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Areas of Expertise

In recent years, wireless communication has become extremely important throughout the world and in particular for Hong Kong and China. At CenWIT, HKUST, we have major research and development efforts, but not limited to, the following wireless communication areas:

  • Adaptive MIMO signal processing

  • Array signal processing

  • Cognitive radio

  • Convex optimization theory for communication systems

  • Cooperative communication systems

  • Cross-layer design, adaptation, and optimization for wireless networks with QoS provisioning

  • Game theory for ad-hoc networks

  • Information theory for communication systems

  • MIMO antenna design

  • MIMO-OFDM systems

  • Multiuser MIMO communications

  • RFID

  • Wideband MIMO channel characterisation

Ongoing Research and Development Projects

CenWIT has many on-going research and development projects that are actively participated in by faculty and students:

  • Design and performance analysis of the radio interface for Beyond 3G (B3G) systems;

  • Research and standardization on key technologies of IEEE802.22 (Wireless Regional Area Networks, WRAN) standard;

  • Research and standardization on key technologies of IEEE802.16m (Mobile WiMax) standard;

  • Algorithm design and analysis for Practical MIMO (P-MIMO) systems;

  • Advanced algorithm and implementation for MBOA PHY layer of Ultra-wide band (UWB) systems;

  • Handset MIMO antenna (A-MIMO) testing and design;

  • Develop enabling technologies for low-cost single-chip CMOS passive RFID tags and readers; and

  • Re-configurable OFDM (R-OFDM) radio baseband VLSI architecture design.

For details, please kindly visit our project website: http://www.ee.ust.hk/wireless_proj

 

Best Paper Awards

2007 IEEE Global Communications Conference (GLOBECOM): Best Paper Award

  • Title: Bandwidth Efficient Cooperative Diversity for Wireless Networks

  • Authors: Wei Zhang and  Khaled BEN LETAIEF

  • Abstract: Cooperative diversity has been recently proposed as a way to form distributed antenna arrays that improve error performance and capacity. In this paper, a bandwidth efficient cooperative diversity scheme is proposed for half-duplex amplifyand-forward wireless relay networks. By employing a signal space diversity technique and allowing the source node to keep on transmitting over the whole duration of the cooperation frame, the proposed cooperative scheme is proved to be able to achieve both full-rate and full-diversity simultaneously. Diversity analysis shows that the achievable diversity gain is M + 1, where M is the number of relay nodes. Moreover, a power allocation scheme is proposed to maximize the coding gain under a total power constraint. Simulation results are shown to demonstrate the full-rate and full-diversity of the proposed scheme.

 

2007 IEEE International Conference on Communications (ICC): Best Paper Award

  • Title: Cooperative Concatenated Coding for Wireless Systems

  • Authors: Ernest S. Lo and  Khaled BEN LETAIEF

  • Abstract: Cooperative transmission has been of growing interest recently where users take advantage of each other's resources for better overall performance. In this paper, coded cooperation for wireless networks is considered and a novel cooperative concatenated coding strategy is proposed. In contrast to previous works, this scheme features additional coding benefits other than spatial diversity. Specifically, we show that remarkable error rate reduction can be achieved even when the receive SNR of all cooperating users is maintained at a specific level. The idea of interleaver gain of concatenated codes is exploited and it is shown that the error rate decreases dramatically with the number of cooperating nodes. Multiple cooperating users with unequal message sizes can also be supported easily and a reduced-complexity cooperative encoding strcuture is provided for good inter-user channels. Code design criteria are also investigated, as well as, the performance under various data-block sizes and number of cooperating users.

 

2006 IEEE International Conference on Communications (ICC): Best Paper Award

  • Title: A Cross Layer Method for Interference Cancellation and Network Coding in Wireless Networks

  • Authors: Wei CHEN, Khaled BEN LETAIEF, and Zhigang CAO

  • Abstract: Multi-hop wireless networks are expected to play an important role in the next-generation wireless systems. One of the central problems in such networks is the network capacity. This paper presents a novel cross layer method for interference cancellation and network coding, which significantly increases the capacity of multi-hop wireless networks. We decompose the multi-hop network into a cell-like sub-network, which we refer to as a wireless switching network. In the proposed approach, multiple nodes, each with its self-information, can communicate via relay nodes. The nodes' self information can then be utilized to cancel the multiuser interference and enable network coding. We shall derive the capacity regions of two cross layer strategies, and show that they are larger than that of the traditional broadcast channel.

 

2006 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP): Best Student Paper Award

  • Title: Potential Games: A Framework for Vector Power Control Problems with Coupled Constraints

  • Authors: Gesualdo SCUTARI, Sergio BARBAROSSA, and Daniel P. PALOMAR

  • Abstract: In this paper, we propose a unified framework, based on the emergent potential games to deal with a variety of network resource allocation problems. We generalize the existing results on potential games to the cases where there exists coupling among the (possibly vector) strategies of all players. We derive sufficient conditions for the existence and uniqueness of the Nash Equilibrium, and provide different distributed algorithms along their convergence properties. Using this new framework, we then show that many power control problems (standard and non-standard) with coupled constraints among the users, can be naturally formulated as potential games, and hence, efficiently solved. Finally, we point out an interesting interplay existing between potential games, classical optimization theory, and Lyapunov stability theory.

 

2002 SITA International Symposium on Information Theory and its Applications (ISITA): Paper Award for Young Researchers

  • Title: A Simple Effective Iterative Detection Scheme for Bit-Interleaved Coded Modulation

  • Authors: Tao LI and Wai Ho MOW

  • Abstract: Bit-interleaved coded modulation (BICM) with iterative detection (ID) is effective for fading channels because it can simultaneously realize high diversity and large Euclidean distance. Two types of iterative detection schemes, based on hard decision feedback (HDP) and soft decision feedback (SDF) respectively, have recently been investigated for BICM. While the HDF/ID scheme exhibits significant performance degradation relative to the SDF/ID scheme, it has a much lower implementation complexity. In this work, we propose a novel BICM-ID scheme based on the so-called uniform soft decision feedback (USDF). Compared with HDF/ID, the USDF/ID scheme is only slightly more complicated but has a much less performance degradation relative to SDF/ID. Thus, the proposed BICM-USDF/ID scheme is rather attractive for practical wireless applications.

 

2000 IEEE Vehicular Technology Conference (VTC) Spring: VTS Japan Chapter Award

  • Title: Adaptive Spatial-Subcarrier Trellis Coded MQAM and Power Optimization for OFDM Transmission

  • Authors: K. K. WONG, S. K. LAI, R. S. CHENG, K. B. LETAIEF, and R. D. MURCH

  • Abstract: Recently, space-time coding or coded modulation has demonstrated that significant increases in system capacity and performance can be achieved by incorporating multiple antennas at the receiver. In this paper, we propose an adaptive spatial-subcarrier trellis coded modulation using MQAM for orthogonal frequency division multiplexing (OFDM) transmission by using instantaneous channel state information and employing multiple antennas at both the transmitter and the receiver. In particular, our objective is to minimize the total transmit power required for each OFDM transmission, by optimizing the power allocation, code rate and modulation scheme in each spatial-subcarrier channel, while maintaining a given data rate and bit error probability. To illustrate the potential of our proposed system, Monte Carlo simulation results are provided.

 

2000 IEEE Antennas and Propagation Symposium: 2nd Winner Up of the Student Paper Contest

  • Title: A Planar Diversity Antenna for Wireless Handsets

  • Authors: S. C. K. KO and R. D. MURCH

  • Abstract: We introduce a compact integrated antenna that has two feed ports with more than 20dB isolation between them. The significance of the design is that it can be utilized in compact wireless communication handsets to provide diversity signals or act as a duplexer allowing the receive and transmit signals to be well isolated. The antenna design is based on merging two patch antennas together and experimental results at 2220MHz include radiation patterns, S-parameters, and signal correlations between ports. These demonstrate that the envelope cross-correlation between ports is less than 0.1 making the antenna suitable for diversity applications.

 

 

 

 

 

 

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