Nokia Corporation

Nokia Networks Oy

Jouko Vankka

Matti Tapani Kiiski

Mauri Honkanen

Timo Viero

Olli Väänänen

The method comprises setting a threshold value, dividing the combined signal into blocks, comparing the values of each block with the set threshold value and if the threshold value is exceeded, decorrelating the block where the threshold value was exceeded and a pre-determined number of channelization codes, which have a pre-determined spreading factor. The decorrelation result is normalized to determine first weighting coefficients. The method also comprises comparing each combination of a first weighting coefficient and a related channelization code with the set objectives and determining second weighting coefficients for the downlink transmissions selected as a result of the comparison. The examined block is re-formed using combinations of the channelization codes and the weighting coefficients that were determined.

Method of limiting signal, and transmitter

Known digital QAM modulators use sine/cosine memories and a plurality of multipliers. This can be avoided by replacing the circuitry which carries out the circular rotation of &lsqb;I(n), Q(n)&rsqb;T performed in all the QAM modulators, with a CORDIC algorithm. The invented QAM modulator is comprised of a plurality of digital rotation stages ( ) coupled in sequence. The first stage ( ) receives the I and Q data streams and the last stage ( ) outputs a vector comprising of the orthogonal I and Q components of a digital intermediate frequency signal. Each of the rotation stages rotates an input vector applied to the stage at a predetermined elementary rotation angle, said input vector being the output vector of the previous digital rotation stage. The modulator further includes an angle computation block ( ) for counting the elementary rotation angles for the rotation stages. The angle computation block is connected to the phase accumulator which receives a frequency control word (F ) and based on that word generates an input word (Z ) applied to the angle computation block.

QAM modulator

Simplifying functions representing raised sine or cosine curves to functions representing simple sine or cosine curves makes it possible to implement an electrical equivalent circuit for a ramp generator. The core of the ramp generator with an output power level controller is second-order direct-form feedback structure ( ), which forms a digital sinusoidal oscillator. The initial values of two state variables x2(n), x2(n&plus;1) of the oscillator are chosen so that they both contain a predetermined first constant value. This first constant value will emerge as the amplitude value of the pure sine wave generated by the oscillator. Particularly the first constant value is equal to the desired nominal level A of the ramp minus the starting level. A second constant value (A&plus;dc) is added to the oscillator output. The added result is scaled ( ) so that the nominal power level is A. A multiplexer ( ) keeps the power level between the ramps constant.

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Helsinki, Finland

Jouko Vankka