Qualcomm Incorporated

Tae Ryun Chang

Jong Hyeon Park

Je Woo Kim

Ju Won Park

Bok Tae Sim

Brian Clarke Banister

Matthias Brehler

Chun Woo Lee

Sameer Nanavati

Ayman Fawzy Naguib

Vincent K Jones

Albert Van Zelst

Serguei A Glazko

Remi Jonathan Gurski

Chae Kwan Lee

A method and apparatus for channel estimation in wireless communications are provided. After an initial channel estimation and an estimation of the effective channel length (ECL) are performed, a weighting based on the ECL may be applied in an effort to remove noise from the initial channel estimate and provide an estimated channel with increased accuracy. Different weightings may apply for different channel lengths. A threshold may be used during the ECL estimation, and the threshold may be predetermined or calculated in an effort to adapt to different channel environments.

Methods and systems for effective channel estimation in OFDM systems

A method and apparatus for decoding of tailbiting convolutional codes (TBCC) are disclosed. The proposed modified maximum-likelihood TBCC decoding technique preserves error correction performance of optimal maximum-likelihood based TBCC decoding, while the computational complexity is substantially decreased since a reduced number of decoding states has been evaluated. Compare to other sub-optimal TBCC decoding algorithms, modified maximum-likelihood TBCC decoding achieves improved packet error rate performance with similar computational complexity.

Methods and systems for modified maximum-likelihood based TBCC decoding

Certain embodiments of the present disclosure provide a hybrid receiver diversity scheme that involves combining received signals in accordance with a combination of multiple receive diversity schemes. Certain embodiments of the present disclosure provide a hybrid transmit diversity scheme that involves transmitting diversity signals to a receiver according to a transmit diversity scheme selected based on signal quality measurements received from the receiver.

Methods and systems for hybrid MIMO schemes in OFDM/A systems

A synchronization and detection method in a wireless device may include performing coarse detection and synchronization with respect to a received signal. The synchronization and detection method may also include performing fine detection and synchronization for acquisition of the received signal. Results of the coarse detection and synchronization may be used for the fine detection and synchronization. The synchronization and detection method may also include performing tracking mode processing when the acquisition of the received signal has been achieved.

Methods and apparatus for synchronization and detection in wireless communication systems

Certain embodiments of the present disclosure provide a method and an apparatus for peak-to-average power ratio (PAPR) reduction of a transmission signal in a single carrier frequency division multiple access (SC-FDMA) system. The method may utilize a permutation of a time domain signal, and/or a permutation of a frequency domain signal or a permutation of a signal transformed by a unitary matrix. The apparatus may include an M-point DFT or some other M&#xd7;M unitary matrix, N-point IDFT, interpolation and frequency conversion units, and a pair of possibly different permutation matrices of size M&#xd7;M, where M can be less or equal than N.

Methods and systems for reducing PAPR of an OFDM signal

Methods and apparatus for initially decoding a frame control header (FCH) in an orthogonal frequency-division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) system in an effort to accurately determine the downlink frame prefix (DLFP) such that the remainder of an OFDM/A frame may be properly decoded are provided. Used, for example, when boosting factors applied in the transmitter to various elements of the OFDM/A frame and/or available pilots for the FCH are unknown, such methods may utilize a preamble channel estimate, the FCH pilots, or a combination thereof.

Methods and systems for initial FCH processing

Certain embodiments of the present disclosure provide techniques for approximate computation of lnorms as a part of the maximum likelihood (ML) detection: tri-maxmin, maxsum and sortsum algorithms. The proposed approximation schemes show better accuracy than conventional approximation schemes&#x2014;the abssum and maxmin algorithms, while the computational complexity is very similar. The error rate performance of the ML detection that utilizes proposed norm-approximation techniques are very close to the reference ML detection with exact calculation of lnorms, while the computational complexity is significantly smaller.

Methods and systems using norm approximation for maximum likelihood MIMO decoding

A method and apparatus for decoding encoded data bits of a wireless communication transmission are provided. A set of a-priori bit values corresponding to known bit values of the encoded data bits may be generated. Decoding paths that correspond to decoded data bits that are inconsistent with the a-priori bit values may be removed from the possible decoding paths to consider, and decoding the encoded data bits by selecting a decoding path from remaining decoding paths of the possible decoding paths that were not removed.

Decoding scheme using A-priori information about transmitted messages

In accordance with a method for processing a received orthogonal frequency division multiple access (OFDMA) signal that comprises a duplicated signal, sub-carriers within the OFDMA signal may be arranged into a duplicated format. The OFDMA signal may be equalized and combined after the sub-carriers have been arranged into the duplicated format. The equalizing and combining may be performed in accordance with a maximum ratio combining (MRC) scheme. The OFDMA signal may be demapped after the equalizing and combining is performed.

Methods and apparatus for maximum ratio combining for duplicated signals in OFDMA systems

A method and apparatus for decoding encoded data bits of a wireless communication transmission are provided. A set of a-priori bit values corresponding to known bit values of the encoded data bits may be generated. Decoding paths that correspond to decoded data bits that are inconsistent with the a-priori bit values may be removed from the possible decoding paths to consider, and decoding the encoded data bits by selecting a decoding path from remaining decoding paths of the possible decoding paths that were not removed. Multiple hypotheses, each corresponding to a different set of a-prior bit values may be evaluated, with the decoded data for a hypothesis selected based on the evaluation output for further processing.

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Santa Clara, CA, United States of America

Tae Ryun Chang