Abstract: Soft bit values are generated for received symbols transmitted based on a modulation constellation by demodulating the received symbols via a sequence of demodulation stages, each demodulation stage producing a symbol decision based on an effective constellation. Each effective constellation used by a non-final one of the demodulation stages includes subsets of centroids approximating a region of the modulation constellation. Adjacent ones of the subsets have one or more common points so that at least two adjacent subsets overlap. The soft bit values for the symbol decisions are determined based on detection metrics computed during demodulation for the points included in the effective constellation constructed incrementally over the sequence of demodulation stages, the effective constellation produced by the final demodulation stage being devoid of one or more points included in the modulation constellation.

Abstract: A receiver includes a constellation processing module and a plurality of equalization stages. The constellation processing module groups points of a constellation associated with a transmitted signal into a plurality of subsets. At least two adjacent ones of the subsets have one or more common constellation points so that the at least two adjacent subsets overlap. The constellation processing module also determines a centroid-based value for each of the subsets of constellation points and groups the centroid-based values into one or more sets. Each of the equalization stages except for a the last equalization stage localizes a search for a final symbol decision using the set of centroid-based values input to or selected by the equalization stage as constellation points. The last equalization stage determines the final symbol decision using the subset of constellation points input to or selected by the last equalization stage.

Abstract: A receiver includes a constellation processing module and a multi-stage demodulator having a plurality of non-final demodulation stages and a final demodulation stage. The constellation processing module derives a set of centroid-based values from subsets of constellation points associated with a plurality of transmitted signals for input to each of the non-final demodulation stages. Each of the non-final demodulation stages demodulates a group of signals input to the non-final demodulation stage using the set of centroid-based values as constellation points and suppresses residual interference associated with using the set of centroid-based values as constellation points for signal demodulation. The final demodulation stage demodulates a group of modified signals input to the final demodulation stage using the subset of constellation points input to the final demodulation stage to determine a final symbol decision for the plurality of transmitted signals.

Abstract: A receiver includes a constellation processing module and a plurality of demodulation stages. The constellation processing module groups points of a constellation associated with a transmitted signal into a plurality of subsets, were at least two adjacent ones of the subsets have one or more common constellation points so that the at least two adjacent subsets overlap. The constellation processing module also determines a centroid-based value for each of the subsets of constellation points and groups the centroid-based values into one or more sets. Each of the demodulation stages except for the last demodulation stage localizes a search for a final symbol decision using the set of centroid-based values input to or selected by the demodulation stage as constellation points. The last demodulation stage determines the final symbol decision using the subset of constellation points input to or selected by the last demodulation stage.

Abstract: As disclosed herein, a “super receiver” structure enriches the information provided for decoding modem bits included in a received sequence of symbols. In particular, an equalizer circuit provides joint metrics to a decoder circuit, where the joint metrics advantageously reflect joint bit probabilities. However, the metrics are computed without need for complex joint probability calculations. The decoder circuit “fuses” the joint metrics with corresponding side information, which indicates the likelihood that one or more bits represented by the joint metric take on a particular value. Such fusing biases the soft value estimation for the other bits represented by the joint metric, thus enabling the decoder to operate on refined soft values in its bit decoding operations.

Abstract: The delay associated with performing interference cancellation in a multi-user receiver is reduced by enabling partial decoding. According to an embodiment, interference is canceled from a received signal having signal contributions from multiple users by partially decoding a first codeword obtained from the received signal and transmitted by a first user via a first signal. The first signal is reconstructed based on the partial decoding of the first codeword and canceled from the received signal to yield a reduced-interference signal. A second codeword obtained from the reduced-interference signal and transmitted by the first user or a second user via a second signal is at least partially decoded. In one embodiment, the first codeword is partially decoded by puncturing one or more coded bits of the first codeword and decoding the first codeword based on the one or more punctured coded bits and estimates of the remaining coded bits.

Abstract: Techniques for spherical decision-feedback sequence estimation are disclosed. A received signal is equalized by forming a trellis comprising a plurality of stages, each stage corresponding to a symbol time and comprising a plurality of nodes, each having a node state. A most likely received symbol sequence is identified by evaluating cumulative state metrics for the nodes according to MLSE or DFSE criteria. The trellis is formed by selecting a set of fan-out branches for each node by identifying, of all possible state transition branches from the node to successor nodes in the succeeding stage, those state transition branches that have a spherical branch metric less than a pre-determined metric limit, and determining the cumulative state metric for each node as a function of the cumulative state metrics for predecessor nodes in the preceding stage and the spherical branch metrics for fan-out branches connecting the predecessor nodes to the node.

Abstract: A wireless communication receiver, such as the receiver included in a wireless communication transceiver implemented in a base station or in a mobile station of a wireless communication network, includes a parametric G-RAKE receiver circuit and a method that compute parametric scaling parameters on a per transmission interval basis. In one embodiment, measured impairment correlations are obtained for an individual transmission slot and used to estimate instantaneous values of the scaling parameters. One or both of those instantaneous values are then constrained according to one or more defined limits. In other embodiments, multiple transmission slots are used to increase the number of measurements available to estimate the scaling parameters, with parameter constraining optionally applied. Further embodiments use iterative methods and/or solve for one parameter, and use the results to obtain the other parameter(s).

Abstract: The computational complexity required for interference suppression in the reception of wireless communications from multiple users is reduced by sharing information among the users. In some situations, information indicative of a statistical characteristic of the interference is shared among the users. Delays used to produce the interference statistic information are determined based on rake finger delays employed by the users. In some situations, a parameter estimate that is used to calculate combining weights for the users is shared among the users.

Abstract: A front-end architecture and processing method for a receiver in a multi-antenna, multi-band radio. Band-dependent components for multiple frequency bands are not duplicated in each receive chain. In one embodiment, a first receive chain includes band-dependent components for the first frequency band only. A second receive chain includes band-dependent components for the second frequency band only. The receive chains may be dedicated to particular antennas, or a switch may be utilized to route signals from different antennas to the different band-dependent components. Each receive chain may include band-independent components, or a single set of band-independent components may be utilized for the different receive chains by multiplexing the output of the band-dependent component sections.

Abstract: A method and apparatus for configuring a variable filter in an OFDM transmitter based on the number of subcarrier frequencies selected for the input data block is described herein. An exemplary OFDM transmitter comprises a control unit, OFDM modulator, and variable filter. The control unit selects the number of subcarriers for the input data block, and configures one or more filter properties for the variable filter based on the selected number of subcarriers. The modulator, which has a size greater than the selected number of subcarriers, pads an input data block generated for the selected number of subcarriers to generate an expanded data block having a size equal to the size of the modulator, and modulates the expanded data block to generate an OFDM signal. The filter, as configured by the control unit, filters the OFDM signal.

Abstract: A method and apparatus for reducing group delay and/or amplitude errors applied to a transmission signal by one or more transmission filters is described herein. The present invention characterizes the errors introduced by one or more transmission filters relative to a desired frequency response, e.g., the group delay and/or amplitude errors relative to a flat group delay and flat amplitude, respectively. Based on the errors, the present invention pre-compensates the digital frequency domain samples used to generate the transmission signal. In so doing, the present invention reduces the errors in the filtered transmission signal without placing limits on the design of the transmission filters.

Abstract: The present invention pertains to a transmitter that can exploit feedback to help it organize information which is subsequently sent to a receiver. More specifically, the transmitter receives a feedback signal from the receiver and then uses data about a channel in the feedback signal to adapt at least one of a coding, interleaving and modulating scheme to organize information which is subsequently transmitted to the receiver. In this way, the transmitter can obtain the best match of a channel and a given information payload.

Abstract: A method and apparatus for updating a square root matrix of a covariance matrix when sample sets are added to or removed from a received signal. When a sample set is added to the received signal, a processor augments the square root matrix to generate an updated square root matrix for future processing. When a sample set is no longer present in the received signal, the processor reduces the square root matrix to generate the updated square root matrix.

Abstract: Channel and correlation characteristics are determined for a composite signal. Respective combining weights for information from the composite signal are determined for respective ones of a plurality of candidate delays based on the determined channel and correlation characteristics. A group of delays, e.g., RAKE correlator delays or chip equalizer filter taps, is selected from the plurality of candidate delays based on the determined weights. Information from the composite signal for the selected delays is processed according to a spreading code to generate a symbol estimate. The invention may be embodied as methods, apparatus and computer program products.

Abstract: A feedforward receiver and method are described herein that address inter-symbol interference in received symbols by using an enhanced equalizer to generate joint soft values (joint information of a previous modem bit x? and a modem bit x) and an enhanced decoder which uses the joint soft values and side information (bias about the previous modem bit x?) to output a more reliable information bit x.

Abstract: A parallel interference cancellation (PIC) receiver incrementally removes interference from signals in parallel modules in successive stages. For each desired signal, as interfering signals are removed, corresponding updates to a data covariance matrix are modeled as computationally tractable rank-one updates to a root matrix of the covariance matrix. Processing of signals and/or covariance information may be initiated, continued, and/or halted at various stages, e.g., in response to signal or data quality. The PIC receiver using root matrix updates is applicable to a variety of demodulation techniques.

Abstract: A method of generating a control signal to enable or inhibit a wide variety of applications is provided. The method generally includes the steps of determining the location of a first mobile radio terminal, determining the location of a second mobile radio terminal, comparing the locations of the terminals, and generating a control signal based upon the comparison. The control signal may be generated if the first and second mobile radio terminals are within a specified distance of one another. Alternatively, the control signal may be generated if the first and second mobile radio terminals are separated by at least a specified distance from one another. Additionally, the control signal may be generated if it is determined that the first mobile radio terminal is at a first specified location and the second mobile radio terminal is at a second specified location spacially separated from the first specified location.

Abstract: Methods and apparatus for processing a composite communication signal comprising two or more received signals of interest are disclosed. An interference-suppressing receiver, which may comprise a G-Rake receiver or a linear chip equalizer, utilizes a square-root covariance matrix in processing received signals, where the square-root covariance matrix represents impairment covariance or data covariance for the composite communication signal. In an exemplary method, a receiver detects symbols, corresponding to a signal of interest, from the composite communication signal, using processing weights calculated from a square-root covariance matrix and a net channel response for the signal of interest.

Abstract: A Generalized Rake (G-Rake) receiver is adapted for Golden code reception in a CDMA system. Signals transmitted by two or more transmit antennas are received at two or more receiver antennas. The signal from each receiver antenna is despread, and channel estimation is performed for each transmit antenna. G-Rake combining weights are calculated based on impairment correlation across G-Rake fingers and channel coefficients corresponding to each transmit antenna. The despread values from each symbol period are combined over a plurality of symbol periods based on the combining weights. The combined values are processed using coefficients derived from the Golden number to generate a set of decision variables, and the Golden encoded symbols are jointly detected from the decision variables. In some embodiments, spherical decoding and triangularization significantly simplify the decoding problem formulation.