US 8,150,324 B2 · Method and system for clipping a baseband input signal

Abstract

A method for clipping a baseband input signal filters the complex baseband input signal with a function H1 for forming a filtered first signal. To form a clipped signal in the baseband the filtered first signal is multiplied by a scaling factor. By a signal analysis of the filtered first signal signal overshoots are predicted from which the scaling factor is determined for the baseband clipping. The filter function H1 is calculated as the quotient from a frequency response HS of a transmission filter used one the one hand and from an error frequency response HF on the other hand, with the error frequency response HF being determined in such a way that the error spectrally shaped with HF, which arises for the limitation of the baseband signal, a frequency-dependent tolerance is not exceeded. Subsequently the clipped signal is filtered with the error frequency response HF for forming a filtered second signal.

Claims19

Dependent claims

A method of clipping a baseband input signal, the method comprising:

filtering a baseband input signal with a filter function Hi(f) to yield a filtered first signal;
calculating a scaling factor, the scaling factor being derived from overshoots in magnitude of the filtered first signal over a threshold c;
multiplying the filtered first signal by the scaling factor to yield a clipped signal;
and filtering the clipped signal with an error frequency response HF(f) to yield a spectrally shaped clipped second signal wherein the method is executed in a multicarrier transmission system and a clipped second signal is formed from each baseband signal thereof,
wherein each clipped second signal is converted by modulation into an intermediate frequency range, wherein the modulated intermediate-frequency signals are assembled into a summation signal to be clipped, and
wherein the clipped summation signal is converted by modulation into a carrier-frequency output signal.

3 more elements

An apparatus for clipping a baseband input signal, comprising:

a first filter filtering the baseband input signal with a filter function Hi(f) to yield a filtered first signal;
a prediction unit determining a scaling factor from overshoots in magnitude of the filtered first signal over a threshold c;
a baseband clipping device yielding a clipped signal by multiplying the filtered first signal, after the filtered first signal is delayed, with the scaling factor;
and
a second filter filtering the clipped signal with an error frequency response HE(f) to yield a spectrally shaped clipped second signal, wherein an output side of the first filter is connected to the baseband clipping device and the prediction unit,
wherein an output side of the baseband clipping device is connected to the second filter, and wherein the filter function Hi(f) is determined as a quotient of a frequency response Hs(f) of a transmit filter and the error frequency response HF(f), the error frequency response HF(f) being determined such that the error spectrally shaped with HE(f), which arises during the limiting of the baseband signal, a frequency-dependent tolerance is not exceeded wherein the apparatus is in a multicarrier transmission system and a clipped second signal is assigned to each baseband signal,
wherein each clipped second signal is delivered to a modulator input and used to yield a modulated intermediate frequency signal, wherein the modulated intermediate frequency signals reach a summation device which combines them into a summation signal, wherein the summation signal is delivered to an intermediate frequency clipping unit, and wherein the clipped summation signal is delivered to a modulator for forming a carrier-frequency output signal.

4 more elements

Dependencies are inferred from the claim text.

Method and system for clipping a baseband input signal

Life of this patent

Method and system for clipping a baseband input signal

Life of this patent

Abstract

Claims19