CN104363195A - Carrier wave injection peak-to-average ratio restraining method based on sequence search - Google Patents

Abstract

The invention discloses a carrier wave injection peak-to-average ratio restraining method based on sequence search. The method includes the steps of firstly, determining the carrier wave search sequence according to the signal adjustment information included in a non-linear distortion frequency domain signal; secondly, obtaining disturbance adjustment signals on all sub-carrier-waves respectively through the constellation point/carrier wave one-dimensional step-by-step search. The method has the advantages that by determining the carrier wave search sequence, the existing search problem based on the two-dimensional combination of constellation points and carriers waves is simplified into a constellation point/carrier wave one-dimensional step-by-step search problem, and therefore the exponential change mode in which the ideal carrier wave inject complexity changes according to the number of the carrier waves shrinks into the linear change mode in which the ideal carrier wave injection complexity changes according to the number of the carrier waves, the complexity of the algorithm is greatly lowered, the real-time performance of the algorithm is improved, and the good compromise between the peak-to-average ratio restraining performance and the complexity is achieved.

Description

Based on the carrier signal injection method for suppressing peak to average ratio of sequential search

Technical field

The present invention relates to a kind of carrier signal injection method for suppressing peak to average ratio, be specifically related to a kind of carrier signal injection method for suppressing peak to average ratio based on sequential search, belong to wireless communication technology field.

Background technology

OFDM (Orthogonal Frequency Division Multiplexing, OFDM) technology is because of its spectral efficient, the strong plurality of advantages such as ability of anti-multipath and low complex degree, is extensively adopted as the physical layer standard of various wireless communication system.But a major defect of this technology is exactly that signal peak-to-average power power ratio (Peak-to-Average Power Ratio, PAPR) is excessive.When signal peak exceedes linearity of amplifier working range, can nonlinear distortion be produced, reduce systematic function.Therefore, must process ofdm signal, reduce signal peak-to-average ratio.

Existing peak-to-average force ratio suppression technology comprises Choose for user sequence (Selective Mapping, SLM), partial transmission sequence (Partial Transmission Sequence, PTS), peak clipping technology (Clipping), companding transform technology (Companding), Tone reservation technology (Tone Reservation, TR), constellation extension technology (Active Constellation Extension, and carrier signal injection technology (Tone Injection, TI) etc. ACE).Carrier signal injection technology is not owing to producing distorted signals and receiving extensive concern without the need to transmitting side information.Desirable carrier signal injection technology realizes ofdm signal peak-to-average force ratio by poor search and suppresses, and its complexity exponentially changes with OFDM carrier number.Therefore, a shortcoming of desirable carrier signal injection technology is exactly that algorithm complex is too high, and poor real is infeasible in actual applications.

Summary of the invention

Spending high problem for solving existing carrier signal injection technical sophistication, the object of the present invention is to provide a kind of carrier signal injection method for suppressing peak to average ratio based on ordered search of low complex degree.

In order to realize above-mentioned target, the present invention adopts following technical scheme:

Based on a carrier signal injection method for suppressing peak to average ratio for ordered search, it is characterized in that, comprise the following steps:

(1) level A is cut, original OFDM signal x according to the input back-off determination soft limiting amplifier of soft limiting amplifier _nlimitation signal is obtained through soft limiting amplifier with distorted signal c _n;

(2) to distorted signal c _ncarry out FFT conversion and obtain frequency domain distortion signal to the amplitude of frequency domain distortion signal carry out arrangement according to descending and obtain corresponding carrier index collection Σ={ k ₍₀₎, k ₍₁₎..., k _(N-1), N is number of sub carrier wave;

(3) initialization iterations and iteration signal, suppose t=0, setting iterations T=N;

(4) in equivalent constellation point sets Ω, the distracter of equivalent constellation point to original constellation point is searched for 1≤i≤8, successively to carrier index k _(t)corresponding carrier signal disturb, find the distracter making current PAPR minimum following formula is utilized to obtain corresponding TI signal

${\stackrel{\‾}{x}}_n^t=\frac{1}{\sqrt{\mathrm{LN}}}(X_{k_{\left(t\right)}}+U_{k_{\left(t\right)}}^{*})e^{i2\mathrm{\π}\frac{k_{\left(t\right)}}{\mathrm{LN}}n}+\frac{1}{\sqrt{\mathrm{LN}}}\underset{k\≠k_{\left(t\right)}}{\overset{N-1}{\underset{k=0}{\mathrm{\Σ}}}}{X}_k{e}^{i2\mathrm{\π}\frac{k}{\mathrm{LN}}n};$

(5) t=t+1, detects iterations t and whether reaches maximum threshold,

If iterations t does not reach maximum threshold, then return step (4);

If iterations t reaches maximum threshold, then algorithm stops.

Usefulness of the present invention is:

1, the present invention is by determining searching carrier order, to be originally a constellation point/carrier wave one dimension substep search problem based on constellation point and carrier wave two dimension Syndicating search problem reduction, thus the complexity that desired carrier injects linearly is changed from being reduced into carrier number index variation with carrier number, greatly reduce the complexity of algorithm, improve the real-time of algorithm, achieve the good compromise between PAPR and complexity;

2, the more existing method of the present invention has less transmit signal power amplification.

Accompanying drawing explanation

Fig. 1 is the main flow figure of method of the present invention;

Fig. 2 is the constellation extension schematic diagram that method of the present invention uses;

Fig. 3 is method of the present invention Simulation on PAPR design sketch under different iterations condition.

Embodiment

Carrier signal injection method for suppressing peak to average ratio based on ordered search of the present invention, with reference to Fig. 1, first the signal adjustment information that nonlinear distortion frequency-region signal comprises is utilized, determine searching carrier order, then by adopting the interference that constellation point/search of carrier wave one dimension substep obtains on each subcarrier respectively to adjust signal, thus the complexity of algorithm is reduced.

Below in conjunction with the drawings and specific embodiments, concrete introduction is done to the present invention.

The constellation extension schematic diagram that method of the present invention uses as shown in Figure 2.

In the present embodiment, by basic constellation is obtained corresponding constellation extension to external expansion one circle, the equivalent constellation point sets number of such basic constellation point is 8.The input back-off IBO=4dB of soft limiting amplifier, soft limiting amplifier cut level A=σ _s10 ^iBO/20, σ _sfor average power signal.The system modulation sub-carrier number N=256 of OFDM.

The step that method for suppressing peak to average ratio of the present invention realizes is as follows:

(1) level A is cut, original OFDM signal x according to the input back-off determination soft limiting amplifier of soft limiting amplifier _nlimitation signal is obtained through soft limiting amplifier with distorted signal c _n.

(2) to distorted signal c _ncarry out FFT conversion and obtain frequency domain distortion signal to the amplitude of frequency domain distortion signal carry out arrangement according to descending and obtain corresponding carrier index collection Σ={ k ₍₀₎, k ₍₁₎..., k _(N-1), N is number of sub carrier wave.

(3) initialization iterations and iteration signal, suppose t=0, setting iterations T=N.

(4) in equivalent constellation point sets Ω, the distracter of equivalent constellation point to original constellation point is searched for 1≤i≤8, successively to carrier index collection k _(t)corresponding carrier signal disturb, find the distracter making current PAPR minimum following formula is utilized to obtain corresponding TI signal

${\stackrel{\‾}{x}}_n^t=\frac{1}{\sqrt{\mathrm{LN}}}(X_{k_{\left(t\right)}}+U_{k_{\left(t\right)}}^{*})e^{i2\mathrm{\π}\frac{k_{\left(t\right)}}{\mathrm{LN}}n}+\frac{1}{\sqrt{\mathrm{LN}}}\underset{k\≠k_{\left(t\right)}}{\overset{N-1}{\underset{k=0}{\mathrm{\Σ}}}}{X}_k{e}^{i2\mathrm{\π}\frac{k}{\mathrm{LN}}n}.$

(5) t=t+1, detects iterations t and whether reaches maximum threshold,

If iterations t does not reach maximum threshold, then return step (4);

If iterations t reaches maximum threshold, then algorithm stops.

The beneficial effect that method of the present invention is brought can be described further by following emulation.

One, simulated conditions

OFDM modulation sub-carrier number is N=256, over-sampling multiple L=4, and the modulation system that transmits is QPSK, and the input back-off of soft limiting amplifier is set to IBO=4dB.The weighing vector number of SLM method is respectively U=52 and U=12.The number of samples of CE-TI method is respectively S=320 and S=160.

Two, content and simulation result is emulated

Emulation 1, method of the present invention is adopted to carry out Simulation on PAPR respectively under iterations T=N/4, N/8, N/16 and N/32 condition, and by the PAPR of the inventive method and Choose for user sequence (SLM) method and compare based on the PAPR of carrier signal injection (CE-TI) method of cross entropy.

Simulation result: as shown in Figure 3, by reducing iterations, method of the present invention also can obtain good peak-to-average force ratio inhibition.Further, when iterations is enough large, the PAPR of the inventive method is better than other method.

Emulation 2, adopt method of the present invention to carry out Simulation on PAPR respectively under iterations T=N/4 and N/16 condition, and the PAPR of the inventive method, complexity and transmit signal power amplification are compared with SLM method and CE-TI method.

Simulation result: as shown in table 1, when the complexity of the inventive method and SLM method is suitable, the PAPR of the inventive method is better than SLM method.Meanwhile, the inventive method is all better than CE-TI method in peak-to-average force ratio suppression, complexity and transmitting power amplification.

Table 1 simulation result contrasts

As can be seen here, method of the present invention can obtain the good compromise between PAPR and complexity.

It should be noted that, above-described embodiment does not limit the present invention in any form, the technical scheme that the mode that all employings are equal to replacement or equivalent transformation obtains, and all drops in protection scope of the present invention.

Claims (1)

1., based on the carrier signal injection method for suppressing peak to average ratio of ordered search, it is characterized in that, comprise the following steps:

(1) level A is cut, original OFDM signal x according to the input back-off determination soft limiting amplifier of soft limiting amplifier _nlimitation signal is obtained through soft limiting amplifier with distorted signal c _n;

(2) to distorted signal c _ncarry out FFT conversion and obtain frequency domain distortion signal to the amplitude of frequency domain distortion signal carry out arrangement according to descending and obtain corresponding carrier index collection Σ={ k ₍₀₎, k ₍₁₎..., k _(N-1)n is number of sub carrier wave;

(3) initialization iterations and iteration signal, suppose t=0, setting iteration sum T=N;

(4) in equivalent constellation point sets Ω, the distracter of equivalent constellation point to original constellation point is searched for 1≤i≤8, successively to carrier index k _(t)corresponding carrier signal disturb, find the distracter making current PAPR minimum following formula is utilized to obtain corresponding TI signal

${\stackrel{\‾}{x}}_n^t=\frac{1}{\sqrt{\mathrm{LN}}}(X_{k_{\left(t\right)}}+U_{k_{\left(t\right)}}^{*})e^{i2\mathrm{\π}\frac{k_{\left(t\right)}}{\mathrm{LN}}n}+\frac{1}{\sqrt{\mathrm{LN}}}\underset{\underset{k\≠k_{\left(t\right)}}{k=0}}{\overset{N-1}{\mathrm{\Σ}}}{X}_k{e}^{i2\mathrm{\π}\frac{k}{\mathrm{LN}}n},$

(5) t=t+1, detects iterations t and whether reaches maximum threshold,

If iterations t does not reach maximum threshold, then return step (4);

If iterations t reaches maximum threshold, then algorithm stops.