Broadcom Corporation

Qualcomm Incorporated

Mediatek Singapore Pte. Ltd.

Junqiang Li

Nelson Ray Sollenberger

Li Fung Chang

Je Woo Kim

Mark Hahm

Matthias Brehler

Madihally J Narasimha

Hongwei Kong

Michael Lee McCloud

Jong Hyeon Park

Joseph Boccuzzi

Methods and devices for LTE cell search with large frequency offset are disclosed. In one embodiment of the invention, a UE divides the received signals into multiple frequency bins and transforms the signals into frequency domain through FFT. The UE performs correlating measures between the received signals and reference signals. The UE then performs an adaptive multi-try based peak selection such that the number of candidate is reduced. In one embodiment of the invention, the multi-try number is adaptively adjusted based on the channel condition. In one embodiment of the invention, the threshold of the peak selection is adaptively adjusted. In other embodiments of the invention, the UE performs non-coherent accumulation and selects a predefined number of coarse bin candidates. The number of non-coherent accumulation is adaptively adjusted. In another embodiment of the invention, the UE performs fractional frequency offset estimation and selects a fine bin candidate.

Methods for LTE cell search with large frequency offset

Methods of simplified MMI VQ based HARQ buffer reduction are disclosed. In one embodiment of the invention, the VQ obtains distribution information from source data based on a predefined codebook subset design. The subset design is predefined. Source data is trained within its corresponding subset to generate codebook. In one embodiment of the invention, the predefined subset algorithm is based on the LLR sign value. In another embodiment of the invention, source data is divided into subset based on predefined algorithm. The index to codebook is generated by search through the corresponding subset of the codebook instead of the whole codebook. In one embodiment of the invention, the training method is a modified Lloyd algorithm for MMI VQ. In another embodiment of the invention, the training method is a modified Lloyd algorithm for Euclidean distance VQ.

Methods for simplified MMI VQ based HARQ buffer reduction for LTE

Certain embodiments of the present disclosure propose methods and systems for classifying the Doppler spread based on the output of the frequency-tracking loop (FTL) discriminator in WiMAX systems to improve the performance of the channel estimation. The Doppler spread may be classified as low, medium or high based on the statistics of the output of the discriminator in the fine-tracking mode.

Methods and systems with simplified doppler spread classification

Techniques proposed in the present disclosure may used to update an FFT window position and perform linear phase compensation for OFDM wireless systems with up to two antennas at the receiver. Techniques presented herein may help resolve a problem of determining an optimum FFT window position under the condition that the length of channel impulse response is larger than the length of cyclic prefix.

Methods and systems for time tracking in OFDM systems

Certain embodiments of the present disclosure relate to a method for tracking of a carrier frequency offset. A soft combined frequency tracking discriminator is proposed as a part of the closed loop structure that can provide fast tracking of the frequency offset in an initial pull-in mode, and can also track small residual frequency variance in a fine-tracking mode.

Methods and systems using fine frequency tracking loop design for WiMAX

Techniques for initial wireless network synchronization by a mobile station are provided. For certain embodiments, the techniques may involve a joint search for the cell identification (ID-cell index) and the coarse carrier frequency offset (CFO) estimation. For certain embodiments, the techniques may be based on hard correlation and binary differential despreading that substantially simplifies computational complexity compare to known techniques that independently search for the ID-cell index and perform CFO estimation.

ID-cell index search algorithm and carrier frequency offset estimation

Techniques for the adjustment of a position of Fast Fourier Transform (FFT) window are provided. The adjustment may be based on the condition that the length of channel impulse response is larger than the length of cyclic prefix. The technique may determine a position of the FFT window that attempts to maximize carrier-to-noise (C/N) ratio value measured at the receiver.

Methods and systems using FFT window tracking algorithm

A Radio Frequency (RF) receiver includes a RF front end and a baseband processing module coupled to the RF front end that is operable to receive a time domain signal that includes time domain training symbols and time domain data symbols. The baseband processing module includes a channel estimator operable to process the time domain training symbols to produce a time domain channel estimate, a Fast Fourier Transformer operable to convert the time domain channel estimate to the frequency domain to produce a frequency domain channel estimate, a weight calculator operable to produce frequency domain equalizer coefficients based upon the frequency domain channel estimate, an Inverse Fast Fourier Transformer operable to converting the frequency domain equalizer coefficients to the time domain to produce time domain equalizer coefficients, and an equalizer operable to equalize the time domain data symbols using the time domain equalizer coefficients.

Frequency domain equalizer for dual antenna radio

A Radio Frequency (RF) receiver includes a RF front end and a baseband processing module coupled to the RF front end that is operable to receive a time domain signal that includes desired signal and interfering signal time domain training symbols and time domain data symbols. The baseband processing module includes a channel estimator operable to process the desired signal and interfering signal time domain training symbols to produce a respective time domain channel estimates, a Fast Fourier Transformer operable to convert the time domain channel estimates to the frequency domain to produce frequency domain channel estimates, a weight calculator operable to produce frequency domain equalizer coefficients based upon the frequency domain channel estimates, an Inverse Fast Fourier Transformer operable to convert the frequency domain equalizer coefficients to the time domain to produce time domain equalizer coefficients, and an equalizer operable to equalize the time domain data symbols using the time domain equalizer coefficients.

Frequency domain equalizer with one dominant interference cancellation for dual antenna radio

A system for processing radio frequency (RF) signals includes a searcher and a Cluster Path Processor (CPP). The searcher detects a maximum signal energy level and position of at least one of a plurality of individual distinct path signals in a signal cluster, wherein at least a portion of the plurality of individual distinct path signals is received within a duration of a corresponding delay spread. The CPP includes a group finger array having a plurality of group fingers and determines a coarse sampling position of the group finger array based upon the position of the at least one of a plurality of individual distinct path signals in the signal cluster. The CPP determines a fine sampling position based upon determines a composite channel energy estimate for the plurality of individual distinct path signals. Using this fine sampling position, the CPP receives at least a portion of the plurality of individual distinct path signals by the group finger array.

Maximum energy delay locked loop for cluster path processing in a wireless device

A baseband processing module of a Radio Frequency receiver produces time domain equalizer coefficients and calculates a power threshold based upon a total power of a plurality of taps of the time domain equalizer coefficients. The baseband processing module then performs a plurality of iterations, during each of which it identifies at least one minimum power tap and determines a total power figure based upon zeroing the at least one minimum power tap. When the total power figure compares favorably to the power threshold, the baseband processing module modifies the plurality of taps by zeroing the at least one minimum power tap and continuing iterating. When the total power figure compares unfavorably to the power threshold, the baseband processing module ceases iterating without modifying the plurality of taps by zeroing the at least one minimum power tap and then produces modified time domain equalizer coefficients.

Power collection based adaptive length equalizer

A Radio Frequency (RF) transceiver includes a RF front end and a baseband processing module coupled to the RF front end that is operable to receive a time domain signal that includes time domain training symbols and time domain data symbols. The baseband processing module processes the time domain training symbols to produce a time domain channel estimate, Fast Fourier Transformer operations that convert the time domain channel estimate to the frequency domain to produce a frequency domain channel estimate, weight calculation operations that produce frequency domain equalizer coefficients based upon the frequency domain channel estimate, Inverse Fast Fourier Transformer operations that convert the frequency domain equalizer coefficients to the time domain to produce time domain equalizer coefficients, and equalization operations that equalize the time domain data symbols using the time domain equalizer coefficients.

Frequency domain equalizer for single antenna radio

A system for processing radio frequency (RF) signals includes a searcher and a plurality of Cluster Path Processor (CPPs). The searcher detects a maximum signal energy level and position of at least one of a plurality of individual distinct path signals in a signal cluster of a first information signal, wherein at least a portion of the plurality of individual distinct path signals is received within a duration of a corresponding delay spread. The sampling position is used as a starting sampling location by the plurality of CPPs, including a first information signal CPP and a second information signal CPP. Fine sampling positions of the plurality of CPPs are based upon channel energy estimates for the plurality of individual distinct path signals. CPP outputs are employed to produce channel estimates, which are themselves used in subsequent equalization operations. Sampling positions may change over time in order to satisfy alignment criteria.

Cluster path processor time alignment for signal suppression/separation in a wireless device

A Radio Frequency (RF) receiver includes a RF front end and a baseband processing module coupled to the RF front end that is operable to determine equalizer coefficients for a composite signal that includes a first information signal and a second information signal. First and second information signal channel estimates and channel powers based upon training symbols are determined. A composite signal power is determined. A noise variance of the composite signal is determined based upon the first information signal channel power, the second information signal channel power, and the composite signal power. A plurality of equalizer coefficients are determined based upon the first information signal channel estimate, the second information signal channel estimate, and the noise variance of the composite signal.

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Sunnyvale, CA, United States of America

Junqiang Li