Peak-to-average power ratio suppression method based on DFT-S-OFDM-CC-TR joint algorithm

Abstract

The invention belongs to the technical field of wireless communication, and particularly relates to a peak-to-average power ratio suppression method based on a DFT-S-OFDM-CC-TR joint algorithm, which comprises the following steps of: 1, forming a DFT-S-OFDM signal, obtaining frequency domain data of the signal by using DFT, and obtaining the DFT-S-OFDM signal through a subcarrier distribution module; and 2, introducing a CC-TR algorithm, gradually optimizing the amplitude distribution of the signal by utilizing multiple iterations of a plurality of peak values, and reducing the peak values in the signal to the maximum extent, thereby reducing the PAPR. A DFT module and a subcarrier distribution module are introduced at a signal sending end to generate a DFT-S-OFDM signal, the DFT-S-OFDM signal is substantially a single-carrier signal, the PAPR of the DFT-S-OFDM signal is lower due to the single-carrier characteristic of the DFT-S-OFDM signal, a CC-TR algorithm is introduced when the DFT-S-OFDM signal enters an IFFT module, and different from a traditional peak clipping algorithm, the CC-TR algorithm adopts a parallel processing mode, so that the PAPR of the DFT-S-OFDM signal is reduced; and a plurality of peak values can be processed at the same time. According to the parallel computing mode, the gradients of a plurality of peak values can be computed at the same time, and the PAPR can be effectively suppressed through multiple iterations.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a peak-to-average power ratio suppression method based on a DFT-S-OFDM-CC-TR joint algorithm. Background Art

[0002] In wireless communications, OFDM signals, as an important form of transmission, need to be converted into analog signals by RF chips before they can be transmitted into the air for wireless transmission. In this process, in order to ensure that the signal has sufficient strength so that it can be successfully received by the receiving end, the signal usually needs to be amplified. However, there is a significant problem with OFDM signals, that is, it has an excessively high peak-to-average power ratio. When amplifying such a high PAPR OFDM signal, the signal can easily enter the nonlinear region due to the limited dynamic range of the power amplifier. Once entering this region, nonlinear distortion will inevitably occur, which will cause the integrated signal to be distorted, seriously affecting the signal quality and transmission accuracy, and bringing negative effects to the performance of the entire integrated system.

[0003] Therefore, we propose a peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm to solve the above problems. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides a peak-to-average power ratio suppression method based on a DFT-S-OFDM-CC-TR joint algorithm, which solves the problems raised in the above background technology.

[0006] (II) Technical solution

[0007] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0008] A peak-to-average power ratio suppression method based on a DFT-S-OFDM-CC-TR joint algorithm comprises the following steps:

[0009] Step 1: Form a DFT-S-OFDM signal, use DFT to obtain the frequency domain data of the signal, and obtain the DFT-S-OFDM signal through a subcarrier allocation module;

[0010] Step 2: Introduce the CC-TR algorithm, which uses multiple iterations of multiple peaks to gradually optimize the amplitude distribution of the signal and minimize the peaks in the signal, thereby reducing the PAPR;

[0011] Step 3: Check the suppression effect of the joint algorithm, and determine whether it is necessary to perform iterative operations again based on the results, and update the number of iterations.

[0012] Furthermore, the specific method of step 1 is:

[0013] When the modulated data completes the serial-to-parallel conversion, it will enter the DFT link, and after performing M-point DFT, the frequency domain data of M points will be obtained, where M is the number of subcarriers assumed to be allocated to the user. The output of DFT is then allocated to subcarriers to allocate them to N subcarriers (M>N). After that, the allocated data is transformed by N-point IFFT to obtain time domain data. The time domain data is then converted from parallel to serial, and a cyclic prefix (CP) is inserted to finally generate a DFT-S-OFDM signal.

[0014] Furthermore, in step 1, there are two main types of subcarrier allocation methods, one of which is centralized subcarrier allocation and the other is distributed subcarrier allocation. The former is completed by continuously arranging M-point DFTs in the entire frequency band, and each point is closely connected, while the latter arranges M-point DFTs in a discrete manner, requiring that there must be a corresponding distance interval between each point. In particular, when the output of the discrete Fourier transform (DFT) algorithm can be equally spaced to the input of the inverse fast Fourier transform (IFFT) in the manner of N / M=S, this situation is called interleaved subcarrier allocation.

[0015] Furthermore, the specific method of step 2 is:

[0016] First, OFDM subcarriers are divided into effective subcarriers and blank subcarriers. Effective subcarriers carry original information, while blank subcarriers are not used for information transmission. Next, the original signal waveform is clipped, and the signal obtained after the peak clipping is reloaded on the blank subcarrier. Then, the original data and the clipped data are superimposed to obtain a signal waveform with a reduced peak-to-average ratio.

[0017] Furthermore, in step 2, after completing a peak clipping process, it is necessary to analyze the peak clipping result. If it is necessary to continue the peak clipping operation, the number of iterations must be updated before continuing the peak clipping process.

[0018] Furthermore, the specific method in step 3 is:

[0019] The DFT-S-OFDM precoding operation is performed on the initial signal, and the CC-TR peak clipping processing is performed on the signal obtained after the precoding processing to test the effectiveness of PAPR suppression. Based on the results obtained, it is determined whether it is necessary to perform the iteration operation again and the number of iterations is updated.

[0020] (III) Beneficial effects

[0021] Compared with the prior art, the present invention provides a peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm, which has the following beneficial effects:

[0022] (1) Compared with OFDM signals, DFT-S-OFDM is essentially a single-carrier signal, and its transmission rate is still similar to OFDM. Both have the characteristics of high-speed transmission. Due to the single-carrier feature of DFT-S-OFDM, its PAPR becomes lower, making it used in both LTE and 5G systems.

[0023] (2) Unlike traditional peak clipping algorithms, the CC-TR algorithm uses parallel processing to process multiple peaks at the same time. This parallel computing method can not only calculate the gradients of multiple peaks at the same time, but also effectively suppress the PAPR through multiple iterations.

[0024] (3) Compared with the single peak-to-average ratio reduction algorithm, the combined algorithm improves the peak-to-average ratio suppression capability and efficiency of the algorithm to a great extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic flow chart of a peak-to-average power ratio suppression method based on a DFT-S-OFDM-CC-TR joint algorithm implemented in the present invention;

[0026] Figure 2 This is a schematic diagram of the method flow of step S101 of an embodiment of the present invention;

[0027] Figure 3 It is a centralized subcarrier allocation diagram in the DFT-S-OFDM signal formation process of the present invention;

[0028] Figure 4 It is an interleaved subcarrier allocation diagram in the DFT-S-OFDM signal formation process of the present invention;

[0029] Figure 5 Schematic diagram of the method flow of step S102 in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example

[0032] like Figure 1 As shown, an embodiment of the present invention proposes a peak-to-average power ratio suppression method based on a DFT-S-OFDM-CC-TR joint algorithm, and the steps are as follows:

[0033] Step 1: Form a DFT-S-OFDM signal, use DFT to obtain the frequency domain data of the signal, and obtain the DFT-S-OFDM signal through the subcarrier allocation module. Figure 2 As shown, the specific method of forming the DFT-S-OFDM signal in step 1 is:

[0034] When the modulated data completes the serial-to-parallel conversion, it will enter the DFT link, and after performing M-point DFT, the frequency domain data of M points will be obtained, where M is the number of subcarriers assumed to be allocated to the user. The output of DFT is then allocated to subcarriers to allocate them to N subcarriers (M>N). After that, the allocated data is transformed by N-point IFFT to obtain time domain data. The time domain data is then converted from parallel to serial, and a cyclic prefix (CP) is inserted to finally generate a DFT-S-OFDM signal.

[0035] In fact, the key to reducing the peak-to-average ratio by using DFT-S-OFDM lies in the subcarrier allocation scheme. There are two main types of subcarrier allocation methods at present, one of which is centralized subcarrier allocation and the other is distributed subcarrier allocation. The former is completed by continuously arranging M-point DFTs in the entire frequency band, and each point is closely connected, while the latter arranges M-point DFTs in a discrete manner, requiring that there must be a corresponding distance interval between each point. In particular, when the output of the discrete Fourier transform (DFT) algorithm can be equally spaced to the input of the inverse fast Fourier transform (IFFT) in the manner of N / M=S, this situation is called interleaved subcarrier allocation.

[0036] Centralized subcarrier allocation Figure 3 As shown in the figure, it is achieved by concentrating the DFT-encoded data X[i] in the middle part of IFFT, becoming The remaining positions are set to 0.

[0037] Interleaved subcarrier allocation Figure 4 As shown in the figure, it is achieved by placing the DFT-encoded data X[i] on the even bits of IFFT, The remaining positions are set to 0.

[0038] Step 2: Introduce the CC-TR algorithm, which uses multiple iterations of multiple peaks to gradually optimize the amplitude distribution of the signal and minimize the peaks in the signal, thereby reducing the PAPR. Figure 5 As shown in FIG. 1 , the specific operation flow of the CC-TR algorithm in step 2 is as follows: First, the OFDM subcarriers are divided into effective subcarriers and blank subcarriers. The effective subcarriers carry the original information, while the blank subcarriers are not used for information transmission. Next, the original signal waveform is clipped, and the signal obtained after the peak clipping is reloaded on the blank subcarrier. Then, the original data and the peak clipped data are superimposed to obtain a signal waveform after the peak-to-average ratio is reduced.

[0039] Step 3: Based on the content discussed in the first two steps, the following steps can be summarized to complete the implementation of the joint algorithm to suppress the peak-to-average ratio:

[0040] (1) Perform DFT-S-OFDM precoding operation on the initial signal.

[0041] (2) Perform IFFT transformation on the signal obtained after precoding processing, so as to convert the frequency domain data Y i Convert to time domain data y i On this basis, the subcarriers are divided into two categories: effective subcarriers and blank subcarriers, and the initial value of the iteration number i is set to i=1.

[0042] (3) In order to perform peak clipping operation, we set a peak clipping threshold A i , and complete the peak shaving process according to the following formula.

[0043]

[0044] (4) The peak clipping preprocessing data f is obtained as shown in the following formula i .

[0045]

[0046] (5)f i Perform a fast Fourier transform (FFT) operation on the frequency domain to obtain its frequency domain form F i Next, put F i All data corresponding to the data subcarriers are set to zero, and only the frequency domain data corresponding to the blank subcarriers are retained. Then the calculation is carried out according to the following formula to obtain the data C after the actual peak clipping processing: i , and finally C i Convert to the time domain.

[0047]

[0048] (6) First, calculate the peak clipping coefficient μ. Then, multiply the peak clipping coefficient μ by the data that has been clipped in the time domain, and then add the product back to the original data. After this operation, we can obtain the integrated interference and pass data after peak clipping. The specific process is shown in the following formula.

[0049] y i+1 =y i +μ m c i

[0050] (7) Check the effectiveness of PAPR suppression and determine whether to perform iterative operation again based on the obtained results, and update the number of iterations.

[0051] This algorithm shows good results in peak-to-average power ratio (PAPR) suppression, and its iteration rate is faster, which can achieve fast and efficient PAPR suppression function.

[0052] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A peak-to-average power ratio suppression method based on DFT-S-OFDM-CC-TR joint algorithm, which features The characteristics are: including the following steps, Step 1: Form a DFT-S-OFDM signal, use DFT to obtain the frequency domain data of the signal, and obtain the DFT-S-OFDM signal through a subcarrier allocation module; Step 2: Introduce the CC-TR algorithm, which uses multiple iterations of multiple peaks to gradually optimize the amplitude distribution of the signal and minimize the peaks in the signal, thereby reducing the PAPR; Step 3: Check the suppression effect of the joint algorithm, and determine whether it is necessary to perform iterative operations again based on the results, and update the number of iterations.

2. The peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm according to claim 1, characterized in that: The specific method of step 1 is: When the modulated data completes the serial-to-parallel conversion, it will enter the DFT stage for After clicking DFT, we get The frequency domain data of the points, where is the number of subcarriers assumed to be allocated to the user, and then the output of DFT is allocated to subcarriers so that it is allocated to Subcarrier ; Afterwards, these allocated data are The IFFT transform is performed at one point to obtain the time domain data, and then the time domain data is converted from parallel to serial, and a cyclic prefix is ​​inserted to finally generate a DFT-S-OFDM signal.

3. The peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm according to claim 2, characterized in that: In step 1, there are two types of subcarrier allocation methods, one of which is centralized subcarrier allocation and the other is distributed subcarrier allocation. Centralized subcarrier allocation uses The point DFT is arranged continuously, and each point is closely connected, while the distributed subcarrier allocation The point DFT is arranged in a discrete manner, requiring that there must be a corresponding distance interval between each point. In particular, when the output of the discrete Fourier transform algorithm is When the subcarriers can be equally spaced to the input of the inverse fast Fourier transform, this is called interleaved subcarrier allocation.

4. The peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm according to claim 1, characterized in that: The specific method of step 2 is: first, the OFDM subcarriers are divided into effective subcarriers and blank subcarriers, the effective subcarriers carry the original information, and the blank subcarriers are not used for information transmission. Then, the original signal waveform is first subjected to peak clipping processing, and the signal obtained after the peak clipping processing is reloaded on the blank subcarrier. Then, the original data and the peak clipped data are superimposed to obtain a signal waveform after the peak-to-average ratio is reduced.

5. The peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm according to claim 4, characterized in that: In step 2, after completing a peak clipping process, it is necessary to analyze the peak clipping result. If it is necessary to continue the peak clipping operation, the number of iterations must be updated before continuing the peak clipping process.

6. The peak-to-average power ratio suppression method based on the DFT-S-OFDM-CC-TR joint algorithm according to claim 1, characterized in that: The specific method in step 3 is: performing DFT-S-OFDM precoding operation on the initial signal, performing CC-TR peak clipping processing on the signal obtained after the precoding processing, checking the effectiveness of PAPR suppression, and determining whether it is necessary to perform iterative operation again based on the obtained results, and updating the number of iterations at the same time.

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