CN1510855A - Improved PTS method - Google Patents

Abstract

An improved PTS method, in the module 6 for threshold comparison and selection, preset a threshold, compare the relevant data PAPR of phase factor of m cluster with this thresholds one by one, once the data PAPR is lower than or equal the threshold, the phase factor corresponding to this data becomes the side information of second-best phase factor, make this second-best phase factor doing multiplication, overlap, output with each relevant group of data, meanwhile output the side information about second-best phase factor. Adopting this communication method either can reduce the ratio between the peak power of the signal and average power, or decrease the complexity of calculation.

Description

A kind of new improvement PTS method

Technical field

The invention belongs to communication technical field, particularly orthogonal frequency division multiple access system.

Background technology

As everyone knows, in the existing communication technology, OFDM (Orthogonal Frequency DivisionMultiplexing, abbreviation OFDM) technology declines and interference free performance with its very high availability of frequency spectrum, good anti-multipath, becomes one of main candidate technologies of following mobile multimedia communication.

Ofdm signal has peak power and average power ratio (Peak-to-average Power, be called for short PAPR) higher shortcoming, to non-linear very sensitive, this has the very big range of linearity with regard to the high power amplifier that requires transmitter, but, than the power device of great dynamic range, mean higher cost.And, behind the linear unit of the ofdm signal that surpasses linear dynamic range, can produce significant inband distortion and out-of-band radiation, thereby cause the error rate to raise by power amplifier and so on.

Partial transmission sequence (Partial Transmit Sequences, be called for short PTS) rule is to reduce a kind of common method of ofdm signal PAPR, its operation principle as shown in Figure 1: in grouping module 1, data point is divided into V group: A ⁽¹⁾, A ⁽²⁾A ⁽ⁱ⁾A ^(V)(i=1,2,3 ... V), each group is carried out IFFT by module I FFT 2, and gained is respectively organized data and many bunches of phase factors ${\mathrm{\α}}_j^{\left(1\right)},{\mathrm{\α}}_j^{\left(2\right)}\·\·\·{\mathrm{\α}}_j^{\left(i\right)}\·\·\·{\mathrm{\α}}_j^{\left(V\right)}$ (i-1,2,3 ... V, j=1,2,3 ... U, wherein U represents that the phase factor corresponding with every group of data has the U kind to select, and therefore has U at most ^VBunch phase factor is available) multiply each other by multiplier 3.Each group is selected the PAPR minimal data by adder 4 stacks in relatively selecting module 5 then, and Dui Ying cluster phase factor is the optimum angle factor with it.The optimum angle factor and the corresponding data of respectively organizing are multiplied each other, and stack is exported, and exports the secondary information of the relevant optimum angle factor simultaneously.Detailed content is seen S.H.M ü ller and J.B.Huber, " OFDM with reducedpeak-to-average power ratio by optimum combination of partial transmit sequences; " Electron.Lett., vol.33, pp.368-369, Feb.1997.

The major defect of existing P TS method is: need (m represents the number of clusters of used phase factor in the system work process, m≤U as can be known to m ^V) bunch phase factor carries out corresponding computing respectively, computation complexity is higher.

Summary of the invention

Task of the present invention provides a kind of new improvement PTS method, adopts method of the present invention, can reduce the computational complexity of PTS method effectively.

Schematic diagram of the present invention: comprise that grouping 1, IFFT 2, multiplier 3, adder 4, thresholding relatively select modules such as 6, as shown in Figure 2.

The course of work of the present invention: as shown in Figure 2, data point is divided into V group: A through grouping module 1 ⁽¹⁾, A ⁽²⁾A ⁽ⁱ⁾A ^(V)(i=1,2,3 ... V), each group is carried out IFFT 2 respectively, and gained is respectively organized data and many bunches of phase factors ${\mathrm{\α}}_j^{\left(1\right)},{\mathrm{\α}}_j^{\left(2\right)}\·\·\·{\mathrm{\α}}_j^{\left(i\right)}\·\·\·{\mathrm{\α}}_j^{\left(V\right)}$ (i=1,2,3 ... V, j=1,2,3 ... U) multiply each other by multiplier 3.Each group is by adder 4 stacks then, and above process is identical with traditional PTS method.Module 6 is innovative contents of the present invention, relatively select in 6 at thresholding, predetermined thresholding, PAPR and this thresholding of m bunch of phase factor corresponding data are compared one by one, be less than or equal to thresholding in case the PAPR of data occurs, the phase factor of this data correspondence is the suboptimum phase factor so, and suboptimum phase factor respectively organize data corresponding with it are multiplied each other, superpose, export; Export the secondary information of relevant suboptimum phase factor simultaneously; If after m time is selected relatively, the data that PAPR is lower than thresholding do not occur, the cluster phase factor of so just selecting PAPR minimal data correspondence is the suboptimum phase factor, this bunch phase factor and the corresponding data of respectively organizing are multiplied each other, superpose, export, export the secondary information of relevant suboptimum phase factor simultaneously: the processing method of this moment and conventional P TS method shown in Figure 1 are identical.

Before setting forth the inventive method, at first introduce term used among the present invention:

1) phase factor α _j(j=1,2,3 ... U) be a plural number, and satisfy two conditions: (1) | α _j|=1; (2) suppose that mapping set is C, for data point b _k∈ C has (b _k* α _j) ∈ C.

2) thresholding is meant the value of determining according to the concrete needs of system.

3) the optimum angle factor is meant the corresponding cluster phase factor of PAPR minimal data in the conventional P TS method.The suboptimum phase factor is meant the cluster phase factor of relatively selecting the back to determine through thresholding in the present invention.

4) secondary information is meant the information that contains selected phase factor (selecteed phase factor is the optimum angle factor in conventional P TS method, and selecteed in the present invention phase factor is the suboptimum phase factor) content.

5) PAPR is the ratio of the peak power and the average power of signal, and the PAPR computational methods of ofdm signal are as follows: supposing the system has N subcarrier, and S (1), S (2) are arranged in the OFDM symbol ... S (N) number pick point, then this moment

PAPR is expressed as: $10\lg \frac{\underset{0\&le;k<N}{\max }{\left|S\left(k\right)\right|}^2}{\frac{1}{N}\underset{i=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\left|S\left(i\right)\right|}^2}---\left(\mathrm{dB}\right)$

The method of improvement PTS of the present invention is: predetermined thresholding, PAPR and this thresholding of m bunch of phase factor corresponding data are compared one by one, be less than or equal to thresholding in case the PAPR of data occurs, the phase factor of this data correspondence is the suboptimum phase factor so, and suboptimum phase factor respectively organize data corresponding with it are multiplied each other, superpose, export; Export the secondary information of relevant suboptimum phase factor simultaneously.

Need to prove, if after m time is selected relatively, the data that PAPR is lower than thresholding do not occur, the cluster phase factor of so just selecting PAPR minimal data correspondence is suboptimum phase factor (the suboptimum phase factor of this moment is equivalent to the optimum angle factor that obtained by conventional P TS method), this bunch phase factor and the corresponding data of respectively organizing are multiplied each other, superpose, export, export the secondary information of relevant suboptimum phase factor simultaneously: the processing method of this moment and conventional P TS method shown in Figure 1 are identical.

The workflow of the inventive method as shown in Figure 3.

Conclusion: in sum, the method for this new improvement PTS had both reduced the ratio of peak power and average power on the basis of original PTS method, had reduced the complexity of calculating again.

Innovative point of the present invention: existing P TS method, in signal peak power and the reduction of average power ratio, computation complexity is higher.The present invention has proposed the method for a kind of new improvement PTS to this, near signal peak power and average power ratio being controlled at thresholding in, effectively reduce computation complexity.

Essence of the present invention: predetermined thresholding, PAPR and this thresholding of m bunch of phase factor corresponding data are compared one by one, be less than or equal to thresholding in case the PAPR of data occurs, the phase factor of this data correspondence is the suboptimum phase factor so, and suboptimum phase factor respectively organize data corresponding with it are multiplied each other, superpose, export; Export the secondary information of relevant suboptimum phase factor simultaneously; If after m time is selected relatively, the data that PAPR is lower than thresholding do not occur, the cluster phase factor of so just selecting PAPR minimal data correspondence is the suboptimum phase factor, this bunch phase factor and the corresponding data of respectively organizing are multiplied each other, superpose, export, export the secondary information of relevant suboptimum phase factor simultaneously: the processing method of this moment and conventional P TS method shown in Figure 1 are identical.

Project Realization of the present invention is compared with conventional P TS method, the characteristics that have are: predetermined thresholding, PAPR and this thresholding of m bunch of phase factor corresponding data are compared one by one, be less than or equal to thresholding in case the PAPR of data occurs, the phase factor of this data correspondence is the suboptimum phase factor so, and suboptimum phase factor respectively organize data corresponding with it are multiplied each other, superpose, export; Export the secondary information of relevant suboptimum phase factor simultaneously; If after m time is selected relatively, the data that PAPR is lower than thresholding do not occur, the cluster phase factor of so just selecting PAPR minimal data correspondence is the suboptimum phase factor, this bunch phase factor and the corresponding data of respectively organizing are multiplied each other, superpose, export, export the secondary information of relevant suboptimum phase factor simultaneously: the processing method of this moment and conventional P TS method shown in Figure 1 are identical.This new improvement PTS method had both reduced PAPR, had reduced computation complexity again.

Description of drawings

Fig. 1 is the fundamental diagram of conventional P TS method:

Wherein, the 1st, grouping module, the 2nd, the IFFT module, the 3rd, multiplier module, the 4th, addition module, the 5th, relatively select module.

A ⁽¹⁾, A ⁽²⁾A ^(V)Be respectively 1,2 ... the set of data points of V group, ${\mathrm{\&alpha;}}_j^{\left(1\right)},{\mathrm{\&alpha;}}_j^{\left(2\right)}\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{\&alpha;}}_j^{\left(V\right)}$ Expression is corresponding to 1,2 ... the phase factor of V group, j=1 wherein, 2,3 ... U; $\widetilde{{\mathrm{\&alpha;}}_j^{\left(1\right)}},\widetilde{{\mathrm{\&alpha;}}_j^{\left(2\right)}}\&CenterDot;\&CenterDot;\&CenterDot;\widetilde{{\mathrm{\&alpha;}}_j^{\left(V\right)}}$ Expression through optimized choice obtain corresponding to 1,2 ... the optimum angle factor of V group, j=1 wherein, 2,3 ... U;

Fig. 2 is the fundamental diagram of the improvement PTS method that proposes of the present invention:

Wherein, the 1st, grouping module, the 2nd, the IFFT module, the 3rd, multiplier module, the 4th, addition module, the 6th, thresholding is relatively selected module.

A ⁽¹⁾, A ⁽²⁾A ^(V)Be respectively 1,2 ... the set of data points of V group, ${\mathrm{\&alpha;}}_j^{\left(1\right)},{\mathrm{\&alpha;}}_j^{\left(2\right)}\&CenterDot;\&CenterDot;\&CenterDot;{\mathrm{\&alpha;}}_j^{\left(V\right)}$ Expression is corresponding to 1,2 ... the phase factor of V group, j=1 wherein, 2,3 ... U; $\widehat{{\mathrm{\&alpha;}}_j^{\left(1\right)}},\widehat{{\mathrm{\&alpha;}}_j^{\left(2\right)}}\&CenterDot;\&CenterDot;\&CenterDot;\widehat{{\mathrm{\&alpha;}}_j^{\left(V\right)}}$ Expression through thresholding relatively select to obtain corresponding to 1,2 ... the suboptimum phase factor of V group, j=1 wherein, 2,3 ... U;

Fig. 3 is a workflow diagram of the present invention.

Embodiment

Main innovation of the present invention is predetermined thresholding, will compare one by one with the PAPR and the thresholding of m bunch of phase factor corresponding data, selects the suboptimum phase factor thus.Thresholding relatively selects module 6 to realize by the method for programming, utilizes prior art can be made into relevant hardware, then, unites other modules, forms whole system of the present invention.

Claims (2)

1, a kind of new improvement PTS method, it is characterized in that it comprises: predetermined thresholding, PAPR and this thresholding of m bunch of phase factor corresponding data are compared one by one, be less than or equal to thresholding in case the PAPR of data occurs, the phase factor of this data correspondence is the suboptimum phase factor so, and suboptimum phase factor respectively organize data corresponding with it are multiplied each other, superpose, export; Export the secondary information of relevant suboptimum phase factor simultaneously.

2, a kind of new improvement PTS method according to claim 1 is characterized in that described PAPR thresholding can be definite according to the concrete needs of system.

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