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Professor and Distinguished Scholar-Teacher K. J. Ray Liu, along with former advisees and ECE alumni Wipawee Siriwongpairat (Ph.D., '05) and Zhu Han (M.S. '99, Ph.D. '03), have been awarded U.S. Patent 7,653,122 for their invention, titled "Method and System for Power Controlled Effective Allocation of Sub-Bands in Ultra-Wideband Communication."

Ultra-wideband (UWB) systems comprise an emerging technology that offers promise to satisfy the growing demand for low cost and high-speed digital wireless home networks. Instead of using the entire UWB frequency band to transmit information, multiband techniques divide the spectrum into several sub-bands. By interleaving the transmitted symbols across sub-bands, multiband UWB systems can still maintain the average transmit or transmission power as if a large gigahertz bandwidth is being used. The advantage is that the information can be processed over much smaller bandwidth, thereby reducing overall design complexity, as well as improving spectral flexibility and worldwide compliance.

Liu and his co-inventors have created a power controlled sub-band assignment and power allocation among users in a multiband UWB system that aims to reduce power consumption without compromising performance. The overall transmit power is minimized under the practical constraints, including packet error rate, transmission rate, and FCC regulations. To ensure the system feasibility in variable channel conditions, an optimization scheme manages the assignment of UWB devices to respective channels subject to their suitability to the requested users' transmission rates. An inexpensive suboptimal approach reduces the complexity of the optimization procedure and achieves a comparable performance to those of the complex full search optimization routine.

More information about their invention can be viewed at the U.S. Patent website.



February 17, 2010


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