Abstract: A wireless communication receiver obtains improved performance under certain fast fading conditions by basing one or more received signal processing operations on pre-despreading chip sample correlations rather than on post-despreading noise correlations, but preserves soft scaling information by determining one or more scaling factors that relate the chip sample correlations to the noise correlations. By way of non-limiting examples, a Generalized RAKE receiver circuit may base combining weight generation on chip sample correlations rather than on post-despreading pilot symbol noise correlations, but scale the combining weights as a function of the one or more scaling factors, or, equivalently, scale the combined values generated from the combining weights. Similar scaling may be performed with respect to chip equalization filter combining weights in a chip equalization receiver circuit.

Abstract: Method, communication system, receiver, baseband processor and computer program for recovering data from a received OFDM-signal containing recurrent redundant information where part of the recurrent redundant information is used to maximize the SINR (Signal to Interference plus Noise Ratio) of the received OFDM-signal.

Abstract: A receiver based on a RAKE receiver architecture includes a logic circuit configured to assign one or more RAKE fingers to a finger placement grid that is independent from a searcher delay grid used by the receiver's searcher in generating multipath delay profiles for received signals. The logic circuit may use the multipath delay profile to “tune” the finger placement grid relative to the searcher delay grid but the delay resolution of the finger placement grid is independent of the searcher delay grid. This independence permits, for example, setting the finger placement grid to a delay resolution based on a Nyquist criterion independently from the delay resolution used by the searcher. The receiver may use two or more finger placement grids, may operate in a mixed mode where fingers are assigned on- and off-grid, and may operate selectively in grid or non-grid modes.

Abstract: A device that estimates information from a signal includes a receiver for receiving an input signal and electronic processing circuitry. The electronic processing circuitry generates a matrix associated with the input signal and determines an approximation of an inverse of the matrix based on the adjoint of the matrix and a scaling factor associated with the determinant of the matrix. This approximation avoids possible mathematical difficulties that may be encountered in certain situations when a typical matrix inversion is calculated. The approximated inverse matrix is applied to the input signal to transform the input signal into an output signal. Information associated with the input signal is then determined based on the output signal.

Abstract: In one of its aspects, the technology concerns a method of processing a signal which includes physical data channels which have been channelized using spreading codes. The method comprises (1) despreading unoccupied spreading codes (e.g., codes which are essentially unobscured by traffic data) included in the signal to obtain unoccupied code despread values, (2) using the unoccupied code despread values to form an impairment covariance matrix; and (3) using the impairment covariance matrix along with a channel estimate to form a processing parameter. The processing parameter can be one of combining sets and a signal quality estimate. In another of its aspects, the technology concerns a coherent, linear equalizer apparatus configured to process a signal which includes physical data channels which have been channelized using spreading codes.

Abstract: The present application describes a new path search and verification method and apparatus for identifying and selecting one or more delays for a receiver. A front-end receiver receives a signal having one or more signal images, where each signal image has a corresponding signal delay. A tree generator builds a hierarchical delay tree from a plurality of delay nodes, each corresponding to one of the signal delays. A tree searcher searches through the delay tree to identify one or more surviving delay nodes, where each surviving delay node corresponds to a candidate delay for the receiver. The receiver may also include a state machine comprising a plurality of ordered states for providing candidate delays for the receiver. The state machine stores the candidate delays and shifts the candidate delays between states within the state machine based on the latest results from the tree searcher.

Abstract: 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.

Abstract: Detecting a symbol of interest comprises despreading a received signal to obtain despread values corresponding to the symbol of interest and to one or more interfering symbols, combining the despread values to generate combined values for the symbol of interest and the interfering symbols, computing spreading waveform correlations between the spreading waveform for the symbol of interest and the spreading waveforms for the interfering symbols, computing interference rejection terms representing the interference present in the combined value for the symbol of interest attributable to the interfering symbols based on the spreading waveform correlations, and generating an estimate of the symbol of interest by combining the combined values with the interference rejection terms. The interference rejection terms are computed by scaling the spreading waveform correlations by corresponding signal powers and compensating the estimates for noise.

Abstract: A method and apparatus for reducing the complexity of waveform correlation computations used by a multicode receiver is described herein. One exemplary multicode receiver includes a despreading unit, channel estimator, and waveform correlation calculator. The despreading unit despreads a received multicode signal to generate despread symbols. The channel estimator estimates channel coefficients associated with the despread symbols. The waveform correlation calculator determines waveform correlations between the transmitted symbols in successive processing windows that span two or more symbol periods and that overlap in time. To reduce the computational complexity associated with computing waveform correlations, the calculator may reuse channel coefficients and/or net channel correlations for multiple symbol periods and/or processing windows.

Abstract: A symbol detector converts initial symbol estimates of received symbols to soft estimates for decoding. The symbol detector computes spreading waveform correlations between a spreading waveform for a symbol of interest and spreading waveforms for one or more interfering symbols. Interference rejection terms are computed by scaling the spreading waveform correlations by corresponding signal powers and compensating for noise. A soft scaling factor for the symbol of interest is computed from the interference rejection terms. The soft scaling factors are then applied to the initial symbol estimates to generate the soft estimates.

Abstract: A spread spectrum signal is processed by correlating the spread spectrum signal with a spreading sequence at a first plurality of correlation times to produce a first plurality of time-offset correlations. The first plurality of time-offset correlations is processed to produce a first symbol representation for a symbol. A first quality is determined for the first symbol representation. Responsive to the determined first quality, it is determined whether to further process the first symbol representation or to process a second symbol representation for the symbol generated from the spread spectrum signal. The first quality may be determined, for example, by decoding the first symbol representations to generate a decoding metric or error check indicator, such as a CRC result. The symbol representations may be generated and/or evaluated for quality in a serial fashion or a parallel fashion.

Abstract: Method and apparatuses taught herein enable link adaptation feedback to be determined in advance for future transmit intervals, based on one or more data sending units sending indications of future transmit resource allocations, and receiving corresponding link adaptation feedback from data receiving units. Knowledge of the future transmit resource allocations enable individual data sending units to predict interference conditions for the future transmit interval, and thereby compute link adaptation feedback that takes advantage of low-interference conditions. Individual data sending units receive link adaptation feedback for the future transmit interval from the data receiving units they are supporting, and make corresponding link adaptations for the future transmit interval.

Abstract: A RAKE receiver circuit generates combining weights based on channel estimates and combining statistics that comprise channel coefficient statistics, noise statistics, and channel estimation error statistics. Together, these statistics incorporate the relationships in noise and channel estimation across two or more RAKE fingers, and thus improve combining weight generation. Exemplary determination of statistics comprises channel coefficient cross-correlations, noise cross-correlations, and channel estimation error cross-correlations. Determination of the statistics can be varied based on, for example, the assumption of default or nominal signal models.

Abstract: A method and apparatus in a radio receiver for canceling interference from a high power, high data rate signal received in a combined signal that includes a contribution from the high power signal and a contribution from a lower power signal. It is first determined whether the high power signal was correctly received. A CRC checksum may be used to determine whether the high power signal was received with a good reliability. Thereafter, the contribution of the high power signal is removed from the received signal only if the high power signal was correctly received. The contribution of the high power signal may be removed by hard-subtracting the contribution of the high power signal from the received signal if all of the bits of the checksum are correct, and soft-subtracting the contribution of the high power signal from the received signal if most, but not all, of the bits in the checksum are correct.

Abstract: Signal processing delays are selected from a candidate set in a wireless receiver based on both present and past channel behavior. According to one embodiment, a subset of signal processing delays are selected for received signal processing by accumulating a history of periodic delay selection computations for a candidate set of signal processing delays during a time interval. The delay selection calculations are based on cross-correlations between different ones of the signal processing delays. At the end of the time interval, a subset of the signal processing delays are selected from the candidate set of delays for received signal processing based on the history of delay selection computations.

Abstract: Processing in a baseband processor is improved by estimating channelization code powers when processing received signals and reducing at least one of interference and noise power from the code power estimates. According to one embodiment of a wireless communication device such as a mobile phone or Local Area Network (LAN) adapter, the device comprises circuitry configured to receive a composite signal having contributions from a signal of interest and one or more interfering signals and a baseband processor. The baseband processor is configured to estimate channelization code powers for a channelization code associated with the signal of interest and one or more channelization codes associated with the one or more interfering signals. The baseband processor is also configured to reduce at least one of interference and noise power from the channelization code power estimates.

Abstract: Channel response and impairment correlation estimates are iteratively determined. According to one embodiment of performing channel estimation for use in received signal processing, a channel response estimate is calculated based on an initial impairment correlations estimate and a measured channel response derived from a received signal. A revised impairment correlations estimate is calculated using a parametric approach based on the channel response estimate and the channel response estimate is recalculated based on the revised impairment correlations estimate. According to one embodiment of a wireless communication device, the device comprises a parameter estimation unit configured to iteratively calculate a medium channel response estimate based on a parametric impairment correlations estimate and a measured net channel response derived from a received signal.

Abstract: According to one embodiment taught herein, a method of determining impairment correlations between a plurality of delays of interest for a received CDMA signal comprises generating kernel functions as samples of a net channel response of the received CDMA signal taken at defined chip sampling phases for delay differences between the plurality of delays of interest. In a parametric Generalized Rake (G-Rake) receiver embodiment, the delays of interest represent the delay positions of the fingers being used to characterized received signal. In a chip equalizer receiver embodiment, the delays of interest represent the delay positions of the equalizer taps. The method continues with determining impairment correlations based on convolving the kernel functions.

Abstract: In a mobile communication system with a shared downlink traffic channel, the mobile terminals in contention for the downlink traffic channel report channel conditions to the base stations. The base station schedules the mobile terminals based on channel quality estimates from the mobile terminals and selects a transmitter configuration. The transmitter configuration may comprise, for example, the antenna configuration, and/or power and code allocations used by the base station. The base station broadcasts the transmitter configuration to all active and inactive mobile terminals. Knowledge of the transmitter configuration by the inactive mobile terminals improves the accuracy and reliability of the channel quality estimates.

Abstract: A flexible Fast Walsh Transform circuit provides configurable FWT sizes, and is suitable for use in radio receivers where the received signal may be generated using varying spreading codes and/or varying numbers of multi-codes. Such signal types are commonly encountered in wireless communication systems like those based on the Wideband CDMA (W-CDMA) or IS-2000 (cdma2000) standards, and particularly with the higher data rate provisions of those standards. In one application, a RAKE receiver includes RAKE fingers that each include one of the flexible FWT circuits, such that each finger despreads the received signal using variably sized FWTs in accordance with the characteristics of the received signal. The flexibility in FWT sizing may derive from, for example, the inclusion of separately selectable but differently sized FWT circuits, or from the inclusion of a configurable FWT circuit capable of generating different sizes of FWTs.