Nokia Corporation

Markku J Heikkila

Jorma Lilleberg

Petri Komulainen

Kari Majonen

An apparatus for determining a symbol estimate includes a detection unit, an information storage, a channel decoder, and an estimator. One or more detectors of the detection unit is configured to detect a first data stream and the one or more detectors or one or more other detectors are configured to detect a second data stream when interference cancellation is carried out and when interference cancellation is not carried out parallel to detection of a first data stream to obtain results of detection. The information storage is configured to store the results of the detection of the second data stream, and the channel decoder is configured to channel decode a detected first data stream. The estimator is configured to determine a symbol estimate by using the stored results of the detection of the second data stream and based on the success of the channel decoding of the first data stream.

Apparatus, computer program and method for determining a symbol estimate

The invention is related to a communication terminal, comprising: means () for creating at least one channel matrix assuming predetermined interfering signals as a part of a desired signal; means () for dividing the at least one channel matrix into multiple sub-matrices; means () for diagonalizing the sub-matrices by using a transformation matrix; means () for forming at least one block-diagonalized matrix using diagonalized sub-matrices; means () for inverting the at least one block-diagonalized matrix; and means () for generating channel equalizer coefficients by using at least one inverted block-diagonalized matrix.

Data processing method, equalizer, receiver, communication system, network element, and terminal using simplified channel matrix inversion

A receiving method and a receiver of a telecommunication system are provided. The receiver comprises one or more antennas, a radio frequency unit connected to the antennas for receiving signals transmitted by one or more transmitters using a multitude of channels, and an estimator. The estimator is configured to select one or more channel pairs, each channel of each channel pair being a given distance from each other, determine symbol estimates for the signals of the channels of the channel pairs, remove the effect of data modulation from the signals of the channels of the channel pairs, obtain noise estimates by subtracting the signals of the channels of the channel pairs from each other, and determine a noise covariance matrix for the desired channel on the basis of the obtained noise estimates.

Determination of a noise covariance matrix for a wireless communication channel

A CDMA receiver () includes a receiver input for coupling to signal outputs of Nreceive antennas (A,B), where the signal outputs are sampled at Nsamples per symbol or chip, a matched filter (), such as a RAKE, and a whitening filter () for coupling the receiver input to an input of the matched filter. The whitening filter contains NNparallel whitening filters w(A-D), individual ones of the whitening filters wreceiving during each symbol interval i, NNnew signal samples via a signal connection matrix () such that a first individual whitening filter receives only one of the new samples, a second individual whitening filter receives the same sample as the first individual whitening filter, and one additional sample, and such that an nth individual whitening filter receives the same n&#x2212;1 samples as the first n&#x2212;1 individual whitening filters, plus one of the remaining samples. The whitening filter has Noutputs for outputting filtered signal samples such that a filtered signal sample appearing in the Noutputs does not correlate with any other filtered signal sample appearing in Noutputs. The whitening filter also includes a delay line () constructed as a plurality of serially coupled delay line elements each having a delay of one symbol interval. The delay line has an input coupled to an output of said signal connection matrix and provides the NNparallel whitening filters wwith delayed versions of the signal samples.

Advanced whitener-rake receiver for WCDMA terminal

A method is disclosed to minimize the mean-square-error of an estimate of an unknown parameter, such as a data symbol transmitted through a channel, such as a WCDMA channel. The method includes steps of (a) replacing a required multiplication of an input signal vector by an inverse covariance matrix, which is one of a total signal covariance matrix or an interference-plus-noise covariance matrix, by linear filtering, wherein directly computed or estimated filter elements of a row or a column of the inverse covariance matrix, corresponding to time instant i, are used as linear filter coefficients; (b) forming a vector g(i) from the filter outputs, the vector g(i) being estimated element by element using the linear filter; and (c) using the vector g(i) in place of a vector that would have been obtained by directly multiplying the signal vector by the inverse covariance matrix. The linear filter w(i) converges or closely converges to a row or column of the required inverse covariance matrix. For the case of the interference-plus-noise covariance matrix, when a desired filter is found through adaptation, the desired filter is used to filter the total signal, including the desired signal, to generate the output vector g(i). The filter outputs generated using either of the total signal covariance matrix or the interference-plus-noise covariance matrix are employed to estimate an unknown parameter through the use of a further filter matched to the pulse shape of the unknown parameter carried by the input signal, where the further filter is a RAKE receiver that performs multipath combining at a chip level and single code correlation, or a RAKE receiver that performs despreading using a code correlator bank, and multipath combining at the symbol level using the correlator outputs.

Method and apparatus for providing blind adaptive estimation and reception

A receiver for use in a CDMA telecommunications system is disclosed. The receiver includes at least one antenna for receiving signals from a CDMA channel, where the received signals include a desired user signal. The receiver also includes combining circuitry, for performing chip waveform filtering and maximal ratio combining, to produce mutually correlated chip estimates of the received signals. The receiver further includes an adaptive separator, for adaptively separating the mutually correlated chip estimates, and a correlator, for despreading the output of the adaptive separator to obtain an estimate for data symbols of the desired user signal. In addition, the receiver further includes estimating circuitry, coupled to the combining circuitry, for estimating a response of the channel, where the combining circuitry utilizes the channel response estimate as a reference.

Unsupervised adaptive chip separation filter for CDMA terminal

A method for optimizing a bit-to-symbol mapping operation. The method has steps of (a) determining a most probable symbol selection error made during a space-time decoding operation; and (b) selecting a bits-to-symbol mapper such that a bit-to-symbol mapping step results in a most probable symbol selection error, made during a space-time decoding operation, causes a minimal number of bit errors. The bits-to-symbol mapping step can be carried out so as to minimize an average number of bit errors resulting from an occurrence of the most probable symbol selection error, as well as from an occurrence of at least a second most probable symbol selection error, during the space-time decoding operation. A space-time coded communications system that operates in accordance with the method is also disclosed.

Method and apparatus providing bit-to-symbol mapping for space-time codes

A receiver for use in a CDMA telecommunications system is disclosed. The receiver includes at least one antenna for receiving signals from a CDMA channel, an estimator for estimating an impulse response of the channel, and an adaptive equalizer. The estimator provides a reference for the adaptive equalizer, and the adaptive equalizer operates to estimate a transmitted chip sequence of the channel and to restore orthogonality among the received signals. The adaptive equalizer includes circuitry for utilizing a blind adaptive algorithm to estimate the transmitted chip sequence of the channel.

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Oulu, Finland

Markku J Heikkila