US Patent issued to Prof. Athina Petropulu
US Patent 7,929,937 B2 was issued to Athina Petropulu, Professor and Chair of Electrical and Computer Engineering of Rutgers University on “System and methods for blind estimation of multiple carrier frequency offsets and separation of user signals in wireless communication systems” on April 19, 2011. Among the inventors are Dr. Visa Koivunen of Aalto University in Finland, Dr. H. Vince Poor of Princeton University and Dr. Yuanning Yu of Qualcomm. Assigned to the Trustees of Princeton University, the patent provides a method for blind estimation of carrier frequency offsets (CFOs) and separation of user signal in wireless communications systems.
Blind estimation of CFOs (i.e., without knowledge of the conditions of the transmitter or the transmission medium/channel) is carrier out in order to improve reception quality by a wireless communications device. A received RF signals is over-sampled by a pre-defined over-sampling factor, and polyphase components are extracted from the over-sampled signal. The polyphase components are used to construct a virtual receiver output matrix, e.g., a model of the received signal and its associated output matrix. System response conditions are blindly estimated by applying a blind system estimation algorithm to the virtual receiver output matrix. A plurality of CFO estimates are obtained from the estimated system response conditions, and can be used by an equalizer to adjust receiver parameters in accordance with the CFO estimates so as to maximize reception quality and to extract multiple user signals from the received signal.