Abstract: Aspects of the present disclosure may involve use of a radio frequency receiver and in such a receiver, tracking multipath gains and delays of multipath reflections corresponding to an OFDM multipath transmission channel. The gains and delays are based on time-domain evolution of the channel impulse response. Multipath reflections are searched for and then used to calculate channel correlation information to provide channel estimations to aid in mitigating or cancelling distortion of the received signal.

Abstract: Aspects of the present disclosure may involve use of a radio frequency receiver and in such a receiver, tracking multipath gains and delays of multipath reflections corresponding to an OFDM multipath transmission channel. The gains and delays are based on time-domain evolution of the channel impulse response. Multipath reflections are searched for and then used to calculate channel correlation information to provide channel estimations to aid in mitigating or cancelling distortion of the received signal.

Abstract: Signal equalization is provided, according to certain aspects, by a frequency-domain equalization circuit, a noise-whitening filter and a noise predictor. A sequencer is used to control ordering of the equalization circuit, a noise-whitening filter and a noise predictor. The equalization circuit provides equalization the frequency domain by converging on symbols of the input signal. The noise-whitening filter and the noise predictor filter colored noise from a signal responsive to the equalization circuit. The sequencer controls operation of the noise-whitening filter by detecting an indication of convergence of the symbols from input signal and causing the noise-whitening filter to commence suppression of colored noise from a signal derived from an output by the equalization circuit.

Abstract: Embodiments of the invention concern a method of equalizing (S9), in a turbo equalizing system (S10), by sphere decoding (S11) a signal transmitted over a channel by a multiple input multiple output system, comprising: receiving (S3) said transmitted signal, building (S4) at least one search tree, providing (S6) likelihoods of bits, for said transmitted signal, from said built search tree(s) and from said received transmitted signal, wherein equalizing method (S9) also comprises receiving feedback signal from a channel decoder (S8) of said turbo equalizing system (S10), and wherein said feedback signal is used to build (S4) said search tree(s).

Abstract: A sphere decoder based turbo equalizer is described. A method comprises assorting in a first vector Quadrature Amplitude Modulation, QAM, symbols on a particular tree level based on first distance properties, assorting in a second vector QAM symbols on the particular tree level based on second distance properties, selecting the QAM symbol with the minimum second distance property in the second vector, wherein said selecting comprises labeling the selected QAM symbol as protected, identifying the selected QAM symbol in the first vector assorted by distance properties, pruning the first vector by eliminating all QAM symbols having a larger first distance property compared to the selected QAM symbol, wherein said pruning is restricted to QAM symbols not being labeled as protected, and repeating the steps d-e selecting the QAM symbol with the next minimum second distance property.

Abstract: Embodiments of the invention concern a method of equalizing (S9), in a turbo equalizing system (S10), by sphere decoding (S11) a signal transmitted over a channel by a multiple input multiple output system, comprising: receiving (S3) said transmitted signal, building (S4) at least one search tree, providing (S6) likelihoods of bits, for said transmitted signal, from said built search tree(s) and from said received transmitted signal, wherein equalizing method (S9) also comprises receiving feedback signal from a channel decoder (S8) of said turbo equalizing system (S10), and wherein said feedback signal is used to build (S4) said search tree(s).

Abstract: A sphere decoder based turbo equalizer is described. A method comprises assorting in a first vector Quadrature Amplitude Modulation, QAM, symbols on a particular tree level based on first distance properties, assorting in a second vector QAM symbols on the particular tree level based on second distance properties, selecting the QAM symbol with the minimum second distance property in the second vector, wherein said selecting comprises labeling the selected QAM symbol as protected, identifying the selected QAM symbol in the first vector assorted by distance properties, pruning the first vector by eliminating all QAM symbols having a larger first distance property compared to the selected QAM symbol, wherein said pruning is restricted to QAM symbols not being labeled as protected, and repeating the steps d-e selecting the QAM symbol with the next minimum second distance property.

Abstract: A receiver (200) for receiving for receiving encoded data transmitted simultaneously as a plurality of M different sequences of transmitted symbols from different transmit antennas using a plurality of m modulation levels, where M and m are integers and each of the transmitted symbols represents a plurality of bits of the encoded data, comprises a demodulator (210) arranged to provide N received symbol combinations by receiving at a plurality of N receive antennas (202, 204), where N is an integer, the plurality of M different sequences of transmitted symbols, wherein each received symbol combination comprises M simultaneously received ones of the transmitted symbols.

Abstract: Sphere decoding of signals for MIMO detection involves a first distance processor arranged to determine a distance between symbols of a received symbol vector and possible transmit symbols, in a search sequence according to a search tree. A line from root to leaf of the search tree represents a possible transmit symbol vector and the sequence of processing root level symbols can be ordered with respect to increasing distance without explicit sorting of the root level symbols based on distance calculations. A next symbol in the sequence is determined, based on a symbol currently being processed by the first distance processor, and a second distance processor determines the distance in respect of the next symbol in the search sequence for the same possible transmit symbol vector, in parallel with the determining of the distance in respect of the current symbol by the first distance processor.

Abstract: A receiver (200) for receiving for receiving encoded data transmitted simultaneously as a plurality of M different sequences of transmitted symbols from different transmit antennas using a plurality of m modulation levels, where M and m are integers and each of the transmitted symbols represents a plurality of bits of the encoded data, comprises a demodulator (210) arranged to provide N received symbol combinations by receiving at a plurality of N receive antennas (202, 204), where N is an integer, the plurality of M different sequences of transmitted symbols, wherein each received symbol combination comprises M simultaneously received ones of the transmitted symbols.

Abstract: A method for demodulating a signal modulated with a first phase modulation technique with a demodulator adapted to demodulate signals modulated with a second phase modulation technique, the first phase modulation technique being based on a first phase constellation diagram and the second phase modulation technique being based on a second phase constellation diagram, the second phase constellation diagram being obtained by rotating the first phase constellation diagram by an angle being a non-nul integer multiple of 90 degrees, the method comprising: a) rotating the signal modulated with the first phase modulation technique by said angle; and b) demodulating the rotated signal with the demodulator. The method enables to use former optimized demodulator.

Abstract: Sphere decoding of signals for MIMO detection involves a first distance processor arranged to determine a distance between symbols of a received symbol vector and possible transmit symbols, in a search sequence according to a search tree. A line from root to leaf of the search tree represents a possible transmit symbol vector and the sequence of processing root level symbols can be ordered with respect to increasing distance without explicit sorting of the root level symbols based on distance calculations. A next symbol in the sequence is determined, based on a symbol currently being processed by the first distance processor, and a second distance processor determines the distance in respect of the next symbol in the search sequence for the same possible transmit symbol vector, in parallel with the determining of the distance in respect of the current symbol by the first distance processor.

Abstract: In a MIMO receiver, initial solutions using sub-optional decoding algorithm are determined for the symbols transmitted from each of a number of transmit antennas at a given time (100). The initial solutions (Sinit1, . . . , SinitNt) are hard-mapped to the nearest possible symbols of transmission (Sest1, . . . , SestNt). For each of the nearest possible symbols limited areas around them in the constellation plane are defined. A list of candidate symbol vectors (list) is then determined, including only symbols lying within the limited areas of the constellation plane. Finally, a joint decoding technique such as ML-technique is implemented to determine the best of the candidate symbol vectors. The number of the calculations can thus be significantly reduced, without having excessively damaging effects on the symbol error rate.