Qualcomm Incorporated

Qualcomm Atheros Inc.

Gaspar Lee

Hao-Ren Cheng

Chih-Yuan Chu

Hao-Jen Cheng

William John McFarland

Paul J Husted

Justin Huang

Kuang-Chung Ou

A method of providing frame synchronization for GPS signals can include performing coherent bit extraction on the GPS bits and then performing coherent frame boundary detection based on the bits of the coherent bit extraction. Concurrently, differential bit extraction on the GPS bits and differential frame boundary detection based on bits of the differential bit extraction can be performed. Whichever of the coherent frame boundary detection and the differential frame boundary detection first finds a frame boundary, then that frame boundary is used for the frame synchronization. A method of providing string synchronization for GLONASS signals includes performing coherent and differential bit extraction on the GLONASS bits.

System and method for detecting packet synchronization

A spur detection and spur cancellation apparatus in a multiple sub-carrier digital communication receiver includes a spur detection block that estimates, using one or more Fourier transforms, a frequency location of a narrowband interference spur in a received digital signal that includes a plurality of sub-carriers, and a spur cancellation block that attenuates the estimated narrowband interference spur. The spur detection block may use a fast Fourier transform (FFT) and/or a discrete Fourier transform (DFT) to locate a frequency and to measure a discrete power spectra of the narrowband interference spur. A channel state information block in the receiver may adjust a channel state information metric based on the located frequency and/or the measured discrete power spectra of the narrowband interference spur.

System and method for spur estimation and mitigation

A system and method are disclosed to synchronize adaptively a transform window in a multiple sub-carrier communication system based on analysis of a time domain channel impulse response. A set of frequency domain channel estimates, derived from received and one-dimensional Wiener filter interpolated channel estimates, are transformed into a time domain channel impulse response estimate containing multiple, repeated constituent responses. Each order of the constituent responses in the time domain channel impulse response estimate is associated with a two-dimensional Wiener interpolation filter. The set of two-dimensional Wiener interpolation filters generate interpolated channel estimates to compare with received channel estimates to determine a best channel impulse response order of the constituent responses. The transform window is adaptively updated using the best channel impulse response order.

System and method for adaptive synchronization

An apparatus and method in a multiple sub-carrier digital communication receiver for reducing inter-channel interference (ICI) includes a channel estimation block for calculating channel estimates, an interpolation block for calculating interpolated channel estimates, and an ICI reduction block for calculating ICI reduced receive symbols. Channel estimates are calculated based on receive symbols or ICI reduced receive symbols using pre-determined transmit symbols. Interpolated channel estimates are calculated by Wiener filter interpolation of a set of channel estimates. ICI estimates are calculated based on a set of interpolated channel estimates and either receive symbols or ICI reduced receive symbols. ICI reduced receive symbols are generated by subtracting ICI estimates from receive symbols.

System and method for inter-channel interference reduction

A method and apparatus in a multiple sub-carrier digital communication receiver estimates a Doppler frequency bandwidth. The Doppler frequency bandwidth is estimated by comparing a first set of channel estimates to a second set of channel estimates generated by Wiener filter interpolation of the first set of channel estimates. The Wiener interpolation filter coefficients are generated for various Doppler frequency bandwidths. Pre-determined transmit pilot symbols may be used to generate the first set of channel estimates in an OFDM communication system. A set of Wiener filter interpolation errors may be generated at one or more sub-carrier frequencies, for each of the different Doppler frequency bandwidths, and averaged across time and/or frequency. The Doppler frequency estimation method and apparatus may select a Doppler frequency estimate based on the set of Wiener filter interpolation errors.

System and method for doppler frequency estimation

A method and apparatus in a multiple sub-carrier digital communication receiver that estimates a communication channel. A second set of channel estimates are generated based on a Wiener filter interpolation of a first set of channel estimates. Pre-determined transmit pilot symbols may be used to generate the first set of channel estimates in an OFDM communication system. The coefficients of the Wiener interpolation filter are based on a channel impulse response estimate that includes two or more narrow regions of non-zero amplitude separated by one or more wide regions of essentially zero amplitude. The Wiener interpolation filter coefficients are also based on a Doppler frequency estimate. The Doppler frequency estimate may be determined from the first set of channel estimates, while the Wiener interpolation filter coefficients may be generated from a pre-determined set of channel impulse responses.

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Bade, Taiwan

Gaspar Lee