sun, and Zhongding Lei, "A Low Complexity VBLAST OFDM Detection Algorithm for Wireless LAN Systems", IEEE Communication Letters, Volume: 8 , Issue: 6, June 2004, Pages:374 - 376
• Y.-C. Liang, S. Sun, and C. K. Ho, "Block-iterative generalized decision feedback equalizers (BI-GDFE) for large MIMO systems: algorithm design and asymptotic performance analysis", IEEE Trans. SP, Vol. 54, No. 6, Part 1, June 2006, pps. 2035 - 2048
• Yongmei Dai, Zhongding Lei, and Sumei Sun, "Ordered Array Processing for Space-Time Coded Systems", IEEE Communication Letters, Volume 8, No. 8, pp. 526 - 528, Aug. 2004
• Yuan Li, Ying-Chang Liang, and Sumei Sun, "Adaptive Trellis and Bit-Interleaved Coded Modulation for Ordered MIMO-OFDM Channels", PIMRC 2005, Berlin, Germany, September 2005, Best Paper Award
• Z. Cai, et al., "A pipelined Architecture for V-BLAST OFDM Detection", Asilomar Conference on Signals, Systems and Computers, Oct. 2005
• Xiaoming Peng, Francois Chin, Sai Ho Wong, Kwok Yuen Sam, Lei Zhongding "A RAKE Combining Scheme for an Energy Detection Based Noncoherent OOK Receiver in UWB Impulse Radio Systems" IEEE ICUWB 2006, Sept 25-27, 2006, Boston, USA
• Z. Cai, J. Hao, P. H. Tan, S. Sun, and F. Chin, "Efficent Encoding of IEEE 802.11n LDPC Codes", IEE Electronics Letters, Vol. 42, No. 25, pp. 1471-1472, 2006

• World-first 162Mbps Pre-IEEE 802.11n STBC MIMO OFDM modem with extended coverage
• WiMedia high rate UWB modem prototype with range extension
• Strong IP portfolio in MIMO, cognitive radio, and UWB systems
• Best Paper Award, IEEE PIMRC 2005
• Best Paper Award, IEEE VTC 1999

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