Telefonaktiebolaget Lm Ericsson (publ)

Mats Klingberg

Richard Hellberg

Tony Fonden

Spendim Dalipi

Bo Göransson

Li Wang

Stefan Engström

Andreas Johnsson

Leonard Rexberg

Youping Su

Ola Angelsmark

Rui Hou

Filip Oredsson

Scott Leyonhjelm

Lars Richard Birger Hellberg

Haiying Cao

Joakim Plahn

Tony Fondén

Gerlach Spee

Jin Ellgardt

Rakesh Ranjan

Johan Åman

Björk Vimar

Vimar Bjoerk

Tony FONDÉN

There is provided mechanisms for PIM removal in an antenna system. A method is performed by a controller of the antenna codebook based beamforming, which transmission radio chains of the antenna system that cause a signal received by receiver radio chains of the antenna system to be impacted by PIM. These transmission radio chains are identified based on which codeword in the codebook is used for the beamforming. The method comprises determining a correction signal by subjecting the signals only as transmitted by the identified transmission radio chains to a model of the PIM. The method comprises removing PIM from the signal received by the receiver radio chains by subtracting the correction signal from the signal received by the receiver radio chains.

Removal of passive intermodulation in antenna systems

A method and a network agent for providing cell assignment for a wireless device served by a network node. An input vector is created for a set of candidate cells based on measurements by the wireless device and/or by the network node related to performance and signals. A future effect of assigning the wireless device to a candidate cell is estimated for each candidate cell by applying the created input vector to an effect estimation function which may be a Q-learning function. A cell in the set of candidate cells is then determined and assigned for the wireless device, based on the estimated future effects of the candidate cells. The cell that provides the best future effect may be selected for cell assignment.

Method and network agent for cell assignment

Systems and methods for ultra-wideband Crest Factor Reduction (CFR) are provided. In some embodiments, a method performed by a wireless node for performing CFR includes performing a first CFR step on a plurality of input signals at a first sampling rate with joint peak detection and band-specific noise shaping; and performing a second CFR step on the resulting plurality of input signals at a second sampling rate with joint peak detection and joint noise shaping where the second sampling rate is higher than the first sampling rate. In this way, Peak-to-Average Power Ratio (PAPR) reduction may be increased while the computational complexity is reduced.

Ultra-wideband crest factor reduction

There is disclosed mechanisms for calibrating a homodyne receiver in a signal distribution network for time division duplex; a corresponding method is performed by a baseband calibration module. The method comprises acquiring a transmission signal being input to a homodyne transmitter of the signal distribution network; acquiring, from a heterodyne transmitter observation receiver of the signal distribution network, a first received version of the transmission signal; acquiring, from a homodyne receiver of the signal distribution network, a second received version of the transmission signal; and, calibrating the homodyne receiver using a comparison of the first received version of the transmission signal and the second received version of the transmission signal, using the first received version of the transmission signal as a reference signal, and using the transmission signal as a calibration signal.

Homodyne receiver calibration

An amplifier circuit is disclosed for providing a radio frequency output signal having a variable signal envelope, comprising a main amplifier device and an auxiliary amplifier and a combiner network for combining an output signal from said first amplifier device and a second output signal from said second amplifier device to provide a combined output signal of variable signal envelope to a load, and a signal processing circuit comprising an input and a non-linear processing section to provide at least said second radio frequency output signal with a signal envelope that has a non-linear dependency from an amplitude characteristic of the input signal such that the degree of non-linearity of the non-linear dependency varies dependent on the amount of change per time unit of the amplitude characteristic of the input signal. Further, a method of power amplifying a radio frequency signal having a variable signal envelope is disclosed.

Radio frequency power amplifier circuit and method

A method for compensating signal distortions in multiple transmitting branches entering a composite amplifier.

Method for compensating signal distortions in composite amplifiers

A method for compensating signal distortions in multiple transmitting branches () entering a composite amplifier (). According to the invention the method comprises the steps of: &#x2014;providing (S) one or more input signals (x) to the composite amplifier. &#x2014;observing (S) an output signal (z) from the composite amplifier () for each provided input signal; &#x2014;deriving (S) an error in each output signal (z) by comparing the output signal with an ideal output signal, said error being caused by said signal distortions; &#x2014;deriving (S) the individual contribution from each transmitting branch () to the error by utilizing a composite amplifier model, said composite amplifier model comprising information about the contribution from each constituent amplifier () to the output signal for each provided input signal: &#x2014;compensating the signal distortions in the transmitting branches () accordingly.

A circuit () for use in a transmitter in a base station in a wireless cellular access system, comprising a main line with a first filter () arranged in the main line with an input side () and an output side () in the main line. The circuit additionally comprises a feed forward cancellation loop with a second filter (), the cancellation loop also having an input point () and an output point (). The cancellation loop is connected to the main line with the output point () of the cancelation loop being connected to the main line on the output side () of the first filter (). Suitably, the first filter () i.e. the main line filter, is a bandpass filter.

Feed forward noise reduction in a transmitter

A detuned composite amplifier includes a nonlinear drive function () that has a phase that varies with the composite amplifier output voltage amplitude. The nonlinear drive function () is configured to transform the output voltage transition point of the prior art into an extended output voltage transition region to increase the efficiency of the composite amplifier.

Efficient composite amplifier

The present invention relates to a predistorter for reducing memory effects in RF power amplifiers. The invention also relates to a method for reducing memory effects in RF power amplifiers and to a base station including such a predistorter. A predistorter according to the invention includes first means () for generating a first signal component, which is an estimate of a drain current of said amplifier, which means () for generating said first signal component comprises a linear filter, second means () for generating a second signal component as a function of said first signal component and at least one first gain function; third means () for generating a third signal component as a function of a conjugate of said first signal component and at least one second gain function, and fourth means () for combining at least said second signal component and said third signal component to form an output signal. The output signal from the predistorter is further used as input to the power amplifier, which when amplified reduces the memory effects of the amplifier.

Method and apparatus for reducing frequency memory effects in RF power amplifiers

A radio transmitter with IQ-modulator error compensation includes a homodyne observation receiver () producing a first real baseband (S) signal from a real radio frequency signal (S). A real-value extracting element () and a down-sampler () convert a complex baseband signal (S) into a second real baseband signal. An adapter () determines parameters controlling an IQ-error compensator () by minimizing the error between the two real baseband signals. In a preferred embodiment he transmitter also includes a phase shifter () providing three different phase shifts to compensate for the fact that the homodyne observation receiver produces a real and not a complex signal.

Adaptation of IQ-error compensation

An adaptive predistortion arrangement includes means () for up-converting a baseband signal (S) into an intermediate frequency signal (S) having frequency aliazing and means () for down-converting a radio frequency signal (S) into an intermediate frequency signal (S) having the same frequency aliazing as the up-converted baseband signal. An adapter () adapts predistortion parameters to keep the up-converted baseband signal equal to the down-converted radio frequency signal.

Adaptive predistortion method and arrangement

A multiple input multiple output power amplifier system includes multiple main amplifiers for amplifying corresponding independent input signals. A common control unit forms a composite signal from the independent input signals. The composite signal is amplified by a peaking amplifier and forwarded to an output network where main amplifier output signals are combined with amplified composite signals into multiple power amplifier output signals.

Power amplifier system

A PAMELA-type of composite power amplifier is configured in such a way that a single power amplifier is operated at low output voltage amplitudes by prohibiting a pair of outphasing power amplifiers to produce any current. Preferably, at output voltage amplitudes above the maximum voltage of the single power amplifier is to be reached, the pair of outphasing power amplifiers is taken into operation providing currents phase shifted by substantially 180 degrees. When also the outphasing power amplifiers reach their maximum voltages, an outphasing operation is performed.

Composite power amplifier

A composite amplifier comprises several Chireix pairs (PA, PA; PA, PA) of power amplifiers connected to a common load. Means () are provided for driving each Chireix pair by drive signals having amplitude dependent phase over at least a part of the dynamic range of the composite amplifier . These parts are preferably different for different pairs.

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Enskede, Sweden

Mats Klingberg