Patent application number | Description | Published |
20090154392 | CODING BLOCK BASED HARQ COMBINING SCHEME FOR OFDMA SYSTEMS - 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. | 06-18-2009 |
20090154627 | METHODS AND APPARATUS FOR IDENTIFYING A PREAMBLE SEQUENCE AND FOR ESTIMATING AN INTEGER CARRIER FREQUENCY OFFSET - In accordance with a method for identifying a preamble sequence and for estimating an integer carrier frequency offset, a signal that comprises a preamble sequence from a set of possible preamble sequences is received. A reduced set of integer carrier frequency offset (CFO) candidates may be determined. Cross-correlation operations may be performed with respect to the received signal and multiple candidate transmitted signals. Each candidate transmitted signal may include one of the set of possible preamble sequences. In addition, each candidate transmitted signal may correspond to one of the reduced set of integer CFO candidates. Multiple correlation values may be determined as a result of the cross-correlation operations. The correlation values may be used to identify the preamble sequence and to estimate the integer CFO. | 06-18-2009 |
20090158109 | SELECTIVE HARQ COMBINING SCHEME FOR OFDM/OFDMA SYSTEMS - A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages at different stages in an orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access (OFDMA) receiver are provided. The type of HARQ combiner used for a particular channel may depend on a number of selection criteria including the modulation order of the transmission, the number of bits needed for the combined signals, and the headroom in the HARQ buffer. For some embodiments, a combination of different types of HARQ combiners may be designed into a 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. | 06-18-2009 |
20090158110 | FORWARD AND REVERSE SHIFTING SELECTIVE 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. | 06-18-2009 |
20090175364 | METHODS AND APPARATUS FOR MAXIMUM RATIO COMBINING FOR DUPLICATED SIGNALS IN OFDMA SYSTEMS - 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. | 07-09-2009 |
20090175387 | DECODING SCHEME USING MULTIPLE HYPOTHESES ABOUT TRANSMITTED MESSAGES - 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. | 07-09-2009 |
20090175388 | DECODING SCHEME USING A-PRIORI INFORMATION ABOUT TRANSMITTED MESSAGES - 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. | 07-09-2009 |
20090175389 | METHODS AND SYSTEMS FOR TURBO DECODING IN A WIRELESS COMMUNICATION SYSTEM - 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. | 07-09-2009 |
20090175394 | METHODS AND APPARATUS FOR SYNCHRONIZATION AND DETECTION IN WIRELESS COMMUNICATION 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. | 07-09-2009 |
20090177951 | PRIORI DECODING SCHEME BASED ON MAP MESSAGES - 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. A-priori bit values may be extracted from various messages, such as DL-MAP, UL-MAP, RNG-REQ, and BW-REQ messages. | 07-09-2009 |
20090213919 | SIGNAL QUALITY ESTIMATION FOR OFDMA SYSTEMS - Certain embodiments utilize raw signals to estimate channel quality, as contrasted to utilizing equalized signals or after channel estimation. For example, signal quality may be estimated by calculating powers of pilot sub-carriers and null sub-carriers of the raw signals. To mitigate channel effect, certain embodiments utilize first and/or second order differentiation schemes. | 08-27-2009 |
20090213971 | COHERENT SINGLE ANTENNA INTERFERENCE CANCELLATION FOR GSM/GPRS/EDGE - A method for midamble estimation comprises the steps of receiving a burst of symbols, selecting a subset of the burst of symbols that comprises a first midamble symbol, calculating, for each symbol in the subset, a corresponding midamble estimation error, and determining the lowest calculated midamble estimation error to locate the first midamble symbol. A receiver comprises an antenna configured to receive a burst of symbols, a timing estimator configured to select a subset of the burst of symbols that comprises a first midamble symbol, a midamble estimator configured to calculate, for each symbol in the subset, a corresponding midamble estimation error, and a processor configured to select the symbol in the subset corresponding to a lowest calculated midamble estimation error as the first midamble symbol. | 08-27-2009 |
20090238063 | METHODS AND APPARATUS FOR DIVERSITY COMBINING OF REPEATED SIGNALS IN OFDMA SYSTEMS - 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. | 09-24-2009 |
20090239494 | METHODS AND APPARATUS FOR COMBINING SIGNALS FROM MULTIPLE DIVERSITY SOURCES - 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. | 09-24-2009 |
20090285316 | METHODS AND SYSTEMS FOR INITIAL FCH PROCESSING - 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. | 11-19-2009 |
20090285317 | METHODS AND SYSTEMS FOR EFFECTIVE CHANNEL ESTIMATION IN OFDM SYSTEMS - 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. | 11-19-2009 |
20090290618 | METHODS AND SYSTEMS FOR HYBRID MIMO SCHEMES IN OFDM/A SYSTEMS - 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. | 11-26-2009 |
20090316823 | METHODS AND SYSTEMS FOR IMPROVING FRAME DECODING PERFORMANCE USING KNOWN INFORMATION - 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 a response message expected to be transmitted in response to a previously transmitted message. Example expected response messages include clear to send (CTS) messages transmitted in response to request to send (RTS) messages and positive acknowledgement (ACK) messages transmitted in response to messages with data payloads. | 12-24-2009 |
20090316840 | METHODS AND SYSTEMS FOR STC SIGNAL DECODING USING MIMO DECODER - Space time coding (STC) may be applied at the transmitter adding redundant information in both space and time dimensions. At the receiver, the received STC signal may be decoded using a spatial multiplexing MIMO decoding, for example, based on either Minimum Mean Square Error (MMSE) or maximum-likelihood (ML) algorithms. A selective STC decoder may incorporate both the conventional maximum ratio combining (MRC) decoding scheme and a MIMO decoding scheme. One of the STC decoding schemes may be selected, for example, based on estimated channel conditions in order to achieve a trade-off between error rate performance and computational complexity. Components used for a non-selected scheme may be powered down. | 12-24-2009 |
20100008432 | METHODS AND SYSTEMS FOR REDUCING PAPR OF AN OFDM SIGNAL - 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×M unitary matrix, N-point IDFT, interpolation and frequency conversion units, and a pair of possibly different permutation matrices of size M×M, where M can be less or equal than N. | 01-14-2010 |
20100067596 | METHODS AND SYSTEMS FOR HYBRID MIMO DECODING - Certain embodiments of the present disclosure allow a receiver to utilize both a minimum mean square error (MMSE) detection algorithm and a maximum likelihood (ML) detection algorithm. The receiver may control, based on various conditions, a mode selection signal to select between output generated with the MMSE detection algorithm and the ML detection algorithm. By sharing logical components, certain embodiments may allow a receiver to implement both ML and MMSE detection algorithms with minimal computational overhead when compared to implementing a single one of the decoding algorithms. | 03-18-2010 |
20100067597 | METHODS AND SYSTEMS FOR MAXIMUM-LIKELIHOOD DETECTION USING POST-SQUARING COMPENSATION - A “post-squaring” detection algorithm, and related devices, that may reduce the complexity of maximum likelihood detection (MLD) schemes while preserving their performance is provided. Rather than search for optimum metrics (such as minimum distance metrics) based on squared norm values, a search may be based on un-squared norm metrics, and the squaring may be postponed, for example, until subsequent log-likelihood ratio (LLR) computation. For certain embodiments, approximations of un-squared norm values may significantly reduce computation complexity. | 03-18-2010 |
20100067600 | MMSE MIMO DECODER USING QR DECOMPOSITION - Aspects of the disclosure provide unbiased channel equalization applied in a MIMO OFDM system with spatial multiplexing. According to certain embodiments, a MMSE receiver can be implemented with the QR decomposition (QRMMSE detection) instead of direct inversion of channel matrix by exploiting an augmented channel matrix. A simple and efficient bias removal technique is presented herein, whereby unbiased QRMMSE equalization may provide identical detection accuracy as a conventional unbiased MMSE approach. For certain embodiments, multiple access interference may be further reduced if the VBLAST version of the unbiased QRMMSE detection is applied. | 03-18-2010 |
20100091912 | METHODS AND SYSTEMS USING NORM APPROXIMATION FOR MAXIMUM LIKELIHOOD MIMO DECODING - Certain embodiments of the present disclosure provide techniques for approximate computation of l | 04-15-2010 |
20100118756 | METHODS AND SYSTEMS FOR SUPPORTING MIMO BURSTS FOR MULTICAST AND BROADCAST SERVICES - Certain embodiments of the present disclosure provide a method for supporting multicast and broadcast services (MBS) with multiple-input multiple-output (MIMO) capabilities. This can be achieved by adding specific MIMO information into existing MBS-MAP messages while providing backward compatibility. | 05-13-2010 |
20100151862 | METHODS AND SYSTEMS FOR HANDOVER IN WIMAX NETWORKS - This application provides techniques for robust handover to a target base station, based on performing initial ranging with the target base station. The techniques might generally include scanning neighboring base stations (BSs), selecting a target BS for a handover at least based on results of the scanning, performing initial ranging with the target BS, and sending a Handover Request to the target BS. | 06-17-2010 |
20100158079 | ID-CELL INDEX SEARCH ALGORITHM AND CARRIER FREQUENCY OFFSET ESTIMATION - 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. | 06-24-2010 |
20100165829 | METHODS AND SYSTEMS FOR PAPR REDUCTION IN SC-FDMA SYSTEMS - Certain embodiments of the present disclosure relate to methods for peak-to-average power ratio (PAPR) reduction of a transmission signal in a single carrier frequency division multiple access (SC-FDMA) system. The proposed methods and systems are based on manipulations of an SC-FDMA transmission signal in a time- and/or a frequency-domain. | 07-01-2010 |
20100167653 | METHODS AND SYSTEMS FOR CO-CHANNEL INTERFERENCE CANCELLATION IN WIRELESS NETWORKS - Certain embodiments of the present disclosure relate to methods for mitigating interference of signals transmitted to a mobile station (MS) from a plurality of neighboring base stations. By applying a proposed spatio-frequency modulation (SFM) technique at a serving base station (BS) and at each interfering BS, a co-channel interference (CCI) from interfering base stations can be efficiently mitigated at the MS and signal transmitted from the serving BS can be more accurately decoded. | 07-01-2010 |
20100197254 | METHODS AND SYSTEMS FOR LEAST SQUARES BLOCK CHANNEL ESTIMATION - Certain embodiments of the present disclosure provide techniques for channel estimation without resorting to the channel second-order statistics. Methods and systems are proposed for improving the performance of an un-constrained least squares channel interpolator by using available side information of the channel, such as signal-to-noise ratio (SNR), Doppler frequency and/or delay spread. | 08-05-2010 |
20100202571 | METHODS AND SYSTEMS FOR FREQUENCY DOMAIN GAIN CONTROL IN OFDM MIMO SYSTEMS - Certain embodiments of the present disclosure provide a method for frequency-domain gain control in system utilizing orthogonal frequency division multiplexing (OFDM) multiple input multiple output (MIMO). The proposed method reduces the complexity of the system while maximizing the internal accuracy of the OFDM MIMO decoder and preserving the performance of the system. | 08-12-2010 |
20110051831 | UNIFIED ITERATIVE DECODING ARCHITECTURE USING JOINT LLR EXTRACTION AND A PRIORI PROBABILITY - Certain aspects of the present disclosure relate to a method and an apparatus for unified iterative demodulation-decoding that can be employed in both multiple-input multiple-output (MIMO) and non-MIMO wireless systems. | 03-03-2011 |
20110051858 | HARDWARE SIMPLIFICATION OF SIC-MIMO DECODING BY USE OF A SINGLE HARDWARE ELEMENT WITH CHANNEL AND NOISE ADAPTATION FOR INTERFERENCE CANCELLED STREAMS - Certain aspects of the present disclosure relate to a method and an apparatus for simplified serial interference cancellation in multiple-input multiple-output (MIMO) and non-MIMO wireless systems by using a single hardware element for multiple interference cancelled streams. | 03-03-2011 |
20110051860 | ITERATIVE DECODING ARCHITECTURE WITH HARQ COMBINING AND SOFT DECISION DIRECTED CHANNEL ESTIMATION - Certain aspects of the present disclosure relate to a method for iterative decoding with re-transmissions of data and to a method for iterative decoding with soft decision directed channel estimation. | 03-03-2011 |
20110206151 | MULTI-TERM DEMAPPING FOR MULTI-CHANNEL WIRELESS COMMUNICATION - Providing for reduced complexity or improved accuracy in de-mapping received wireless data streams for multi-channel wireless communication is described herein. By way of example, a low-complexity likelihood algorithm can be employed to de-map data bits from the wireless data streams. In one particular example, the likelihood algorithm can approximate a received bit with a subset of received wireless symbols correlated the bit, reducing algorithm complexity. In other examples, a limited set of received wireless symbols can be employed for the subset, further reducing algorithm complexity. According to at least one other example, logarithmic terms of the algorithm can be approximated with non-logarithmic functions, such as a look-up table, series expansion, polynomial approximation, or the like. These approximations can enhance symbol de-mapping accuracy while maintaining or improving processing overhead for a wireless receiver. | 08-25-2011 |
20110268019 | USING JOINT DECODING ENGINE IN A WIRELESS DEVICE - A method for using a joint decoding engine in a wireless device is disclosed. A first symbol stream and a second symbol stream in a received multiple input multiple output (MIMO) signal is determined. A scaled channel estimate for a wireless transmission channel and a scaled noise covariance of the MIMO signal are also determined. The scaled channel estimate and the first symbol stream are whitened. Max log maximum a posteriori (MLM) processing is performed on the whitened first symbol stream to produce a first data stream. The first data stream may be de-rate matched and decoded to produce a decoded first data stream. | 11-03-2011 |
20120014428 | METHODS AND SYSTEMS FOR INITIAL FCH PROCESSING - 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. | 01-19-2012 |
20130272168 | REDUCING TRANSIENT EFFECTS WHEN CHANGING TRANSMIT CHAIN POWER - A method, an apparatus, and a computer program product for a wireless communication device are provided. The apparatus determines a receive timing for receiving through at least one receive chain element. The apparatus determines a time to turn on/off at least one transmit chain element based on the determined receive timing and based on receiver impact to the at least one receive chain element caused by turning on/off the at least one transmit chain element. The apparatus reduces receiver impact to the at least one receive chain element by turning on/off the at least one transmit chain element at the determined time. | 10-17-2013 |
20150016352 | METHODS AND APPARATUS FOR PERFORMING RANDOM ACCESS CHANNEL PROCEDURES - Certain aspects of the present disclosure generally relate to methods and apparatus for performing random access channel (RACH) procedures with a base station. For example, certain aspects provide methods and apparatus for performing RACH procedures when a user equipment moves out of range from the base station (e.g., for RACH procedure success). One method includes attempting a RACH procedure with a first base station, determining the UE is out of range from the first base station for RACH procedure success, and, upon determining the UE is out of range from the first base station for RACH procedure success, reattempting the RACH procedure with the first base station or a second base station. | 01-15-2015 |