| Patent application number | Description | Published |
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| 20080205562 | Method and Apparatus for Impairment Correlation Estimation in MIMO Systems - The teachings herein disclose methods and apparatus that simplify impairment correlation estimation for received signal processing, based on determining, for any given processing interval, which impairment contributors should be considered in the estimation of overall received signal impairment correlations. These simplifications reduce computational processing requirements, allowing reduced circuit complexity and/or reduced operating power, and improve receiver performance. A corresponding transmitter and transmission method include transmitting multiple information streams to targeted receivers according to ongoing scheduling, and controlling the ongoing scheduling to reduce the number of impairment contributors considered in impairment correlation estimation at the targeted receivers. In one embodiment, a receiver identifies which impairment contributors to consider based on receiving control information. In another embodiment, the receiver identifies the impairment contributors to consider based on background processing, e.g., background determination of parametric model fitting parameters for a plurality of impairment contributors, and observing those model fitting parameters over time. | 08-28-2008 |
| 20080273608 | Method and Apparatus for Correcting IQ Imbalance in an OFDM Receiver - Methods and apparatus for processing received OFDM signals to compensate for distortions caused by IQ imbalances are disclosed. Receiver circuits may be configured to demodulate symbols from a first logical channel, using an uncompensated received OFDM signal that includes the effects of those distortions. Receiver circuits may be further configured to calculate an IQ imbalance parameter, using the demodulated symbols, for use in compensating the received OFDM signal to reduce the effects of the IQ imbalances. The compensated signal produced thereby may be used for demodulating symbols from a second logical channel, perhaps corresponding to a user data channel. | 11-06-2008 |
| 20080291978 | Receiver Parametric Covariance Estimation for Transmit Diversity - A parametric form of G-Rake and chip equalization for closed-loop transmit diversity is provided, that accounts for impairment correlation between transmit antennas. In a closed-loop transmit diversity system, the base station transmits a signal from two or more antennas, using one of a predetermined set of relative phase offsets at one of the antennas. The parametric estimation of the impairment or data covariance is performed by summing terms, including a term for each possible phase offset. The terms are weighted by fitting parameters. The fitting parameters are jointly solved by fitting the impairment or data covariance estimate to a measured impairment or data covariance. In another aspect, a measured impairment covariance is formed by exploiting a special relationship between the pilot channels of the different transmit antennas. | 11-27-2008 |
| 20080291981 | Method and Apparatus for Removing Pilot Channel Amplitude Dependencies from RAKE Receiver Output - A receiver utilizes pilot channel propagation channel estimates and a signal-to-interference metric derived from the pilot channel to form combining weights for use in obtaining soft symbols from a desired channel for subsequent decoding. The soft symbols thus obtained are substantially independent of the pilot channel amplitude. | 11-27-2008 |
| 20080298227 | Method for Interference Estimation for Orthogonal Pilot Patterns - In an OFDM communications system receiver, channel estimates are processed to remove or reduce noise, exploiting the orthogonality of pilot patterns. The de-noised channel estimates are then used to compute inter-cell interference. The noise effects of orthogonal pilot patterns are selectively removed from channel samples in estimating inter-cell interference, depending on whether data subcarriers are subject to the same interference as pilot subcarriers, and whether data subcarriers are subject to interference from sectors with pilot patterns orthogonal to those in the transmitting sector. A further calculation removes noise from cells not identified by an orthogonal pilot sequence, which may be particularly applicable when large variations exist in the frequency domain of the propagation channel across a pilot pattern. | 12-04-2008 |
| 20080298510 | Memory-Saving Method for Generating Soft Bit Values from an OFDM Signal - Methods and receiver circuits for determining and employing decision boundary estimates for use in de-mapping QAM symbols in an OFDM receiver are disclosed. The disclosed methods efficiently use memory resources, while taking account of the frequency-selective and time-varying nature of the signal propagation. An OFDM receiver calculates a decision boundary estimate using QAM-modulated symbols selected from a group of OFDM tones and determines soft bit values for symbols selected from an adjacent tone using the decision boundary estimate. The receiver updates the decision boundary estimate using the symbols from the adjacent tone and determines soft bit values for symbols selected from a next-adjacent tone using the updated decision boundary estimate. Once the decision boundary estimate has been updated and the soft bit values have been determined for each tone, the symbol data for that tone may be discarded. | 12-04-2008 |
| 20080310562 | Efficient Covariance Computation by Table Lookup - The impairment processor described herein uses a look-up table operation to reduce the computational complexity associated with determining an impairment correlation between first and second sample streams for an interference rejection receiver. One exemplary impairment processor iteratively computes multiple partial impairment correlations based on values selected from look-up table(s), and combines the partial impairment correlations to obtain a final impairment correlation between the first and second sample streams. During each iteration, the impairment processor computes a pair of delay offsets corresponding to the respective processing and path delays of the first and second sample streams, computes an index value as a function of a difference between the pair of delay offsets, selects a pre-computed value from the look-up table based on the index value, determines a pulse correlation estimate based on the selected pre-computed value, and determines the partial impairment correlation for that iteration based on the pulse correlation estimate. | 12-18-2008 |
| 20090041163 | Selecting Delay Values for a RAKE Receiver - Multipath components of transmitted data symbols are received with individual delays and processed by a RAKE having a number of fingers. A delay profile indicating magnitudes for a first number of delay values is provided. Estimated magnitudes for a second number of delay values located between the first number of delay values are calculated by interpolation, and a combined delay profile is provided by combining the magnitudes for the first and second number of delay values. Delay values for peaks in the combined delay profile are determined, and a number of peak delay values (P | 02-12-2009 |
| 20090075647 | UE Measurement Scheduling Based on Measurement Bandwidth - The method and apparatus described herein uses variable length snapshot periods to determine signal strength measurements. A mobile station determines the measurement bandwidth associated with a base station, and sets the snapshot period based on the measurement bandwidth. The mobile station determines the signal strength of serving and neighboring cells during snapshot periods. Such signal strength measurements may be used to assist and/or direct handover operations. | 03-19-2009 |
| 20090149147 | Speed-Based, Hybrid Parametric/Non-parametric Equalization - A mobile receiver having a multi-mode interference suppression function and a way to estimate its speed utilizes a parametric approach to interference suppression at high speeds, and a nonparametric approach at low speeds. In particular, if the mobile receiver is currently operating in a nonparametric mode and its speed exceeds a first predetermined threshold, the mobile receiver switches to a parametric mode. Conversely, if the mobile receiver is currently in parametric mode and its speed is less than a second predetermined threshold, the mobile receiver switches to nonparametric mode. In one embodiment, the speed may be estimated by a Doppler frequency in the received signal, and the thresholds are Doppler frequencies. In one embodiment, the first and second thresholds are different, creating a hysteresis in the mode switching. | 06-11-2009 |
| 20090245338 | METHOD AND DEVICE FOR CHANNEL RESPONSE DETERMINATION - A method and a device for channel response determination for a wireless communication system. The method comprises generating a first vector of channel responses from channel estimations obtained by using a training signal. A second vector of regularized channel responses is generated by applying to the first vector a regularization algorithm. The algorithm is operative such that a second difference between consecutive regularized channel responses of the second vector is less than a first difference between consecutive channel responses of the first vector. | 10-01-2009 |
| 20090304132 | Method and Apparatus for Efficient Estimation of Interference in a Wireless Receiver - Methods and apparatus for determining an impairment covariance matrix for use in an interference-suppressing CDMA receiver are disclosed. In several of the disclosed embodiments, precise information regarding signal propagation delays is not needed. An exemplary method includes the selection of a plurality of processing delays for processing a received CDMA signal. Net channel coefficients for the processing delays are estimated and used to calculate an impairment covariance matrix. The impairment covariance matrix is calculated as a function of the estimated net channel coefficients and the processing delays, without estimating a propagation medium channel response for the received signal. | 12-10-2009 |
| 20090310715 | RECEIVER AND METHOD FOR PROCESSING RADIO SIGNALS USING SOFT PILOT SYMBOLS - A receiver and method for receiving and processing a sequence of transmitted symbols in a digital communication system utilizing soft pilot symbols. A set of soft pilot symbols are transmitted with higher reliability than the remaining symbols in the sequence by modulating the soft pilot symbols with a lower order modulation such as BPSK or QPSK while modulating the remaining symbols with a higher order modulation such as 16QAM or 64QAM. The receiver knows the modulation type and location (time/frequency/code) of the soft pilot symbols, and demodulates them first. The receiver uses the demodulated soft pilot symbols as known symbols to estimate parameters of the received radio signal. Unlike traditional fixed pilots, the soft pilots still carry some data. Additionally, the soft pilots are particularly helpful in establishing the amplitude reference essential in demodulating the higher order modulation symbols. | 12-17-2009 |
| 20100039972 | Controlling a Power Level in a Wireless Communications System with Different Scrambling Codes - A power level of signals transmitted in a wireless communications system under a first or a second scrambling code, is controlled in an inner power control loop, where a quality measure is repetitively estimated and control commands generated from the quality measure and a quality measure reference value, which in an outer power control loop is adjusted in dependence on a performance level calculated for signals received during a time interval. A first value is adjusted in dependence on a performance level for time intervals with all signals transmitted under the first scrambling code and used during such time intervals. A second value is adjusted in dependence on a performance level for time intervals with at least some signals transmitted under the second scrambling code and used during at least a part of such time intervals. | 02-18-2010 |
| 20100054309 | NONPARAMETRIC MIMO G-RAKE RECEIVER - With a nonparametric G-Rake receiver, combining weights may be determined using a nonparametric mechanism in multiple-input, multiple-output (MIMO) scenarios. In an example embodiment, a method for a receiving device having a nonparametric G-Rake receiver entails calculating an impairment covariance matrix and determining combining weights. More specifically, the impairment covariance matrix is calculated based on a pilot channel using a nonparametric mechanism in a MIMO scenario in which a code-reuse interference term exists. The combining weights are determined for the nonparametric G-Rake receiver responsive to the impairment covariance matrix and by accounting for the code-reuse interference term. | 03-04-2010 |
| 20100087219 | Method and Device for Power Control - A method for generating a filtered signal quality value used in a power control system of a wireless communication apparatus. An estimated signal quality value of a received signal is generated. A filtered signal quality value is generated based on the estimated signal quality value. The filtered signal quality value is generated in dependence of at least one of registering a difference between a first and a second reference signal quality value, and a change in transmitted power of said received signal. A power control device comprising a signal quality estimator, a BLER estimator, a regulator, and an inner loop is configured to implement the method. | 04-08-2010 |
| 20100172396 | METHOD AND APPARATUS FOR SETTING RECEIVED SIGNAL PROCESSING DELAYS AS A FUNCTION OF CHANNEL DISPERSIVENESS - A method and apparatus provide for setting processing delay assignments in a CDMA receiver using a flat-channel placement or using a dispersive channel placement, in dependence on characterizing the channel as flat or dispersive. For example, a receiver maintains a logical flag reliably indicating the current channel state as flat or dispersive, and assigns or otherwise sets processing delays—e.g., for received signal demodulation—using a flat-channel placement algorithm or a dispersive-channel placement algorithm. The “flat-channel” placement algorithm generally provides better performance in flat-channel environments, and the “dispersive-channel” placement algorithm generally provides better performance in dispersive channel environments. Such processing may be regarded as “activating” a simplified processing delay placement grid that offers better performance if the channel truly is flat, with the underlying advantage of providing a reliable mechanism for detecting flat channel conditions. | 07-08-2010 |
| 20100215075 | Estimating the Ratio of Traffic Channel Power to Pilot Power in a MIMO Wireless Communication System - Methods and apparatus for processing a received multi-stream (MIMO) signal, and in particular for estimating a per-code traffic-channel-to-pilot power ratio for the MIMO signal are disclosed. An exemplary method includes the calculation of an average symbol amplitude or average symbol power level from a plurality of de-spread traffic channel symbols received in a first transmission slot and the estimation of a corresponding pilot symbol amplitude or pilot symbol power level, based on an estimated propagation channel response and at least one of a plurality of precoding vectors used to generate the MIMO signal. A per-code traffic-channel-to-pilot power ratio for the first transmission slot is computed by dividing the average symbol amplitude or average symbol power level by the corresponding pilot symbol amplitude or pilot symbol power level. | 08-26-2010 |
| 20100215083 | Method for Allocating Rake Fingers in Multi-Carrier Systems - A multi-carrier RAKE receiver is described herein. The multi-carrier RAKE receiver distributes RAKE fingers between a plurality of received carriers based on a comparison between the signal-to-interference ratios (SIRs) determined for each carrier. In one embodiment, the RAKE fingers are distributed evenly between the carriers when a comparison between the largest and smallest SIR is less than or equal to a threshold. In another embodiment, the RAKE fingers are distributed to favor the carrier(s) with the strongest SIR(s) when the comparison between the largest and smallest SIR exceeds the threshold. By distributing the RAKE fingers to favor the carriers with the strongest SIRs, the embodiments of the present invention enable the system designers to limit the total number of available RAKE fingers without sacrificing performance. | 08-26-2010 |
| 20100215132 | Method and Apparatus for Allocating Processing Delays in Multi-Carrier Systems - A multi-carrier linear equalization receiver, e.g., a RAKE receiver or chip equalization receiver, is described herein. The multi-carrier receiver distributes processing delays among a plurality of received carriers based on a comparison between the signal-to-interference ratios (SIRs) determined for each carrier. The receiver initially allocates a minimum number of processing delays to each carrier. In one embodiment, any remaining additional processing delays are distributed evenly between the carriers when a comparison between the largest and smallest SIR is less than or equal to a threshold. In another embodiment, the remaining additional processing delays are distributed to favor the carrier(s) with the strongest SIR(s) when the comparison between the largest and smallest SIR exceeds the threshold. By distributing the additional processing delays to favor the carriers with the strongest SIRs, the embodiments of the present invention enable system designers to limit the total number of available processing delays without sacrificing performance. | 08-26-2010 |
| 20100238980 | Signal Reception with Adjustable Processing Delay Placement - The placement of processing delays may be adjusted to facilitate signal reception. In an example embodiment, a composite signal having multiple signal images corresponding to multiple reception delays is received. A root-mean-square (RMS) delay spread is ascertained for the multiple reception delays that correspond to the multiple signal images of the composite signal. A set of temporal points is produced responsive to the RMS delay spread. Multiple processing delays are placed based on the set of temporal points. In different example implementations, the set of temporal points (e.g., of a grid) may be produced by adjusting a spacing between temporal points, by adjusting a total number of temporal points in the set, or by changing a center location of the set. The spacing and number of points may be adjusted responsive to the RMS delay spread. The center location may be adjusted responsive to at least one calculated delay. | 09-23-2010 |
| 20100248665 | Automatic Gain Control in Multi-Carrier Wireless Systems - Methods and apparatus for providing automatic gain control (AGC) for received multi-carrier signals are disclosed. A receiver circuit comprises a common analog signal path, which includes an analog variable-gain circuit and an analog-to-digital converter, and further comprises first and second carrier-specific, digital variable-gain circuits corresponding to first and second carriers of the received multi-carrier signal, respectively. The receiver circuit further includes a gain control circuit configured to control the analog and digital variable-gain circuits and to allot gain adjustments to the analog variable-gain circuit based on a difference between carrier signal levels for the first and second carriers. In some embodiments, the gain control circuit selectively operates in an all-carrier mode, in which analog gain adjustments are calculated from both of the carrier signal levels, or in an unequal-priority mode, in which analog gain adjustments are calculated from only one of the first and second carrier signal levels. | 09-30-2010 |
| 20100260237 | Method and Appratus for Direct Estimation of Impairment Correlations for Received Signal Processing - According to the teachings disclosed in this document, a receiver estimates impairment correlations for a received signal using received pilot values. This direct estimation of impairment correlations based on direct pilot observations, provides for a rich capture of all impairment sources bearing on the received signal. Advantageously, however, estimation noise is reduced by generating a structured covariance matrix from the measured covariance matrix, and carrying out structured filtering within the structured covariance matrix. Structured filtering involves averaging matrix elements that correspond to the same processing delay difference as used for measured impairment correlation estimation. In one or more embodiments, averaged net channel estimates are used to obtain a rank one matrix, which is used to convert a measured covariance matrix to a structured covariance matrix, for carrying out structured filtering. | 10-14-2010 |
| 20100303132 | Method and Apparatus for Allocating Processing Delays in Multi-Carrier Systems - A multi-carrier linear equalization receiver, e.g., a RAKE receiver or chip equalization receiver, is described herein. The multi-carrier receiver distributes processing delays among a plurality of received carriers based on a dispersion determined for each carrier. The receiver initially allocates a minimum number of processing delays sufficient for light dispersion to each carrier. For the dispersive carriers, the receiver allocates one or more additional processing delays. In one embodiment, the additional processing delays are allocated to the dispersive carriers based on SIR. | 12-02-2010 |
| 20100315963 | Measurement of Cell-Specific Reference Symbols in the Presence of MBMS Single Frequency Network Transmissions - A network unit of an own cell is operated in a radio communication system utilizing a radio interface that includes a radio frame made up of a number of sub-frames. The own cell serves one or more user equipments. Operation includes obtaining information about a scheduling of MBSFN data transmissions in one or more neighboring cells. The information thereby obtained is used to generate an information signal that, for a given sub-frame, enables the one or more user equipments to determine whether neighboring cell measurements can be performed using a unicast group of Orthogonal Frequency Division Multiple access (OFDM) symbols. The information signal is transmitted to the one or more user equipments, which can then use the information to determine how to locate cell-specific reference symbols when doing measurements of neighboring cells. | 12-16-2010 |
| 20110075706 | CHANNEL GEOMETRY DETECTOR - Adaptive reconfiguration of a wireless receiver is enabled based on channel geometry. According to an embodiment, the wireless receiver includes a geometry factor processing module and signal processing modules, e.g. such as but not limited to an SIR estimation module, a power estimation module, a despreading module, a low-pass filter, a combing weight generation module, a coefficient estimation module, a synchronization control channel interference canceller module, etc. The geometry factor processing module determines a geometry factor for the channel over which signals are transmitted to the wireless receiver, the geometry factor being a measure of the ratio of total transmitted power received by the wireless receiver to total interference plus noise power at the wireless receiver. One or more of the receiver signal processing modules are reconfigurable based on the geometry factor. | 03-31-2011 |
| 20110129000 | METHOD AND APPARATUS FOR EFFICIENT AMLD MATRIX COMPUTATIONS - The computation of code-specific channel matrices for an Assisted Maximum Likelihood Detection (AMLD) receiver comprises separately computing high rate matrices that change each symbol period, and a low rate matrix that is substantially constant over a plurality of symbol periods. The high and low rate matrices are combined to generate a code-specific channel matrix for each receiver stage. The high rate matrices include scrambling and spreading code information, and the low rate matrices include information on the net channel response and combining weights. The low rate matrices are efficiently computed by a linear convolution in the frequency domain of the net channel response and combining weights (with zero padding to avoid circular convolution), then transforming the convolution to the time domain and extracting matrix elements. Where the combining weights are constant across stages, a common code-specific channel matrix may be computed and used in multiple AMLD receiver stages. | 06-02-2011 |
