| Patent application number | Description | Published |
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| 20080205539 | Method and System for Achieving Spatial Diversity of a Wireless Communications Network - A method and system are provided for achieving spatial diversity of a wireless communications network. The method comprises arranging antennas on a transmitting wireless station into a plurality of antenna subgroups, wherein each of the antenna subgroups forms a virtual antenna, creating a plurality of beamformed MIMO channels using the plurality of virtual antennas, wherein each of the beamformed MIMO channel comprises a plurality of sub-carriers and corresponds to a virtual antenna, dividing sub-carriers in each of the plurality of beamformed MIMO channels into at least a first and second cluster, distributing a first amount of transmitting power to the first cluster and a second amount of transmitting power to the second cluster, wherein the first amount of transmitting power is substantially larger than the second amount of transmitting power. | 08-28-2008 |
| 20080207270 | Method for Generating Downlink Beamforming Weighting Vectors - Techniques are provided for generating downlink beamforming weighting vectors by using channel information about one or more uplink sub-channels in a wireless communications network in the case of frequency mismatch between downlink channels and uplink channels for a specific user. The method comprises calculating an average channel covariance matrix of one or more uplink sub-channels assigned to a specific user, dividing a sector of a cell into a plurality of sub-sectors, transforming the average channel covariance matrix into a plurality of average sub-sector channel covariance matrices and obtaining an average uplink beamforming weighting vector group corresponding to the plurality of sub-sectors, selecting direction of arrival (DOA) sub-sectors from the plurality of sub-sectors by using the plurality of average sub-sector channel covariance matrices, and computing a time delay sequence for the DOA sub-sectors, and generating downlink beamforming weighting vectors by using the average uplink beamforming weighting vectors corresponding to the DOA sub-sectors and the information derived from the time delay sequence. | 08-28-2008 |
| 20080225972 | Method and System for Partitioning an Antenna Array and Applying Multiple-Input-Multiple-Output and Beamforming Mechanisms - A system and method are provided for configuring an antenna array having a predetermined number of antennas. After providing an antenna correlation matrix for all antennas with regard to a mobile terminal, the antenna array is virtually partitioned into two or more sub-arrays based on the antenna correlation matrix such that correlations among antennas within each sub-array are higher than correlations among antennas belonging to different sub-arrays. One or more beamforming weights are generated corresponding to each antenna within the sub-arrays for applying to one or more signals transmitted therefrom, and at least one predetermined multiple-input-multiple-output (MIMO) mechanism is further applied among the sub-arrays by treating each sub-array as a virtual antenna. | 09-18-2008 |
| 20080238775 | Beamformed Space Time Code Communication with Testing Spatial Signature Generation - An apparatus, logic and method are provided to improve beamformed space time code (STC) wireless communication. A first device comprising a plurality of antennas receives signals at the plurality of antennas transmitted from a first antenna of a second device. A testing spatial signature for a second antenna of the second device is computed based on the signals received at the plurality of antennas of the first device from the first antenna of the second device. Using the testing spatial signature and the signals received at the plurality of antennas of the first device from the first antenna of the second device, beamforming weights are computed to be applied to a space time code signal to be transmitted from the first device to the second device via the plurality of antennas of the first device. | 10-02-2008 |
| 20080240208 | Adaptive Switching Techniques for Hybrid Automatic Repeat Request Systems - Apparatus, system, and method for an adaptive transmission selection technique. A retransmission scheme is selected for a multiple-input-multiple-output (MIMO) wireless communications system. Techniques are provided herein for selecting from a plurality of wireless communication techniques when a first device needs to retransmit a signal (one or more packets of data) to a second device. The first device determines when the signal which was originally wirelessly transmitted using beamforming techniques via multiple antennas of the first device to the second device needs to be retransmitted to the second device. If a retransmission is needed, the first device determines channel conditions with respect to the second device. The first device selects a retransmission scheme from a plurality of transmission schemes based on the channel conditions for retransmitting the signal via the multiple antennas of the first device to the second device. A first retransmission technique is selected when the channel conditions are static. A second retransmission technique is selected when the channel conditions are relatively slowly changing, and a third retransmission technique is selected when the channel conditions are relatively quickly changing. | 10-02-2008 |
| 20080261658 | Hybrid Time-Spatial Multiplexing for Wireless Broadcast Messages through Antenna Radiation Beam Synthesis - A hybrid time-spatial multiplexing technique is provided for beamforming broadcast messages to mobile stations that may be within a coverage region or cell of a base station. The coverage region is divided into a plurality of plurality of segments. The mobile stations are assigned to at least one of the segments based on their locations within the coverage region or other criteria. The base station computes beamforming antenna weights which are configured to produce a radiation beam pattern from a plurality of antennas of the base station to respective ones of each of the plurality of segments in the region. A broadcast message is transmitted to each segment of the region in a time-division multiplexed manner using the beamforming antenna weights associated with the radiation beam pattern for the corresponding segment. | 10-23-2008 |
| 20080320355 | System for Identifying Localized Burst Errors - A system for detecting one or more localized burst errors in a receiving message comprised of a plurality of codewords. The system comprises a trellis code decoder for decoding a receiving message with a plurality of codewords and calculating one or more cumulative metrics of a maximum likelihood path and one or more alternative paths from the receiving message, an error detection code (EDC) decoder for detecting existence of one or more errors in the decoded receiving message received from the trellis decoder, and a localized burst error detector activated by the EDC decoder upon detecting the existence of one or more errors in the decoded receiving message to identify at least one corrupted codeword among the plurality of codewords using the one or more cumulative metrics of a maximum likelihood path and the one or more alternative paths, wherein the system requests the re-transmission of the corrupted codeword. | 12-25-2008 |
| 20090004988 | SYSTEM AND METHOD FOR IMPROVING THE ROBUSTNESS OF SPATIAL DIVISION MULTIPLE ACCESS VIA NULLING - The present invention discloses a base transceiver station (BTS) equipped with a plurality of antennas for improving the robustness of spatial division multiple access via nulling. The BTS comprises of a first matrix module receiving a plurality of signals from one or more customer premises equipments (CPEs) through the plurality of antennas and producing correspondingly a first plurality of covariance matrices representing the plurality of signals, a second matrix module receiving the first plurality of covariance matrices and generating correspondingly a set of derivative spatial signature matrices representing the CPEs respectively, a third matrix module receiving the derivative spatial signature matrices and producing correspondingly a second plurality of covariance matrices representing interferences of the CPEs, and an eigenvector module generating a plurality of beamforming vectors for the CPEs from the plurality of derivative spatial signature matrices and the second plurality of covariance matrices. | 01-01-2009 |
| 20090022254 | PHYSICAL CARRIER TO INTERFERENCE-PLUS-NOISE RATIO TECHNIQUES FOR WIDEBAND WIRELESS COMMUNICATION NETWORKS - Techniques are provided to compute the physical carrier to interference-plus-noise ratio (PCINR) in a wireless communication system. In one embodiment, the PCINR is computed from received signals in active subcarriers in a preamble of a wireless transmission frame. In another embodiment, the PCINR is computed from a block of contiguous subcarriers in a symbol of received wireless transmission. The PCINR may be used to adjust a system parameter associated with wireless communication between wireless communication devices. | 01-22-2009 |
| 20090042530 | PILOT-BASED TWO-DIMENSIONAL CHANNEL ESTIMATION - Techniques are provided herein to estimate channel information based a received burst that is comprises of consecutive transmissions. Each transmission comprises a plurality of data subcarriers and a plurality of pilot subcarriers on a radio frequency (RF) channel, wherein locations of the pilot subcarriers in the consecutive transmissions are different. Channel information at the pilot subcarriers is computed for each transmission in the burst. A time variation parameter and a frequency variation parameter of the channel for the burst are computed using the channel information at the pilot subcarriers for the transmissions in the burst. Channel information for at least one data subcarrier of a transmission in the burst is computed by interpolation and/or extrapolation of the channel information at the pilot subcarriers using the time variation parameter and the frequency variation parameter. The channel information for the remaining data subcarriers is computed by interpolation and/or extrapolation using the estimated channel information at the pilot subcarriers and the at least one data subcarrier. | 02-12-2009 |
| 20090042618 | GENERALIZED MIMO-BEAMFORMING WEIGHT ESTIMATION - Techniques are provided to enable wireless communication between first and second wireless communication devices each having a plurality of antennas, where the second device sends the transmissions via less than all of its plurality of antennas. Each transmission may comprise a plurality of time-frequency instances. At the first communication device, data is derived representing parameters of a communication channel between the plurality of antennas of the first device and all of the plurality of antennas of the second device from the transmissions received at the plurality of antennas of the first device. Beamforming weights for transmitting one or more signal streams via the plurality of antennas of the first device to the plurality of antennas of the second device are computed based on the data representing parameters of the communication channel between the plurality of antennas of the first device and the plurality of antennas of the second device. The beamforming weights are applied to the one or more signal streams to be transmitted via the plurality of antennas of the first device to the plurality of antennas of the second device. | 02-12-2009 |
| 20090051594 | Low Complexity Blind Beamforming Weight Estimation - Techniques are provided to compute beamforming weights at a communication device, e.g., a first communication device, based on transmissions received at a plurality of antennas from another communication device, e.g., a second communication device. A plurality of transmissions are received at the plurality of antennas of the first communication device from the second communication device. A covariance matrix associated with reception of a plurality of transmissions at the plurality of antennas of the first communication device is computed. Corresponding elements (e.g., all the rows or all the columns) of the covariance matrix are combined to produce a weighted channel signature vector. A receive beamforming weight vector is computed from the weighted channel signature vector. | 02-26-2009 |
| 20090080560 | CLOSED-LOOP BEAMFORMING WEIGHT ESTIMATION IN FREQUENCY DIVISION DUPLEX SYSTEMS - A closed-loop beamforming weight estimation process in which, at a first device, respective ones of a plurality of beamforming weight vectors are applied to subcarriers associated with a pattern of subcarriers assigned to a corresponding subcarrier stream such that the plurality of subcarriers assigned to a subcarrier stream is weighted by a corresponding one of the plurality of beamforming weight vectors to produce a plurality of beamformed streams transmitted from a plurality of antennas of the first device to a second device. The second device estimates and analyzes the channel information for each of the received beamformed streams to identify at least one of the beamformed streams that is preferred over the others. The second device transmits to the first device a feedback signal that contains information identifying the preferred beamformed stream. The first device computes a plurality of new beamforming weight vectors based on the information identifying the preferred beamformed stream. The first device applies the new beamforming weight vectors to streams of subcarriers to repeat the process until system parameters or conditions are met. | 03-26-2009 |
| 20090086855 | LINK ADAPTATION BASED ON GENERIC CINR MEASUREMENT ACCORDING TO LOG-LIKELIHOOD RATIO DISTRIBUTION - Techniques are provided to compute the carrier to interference-plus-noise ratio (CINR) in a wireless communication system using log-likelihood ratio (LLR) data generated from a received transmission. The LLR data are collected as they are sent from a detector to a forward error correction (FEC) decoder in a wireless communications device. In one embodiment, decision-aided LLR based CINR is computed using the decoded bits output from the FEC decoder as feedback. In another embodiment, blind LLR based CINR is computed without feedback. The CINR may be used to adjust a modulation and/or coding parameters associated with wireless communication between wireless communication devices. | 04-02-2009 |
| 20090088090 | OMNI-DIRECTIONAL AND LOW-CORRELATED PRE-CODING BROADCAST BEAMFORMING - Techniques are provided herein to compute beamforming weight vectors for pre-coding broadcast signals. First, system parameters for a device configured to wirelessly transmit one or more broadcast signals via a plurality of antennas are determined. Based on the system parameters a plurality of beamforming weight vectors are computed. The beamforming weight vectors are computed such that they have omni-directional like characteristics and such that correlation between beamforming weight vectors is relatively low. The plurality of beamforming weight vectors are applied to each of the one or more broadcast signals for transmission by the device to produce beamformed transmit signals for transmission via the plurality of antennas. | 04-02-2009 |
| 20090098838 | BEAMFORMED MULTI-INPUT MULTIPLE-OUTPUT COMMUNICATION WITH UPLINK TRANSMISSION ROTATION - Techniques are provided to enable computation of beamforming weights for beamforming MIMO wireless communication between first and second wireless communication devices. At the first device comprising a first plurality of antennas, signals are received that are wirelessly transmitted from a different one of a second plurality of antennas of the second device during a corresponding one of a plurality of time slots. The first device computes beamforming weights from the received signals. When signals are to be transmitted from the first device to the second device, the first device applies the beamforming weights to signals to be transmitted from the first plurality of antennas of the first device to the second plurality of antennas of the second device. | 04-16-2009 |
| 20090102715 | Beamforming Multiple-Input Multiple-Output Hybrid Automatic Repeat Request Retransmission - Techniques are provided for improving hybrid automatic repeat request retransmissions techniques in a beamformed multiple-input multiple-output wireless communication environment. At a first device comprising a first plurality of antennas, a plurality of beamforming weight vectors are applied to a corresponding plurality of signal streams for simultaneous transmission to a second device having a plurality of antennas. A determination is made whether the plurality of signal streams need to be retransmitted from the first device to the second device. When a retransmission needs to be made, an order in which the plurality of beamforming weight vectors are applied to the plurality of signal streams is switched for a retransmission attempt of the plurality of signal streams from the first device to the second device. | 04-23-2009 |
| 20090116569 | Bi-Directional Beamforming Multiple-Input Multiple-Output Wireless Communication - Techniques are provided herein to configure first and second wireless communication devices in order to perform bi-directional beamformed multiple-input multiple-output (MIMO) communication. Each device uses received signals from the other device to compute beamforming weight vectors for application to a plurality of signal streams to be simultaneously beamformed transmitted to the other device. | 05-07-2009 |
| 20090135938 | PERFORMANCE OF A TRELLIS-BASED DECODER USING STATES OF REDUCED UNCERTAINTY - A method and system are provided for improving the performance of a trellis-based decoder. States with reduced uncertainty (SRUs) are defined for one or more predetermined fields in an encoded message. Metrics are set for the SRUs such that candidate paths through a trellis-based decoding process are eliminated for those states that are not SRUs. | 05-28-2009 |
| 20090270118 | Frequency Band Extrapolation Beamforming Weight Computation for Wireless Communications - Techniques are provided to facilitate the computation of beamforming weights used by a first communication device when sending a transmission via a plurality of antennas to a second communication device where knowledge of the behavior of the channel between the first communication device and the second communication device is limited to a portion of a wide frequency band. A frequency extrapolation beamforming weight computation process is provided to derive knowledge in other frequency subbands based on information contained in the received transmission from the second communication device. | 10-29-2009 |
| 20090322614 | ORTHOGONAL/PARTIAL ORTHOGONAL BEAMFORMING WEIGHT GENERATION FOR MIMO WIRELESS COMMUNICATION - Techniques are provided for computing beamforming weight vectors useful for multiple-input multiple-output (MIMO) wireless transmission of multiple signals streams from a first device to a second device. The techniques involve computing a plurality of candidate beamforming weight vectors based on the one or more signals received at the plurality of antennas of the first device. A sequence of orthogonal/partially orthogonal beamforming weight vectors are computed from the plurality of candidate beamforming weight vectors. The sequence of orthogonal/partially orthogonal beamforming weight vectors are applied to multiple signal streams for simultaneous transmission to the second device via the plurality of antennas of the first device. | 12-31-2009 |
| 20090323847 | OPEN-LOOP BEAMFORMING MIMO COMMUNICATIONS IN FREQUENCY DIVISION DUPLEX SYSTEMS - Techniques are provided for wireless communication between a first wireless communication device and a second wireless communication device. At a plurality of antennas of the first wireless communication device, one or more signals transmitted by a second wireless communication device in a first frequency band are received. Beamforming weights are computed from information derived from the signals received at the plurality of antennas using one or more of a plurality of methods without feedback information from the second wireless communication device about a wireless link from the first wireless communication device to the second wireless communication device. The beamforming weights are applied to at least one transmit signal to beamform the at least one transmit signal for transmission to the second wireless communication device in a second frequency band. | 12-31-2009 |
| 20100130135 | DYNAMIC CHANNEL ESTIMATION BASED ON CHANNEL CONDITIONS - A dynamically adaptive channel estimation process is provided for use in a wireless communication device. At a first device, a wireless transmission is received from a second device. The transmission comprises a plurality of successive symbols each of which comprises a plurality of subcarriers. The first device is configured to compute channel characterizing information for a wireless channel between the first device and the second device based on the received values at subcarriers of the successive symbols. The first device is configured to select one of a plurality of channel estimation schemes based on the channel characterizing information, and to compute an estimate of channel information for the wireless channel using the selected one of the plurality of channel estimation schemes. | 05-27-2010 |
| 20100130156 | OFFSET DIRECT CONVERSION RECEIVER - An offset direct conversion receiver apparatus and corresponding receiving method are provided. A received wireless signal is directly downconverted and demodulated to a baseband offset frequency that is offset from zero frequency to produce an in-phase (I) baseband offset signal centered at the baseband offset frequency and a quadrature-phase (Q) baseband offset signal centered at the baseband offset frequency. The I baseband offset signal and Q baseband offset signal are bandpass filtered to produce an I bandpass signal and a Q bandpass signal, respectively. The I bandpass signal and the Q bandpass signal are downconverted from the baseband offset frequency to zero frequency to produce an I baseband receive signal and a Q baseband receive signal. A technique and logic are also provided to select the best baseband offset frequency used in an offset direct conversion receiver. | 05-27-2010 |
| 20100150127 | MULTI-CARRIER CODE DIVISION MULTIPLE ACCESS BEAMFORMING - Techniques are provided to performing beamforming on a wireless communication link that employs multi-carrier code division multiple access (MC-CDMA) signal formatting techniques. At a first wireless communication device, a waveform is received at each of a plurality of antennas, where the waveform comprises a multi-carrier code division multiple access ranging transmission from each of one or more of a plurality of second wireless communication devices such that MC-CDMA ranging transmissions from two or more second wireless communication devices overlap in time and frequency. All codes in a set of possible codes that may be used by the second wireless communication devices are searched to determine whether which codes in the set are present in the one or more MC-CDMA ranging transmissions contained in the received waveform. For each of the one or more codes that are determined to be present in the received waveform, estimated channel path responses are computed at each of the plurality of antennas of the first wireless communication device. A downlink beamforming weight vector is computed from the estimated channel path responses computed for a corresponding code. | 06-17-2010 |
| 20100150129 | SEGMENTED TRANSMISSION FOR BROADCAST MESSAGES USING MULTIPLE ANTENNAS - Techniques are provided herein to segment subcarriers for broadcast transmission to one or more mobile stations. A broadcast message to be transmitted from a first device is generated. The broadcast message comprises a plurality of symbols and each symbol is to be transmitted at a different one of a plurality of frequency subcarriers. The plurality of subcarriers is divided into groups and each group of subcarriers is assigned to a corresponding one of a plurality of antennas of the first device. The groups of subcarriers are transmitted from corresponding ones of the plurality of antennas. | 06-17-2010 |
| 20100157861 | BEAMFORMING SPATIAL DE-MULTIPLEXING FOR COLLABORATIVE SPATIALLY MULTIPLEXED WIRELESS COMMUNICATION - Techniques are provided herein to enable collaborative spatial multiplexing in a wireless communication system. At M plurality of antennas of a first wireless communication device, N plurality of spatially multiplexed transmissions are received from corresponding ones of N plurality of second wireless communication devices. The first wireless communication device produces M receive signals from the transmissions received at the M plurality of antennas. The first wireless communication device applies beamforming weight vectors to the M receive signals and in so doing produces N signals or signal streams, where N is less than or equal to M. The first wireless communication device then recovers the modulated data for each of the transmissions from the N signals. | 06-24-2010 |
| 20100189199 | Log-likelihood ratio algorithm for use in reducing co-channel interference in wireless communication systems - In one embodiment, an apparatus includes a receiver configured to receive a transmission from a wireless communication device, the transmission associated with resource units, a detector configured to generate log-likelihood ratio data from the received transmission, and a controller configured to calculate noise and interference for each of the resource units and modify the generated log-likelihood ratio data based on the calculated noise and interference. | 07-29-2010 |
| 20100220810 | Transmitter Characterization for Digital Pre-Distortion Using Offset Preamble Subcarriers - Techniques are provided to pre-distort a signal that is transmitted by a transmitter of a wireless communication device, e.g., a device configured for wireless radio frequency communication. The transmitter of the device inherently introduces distortion to the baseband signal to be transmitted. In at least one frame of a baseband signal to be transmitted, at least one subcarrier in a preamble of the frame is shifted in frequency such that the at least one subcarrier is offset from a normal subcarrier frequency position. The at least one frame of the baseband signal is supplied to the transmitter that is configured to produce a transmit signal for transmission. The transmit signal at an output of the transmitter is sampled or detected and inter-modulation distortion in the transmit signal is determined at one or more frequencies as a result of shifting of the frequency of the at least one subcarrier in the preamble of the at least one frame. The baseband signal is pre-distorted based on the inter-modulation distortion prior to coupling to the transmitter for transmission. | 09-02-2010 |
| 20100238797 | Adaptive Subchannel Disabling in Beamformed Wireless Communication Systems - Techniques are provided herein to adaptively and independently disable use of subchannels in transmission sent from a first wireless communication device to a second wireless communication device. The first wireless communication device receives transmission sent to it by the second wireless communication device. The transmissions occupy some or all of a plurality of subchannels within a frequency band that are available for use in the transmission. The transmissions received at the first wireless communication device are evaluated in each subchannel for an over-the-air wireless link between the first wireless communication device and the second wireless communication device. Based on the evaluation, zero or more of the plurality of subchannels are independently disabled in transmissions that are sent by the first wireless communication device to the second wireless communication device. | 09-23-2010 |
| 20100246720 | Channel Variation Detection of Wireless Channel for Adaptive Transmission Schemes - Techniques are provided to determine channel variation of a wireless channel between a first wireless communication device and a second wireless communication device. The first wireless communication device receives a wireless transmission sent by the second wireless communication device. Received data is recovered from the wireless transmission received at the first wireless communication device. The received data is processed with each of multiple channel variation compensations to produce corresponding processed received data subjected to respective ones of the multiple channel variation compensations. For symbols in the received data and in each of the processed received data, distances are computed to their closest symbols in a symbol constellation set used by the second wireless communication device in the wireless transmission. A corresponding distance metric is computed from the distances for symbols in the received data and from the distances for symbols in each of the processed received data. Thus, there is distance metric for the received data, and a distance metric for each of the processed received data. Channel variation of a wireless channel between the first wireless communication device and the second wireless communication device is estimated based on the distance metrics. | 09-30-2010 |
| 20100279616 | Self-Optimizing Wireless Network Base Station - A wireless base station apparatus is provided that is configured to automatically optimize the radiation pattern it uses when installed for operation in a wireless network in order to serve wireless client devices within a coverage area. The wireless base station is configured to determine its geographical location and to evaluate its geographical location based on stored geographical map data that indicates the physical geographical environment surrounding its geographical location. Based on the physical geographical environment surrounding the geographical location, the base station determines a radiation pattern best suited to serve wireless client devices within a coverage area. | 11-04-2010 |
| 20100321237 | Beamforming Techniques to Improve Ranging Signal Detection - Techniques are provided herein to detect ranging codes in energy received at a plurality of antennas of a wireless communication device. Energy is received at a plurality of antennas of a first wireless communication device and received signals are generated from the received energy. The received energy comprises a ranging transmission from one or more second wireless communication devices, wherein each ranging transmission comprises a ranging code selected from a set of possible ranging codes. A ranging code specific receive beamforming weight vector is generated for a ranging code in the set of possible ranging codes from the received signals. The ranging code specific receive beamforming weight vector is applied to corresponding ranging code specific signals derived from the received signals to produce ranging code specific beamformed signals. The ranging code specific beamformed signals are correlated to produce correlation results. A determination is made as to whether the ranging code is present in the received energy based on the correlation results. | 12-23-2010 |
| 20110012787 | Combined Beamforming and Nulling to Combat Co-Channel Interference - Techniques are provided to improve receive beamforming at a wireless communication device that receives energy in a frequency band at M plurality of antennas, where the received energy includes desired signals and interference signals. The wireless communication device has no knowledge of the spatial signatures of the desired signals and interference signals. A weighted sum signal vector is computed from the received signals and a covariance matrix is computed from the receive signals. Eigenvalue decomposition of the covariance matrix is computed to obtain M eigenvalues of corresponding M eigenvectors of the covariance matrix. A correlation rate is computed between the M eigenvectors and the weighted sum signal vector. A combined receive beamforming and nulling weight vector is computed from the M eigenvectors and the weighted sum signal vector and based further on the correlation rate. The combined receive beamforming and nulling weight vector is applied to the received signals so as to receive beamform the desired signals and null out the interference signals. | 01-20-2011 |
| 20110013708 | Signal Sequence Detection Techniques for OFDM/OFDMA Systems - Energy in a frequency band is received at a wireless communication device and data is generated representing samples of a received time domain waveform from the received energy. Data for groups of samples of the received time domain waveform is processed to transform the data for the received time domain waveform to produce data for an intermediate domain signal that is in neither the time domain nor the frequency domain. The data representing the intermediate domain signal is analyzed to determine whether a sequence having a predetermined pattern from a set of possible sequences is present in the received energy, and ultimately to determine a sequence of the predetermined pattern whose presence is detected in the received energy. | 01-20-2011 |
| 20110013711 | Beamforming Weight Estimation Using Wideband Multipath Direction of Arrival Analysis - Techniques are provided for computing downlink beamforming weights based on the received data at a base station from a mobile station in a MIMO communication system. An uplink transmission is received at a plurality of antennas at a first communication device from a second communication device, where the uplink transmission comprises a plurality of uplink subbands. The uplink spatial signature is estimated for each of the plurality of uplink subbands. The uplink spatial signature is decomposed into a plurality of direction of arrival (DOA) components for each uplink subband using a transform. Data representing multiple propagation paths between the first communication device and the second communication device is computed for each DOA component. A plurality of direction of departure (DOD) components for each of a plurality of downlink subbands is computed based on the data representing the multiple propagation paths. A downlink spatial signature for each downlink subband from the plurality of DOD components is computed using an inverse of the transform. Downlink beamforming weights are computed for each of the plurality of downlink subbands based on the downlink spatial signature, where the downlink beamforming weights are for use by the first communication device when beamforming a downlink transmission via the plurality of antennas of the first communication device to the second communication device. | 01-20-2011 |
| 20110045787 | Calibration-Less Transmit Beamforming - A calibration-less transmit beamforming apparatus and method are provided. In a wireless communication device that comprises a plurality of antennas, a gain block is provided in the front-end module associated with each antenna and the same gain block is used during transmit and receive operations. As a result, the transmit phase offset and receive phase offset for each antenna are made to be equal, thereby achieving conditions for transmit beamforming without the need for complex antenna calibration algorithms and hardware. | 02-24-2011 |
| 20110045792 | Beamforming Weight Generation Using Adaptive Trigonometric Waveform Interpolation Techniques - Techniques are provided herein to generate beamforming weight vectors for transmissions to be made from a first wireless communication device, e.g., a base station, to a second wireless communication device, e.g., a client device. The first device has a plurality of antennas and receives uplink transmissions from the second device, each uplink transmission comprising a group of frequency subcarriers. The first device computes channel information from the received uplink transmission and computes one or more trigonometric waveforms determined to approximate the channel information. One or more downlink beamforming weight vectors are computed at any given frequency subcarrier (thus in any frequency subband) by interpolation using the one or more trigonometric waveforms. | 02-24-2011 |
| 20110090974 | Scheduling Collaborative Uplink Transmissions in OFDMA Systems Using Multipath Direction of Arrival Analysis - Techniques are provided for receiving uplink transmissions at a plurality of antennas at a base station from a plurality of client stations. Uplink spatial transmissions are analyzed to produce a plurality of direction of arrival (DOA) components associated with the plurality of client stations. The DOA components associated with the plurality of client stations are compared and two or more client stations are selected to participate in an uplink collaborative spatial multiplexing transmission session based on dissimilarities of their DOA components. | 04-21-2011 |
| 20110105172 | Adaptive Power Balancing and Phase Adjustment for MIMO-Beamformed Communication Systems - Techniques are provided for improving performance of a multiple-input multiple-output (MIMO) wireless communication system. At a first wireless communication device (e.g., a base station) having a plurality of antennas, uplink transmissions are received from a second wireless communication device (e.g., a client device). The base station determines a measure of multipath conditions between it and the second wireless communication device based on the received uplink transmissions. The base station applies downlink beamforming weight vectors together with power balance and phase adjustment factors depending on the measure of multipath conditions to transmit multiple downlink data streams across the plurality of antennas simultaneously to the second wireless communication device. | 05-05-2011 |
| 20110124290 | MIMO Mode Switch Management for Beamformed MIMO Systems - Techniques are provided herein for improving multiple-input multiple-output (MIMO) wireless communications, and in particular to dynamically determining when to switch MIMO transmission modes on a communication link between two devices that are capable of supporting multiple MIMO transmission modes. A base station receives from a client device one or more signals containing information representing a first signal-to-noise ratio (SNR) measurement and a second SNR measurement made by the client device. The first SNR measurement is associated with a first MIMO transmission mode and the second SNR measurement is associated with a second MIMO transmission mode. The base station computes a MIMO channel quality indicator from the first SNR measurement and the second SNR measurement, and evaluates the MIMO channel quality indicator to determine whether to switch MIMO transmission modes for transmissions to the client device. | 05-26-2011 |
