Abstract: A receiver, such as a CDMA MIMO receiver, includes a LMMSE-based chip-level equalizer constructed so as to implement a FFT accelerated iterative algorithm having a complexity of order O(N log2(N)), where N is the dimension of a covariance matrix. The equalizer uses one of an overlap-save or an over-lap add FFT architecture.

Abstract: In the reception of a downlink MIMO CDMA signal, the receiving unit performs a simplified process of linear equalization that eliminates the need for inverting the correlation matrix. The correlation matrix is approximated to a good degree by a circulation matrix that is diagonalized by FFT operations, thus substituting two FFTs and one IFFT having a complexity of O ( L F ? ( N ? ? ? ) 3 + ( N ? ? ? ) 2 + 2 ? ( N ? ? ? ) 2 ? L F ? log 2 ? L F ) for the direct matrix inversion having a complexity of O(LF3).

Abstract: Receiving downlink CDMA signals in a fast-fading environment is facilitated at higher receiver velocities by updating the block-adaptive linear minimum mean square error (LMMSE) downlink CDMA equalizer. The autocorrelation matrix of the observed data is updated by passing block-wise autocorrelation slides through a filter. Each autocorrelation slide is an autocorrelation matrix estimated from a short block of observed data over which the channel can be considered constant. This method achieves a reliable estimate for the autocorrelation matrix when the block size must be small to ensure that the block-wise stationarity assumption holds in cases of fast fading channels. In addition, small block sizes make it possible to satisfy the equalizer delay constraint imposed by hardware and certain voice transmission standards such as CDMA2000 1X where demodulated data must be delivered within only several symbol periods of the signal arrival time.

Abstract: In the reception of a downlink MIMO CDMA signal, the receiving unit performs a simplified process of linear equalization that eliminates the need for inverting the correlation matrix. The correlation matrix is approximated to a good degree by a circulation matrix that is diagonalized by FFT operations, thus substituting two FFTs and one IFFT having a complexity of O ( L F ? ( N ? ? ? ) 3 + ( N ? ? ? ) 2 + 2 ? ( N ? ? ? ) 2 ? L F ? log 2 ? L F ) for the direct matrix inversion having a complexity of O(LF3).

Abstract: A system, apparatus and method for a multi-stage Parallel Residue Compensation (PRC) receiver for enhanced suppression of the Multiple Access Interference (MAI) in Code Division Multiple Access (CDMA) systems. The accuracy of the interference estimation is improved with a set of weights computed from an adaptive Normalized Least Mean Square (NLMS) algorithm. In order to reduce complexity, the commonality of the multi-code processing is extracted and used to derive a structure of PRC to avoid direct interference cancellation. The derived PRC structure reduces the interference cancellation architecture from a complexity that is proportional to the square of the number of users to a complexity that is linear with respect to the number of users. The complexity is further reduced by replacing dedicated multiplier circuits with simple combinational logic.

Abstract: An apparatus and corresponding method for receiving a MIMO cellular communication signal, the apparatus including: a Kalman filter type of equalizer, responsive to a received signal, for providing a corresponding processed signal indicating information conveyed by the received signal, responsive to a set of values indicating predicted state error correlation at a first instant of time given all noise estimates up through the first instant, for providing ta set of values indicating a product of measurement values and predicted state error correlation at a later instant of time given all process noise estimates up through the later instant. The filter is implemented so as to make use of the displacement structure of the state transition matrix of the Kalman filter allowing shifting operations in place of vector and matrix multiplications.

Abstract: Receiving downlink CDMA signals in a fast-fading environment is facilitated at higher receiver velocities by updating the block-adaptive linear minimum mean square error (LMMSE) downlink CDMA equalizer. The autocorrelation matrix of the observed data is updated by passing block-wise autocorrelation slides through a filter. Each autocorrelation slide is an autocorrelation matrix estimated from a short block of observed data over which the channel can be considered constant. This method achieves a reliable estimate for the autocorrelation matrix when the block size must be small to ensure that the block-wise stationarity assumption holds in cases of fast fading channels. In addition, small block sizes make it possible to satisfy the equalizer delay constraint imposed by hardware and certain voice transmission standards such as CDMA2000 1× where demodulated data must be delivered within only several symbol periods of the signal arrival time.

Abstract: Disclosed is a LMMSE receiver that restores orthogonality of spreading codes in the downlink channel for a spread spectrum signal received over N receive antennas. The FFT-based chip equalizer tap solver reduces the direct matrix inverse of the prior art to the inverse of some submatrices of size N×N with the dimension of the receive antennas, and most efficiently reduces matrix inverses to no larger than 2×2. Complexity is further reduced over a conventional Fast Fourier Transform approach by Hermitian optimization to the inverse of submatrices and tree pruning. For a receiver with N=4 or N=2 with double oversampling, the resulting 4×4 matrices are partitioned into 2×2 block sub-matrices, inverted, and rebuilt into a 4×4 matrix. Common computations are found and repeated computations are eliminated to improve efficiency. Generic design architecture is derived from the special design blocks to eliminate redundancies in complex operations. Optimally, the architecture is parallel and pipelined.

Abstract: A receiver, such as a CDMA MIMO receiver, includes a LMMSE-based chip-level equalizer constructed so as to implement a FFT accelerated iterative algorithm having a complexity of order O(Nlog2(N)), where N is the dimension of a covariance matrix. The equalizer uses one of an overlap-save or an over-lap add FFT architecture.

Abstract: In the reception of a downlink MIMO CDMA signal, the receiving unit performs a simplified process of linear equalization that eliminates the need for inverting the correlation matrix.