Telefonaktiebolaget Lm Ericsson (Publ)

Lars Richard Birger Hellberg

Mats Klingberg

Tony Fonden

A non-linear processing device () is presented, in which fractional-delay filtering ()&#x2014;fractional as compared with a sample rate used in the processing steps&#x2014;is used between successive processing steps (). A corresponding method is also presented. The fractional delay () exposes the signal in-between the original samples to the non-linear processing (). A lower sample rate or a higher signal quality can thus be achieved. The so-called fractional sample delays are preferably chosen differently for different systems depending on bandwidths, number of channels, number of non-linear processing steps () and other varying factors. The multi-step non-linear processing () concept of the invention is preferably used within a cascade of non-linear modifications and/or filtering steps ().

Multi-step non-linear time-discrete processing

In a non-linear processing system, the main non-linear processing and filtering is performed with low precision in a separate branch. A low-precision version () of the input signal () is created in an extractor (), which is processed non-linearly in a low-precision non-linear processing unit () under constraints put on the non-linear processing. Quantisation errors or other artefacts, created by the use of low precision signals are finally removed by a precision restoring processing in a precision restoring unit () using the full-precision signal ().

Non-linear processing of signals

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 linear power amplifier amplifies a linear baseband signal having I and Q components. An up-converting mixer uses optically activated switches to mix the amplified baseband signal with a local oscillator signal at specified carrier frequency. The optically activated switches are activated according to a switching sequence that produces a constant impedance over each carrier frequency cycle. In this way, the optically activated switches prevents introduction of non-linearities during the up-conversion process.

Linear RF power amplifier with optically activated switches

A radio receiver converts an original frequency of a modulated received signal into a plurality of digitization frequencies and digitizes the modulated received signal at each one of the plurality of digitization frequencies. The receiver determines a plurality of reception quality measures associated with each one of the digitized modulated received signals at each one of the plurality of digitization frequencies. The receiver demodulates the modulated received signal using a digitized modulated signal at a digitization frequency that provides a better reception quality than those of another digitization frequency.

Radio receiver that digitizes a received signal at a plurality of digitization frequencies

The present invention relates generally to the problem of filtering, decimation or interpolation and frequency conversion in the digital domain, and more particularly to the use of the stand-alone or improved modified fast convolution algorithm in wideband multichannel receiver, channelization, and transmitter, de-channelization, structures of a radio communication system. The invention consists of essentially 3 steps: making sure that we use different overlaps on consecutive blocks that, on average, give the same overlap on both the input and output ends; aligning the signal in consecutive blocks of time; and compensating for phase shifts due to frequency shifting. The essence of the invention is that it decouples the input and output transform lengths in the fast convolution algorithm from each other and from the overlap, making it possible to use any transform length on the input together with any transform length on the output and at the same time use any overlap. This provides an enormous amount of freedom compared with the limitations of state of the art.

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Huddinge, Sweden

Lars Richard Birger Hellberg