Apparatus, methods, and computer program products for improving precoding downlink signaling are provided. An example method may include determining one or more noise covariance parameters for a noise covariance report, the noise covariance parameters being associated with a noise covariance matrix for whitening. The example method further may include transmitting, to a base station, the noise covariance report including the one or more noise covariance parameters or a noise whitening matrix for the whitening, the noise covariance report being transmitted based on a transmission periodicity of one or more slots.

This document discloses a solution for computing beamforming coefficients for a radio channel between two apparatuses. According to an aspect, a method comprises: obtaining a channel matrix representing a radio channel between an apparatus and another apparatus; obtaining an initial eigenvector estimate for an eigenvector of the channel matrix; computing an intermediate eigenvector estimate based on the channel matrix and the initial eigenvector estimate; computing an error vector representing an error between the initial eigenvector estimate and the intermediate eigenvector estimate; computing a final eigenvector estimate based on the error vector and the intermediate eigenvector estimate; and determining beamforming coefficients based on the final eigenvector estimate and communicating with said another apparatus by using the beamforming coefficients.

This document discloses a solution for computing beamforming coefficients for a radio channel between two apparatuses. According to an aspect, a method comprises: obtaining a channel matrix representing a radio channel between an apparatus and another apparatus; obtaining an initial eigenvector estimate for an eigenvector of the channel matrix; computing an intermediate eigenvector estimate based on the channel matrix and the initial eigenvector estimate; computing an error vector representing an error between the initial eigenvector estimate and the intermediate eigenvector estimate; computing a final eigenvector estimate based on the error vector and the intermediate eigenvector estimate; and determining beamforming coefficients based on the final eigenvector estimate and communicating with said another apparatus by using the beamforming coefficients.

One embodiment is directed to adaptive predictive uplink receive chain processing that involves determining predicted data for one or more early data symbols of a slot based on first baseband IQ data received for the slot. The predicted data for the early data symbols of the slot comprises a predicted version of data used at some point in performing a first portion of uplink receive processing for the early data symbols. The first portion of the uplink receive processing for the early data symbols of the slot is performed using the predicted data. Actual data corresponding to the predicted data is determined based on at least second baseband IQ data received for the slot. In connection with performing a remaining portion of the uplink receive processing for the early data symbols, the preliminary output data for the early data symbols of the slot are adapted based on the actual data.

An improved receiver design implements a method for modeling users in SIC turbo loop multiuser detection architectures that reduces the number of implementation cycles, and thereby reduces the computational overhead associated with computing the inverse of the received signal covariance matrix, by efficiently reusing components of a QR decomposition. By reusing some of the computational results from the previous turbo loop's equalizer calculation, the disclosed receiver significantly reduces the computational burden of updating the linear equalizer on each turbo loop. Depending on the embodiment, this reduction can be accomplished in at least two different ways, depending on the dimensionality and other aspects of the implementation.

An apparatus including a processor configured to receive a digital communication signal having a plurality of transmitted layers. The processor is configured to determine an estimated channel matrix based on the digital communication signal, determine a first estimated transmitted symbol vector and a mean square error matrix based on a linear analysis of the received digital communication signal. A first set of bit LLR are determined based on a LMMSE type detector and a second set of bit LLR are determined based on a novel simplified tree search process. The two sets of bit LLR are then combined and used to detect the data in the received communication signal. The simplified tree search process uses a specially formed channel shortening process to determine a set of shortened channel correlation matrices that allow the second set of bit LLR to be determined using an alternative marginalized tree search process.

An apparatus including a processor configured to receive a digital communication signal, wherein the digital communication signal includes a common reference signal and transmitted data. The processor determines a first interfering channel matrix for a first interfering cell based on a channel estimation of the common reference signal, and estimates a first power offset ratio and a first effective pre-coding matrix for the first interfering cell by evaluating a maximum likelihood metric, wherein the maximum likelihood metric is based on a first interfering channel correlation. The processor then reconstructs a channel covariance matrix based on the estimated first power offset ratio and the first effective pre-coding matrix and detects the transmitted data based on the reconstructed channel covariance matrix.

A precoding method, a precoding apparatus, a Frequency Domain Equalization (FDE) method, and an FDE apparatus are provided in the embodiments of the present invention. The precoding method includes: performing offset modulation for a transmitting signal vector; calculating a precoding matrix according to the offset-modulated transmitting signal vector and a receiver decision signal vector, where the precoding matrix is used for performing precoding for the transmitting signal vector; and performing precoding for the transmitting signal vector according to the precoding matrix. Linear precoding is performed by using the offset-modulated signal on the transmitter, and therefore, the interference caused by multiple antennas and multipath propagation is reduced, the system BER is reduced, and the complexity of implementation is low.

An apparatus and associated methodology providing read channel circuitry having a signal equalizer that sends an equalized signal to a bit detector. The read channel circuitry is capable of sampling values of the equalized signal to identify a bit transition from among a predefined plurality of different bit transitions. The apparatus may have channel optimization (CO) logic that, based on the input signal and the sampling of the equalized signal, defines first values for a programmable parameter of the bit detector that substantially maximizes vector separations among vectors of waveform target samples corresponding to the predefined plurality of different bit transitions, while the CO logic also defines second values for a programmable parameter of the equalizer that substantially minimizes the mean squared separation of the equalized signal segment for each bit transition from the waveform target corresponding to that bit transition.

Apparatuses, methods, and systems are disclosed for calculating an EVM of a transmitter. One apparatus includes a processor and a receiver that receives a multiple-layer MIMO signal from a transmitter via a propagation channel. The processor measures the received multiple-layer MIMO signal using an unbiased linear MMSE MIMO equalizer and calculates an EVM of the transmitter, where the EVM for each transmission layer is calculated as 100 times the square root of the mean square error of the layer estimate at the output of the unbiased linear MMSE MIMO equalizer.