CN1163038C

CN1163038C - Phase shifting method for reducing peak-to-average ratio of multiple carrier signal

Info

Publication number: CN1163038C
Application number: CNB011054433A
Authority: CN
Inventors: 璇周; 周璇
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2001-02-27
Filing date: 2001-02-27
Publication date: 2004-08-18
Anticipated expiration: 2021-02-27
Also published as: CN1371203A

Abstract

The present invention relates to a phase staggered method for reducing the peak-average ratio of a multi-carrier signal. Initial phases of all carriers are arranged, and the arrangement times of the iteration are N; multi-carrier compound envelopes are built up by using the initial phases; the multi-carrier compound envelopes are sampled so that a discrete envelope is obtained; a time-domain signal of the discrete envelope carries out the clipping so that a sampling point which carries out the clipping is obtained; the sampling point is used as the input of the discrete fourier transform so as to carry out the discrete fourier transform, and then a fourier frequency spectrum is obtained. A multi-carrier initial phase of which the iteration time is 1 can be obtained by the calculation of the fourier frequency spectrum, the process is repeated until the iteration times are N, and the initial phase is obtained, namely an initial phase to be obtained.

Description

A kind of phase shifting method that reduces the multicarrier signal peak level ratio

Technical field

The present invention relates to a kind of phase shifting method that reduces the multicarrier signal peak level ratio.

Background technology

At present, the main method of the peak-to-average ratio (peak power is to the ratio of average power) of reduction multicarrier composite signal has probability slicing, signal compensation and phase shifting method.Wherein, the probability slicing is realized fairly simple, but because the signal distortion that slicing brings tends to induce one to system spuious.Though signal compensation can not cause the distortion of signal, the transmitting power that induces one to add large-signal of compensating signal.And phase shifting has been avoided above-mentioned defective, and is widely adopted.

Phase shifting method roughly can be divided into two classes, and a class is to be applicable to that constant amplitude equifrequent multi-carrier signal at interval is synthetic, another kind of be applicable to amplitude equifrequent uneven signal is synthetic at interval.

In general, adopt the method for phase shifting to come the compressed signal envelope, the easiest what expect is to find one group of optimum angle group with the method that limit is searched.But it is fewer owing to operand is suitable for carrier number too greatly and only that method is searched in limit, and in the less demanding application of real-time.For solving carrier number phase shifting problem more for a long time, empirical equation (1), empirical equation (2) and semiempirical formula (3) have been drawn from a large amount of experiments.

θ _k＝π(k-1)(k-1)/N (1)

θ _k＝πk·k/N (2)

θ _k＝π(k-1)(k-2)/N (3)

More than various in, θ _kInitial phase for each carrier wave of being used to stagger; N is a carrier number; K is the harmonic number of each carrier wave, for frequency be respectively 1,2,3, the k value of its corresponding each carrier wave of 4...15 is respectively 1,2,3,4...15.

Above-mentioned various phase shifting algorithm is except the equally spaced application conditions restriction of constant amplitude, and its carrier number of effect that staggers that obtain requires big (requiring at tens more than the carrier wave usually).

With respect to the former, change amplitude, the synthetic phase shifting of unequal interval multi-carrier signal are then wanted the many of complexity.Since the ambiguity of oscillation amplitude change and frequency interval, the feasible analytic solutions that are difficult to try to achieve an initial phase, and what therefore adopt usually is iterative algorithm.More representational algorithm has at present: Xia Luoke (Schroeder) method, pareira gram (Patrick) method and temporal frequency domain exchange algorithm.In these three kinds of algorithms, the temporal frequency domain exchange algorithm is because effect is obvious, realizes simple and its main computing that relates to all has fast algorithm and is widely used.

As shown in Figure 1, be the theory diagram of temporal frequency domain exchange algorithm.This algorithm has adopted the thinking of retrodicting, and it finds the solution the initial phase place value of each carrier wave from compression envelope peak this purpose.The initial phase of each carrier wave at first is set, make up fourier spectrum by initial phase and amplitude then, contrary discrete Fourier transform (DFT) (IDFT), obtain time domain waveform, time domain waveform is sampled, and to the time domain waveform signal wave elimination after the sampling, and carry out discrete Fourier transform (DFT) (DFT) again, calculate initial phase.So iterate repeatedly, obtain each the carrier wave initial phase that requires.Here, the scope of slicing can be chosen as former composite signal envelope peaked 75% ~ 95%.Be not easy when cutting very little the convergence, cut then resulting too much phase shifting poor effect.In this algorithm, discrete Fourier transform (DFT) is used for finding the solution the initial phase of each carrier wave.

From above description as can be seen, the main operand of temporal frequency domain exchange algorithm is made up of three parts: discrete Fourier transform (DFT) DFT, contrary discrete Fourier transform (DFT) IDFT and make up fourier spectrum by initial phase and amplitude.Though DFT, IDFT have corresponding fast algorithm, more for a long time, operand is still bigger for sampling number.In addition, in the above algorithm,, to meet the requirements of each carrier wave initial phase by the number of times that increase iterates algorithm like this, therefore increase operand, increase the cost of system simultaneously because the initial phase of each carrier wave is provided with at random.

Summary of the invention

The object of the present invention is to provide a kind of phase shifting method that reduces the multicarrier signal peak level ratio, this method makes system cost reduce by reducing total operand.

The object of the present invention is achieved like this, and a kind of phase shifting method that reduces the multicarrier signal peak level ratio comprises the following steps: to be provided with the initial phase of each carrier wave, and to set iterations be N; Utilize above-mentioned initial phase to make up the synthetic envelope of multicarrier; To the synthetic envelope sampling of multicarrier, obtain discrete envelope; To the time-domain signal slicing of discrete envelope, the sampling point behind the acquisition slicing; With the input of the sampling point behind this slicing as discrete Fourier transform (DFT), carry out discrete Fourier transform (DFT), obtain fourier spectrum; Calculate by fourier spectrum, obtain the initial phase that iterations N equals 1 multicarrier; Repeat said process, when iterations was N, the initial phase that is obtained was the initial phase of being asked.

Owing to adopted above-mentioned method, the fourier spectrum that adopted in the existing phase shifting method made up and two modules of IDFT are used and replaced synthesizing the envelope direct sampling, this improvement can reduce the operand of half, and do not change algorithm effects, and adopt the thickness searching method to obtain a proper initial phase, accelerate to iterate the convergence rate of computing, thereby reduce the total operand in the whole process, the cost that system is realized reduces.

The present invention is further illustrated below in conjunction with embodiment and accompanying drawing.

Description of drawings

Fig. 1 is existing temporal frequency domain exchange algorithm theory diagram;

Fig. 2 is the process block diagram of phase shifting method of the present invention.

Embodiment

As shown in Figure 2, the present invention, that is: a kind of phase shifting method that reduces the multicarrier signal peak level ratio comprises the following steps:

The first step: for any k carrier wave to be combined:

x _i＝A _i(cosw _it+θ _i) (4)

Wherein, i=0,1 ..., k-1.The initial phase θ of each carrier wave at first is set _i, and the setting iterations is N.Wherein, the setting up procedure of the initial phase of each carrier wave is:

A, use randomizer produce M group phase-group at random: [θ ₀ ^j, θ ₁ ^j... θ _K-1 ^j], j=0,1 ..., M-1.Then, in this M phase-group difference substitution formula (4), one group of phase place obtaining synthetic envelope peak minimum is as the result who just searches for.

B, find out in the above k carrier wave one (being made as m carrier wave for sake of convenience here) of energy maximum.And one group of phase value of the above gained of search just, in initial phase substitution (4) formula.

The initial phase θ of c, adjustment carrier wave m _m(adjusting range is 2 π/n, and the adjustment number of times is n), and adjusted phase theta _m ^l(l=0,1, n-1) in difference substitution (4) formula.

D, will adjust ceiling capacity carrier wave m and the synthetic new envelope of other carrier wave behind the initial phase, and obtain corresponding synthetic one group of minimum phase-group of envelope peak.

Second step: utilize above-mentioned one group of initial phase carefully electing to make up the synthetic envelope of multicarrier: y=∑ yi.

The 3rd step:, obtain discrete envelope: z=[z to the synthetic envelope sampling of multicarrier ₀, z ₁..., z _i].

The 4th step: to the time-domain signal slicing of discrete envelope, the sampling point behind the acquisition slicing: z '=[z ₀', z ₁' ..., z _i'].

The 5th step: with the input of the sampling point behind the slicing, carry out discrete Fourier transform (DFT), obtain fourier spectrum: y=[Y as discrete Fourier transform (DFT) ₀, Y ₁..., Y _i].

The 6th step:, can obtain the initial phase that iterations equals 1 multicarrier by calculating: [ψ by fourier spectrum ₀, ψ ₁..., ψ _K-1].

Repeat above-mentioned second and went on foot for the 6th step, when iterations was N, the initial phase that is obtained was the initial phase of being asked.

Claims

1. a phase shifting method that reduces the multicarrier signal peak level ratio is characterized in that, comprises the following steps:

The initial phase of each carrier wave is set, and the setting iterations is N;

Utilize above-mentioned initial phase to make up the synthetic envelope of multicarrier;

To the synthetic envelope sampling of multicarrier, obtain discrete envelope;

To the time-domain signal slicing of discrete envelope, the sampling point behind the acquisition slicing;

With the input of the sampling point behind this slicing as discrete Fourier transform (DFT), carry out discrete Fourier transform (DFT), obtain fourier spectrum;

Calculate by fourier spectrum, obtain the initial phase that iterations N equals 1 multicarrier;

Repeat said process, when iterations was N, the initial phase that is obtained was the initial phase of being asked.