Apparatus and methods for performing symbol detection on a plurality of mutually interfering information streams transmitted in a wireless communication system are disclosed. The apparatus comprises a detector configured to receive an input signal comprising a plurality of mutually interfering information streams, and to detect a transmitted symbol for one of the plurality of mutually interfering information streams by searching for a vector solution to an optimization problem, and a detection evaluation module configured to classify the detected symbol as reliable or unreliable, and/or to determine whether current system conditions permit reliable symbol detection and to take a predetermined action to improve the detection reliability according to a result of the determination. In some embodiments a decoding algorithm is then applied to the plurality of detected symbols to recover information from said one of the mutually interfering information streams.

A receiver decodes received data streams based on a subset of candidate decoding constellation points. A first stage of a decoder of the receiver selects a subset of candidate decoding constellation points by identifying a decoded value for an initial data stream of the set of data streams. A second stage then applies MMSE error detection to each of the constellation points in the selected subset, and calculates an error metric based on the MMSE error detection results. The decoder selects the constellation points having the lowest error metrics, and uses the selected constellation points as an initial set of points for decoding the next data stream to be decoded.

An OFDM transmitter comprising an input for acquiring or receiving a signal to be transmitted, an output for transmitting a PAPR reduced version of the signal, a processor and memory storing code for execution by the processor. The processor, when executing the code, is configure to determine a plurality of possible values of tone reservation, hereinafter referred to as TR, tones for use in TR based PAPR reduction and to perform a tree search over some or all of the possible values under a first constraint that the average power per TR tone does not exceed the average power per tone used for data transmission and a second constraint that selected values for the TR tones reduce PAPR.

Embodiments of the invention provides a decoder for decoding a signal received through a transmission channel in a communication system, said signal carrying information symbols selected from a given alphabet and being associated with a signal vector, said transmission channel being represented by a channel matrix, wherein said decoder comprises: a sub-block division unit (301) configured to divide the received signal vector into a set of sub-vectors in correspondence with a division of a matrix related to said channel matrix; a candidate set estimation unit (305) for recursively determining candidate estimates of sub-blocks of the transmitted signal corresponding to said sub-vectors, each estimate of a given sub-block being determined from at least one candidate estimate of the previously processed sub-blocks, wherein said candidate set estimation unit is configured to determine a set of candidate estimates for at least one sub-block of the transmitted signal by applying at least one iteration of a decoding algorithm using the estimates determined for the previously processed sub-blocks, the number of candidate estimates determined for said sub-block being strictly inferior to the cardinal of the alphabet and superior or equal to two, the decoder further comprising a signal estimation unit (306) for calculating an estimate of the transmitted signal from said candidate estimates determined for said sub-blocks.

An apparatus for deriving a submatrix {tilde over (G)}.sup.1 is described. The apparatus for deriving a submatrix {tilde over (G)}.sup.1 is configured to select an N-elements-column and an N-elements-row of an NN-Matrix G or G.sup.1. The apparatus for deriving a submatrix {tilde over (G)}.sup.1 is configured to rearrange the selected column to the rightest column and the selected row to the lowest row of G or G.sup.1 so as to generate a NN-matrix G.sub.p or G.sub.p.sup.1. The apparatus for deriving a submatrix {tilde over (G)}.sup.1 is configured to calculate a submatrix {tilde over (G)}.sup.1 by

[00001]${\tilde{G}}^{-1}=A-\frac{\mathrm{AbcA}}{d^{-1}+c^T.Math.\mathrm{Ab}},$

wherein the parameters (N1)(N1)-submatrix A, b, d, c are obtained from the G.sub.p or the G.sub.p.sup.1; wherein

[00002]$G_p=\left[\begin{array}{cc}\tilde{G}& b\\ c^T& d\end{array}\right],.Math.G_p^{-1}=\left[\begin{array}{cc}A& \tilde{b}\\ {\tilde{c}}^T& \tilde{d}\end{array}\right].$

The present invention concerns a method for computing a soft estimate of coded bits forming transmitted symbol vectors of a multi-dimentional constellation, the transmitted vectors being received by a receiver from a source through a channel, characterized in that the method comprises the steps of: obtaining from the receiver memory a predetermined list of vectors with integer or gaussian integer entries, obtaining a channel matrix estimation between the source and the receiver and received symbols, obtaining a reduced channel matrix and a change of basis matrix from the channel matrix estimation, computing a vector with integer coordinates at least from the reduced channel matrix and the received symbols, shifting the predetermined list of vectors around the vector with integer coordinates and obtaining a shifted list of vectors, computing a soft estimation of the coded bits according to vectors belonging to the shifted list of vectors and to a transformed multi-dimentional constellation obtained from the multi-dimentional constellation and the change of basis matrix.

The disclosure discloses a path detection method including after obtaining an equalizing signal of a received signal, Maximum Likelihood (ML) path detection and ML complementary set path detection are performed on the equalizing signal according to the pre-set maximum number of reserved nodes and maximum number of expanded branches of each layer; in the process of the detections, an accumulated path measurement value is calculated after finishing the search of each layer and each path, and the accumulated path measurement value is compared with a pre-set search measurement threshold; when the accumulated path measurement value is less than the search measurement threshold, the search of this path is continued; otherwise the search of this path is finished and the search of the next path is started until all the paths are searched. The disclosure also discloses a path detection device, Sphere Decoding (SD) detection device and computer storage medium.

A method, device, and a computer program are provided to decode a signal received through a transmission channel in a communication system, the received signal being represented by a signal vector. The method comprises: calculating an initial estimate of a transmitted symbol vector carried by the received signal vector; calculating a bound parameter (201) from a linear function of the initial estimate of the transmitted symbol vector, the linear function being defined by a slope coefficient and an intercept coefficient, the method further comprising: determining estimated symbols representative of the transmitted symbols carried by the received signal, the estimated symbols being determined from a set of candidate lattice points, each lattice point comprising a set of components, each component of a candidate lattice point being searched in a search interval (203), the search interval having at least one search interval bound computed from the bound parameter; determining (205) the estimated symbols from the closest lattice point to the received signal vector among the candidate lattice points.

Communication device adapted for receiving a MIMO signal is provided. The device comprises a first detector adapted to perform a first symbol detection on the MIMO signal using a first detection method, a detection error determination unit adapted to determine a first detection error of the first symbol detection, a detection error judging unit adapted to determine if the first detection error is above or below a detection threshold, and a second detector, adapted to perform a second symbol detection on the MIMO signal using a second detection method, if the detection error judging unit has determined that the first detection error is above the detection threshold. The communication device is adapted to use results of the symbol detection as final symbol detection results, if the detection error judging unit has determined that the first detection error is below the detection threshold.

There is provided a decoder for decoding a data signal received through a transmission channel in a communication system, the decoder (310) comprising a symbol estimation unit (311) configured to determine estimated symbols representative of the transmitted symbols carried by the received signal, the estimated symbols being determined from nodes of a decoding tree based on a weight metric associated with each of the node. The decoder further comprises a termination alarm monitoring unit (312) for monitoring a termination alarm depending on the current decoding computation complexity, the termination alarm being associated with a metric parameter, the symbol estimation unit being configured to reduce the weight metric of each node of the decoding tree by a quantity corresponding to a function of the metric parameter associated with the termination alarm, in response to the triggering of the termination alarm.