Telefonaktiebolaget Lm Ericsson (Publ)

Mattias Hyll

Antoni Fertner

Anders Orling

Fredrik Huss

Albin Johansson

Ke Zhong

Mikhail Ivanov

Embodiments of the present disclosure provide methods and apparatus for detection of radio signal. A method performed by a reception apparatus may comprise: obtaining (S) time domain samples of a radio signal; processing (S) the time domain samples by a plurality of match filters respectively, to generate a plurality of filtered results of the time domain samples; classifying (S) a filtered result of the plurality of filtered results by a classifier; discarding (S) a filtered result classified as being not associated to the code sequence; and determining (S) whether the code sequence is used in the radio signal, when a filtered result of the radio signal is classified as being associated to the code sequence. Some processing procedures may be avoided based on the classification result of the detected radio signal, and computational complexity may be reduced.

Method and apparatus for detection of radio signal

According to embodiments herein an ambiguity problem when compensating for frequency offset may be solved by compensating a received reference symbol according to two different frequency offset hypotheses; the estimated frequency offset and the a mirrored version of the same. Then by comparing the compensated reference symbol of the different frequency hypotheses with a target reference symbol, which is known at the receiver node, the frequency offset hypothesis which is most likely is used to compensate a received data symbol.

Receiver node and a method therein for compensating frequency offset

Equalizer updating and accurate sampling rate control in a DMT receiver are simultaneously performed using a known signal, such as a pilot tone. The known signal is separated into its real and imaginary components. The equalizer uses separate mechanisms to process the real and imaginary components. The real component is used to control sampling rate timing in the receiver. The imaginary component of the received signal is used in an equalization adaptation procedure, e.g., updating an equalizer coefficient value. In one example embodiment, the real component of the received signal is set to zero for purposes of equalization, and the unequalized, real component is used to recover/track sampling rate timing. Because the real component has not been equalized, simultaneous timing recovery/tracking and equalization is achieved. Only the imaginary component is equalized and used to update the equalizer coefficient value. Thereafter, the unequalized real component and the equalized imaginary component are combined. In another example embodiment, a real-valued equalizer coefficient is determined for the known signal. Both real and imaginary components of the known sigal are equalized with the real-valued equalizer coefficient. The so-equalized real component adapts to a normalized amplitude for the timing control signal which is desirable in certain timing control applications. The equalized real and imaginary components are combined. The equalizer coefficient is updated using only the imaginary component of the received signal.

Method and apparatus for equalizer updating and sampling rate control

A method and an apparatus transmit and receive information in a cable TV network including at least one base station connected to a branching cable network, branching from the base station to at least two subscribers, provided with transmitters. A unique carrier frequency is assigned to each of the subscriber's transmitters, the carrier frequencies being orthogonal. Signals from the subscriber's transmitters are transmitted simultaneously, received in the base station as a broadband signal, and separated using a common algorithm.

Device and method relating to cable TV networks

The present invention significantly reduces the number of complex computations that must be performed to compute a DFT or IDFT when a pattern is identified in an original input data sequence and is used to modify the data sequence in order to reduce the size of the sequence to be transformed. A DFT (IDFT) is performed on the modified input data sequence to generate a transformed sequence. The transformed data sequence is then manipulated to generate an output sequence that corresponds to the DFT (IDFT) of the original input data sequence without having actually calculated the DFT (IDFT) of the entire, original input data sequence. Three symmetrical patterns are used in the invention to simplify and render more efficient DFT and IDFT computations: Hermite symmetry, index-reversed, complex-conjugate symmetry, and mirror symmetry. As a result, the number of complex multiplications required to perform the DFT (or IDFT) is considerably less than the number of complex multiplications required to calculate the DFT (or IDFT) of the original input data sequence. The computational reduction increases signal processing speed and decreases power consumption, both attributes are highly desirable in virtually every DFT/IDFT application.

Computationally efficient analysis and synthesis of real signals using discrete fourier transforms and inverse discrete fourier transforms

A communications system employing the Discrete Multitone (DMT) line code divides the used frequency band W into a large number of subchannels, each with a bandwidth .DELTA.f=W/N. The signal in each subchannel is independently modulated at the symbol rate 1/.DELTA.f. Because of noise and the non-ideal characteristics of the transmission channel, the signal-to-noise ratio (SNR) varies for different subchannels across the frequency band. Each subchannel is used to transmit an integer number of bits in a two-dimensional signal constellation, the susceptibility to noise increasing with the size of the constellation assuming that the same signal energy is used. In order to use the transmission channel optimally, subchannels are assigned different numbers of bits depending on their specific SNR values, i.e., a subchannel with a high SNR value is assigned a large number of bits and vice versa. An optimal bit allocation is determined that ensures a certain bit error rate (BER) is obtained for all subchannels. In order to simplify numerical computations, thresholding is employed to make initial bit assignments. Further simplification of the bit loading procedures is obtained by ending bit allocation optimization efforts after a targeted BER is achieved.

Reduced complexity bit allocation to subchannels in a multi-carrier,

The present invention significantly reduces the number of complex computations that must be performed in computing the discrete Fourier transform (DFT) and inverse DFT (IDFT) operations. In particular, the DFT and IDFT operations are computed using the same computing device. The computation operations are substantially identical for both operations with the exception that for the IDFT operation, the data are complex conjugated before and after processing. Using the same computing device/operations, both DFT and IDFT computations are optimized for maximum efficiency. A common transform process is selectively connected to first and second data processing paths. A DFT operation is performed on an N-point sequence on the first data processing path, and an IDFT operation is performed on an N-point sequence on the second data processing path using the same N-point fast Fourier transform (FFT).

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Stockholm, Sweden

Mattias Hyll