Qualcomm Incorporated

Bok Tae Sim

Jong Hyeon Park

Je Woo Kim

Ju Won Park

Tae Ryun Chang

Sameer Nanavati

Serguei A Glazko

Chun Woo Lee

James Young Hurt

Qiang Huang

Chae Kwan Lee

James Y Hurt

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 for combining signals coming from multiple diversity sources may include performing maximal-ratio combining (MRC) based equalization and combining for receiver antenna diversity. The method may also include performing MRC-based equalization and combining for repetition diversity. The method may also include performing MRC-based equalization and combining for duplication diversity. The MRC-based equalization and combining for receiver antenna diversity, the MRC-based equalization and combining for repetition diversity, and the MRC-based equalization and combining for duplication diversity may each be performed separately.

Methods and apparatus for combining signals from multiple diversity sources

In accordance with a method for diversity combining in an orthogonal frequency division multiple access (OFDMA) system, repetition diversity equalization and combining may be performed with respect to received OFDMA signals. In addition, receiver antenna diversity equalization and combining may be performed with respect to the received OFDMA signals. The repetition diversity equalization and combining and the receiver antenna diversity equalization and combining may be performed in accordance with a maximum ratio combining (MRC) scheme.

Methods and apparatus for diversity combining of repeated signals in OFDMA 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

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

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

Certain embodiments provide methods and apparatus for decoding a string of data bits, encoded with a turbo encoding scheme, in a wireless communication system. One or more a-priori bit values corresponding to expected bit values at one or more identified bit locations in the string of data bits may be identified. One or more branch metrics used in a turbo decoding scheme may be manipulated to effectively remove decoding paths, from a collection of possible decoding paths, based at least on the identified one or more a-priori bit values, resulting in one or more remaining decoding paths. The string of data bits may be decoded by selecting a decoding path from the one or more remaining decoding paths.

Methods and systems for turbo decoding in a wireless communication system

A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages divided into coding blocks in an orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access (OFDMA) receiver are provided. According to such a coding-block-based HARQ combining scheme, the quality of each coding block may be compared to a threshold to determine whether the decoded bits or the HARQ combined signal should be saved for each coding block for subsequent HARQ iterations. In addition to reducing the required HARQ buffer size while preserving the combining gain, coding-block-based HARQ combining may also provide fast decoding and reduced power consumption when compared to conventional HARQ combining techniques.

Coding block based HARQ combining scheme for OFDMA systems

A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages at different stages in an OFDM/OFDMA receiver are provided. A combination of different types of HARQ combiners may be designed into the receiver and selected on a per-channel basis. Proper selection of a HARQ combining scheme may reduce the required HARQ buffer size and may provide an increased combining gain when compared to conventional HARQ combining techniques. Furthermore, the HARQ combiner type may be dynamically selected through forward and reverse shifting between the different types of HARQ combining schemes in an effort to decrease the bit error ratio (BER) without saturating the HARQ buffer.

Forward and reverse shifting selective HARQ combining scheme for 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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San Ramon, CA, United States of America

Bok Tae Sim