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: 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: A two-stage approach to MIMO detection improves receiver performance in a computationally tractable manner. A whitening joint detector processes a MIMO symbol stream. The whitening joint detector includes a pre-filter operative to suppress a first subset of the received MIMO streams as colored noise. The whitening joint detector further includes a primary joint detector operative to process a second subset of the MIMO streams and to output a preliminary solution obtained by minimizing a whitening joint detection metric. A secondary detector then operates in the vicinity of the primary joint detector preliminary solution. The secondary detector improves the preliminary solution by comparison to a full joint detection metric.

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 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: 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 two-stage approach to MIMO detection improves receiver performance in a computationally tractable manner. A whitening joint detector processes a MIMO symbol stream. The whitening joint detector includes a pre-filter operative to suppress a first subset of the received MIMO streams as colored noise. The whitening joint detector further includes a primary joint detector operative to process a second subset of the MIMO streams and to output a preliminary solution obtained by minimizing a whitening joint detection metric. A secondary detector then operates in the vicinity of the primary joint detector preliminary solution. The secondary detector improves the preliminary solution by comparison to a full joint detection metric.

Abstract: A compression/decompression method for backhaul communication of a complex-valued radio signal between base stations and the network processing unit, such as a Central Processor of a Coordinated MultiPoint (CoMP) system, significantly reduces backhaul bandwidth. The spatial and temporal correlations of the wireless IQ signal are exploited in order to remove redundancy and substantially reduce signal bandwidth. Feature component signals of significance are extracted through linear transformation to form the radio signal, and are individually quantized, possibly at different bit rates in accordance with their relative importance. The transformation can either be pre-determined or computed in real-time based on the spatial and temporal statistics of the radio signal. In the latter case, the transformation matrix or matrices are also sent over the backhaul in order to allow the radio signal to be reconstructed at the receiving end. Different methods of generating the transformation matrices are proposed.

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 system and method in which two base stations—a Primary Base Station (PBS) and a Secondary Base Station (SBS)—are used to accomplish a Virtual 2-antenna Receiver (V2RX) scheme. The PBS may perform the initial transmissions of symbols, but, instead of the PBS, the SBS may handle the subsequent reception of terminal-specific Channel State Information (CSI) and the broadcast of an additional signal. The SBS can be much simpler in design than the PBS, and can be located physically closer to the terminals, requiring less power for the feedback signals (from the terminals) and also for SBS's own broadcast of the additional signal to terminals. The reception and usage of stale CSI using a secondary base station can be important for dense networks with a large number of simple terminals. Because of the rules governing abstracts, this abstract should not be used to construe claims.

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: Methods may be provided to simultaneously receive first and second RF (radio frequency) carriers over respective first and second RF carrier frequencies. More particularly, the first and second RF carriers may be provided at an RF mixer stage. During a first time period, the first and second RF carriers may be down converted through the RF mixer stage using a first RF mixer frequency to generate first downconverted signals, and the first downconverted signals may be processed to provide first and second DC carriers corresponding to the first and second RF earners. During a second time period, the first and second RF carriers may be downconverted through the RF mixer stage using a second RF mixer frequency to generate second downconverted signals with the first and second RF mixer frequencies being different, and the second downconverted signals may be processed to provide the first and second DC carriers corresponding to the first and second RF carriers. Related devices are also discussed.

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 teachings herein provide a method and apparatus for partitioning sets of MIMO streams, for joint processing. In particular, there is an optimum or otherwise best partitioning of a set of MIMO streams into a first subset to be jointly processed and a second subset to be suppressed as interference with respect to that joint processing. Of course, more than one partitioning may be used, e.g., across different joint processing stages and/or at different times, such that all streams of interest are processed. Correspondingly, the present invention provides a method and apparatus for selecting an optimum or otherwise relative “best” subset of MIMO streams for processing together in a joint process, from among a larger set of MIMO streams. The method and apparatus may, for example, be employed in a multi-stage joint processing receiver, where subset selections are performed on a per-stage basis.

Abstract: According to a method and apparatus taught herein, a decoding circuit and method decode linear block codes based on determining joint probabilities for one or more related subsets of bits in received data blocks. The use of joint probabilities enables faster and more reliable determination of received bits, meaning that, for example, joint probability decoding requires fewer decoding iterations than a comparable decoding process based on single-bit probabilities. As a non-limiting example, the decoding circuit and method taught herein provide advantageous operation with Low Density Parity Check (LDPC) codes, and can be incorporated in a variety of communication systems and devices, such as those associated with wireless communication networks.

Abstract: In a receiver with a multi-stage equalizer, such as an SLI equalizer, cumulative symbol estimates generated in one or more early stages of the equalizer are used as effective pilot symbols to improve channel estimation for later stages.

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.

Abstract: An iterative demodulator and decoder uses feedback attenuation to maintain proper balance between the demodulator and decoder. Balance is maintained by attenuating the influence of extrinsic information fed back from the decoder to the demodulator to prevent strong decisions by the decoder from overwhelming the demodulator.

Abstract: A two-stage approach to MIMO detection improves receiver performance in a computationally tractable manner. A whitening joint detector processes a MIMO symbol stream. The whitening joint detector includes a pre-filter operative to suppress a first subset of the received MIMO streams as colored noise. The whitening joint detector further includes a primary joint detector operative to process a second subset of the MIMO streams and to output a preliminary solution obtained by minimizing a whitening joint detection metric. A secondary detector then operates in the vicinity of the primary joint detector preliminary solution. The secondary detector improves the preliminary solution by comparison to a full joint detection metric.

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.