Telefonaktiebolaget Lm Ericsson (publ)

Tore André

Daniel Chen Larsson

Jinliang Huang

Yi-Pin Eric Wang

Jacob Österling

Leonard Rexberg

Peter Michael Deane

Vimar Björk

Daniel Larsson

Marius Cismasu

Thord Hyllander

Torbjörn Gunnar Widhe

Uno Torstensson

Disclosed is a method and an apparatus for handling signals in an OFDM-based communication network () received at a receiver (). The method comprises obtaining a signal in time domain, the signal comprising a payload signal sent from a transmitter () towards the receiver () as well as an interference signal, the payload signal residing in a first frequency band and the interference signal residing in a second frequency band outside the first frequency band. The method further comprises separating the payload signal from the interference signal using a filter, and processing () the payload signal with a time window (W, W), or the separated interference signal with a time window, (W, W), or processing both the separated payload signal with a window (W, W) and the obtained signal with a window (W, W), the window (W, W, W) being substantially an OFDM symbol wide, so as to achieve a output signal/first output signal comprising the payload signal and a time-windowed interference signal and/or a second output signal comprising the interference signal and a time-windowed payload signal. The windowed signals become attenuated by the FFT so that the wanted signal are achieved undisturbed.

Methods and apparatuses for windowing-based channel filtering in an OFDM-based communication network

Systems and methods for detecting peaks in a multi-band transmit signal are disclosed. In some embodiments, a method of operation of a multi-band transmitter for detecting peaks in a multi-band transmit signal which includes multiple transmit signals on a respective multiple frequency bands includes receiving a first band input signal for a first frequency band of the multi-band transmit signal and at least one additional band input signal for a respective at least one additional frequency band of the multi-band transmit signal. The method also includes detecting a peak of a combination of the first band input signal and the at least one additional band input signal taking into account phase information of the first band input signal and the at least one additional band input signal. In this manner, the detected peak might not be overestimated as when the peak detection fails to take into account the phase information.

Coherent multi band peak detection

This disclosure relates to a peak reduction circuit and method for reducing peaks by identifying peak sample values exceeding a pre-set threshold value in an aggregated baseband carrier signal and determining a maximum peak sample by detecting its maximum peak absolute value and phase. A search is performed a pre-determined search length beyond an identified peak. A stored, predetermined filter impulse response based on the carrier passband configuration is retrieved and its amplitude and phase of the predetermined filter impulse response is adjusted by means of the phase and absolute value of the determined maximum peak sample. Finally, the aggregated baseband carrier signal and the adjusted predetermined filter impulse response are combined by synchronizing their maximum peaks and their opposite phase values for adjusting the aggregated baseband carrier signal to said pre-set threshold value.

Method and peak reduction unit for limiting a peak or group of peaks of an aggregated baseband carrier signal in a radio transmitter

A method of calibrating transmit and/or receive paths of an antenna comprising at least two antenna columns, each of which comprising two co-located sub-arrays of antenna elements. The method includes the steps of transmitting a measurement signal on at least one of the antenna elements, and receiving a representation of the measurement signal on at least one other of the antenna elements, the representation comprising at least a mutual coupling component dependent on the mutual coupling between the at least one antenna element and the at least one other antenna element. Further, the method includes the steps of repeating the transmitting and receiving step for at least a subset of all combinations of antenna elements of the antenna, wherein each combination of antenna elements comprises antenna elements having a same or different polarization, and subsequently comparing the received representations of the measurement signal between different combinations of antenna elements, and estimating at least a respective phase difference between antenna elements with the same polarization based on the comparison. Finally, the method includes the step of calibrating transmit and/or receive paths of antenna elements with the same polarization based on the estimated phase difference.

Method and arrangement for phase calibration of transmit and/or receive paths of an antenna array

The present disclosure relates to a receiving node, and to a related method for determining when to apply a turbo equalization mode to compensate for Inter-Symbol Interference in a radio signal received over a radio channel from a transmitting node. The method comprises decoding the received radio signal into a decoded signal, determining a current error level in the decoded signal, predicting a turbo equalization gain based on instantaneous channel information of the radio channel and deciding whether to apply the turbo equalization mode depending on the predicted turbo equalization gain and the determined current error level in the decoded signal.

Inter symbol interference reduction by applying turbo equalization mode

At a node of a wireless network, equalization operations performed on signals received from a transmitter are adaptively switched to be equalized by an iterative turbo receiver or a linear receiver. A theoretical expression of a post-equalization SINR of a capacity-achieving receiver is used to estimate the post-equalization SINR performance of the turbo receiver. The estimated post-equalization SINR performance is then used as a basis to determine whether the received signal is to be equalized by the turbo receiver or the linear receiver.

Adaptively switching equalization operations in a node of a wireless network

A method and base station for forming an OFDM signal from a baseband signal includes a partitioning unit configured to partition a block of baseband signal samples into sub-blocks. A sub-carrier mapper maps the sub-blocks onto adjacent sub-carrier blocks of an OFDM multi-carrier to form corresponding unprefixed OFDM symbols. A cyclic prefix adder adds a cyclic prefix to each mapped sub-block to form prefixed OFDM symbols. Phase compensations force the unprefixed OFDM symbol part of all subsequently up-converted prefixed OFDM symbols to start at the same phase. Up-converters up-convert the phase compensated prefixed OFDM symbols to respective radio frequency bands having center frequencies and bandwidths that preserve the OFDM multi-carrier structure. A combiner combines the up-converted phase compensated prefixed OFDM symbols into an OFDM signal.

Method and base station for orthogonal frequency division multiplexing (OFDM) signal processing

A receiving unit receiving packets of a packet stream having an evaluating unit for comparing the arrival times of the packets to a generated clock signal. The generated clock signal is used in transmitting information carried in the packets from the receiving unit. From the delays, a signal producing unit determines a characteristic delay value, which is characteristic of or typical of the statistical distribution of the delays. This characteristic delay value may be an average of the smallest delays of the distribution of delays for the latest received packets, and is used for adjusting the frequency of the generated clock signal. The average may be calculated or derived from all of the smallest delays of the distribution obtained for a predetermined share of the latest received packets.

Generation of clock signal from received packet stream

The present invention relates to an apparatus for cancellation of electromagnetic interferences (n), including means () for dividing a reference signal (s) into a first and second signal (s, s) having different phases, tow multipliers () for each multiplying a weight coefficient to one of the phase displaced signals (s, s) each and for outputting a multiplied signal each, and adder () for adding the two multiplied signals and for outputting a corrected reference signal (s), and a subtracter () for subtracting the corrected reference signal (s), from an input signal (s) and for outputting an error signal (s). According to the invention different weight coefficients (l(f), Q(f)) are used for different frequencies or frequency bands (f) of the interference (n).

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Älvsjö, Sweden

Tore André