Communication & Signal Processing
Space-time/frequency coding for MIMO and cooperative communications systems
- Multi-layered schemes in MIMO systems
- OFDM for Cooperative Networks
- Radar Imaging
- 50% Efficient Solar Cells
- Capacity optimization
- Channel coding for non-standard channels with memory
- Exploiting Diversity in Wireless Networks
- Image Compression
- Low-density generator matrix codes
- Message Authentication in Noisy Environments
- Multi-tone blue noise dithering
- Inverse Lithography
- Space-time/frequency coding for MIMO and cooperative communications systems
- Steganalysis of Digital Images and Videos
- Turbo-like codes for distributed source and joint source-channel coding
- Compressive sensing in imaging, sensor networks, and UWB radios
- Lossless Data Compression
NSF and AFOSR
Employing multiple antennas has become a major technique for high speed wireless transmission systems due to its potential capacity gain over single antenna systems. Space-time coding and modulation is a way to achieve the capacity similar to what the coding and modulation does in the conventional single antenna systems. While in single antenna coding and modulation, one deals with scalars and sequences of scalars, in multiple antenna space-time coding and modulation, one deals with matrices and sequences of matrices, which makes it more difficult to study. The aim of this project is to design better space-time, space-frequency codes for MIMO and cooperative systems to achieve full spatial diversity and better coding gain and in the meantime, have fast/efficient decoding/demodulation algorithms. Fruitful results from this project can be immediately applied to emerging wireless communications standards, such as 3GPP, 4G etc.
Y. Shang and X.-G. Xia, Shift Full Rank Matrices and Applications in Space-Time Trellis Codes for Relay Networks with Asynchronous Cooperative Diversity, IEEE Trans. on Information Theory, July 2006
W. Zhang, X.-G. Xia, and P. C. Ching, High-rate full-diversity space-time-frequency codes for broadband MIMO block-fading channels, IEEE Trans. on Communications, to appear.
K. Lu, S. Fu, and X.-G. Xia, Closed Form Designs of Complex Orthogonal Space-Time Block Codes of Rates (k+1)/(2k) for 2k-1 or 2k Transmit Antennas, IEEE Trans. on Information Theory, Dec. 2005.
G. Wang and X.-G. Xia, On Optimal Multi-Layer Cyclotomic Space-Time Code Designs, IEEE Trans. on Information Theory , March, 2005. Also, A Correction to the Definition of Diversity Product in "On Optimal Multi-Layer Cyclotomic Space-Time Code Designs", IEEE Trans. on Information Theory, July, 2005.
H. Wang, G. Wang, and X.-G. Xia, Some 2 by 2 Unitary Space-Time Codes from Sphere Packing Theory with Optimal Diversity Product of Code Size 6, IEEE Trans. on Information Theory, Dec. 2004.
G. Wang, H. Liao, H. Wang, and X.-G. Xia, Systematic and Optimal Cyclotomic Lattices and Diagonal Space-Time Block Code Designs, IEEE Trans. on Information Theory, Dec. 2004.
W. Su and X.-G. Xia, Signal Constellations for Quasi-Orthogonal Space-Time Block Codes with Full Diversity, IEEE Trans. on Information Theory, Oct. 2004.
Wang and X.-G. Xia, An Orthogonal Space-Time Coded CPM System with Fast Decoding for Two Transmit Antennas, IEEE Trans. on Information Theory, March 2004.
H. Wang and X.-G. Xia, Upper Bounds of Rates of Complex Orthogonal Space-Time Block Codes, IEEE Trans. on Information Theory , Oct. 2003.
X.-B. Liang and X.-G. Xia, Unitary Signal Constellations for Differential Space-Time Modulation with Two Transmit Antennas: Parametric Codes, Optimal Designs, and Bounds, IEEE Trans. on Information Theory, August 2002.