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Huaping Liu
Research Activities
Research Areas
- Performance analysis of MIMO systems.
- Ultra-wideband technologies for short and medium-range wireless communications.
- Channel modeling for confined areas by metals with vibrating metal parts.
- Coding and adaptive power control for frequency hopping spread spectrum systems.
- Low-power wireless sensor system design for space and military applications.
- Capacity studies for CDMA systems with multimedia traffic.
Research Description
My research focuses on design and performance analysis of wireless communication systems and novel techniques for multiuser time-varying environments with applications cellular and indoor wireless communications. Current specific interests include ultra-wideband techniques, detection and signal processing for MIMO systems, and spread spectrum communications. Although UWB has the potential to support high-data-rate applications over short distance, the channel multipath delay limits the maximum pulse repetition interval if severe intersymbol interference is to be avoided. Also UWB systems have to operate in the presence of narrowband interference. We have investigated receiver architecture and signal processing techniques for UWB systems employing MIMO scheme to increase UWB system throughput and at the same time suppress narrowband interference. We have been conducting research on hybrid pulse amplitude and position modulated UWB systems and on optimizing pulse position modulated UWB schemes combined with direct-sequence spreading for multiple access. We also studied the impact of fading correlation on the error performance of MIMO receivers and analyzed error performance of MIMO systems in frequency selective Rayleigh and indoor channels.
Applications of Research
Some of my research results have been applied to the design of wireless systems for robust communications in hostile RF environments and for wireless sensor systems. My research can also be applied to design of robust and high-rate communication system for mobile and indoor environments.
Recent Research Collaborations & Projects
- NSF CDADIC: "Simulations of ultra-wideband systems," Sept. 2002-Sept. 2003, $40,000
- AFRL and NSF CDADIC: "Low Power Wireless Sensor System Design for Space and Military Applications," (with D. Allstot) Sept. 2002-Sept. 2003, $125,000
- Sandia National Laboratories/Oregon ETIC: "Wireless solutions for hostile environments," Jan. 2002-July 2003, $300,000
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