CN105245480A - Digital signal processing method and device - Google Patents
Digital signal processing method and device Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
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Abstract
The invention provides a digital signal processing method and device. The method comprises that a first digital signal with N points is interpolated to obtain a second digital signal, each point of the first digital signal is interpolated into M points, each of N and M is greater than or equivalent to 2, and the phase difference between two adjacent points among the M points is Q; the N*M points in the second digital signal is divided into N groups sequentially, and the N points of the first digital signals are placed at positions except the two ends in the corresponding group; a point of the highest amplitude is selected in each of the N groups to obtain a third digital signal, and the phase difference between each point in the third digital signal and a corresponding point among the N points is lower than (M-1)*Q; and peak clipping is carried out on the first digital signal according to the third digital signal Thus, the problem that the error of phase difference between an offset pulse and a main signal is relatively large when peak clipping is implemented in related technology is solved.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a digital signal processing method and apparatus.
Background
The mobile communication base station transmitter gradually transits from an original single-frequency-band single-mode single-carrier to a multi-frequency-band multi-mode multi-carrier, and particularly along with the large-scale commercial Long-term evolution (Long-term evolution, abbreviated as LTE) of the4th generation mobile communication technology (abbreviated as 4G), the configuration bandwidth of a signal supports hundreds of MHz at most, and the multi-carrier large-bandwidth configuration has a high peak-to-average power ratio (PAPR). Too much peak power may easily exceed the saturation point of the power amplifier, resulting in severe signal compression and thus affecting the Adjacent Channel Leakage Ratio (ACLR) of the signal transmitted from the antenna port. In order to reduce such non-linear distortion, it is usually required to ensure that the peak value of the signal cannot exceed the saturation compression point of the power amplifier, which requires that the average power of the signal should be backed off according to the peak-to-average ratio, resulting in reduced efficiency of the power amplifier, and since the power back-off also reduces the coverage area of the base station, the PAPR of the signal should be reduced in the digital domain in order to reduce the back-off of the average power, and peak clipping is a technique for reducing the PAPR of the signal in the digital domain.
The peak clipping technique adopted in the industry at present is mainly a peak pulse shaping cancellation algorithm, which trades off the low PAPR at the cost of Error Vector Magnitude (EVM) of the sacrifice signal. The peak pulse shaping cancellation algorithm mainly comprises two modules of peak value searching and shaping filter calculation, wherein the peak value searching method determines the final peak clipping performance. The peak search currently adopted in the industry for wideband signals is usually a conventional interpolation filtering and peak extracting method, which can find a large peak, but the offset pulse and the main signal have a relatively large phase error due to interpolation and peak extracting, and the phase error is larger when the interpolation multiple is higher, and the phase error affects the post-peak-clipping PAPR and the EVM.
In order to solve the problem of large phase error between the cancellation pulse and the main signal during peak clipping in the related art, no effective solution has been proposed at present.
Disclosure of Invention
The invention provides a digital signal processing method and a digital signal processing device, which at least solve the problem that the phase error between a cancellation pulse and a main signal is large when peak clipping is carried out in the related technology.
According to an aspect of the present invention, there is provided a digital signal processing method including: interpolating a first digital signal with N points to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are greater than or equal to 2, and the phase difference between two adjacent points in the M points is Q; sequentially dividing N M points in the second digital signal into N packets, wherein the N points in the first digital signal are located at positions other than two end points in the corresponding packets; selecting a point with the largest amplitude from each of the N groups to obtain a third digital signal, wherein the phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q; and performing peak clipping processing on the first digital signal according to the third digital signal.
Optionally, the performing peak clipping processing on the first digital signal according to the third digital signal includes: searching points with the amplitude value larger than or equal to a first threshold value and points with the amplitude value smaller than the first threshold value from the third digital signal; setting the amplitude of the point smaller than the first threshold value to be 0, and reducing the amplitude of the point larger than or equal to the first threshold value by the first threshold value to obtain a fourth digital signal; and performing peak clipping processing on the first digital signal by using the fourth digital signal, wherein the peak clipping processing is used for reducing the amplitude of a point in the first digital signal, which corresponds to the point which is greater than or equal to the first threshold value.
Optionally, the performing peak clipping processing on the first digital signal by using the fourth digital signal includes: subtracting the fourth digital signal from the first digital signal to obtain a peak-clipped fifth digital signal; or filtering the fourth digital signal to obtain a sixth digital signal, and subtracting the sixth digital signal from the first digital signal to obtain a seventh digital signal after peak clipping.
Optionally, the interpolating the first digital signal with N points to obtain the second digital signal includes: setting an i-th point in the first digital signal as an ((i-1) × M +1) th point in the second digital signal, setting a (M-1) th point generated by interpolating the i-th point in the first digital signal between the ((i-1) × M +1) th point and the ((i) × M +1) th point in the second digital signal, wherein i is more than or equal to 1 and less than or equal to N; said sequentially dividing N M points in said second digital signal into N packets comprises: setting 1 st to P th points in the second digital signal as a 1 st packet of the N packets, wherein P ≦ 2 ≦ M-1; setting the (P +1) + (j-2) × M) th to ((P +1) + (j-1) × M-1) th points in the second digital signal as the jth grouping, wherein, j is more than or equal to 2 and less than or equal to N.
Optionally, the
Optionally, selecting a point with the largest amplitude from each of the N packets to obtain a third digital signal includes: obtaining the amplitude and phase of each point in each of the N groups; obtaining the amplitude of the point with the maximum amplitude from each group; and generating a point in the third digital signal according to the acquired amplitude value and the corresponding phase of the point with the maximum amplitude value.
According to another aspect of the present invention, there is provided a digital signal processing apparatus including: the interpolation module is used for interpolating a first digital signal with N points to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are greater than or equal to 2, and the phase difference between two adjacent points in the M points is Q; a dividing module, configured to sequentially divide N × M points in the second digital signal into N packets, where the N points in the first digital signal are located at positions other than two end points in the corresponding packets; a selecting module, configured to select a point with a largest amplitude from each of the N packets to obtain a third digital signal, where a phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q; and the processing module is used for carrying out peak clipping processing on the first digital signal according to the third digital signal.
Optionally, the processing module includes: a searching unit configured to search for a point whose amplitude is equal to or greater than a first threshold value and a point whose amplitude is less than the first threshold value from the third digital signal; a setting unit, configured to set an amplitude of a point smaller than the first threshold to 0, and reduce the amplitude of the point greater than or equal to the first threshold by the first threshold to obtain a fourth digital signal; and the processing unit is used for performing peak clipping processing on the first digital signal by using the fourth digital signal, wherein the peak clipping processing is used for reducing the amplitude of a point, corresponding to the point which is greater than or equal to the first threshold, in the first digital signal.
Optionally, the processing unit comprises: the processing subunit is configured to subtract the fourth digital signal from the first digital signal to obtain a peak-clipped fifth digital signal; or the filtering subunit is configured to filter the fourth digital signal to obtain a sixth digital signal, and subtract the sixth digital signal from the first digital signal to obtain a seventh digital signal after peak clipping.
Optionally, the interpolation module is configured to interpolate the first digital signal to obtain the second digital signal by: setting an i-th point in the first digital signal as an ((i-1) × M +1) th point in the second digital signal, setting a (M-1) th point generated by interpolating the i-th point in the first digital signal between the ((i-1) × M +1) th point and the ((i) × M +1) th point in the second digital signal, wherein i is more than or equal to 1 and less than or equal to N; the dividing module is configured to sequentially divide N × M points in the second digital signal into N groups by: setting 1 st to P th points in the second digital signal as a 1 st packet of the N packets, wherein P ≦ 2 ≦ M-1; setting the (P +1) + (j-2) × M) th to ((P +1) + (j-1) × M-1) th points in the second digital signal as the jth grouping, wherein, j is more than or equal to 2 and less than or equal to N.
Optionally, the
Optionally, the selecting module includes: a first obtaining unit configured to obtain an amplitude and a phase of each point in each of the N packets; a second obtaining unit configured to obtain an amplitude value of a point having a maximum amplitude value from each of the packets; and the generating unit is used for generating the point in the third digital signal according to the acquired amplitude value and the corresponding phase of the point with the maximum amplitude value.
According to the invention, a first digital signal with N points is interpolated to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are more than or equal to 2, and the phase difference between two adjacent points in the M points is Q; sequentially dividing N M points in the second digital signal into N packets, wherein the N points in the first digital signal are located at positions other than two end points in the corresponding packets; selecting a point with the largest amplitude from each of the N groups to obtain a third digital signal, wherein the phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q; and performing peak clipping processing on the first digital signal according to the third digital signal. The problem that the phase error between the offset pulse and the main signal is large when peak clipping is carried out in the related technology is solved, and the effect of reducing the phase error between the offset pulse and the main signal is further achieved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a flow chart of a digital signal processing method according to an embodiment of the present invention;
fig. 2 is a block diagram of a digital signal processing apparatus according to an embodiment of the present invention;
fig. 3 is a block diagram of the structure of the processing module 28 in the digital signal processing apparatus according to the embodiment of the present invention;
fig. 4 is a block diagram of the structure of the processing unit 36 in the digital signal processing apparatus according to the embodiment of the present invention;
fig. 5 is a block diagram of a selection module 26 in the digital signal processing apparatus according to the embodiment of the present invention;
FIG. 6 is a comparison of a main signal to be peak-clipped and a main signal after clipping in accordance with an embodiment of the present invention;
FIG. 7 is a signal obtained after a hard peak reduction process according to an embodiment of the present invention;
FIG. 8 is a diagram of cancellation pulses formed after filtering by a shaping filter according to an embodiment of the present invention;
fig. 9 is a schematic diagram of the position and structure of wideband peak clipping at a digital link module of a mobile communication transmitter based on the minimum phase error method according to an embodiment of the present invention;
FIG. 10 is a block diagram of a peak search module for searching peaks based on a minimum phase error method according to an embodiment of the present invention;
fig. 11 is a block diagram of a minimum phase error peak search module that searches for peaks based on a minimum phase error method according to an embodiment of the present invention.
Detailed Description
The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
In order to solve the problem that the phase error between the offset pulse and the main signal is large when peak clipping is performed in the related art, the key point is to reduce the phase error caused by peak search while achieving the purpose of reducing the peak-to-average ratio.
In the present embodiment, a digital signal processing method is provided, and fig. 1 is a flowchart of a digital signal processing method according to an embodiment of the present invention, as shown in fig. 1, the flowchart includes the following steps:
step S102, a first digital signal with N points is interpolated to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are more than or equal to 2, and the phase difference between two adjacent points in the M points is Q;
step S104, sequentially dividing N points in the second digital signal into N groups, wherein the N points in the first digital signal are positioned at positions except two end points in the corresponding groups;
step S106, selecting a point with the maximum amplitude from each of the N groups to obtain a third digital signal, wherein the phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q;
and step S108, performing peak clipping processing on the first digital signal according to the third digital signal.
Through the steps, when N × M points are grouped, the points in the first digital signal are all located at the non-endpoint positions in each group, and the phase error between the point with the largest amplitude selected in each group and the point in the first digital signal in the corresponding group is smaller than (M-1) × Q, and for the point in the first digital signal in the related art located at the starting endpoint position in each group, the scheme in the embodiment of the invention can effectively reduce the phase error between the third digital signal (the phase of the third digital signal is consistent with the phase of the cancellation pulse) and the first digital signal (corresponding to the main signal), thereby reducing the phase error between the cancellation pulse and the main signal. The problem that the phase error between the cancellation pulse and the main signal is large when peak clipping is performed in the related art is solved, and the effect of reducing the phase error between the cancellation pulse and the main signal is achieved (refer to fig. 6 described later for a comparison diagram before and after peak clipping of the first digital signal, and it should be noted that fig. 6 is only one example).
In an alternative embodiment, the operation performed in step S108 is to perform peak clipping processing on the first digital signal according to the third digital signal, the processing method may be various, and the step S108 is exemplified as follows: searching points with the amplitude value larger than or equal to a first threshold value and points with the amplitude value smaller than the first threshold value from the third digital signal; setting the amplitude of the point smaller than the first threshold value to be 0, and reducing the amplitude of the point larger than or equal to the first threshold value by the first threshold value to obtain a fourth digital signal; the first digital signal is subjected to peak reduction processing for reducing the amplitude of a point corresponding to a point equal to or greater than the first threshold value in the first digital signal using the fourth digital signal (the fourth digital signal may be as shown in fig. 7 (fig. 7 is merely an example), which will be described later).
In an optional embodiment, the performing peak reduction processing on the first digital signal by using the fourth digital signal includes: subtracting the fourth digital signal from the first digital signal to obtain a fifth digital signal after peak clipping; alternatively, the fourth digital signal is filtered to obtain a sixth digital signal, and the sixth digital signal is subtracted from the first digital signal to obtain a seventh digital signal after peak clipping (the sixth digital signal obtained by filtering the fourth digital signal may be as shown in fig. 8 (fig. 8 is only one example) which will be described later).
In an alternative embodiment, interpolating the first digital signal having N points to obtain the second digital signal comprises: setting the ith point in the first digital signal as the ((i-1) × M +1) th point in the second digital signal, setting the (M-1) th point generated by interpolating the ith point in the first digital signal between the ((i-1) × M +1) th point and the ((i) × M +1) th point in the second digital signal, wherein, i is more than or equal to 1 and less than or equal to N; sequentially dividing N × M dots in the second digital signal into N packets includes: setting the 1 st point to the P th point in the second digital signal as the 1 st grouping in the N groupings, wherein P is more than or equal to 2 and less than or equal to (M-1); setting the (P +1) + (j-2) × M) th to ((P +1) + (j-1) × M-1) th points in the second digital signal as the jth grouping, wherein, j is more than or equal to 2 and less than or equal to N. That is, N points in the first digital signal may be respectively assigned to N groups by the grouping, and a position of each point in the N points in the first digital signal in the corresponding group is a non-end point, and a phase difference between a point with a maximum amplitude subsequently selected from each group and a point in the first digital signal in the corresponding group may be reduced by the interpolation and grouping method.
In an alternative embodiment, the aboveWherein,for rounding down the result obtained for M/2, when P isIn this case, the first digital signal in each group is divided into two groups, and the first digital signal in each group is divided into two groups.
In an alternative embodiment, in step S106, it is described that a point with the largest amplitude is selected from each of the N packets to obtain the third digital signal, and the implementation manner of this step may be various, for example: obtaining the amplitude and phase of each point in each of the N groups; obtaining the amplitude of the point with the maximum amplitude from each group; and generating a point in the third digital signal according to the amplitude value and the corresponding phase position of the point with the maximum acquired amplitude value.
Through the above description of the embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but the former is a better implementation mode in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.
In this embodiment, a digital signal processing apparatus is further provided, and the apparatus is used to implement the foregoing embodiments and preferred embodiments, and the description already made is omitted for brevity. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.
Fig. 2 is a block diagram of a digital signal processing apparatus according to an embodiment of the present invention, and as shown in fig. 2, the apparatus includes an interpolation module 22, a division module 24, a selection module 26, and a processing module 28, which will be described below.
The interpolation module 22 is configured to interpolate a first digital signal having N points to obtain a second digital signal, where each point in the first digital signal is interpolated into M points, where N and M are both greater than or equal to 2, and a phase difference between two adjacent points in the M points is Q; a dividing module 24, connected to the interpolation module 22, for sequentially dividing N × M points in the second digital signal into N groups, wherein the N points in the first digital signal are located at positions other than two end points in the corresponding groups; a selecting module 26, connected to the dividing module 24, configured to select a point with the largest amplitude from each of the N groups to obtain a third digital signal, where a phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q; and the processing module 28 is connected to the selecting module 26, and is configured to perform peak clipping processing on the first digital signal according to the third digital signal.
Fig. 3 is a block diagram of a processing module 28 in the digital signal processing apparatus according to the embodiment of the present invention, and as shown in fig. 3, the processing module 28 includes a searching unit 32, a setting unit 34, and a processing unit 36, and the processing module 28 is explained below.
A search unit 32 for searching for a point whose amplitude is equal to or greater than a first threshold value and a point whose amplitude is smaller than the first threshold value from the third digital signal; a setting unit 34, connected to the searching unit 32, for setting the amplitude of the point smaller than the first threshold to 0, and reducing the amplitude of the point greater than or equal to the first threshold by the first threshold to obtain a fourth digital signal; and a processing unit 36, connected to the setting unit 34, for performing peak reduction processing on the first digital signal by using the fourth digital signal, wherein the peak reduction processing is used for reducing the amplitude of a point corresponding to a point greater than or equal to the first threshold in the first digital signal.
Fig. 4 is a block diagram of a processing unit 36 in the digital signal processing apparatus according to the embodiment of the present invention, and as shown in fig. 4, the processing unit 36 includes a processing sub-unit 42 or a filtering sub-unit 44, and the processing unit 36 is explained below.
The processing subunit 42 is configured to subtract the fourth digital signal from the first digital signal to obtain a peak-clipped fifth digital signal; and the filtering subunit 44 is configured to filter the fourth digital signal to obtain a sixth digital signal, and subtract the sixth digital signal from the first digital signal to obtain a seventh digital signal after peak clipping. Therein, the processing subunit 42 and the filtering subunit 44 in fig. 4 are drawn with dashed lines, indicating that the processing unit 36 comprises the processing subunit 42, or that the processing unit 36 comprises the filtering subunit 44.
In an alternative embodiment, the interpolation module 22 may interpolate the first digital signal to obtain the second digital signal by: setting the ith point in the first digital signal as the ((i-1) × M +1) th point in the second digital signal, setting the (M-1) th point generated by interpolating the ith point in the first digital signal between the ((i-1) × M +1) th point and the ((i) × M +1) th point in the second digital signal, wherein, i is more than or equal to 1 and less than or equal to N; the dividing module 24 may divide the N × M dots in the second digital signal into N groups in sequence by: setting the 1 st point to the P th point in the second digital signal as the 1 st grouping in the N groupings, wherein P is more than or equal to 2 and less than or equal to (M-1); setting the (P +1) + (j-2) × M) th to ((P +1) + (j-1) × M-1) th points in the second digital signal as the jth grouping, wherein, j is more than or equal to 2 and less than or equal to N.
In an alternative embodiment, the above
Fig. 5 is a block diagram of a selecting module 26 in the digital signal processing apparatus according to the embodiment of the present invention, and as shown in fig. 5, the selecting module 26 includes a first obtaining unit 52, a second obtaining unit 54, and a generating unit 56, and the selecting module 26 is explained below.
A first obtaining unit 52 for obtaining the amplitude and phase of each point in each of the N packets; a second obtaining unit 54, connected to the first obtaining unit 52, for obtaining the amplitude of the point with the largest amplitude from each packet; a generating unit 56, connected to the second acquiring unit 54, for generating a point in the third digital signal according to the amplitude and the corresponding phase of the acquired point with the largest amplitude.
The above embodiments mainly describe how to interpolate, group, and search for peaks, and the following description is made in conjunction with the overall peak clipping process:
the embodiment of the invention also provides a broadband peak clipping method and a broadband peak clipping device aiming at the minimum phase error peak searching of the broadband multi-carrier signal. The peak value searching method of the minimum phase error is adopted for the broadband multi-carrier signal, the peak value of the signal is accurately estimated, the peak clipping scheme of high-speed peak searching and low-speed peak clipping is realized, the radio frequency index of the broadband signal is improved, the efficiency of power amplifier output is improved, the expenditure of logic resources is reduced, and the cost is saved. The peak searching broadband peak clipping device based on the minimum phase error comprises the following modules:
the device comprises a main signal delay module, a digital up-conversion module, a signal module value phase separation module, a peak value searching module of minimum phase error, a hard peak clipping module, a module value and phase synthesis module of peak value, a shaping filter calculation module and a peak value offset module; the following explains each module:
the main signal delay module is mainly used for delaying the peak clipping inlet signal for a certain time to ensure that the generated offset pulse is aligned with the time.
And the digital up-conversion module is used for carrying out multi-stage up-sampling on the received digital intermediate frequency signal, so that the signal rate is improved, and the accuracy of peak value estimation is improved.
And the signal modulus phase separation module is used for performing modulus and phase separation on the up-converted IQ complex signal.
And the peak value searching module of the minimum phase error performs large peak value searching according to the modulus value of the signal and ensures that the phase error with the signal before the up-sampling is as small as possible.
The hard peak clipping module subtracts the signal module value after the peak value search and a preset peak clipping threshold to obtain a signal peak value to be counteracted;
module for synthesizing module value and phase of peak signal: the peak signal and its corresponding phase are combined into a complex signal.
And the shaping filter calculation module generates a shaping filter coefficient matched with the main signal according to the carrier filter coefficient, the frequency control word and the power information of the main signal.
A peak cancellation module: and filtering the peak signal to generate a cancellation pulse, and subtracting the cancellation pulse from the delayed main signal to achieve the purpose of peak clipping.
The minimum phase error peak search module further comprises: a peak grouping module and a peak extracting module.
The peak value grouping module groups the multilevel up-sampled peak value signals according to a principle of ensuring the minimum phase error of all peak values and the main signal before up-sampling, wherein the length of the signals in each group is a multiple of multilevel interpolation, and the positions of the peak values after interpolation and the main signal before interpolation are self-adaptively configured according to the peak-to-average ratio after peak clipping in each group.
And the peak value extraction module screens the peak value signals in each group, extracts according to the principle that the peak value is the largest, records the position of the extracted peak value, extracts the phase according to the position of the peak value, and ensures that the extracted peak value signals are consistent with the main signal rate of peak clipping.
Fig. 6 is a comparison graph of a main signal to be peak-clipped and a main signal after peak clipping according to an embodiment of the present invention, wherein a solid line represents a signal modulus at a peak clipping entrance; the dashed dotted line represents the modulus of the signal after peak clipping, and the 1413 th sampling point is taken as an example in fig. 6. The method comprises the following steps:
step 1, receiving a signal of a current link and configuration information of the signal, and then configuring information such as a corresponding peak clipping threshold, a carrier filter coefficient, a carrier frequency control word and the like.
And 2, performing multi-stage digital up-conversion processing, performing multi-stage interpolation filtering processing on the signal according to the bandwidth of the input signal, and performing peak value estimation.
And 3, separating the signal modulus and the phase. The modulus and phase of the current in-phase/Quadrature (IQ) complex signal are calculated.
And 4, peak grouping processing. The modulus values of the signals are grouped by multiples of the interpolation.
And step 5, peak value extraction processing. And carrying out digital down-conversion processing on the peak signals in each group, and extracting to the rate same as the main signal.
And 6, carrying out hard peak clipping treatment. That is, the peak signal is subtracted from the preset peak clipping threshold to obtain the peak signal to be cancelled, as shown in fig. 7, fig. 7 is a signal obtained after the hard peak clipping processing according to the embodiment of the present invention, and a point 1413 in fig. 7 is a mode value of the original signal (i.e., the main signal to be subjected to peak clipping) is subtracted from the peak clipping threshold to obtain a mode value to be cancelled.
And 7, synthesizing the modulus and the phase into an IQ complex signal for processing. And synthesizing the peak signal and the corresponding phase into an IQ complex signal.
And 8, generating a forming filter. And calculating the shaping filter coefficient of the signal according to the frequency control word, the carrier filter coefficient and the carrier power information of the signal.
And 9, peak value cancellation processing. Firstly, filtering the signal after peak value extraction and the generated shaping filter coefficient to generate a cancellation pulse for peak clipping cancellation with the original signal. Then, the main signal and the cancellation pulse are subtracted correspondingly to obtain a final signal with a certain peak-to-average ratio after peak clipping, and the final signal is sent to a digital predistortion module, as shown in fig. 8, fig. 8 shows the cancellation pulse formed after filtering by a shaping filter according to the embodiment of the invention. After the pulse is offset with the delayed signal, a peak-clipped signal shown by a dot-dash line in fig. 6 is obtained.
Fig. 9 is a schematic diagram of a position and a structure of a wideband peak clipping module based on a minimum phase error method peak searching in a digital link module of a mobile communication transmitter according to an embodiment of the present invention, as shown in fig. 9, the apparatus in the embodiment of the present invention is located after a Digital Up Converter (DUC) module of a digital link in the transmitter and before a digital pre-Distortion (DPD) module, and mainly includes a main signal delay module (i.e., the delay module in fig. 9), a peak searching module, and an online shaped filter coefficient calculating module (i.e., the shaped filter calculating module in fig. 9).
The main signal delay module delays the signal at the peak clipping inlet for a certain time to ensure that the generated cancellation pulse is aligned with the time. The peak search module is used to find the large peak of the signal by an algorithm to generate the cancellation pulse. The shaping filter calculation module is used for preventing the signal ACLR after peak clipping from deteriorating and generating filter coefficients matched with the main link signal in real time.
Fig. 10 is a structural diagram of a peak search module for searching peaks based on a minimum phase error method according to an embodiment of the present invention, as shown in fig. 10, the peak search module mainly includes digital up-conversion, signal-to-module phase separation, peak search for minimum phase error, phase extraction, hard peak clipping, and IQ complex signal synthesis, and the peak search module mainly performs the following operations:
step 1, performing multi-stage interpolation on signals entering peak clipping, and performing large peak estimation, wherein interpolation multiples can be flexibly selected and configured according to the total bandwidth of the signals;
step 2, separating the modulus and the phase of the IQ complex signal by using a digital signal processing algorithm, respectively solving the modulus and the phase of the signal, wherein the modulus is used for searching a peak value, and the phase is delayed and sent to a phase extraction module; the module uses the module signal module value and phase separation algorithm including but not limited to multi-stage cordic iterative algorithm;
step 3, performing peak value search according to the magnitude of the modulus of the signal, mainly including peak value grouping and peak value extraction, and the specific implementation details will be detailed in fig. 11;
step 4, extracting phases according to the address of the large peak signal output in the step 3, and sending the extracted phases to an IQ complex signal synthesis module;
step 5, subtracting the searched large peak value signal from a preset peak clipping threshold to generate a noise signal to be cancelled;
and 6, synthesizing the noise signal after hard peak clipping and the correspondingly extracted phase into an IQ complex signal by using a digital signal processing algorithm for filtering with a forming filter coefficient. The digital signal processing algorithm includes, but is not limited to, a multi-stage cordic iterative algorithm, etc.
Fig. 11 is a structural diagram of a minimum phase error peak value searching module for searching peaks based on a minimum phase error method according to an embodiment of the present invention, which mainly includes two modules of peak value grouping and peak value extracting.
And the peak value grouping module is used for grouping the peak value signals after the multilevel up-sampling according to the principle of ensuring the minimum phase error between all the peak values and the main signals before the up-sampling, the length of the signals in each group is the multiple of the multilevel interpolation, in each group, grouping parameters are configured in a self-adaptive mode according to the peak-to-average ratio after the peak clipping, the positions of the peak values after the interpolation and the main signals before the interpolation are configured according to the grouping parameters, and the phase errors between the peak values of all the signals and the main signals are enabled to be optimal through the grouping.
And the peak value extraction module screens the peak value signals in each group, performs peak value extraction according to the principle of maximum peak value, sends the extracted peak value address to the phase extraction module, and realizes the peak clipping scheme under the conditions of high peak searching speed and low peak clipping speed, wherein the extracted peak value signal has the same speed as the main signal of the peak clipping.
The present invention has been described herein in detail with respect to specific embodiments thereof, which are set forth to facilitate a person skilled in the art in making and using the invention. The invention is not limited to single-band peak clipping, and is applicable and compatible to application scenes of double frequency bands and multiple frequency bands. The present invention is not limited to correcting the suppression of the peak-to-average ratio of signals in a communication system, and is used in other scenarios involving single carrier and multi-carrier peak-to-average ratio reduction.
It should be noted that, the above modules may be implemented by software or hardware, and for the latter, the following may be implemented, but not limited to: the modules are all positioned in the same processor; alternatively, the modules are respectively located in a plurality of processors.
The embodiment of the invention also provides a storage medium. Alternatively, in the present embodiment, the storage medium may be configured to store program codes for performing the following steps:
s1, interpolating a first digital signal with N points to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are greater than or equal to 2, and the phase difference between two adjacent points in the M points is Q;
s2, sequentially dividing N × M points in the second digital signal into N groups, wherein N points in the first digital signal are located at positions other than two end points in the corresponding groups;
s3, selecting a point with the largest amplitude from each of the N groups to obtain a third digital signal, wherein the phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q;
and S4, performing peak clipping processing on the first digital signal according to the third digital signal.
Optionally, in this embodiment, the storage medium may include, but is not limited to: various media capable of storing program codes, such as a usb disk, a Read-only memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic disk, or an optical disk.
Alternatively, in the present embodiment, the processor performs S1-S4 according to program code already stored in the storage medium.
Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments and optional implementation manners, and this embodiment is not described herein again.
In summary, the minimum phase error search method provided in the embodiment of the present invention has the following advantages compared with the conventional peak search method currently used in the industry, in which firstly, a multi-stage interpolation filtering peak estimation technique is used, and interpolation multiples are flexibly configured according to signal bandwidths, so that peak regeneration after peak clipping is effectively avoided; secondly, a peak value searching algorithm based on the minimum phase error is provided, and the EVM index after the broadband signal is subjected to peak clipping is improved on the premise of ensuring the peak-to-average ratio; thirdly, in consideration of the resource use condition during realization, the method adopts a high-speed peak searching and low-speed peak clipping method, effectively reduces the logic resource overhead, and greatly reduces the cost.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (12)
1. A digital signal processing method, comprising:
interpolating a first digital signal with N points to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are greater than or equal to 2, and the phase difference between two adjacent points in the M points is Q;
sequentially dividing N M points in the second digital signal into N packets, wherein the N points in the first digital signal are located at positions other than two end points in the corresponding packets;
selecting a point with the largest amplitude from each of the N groups to obtain a third digital signal, wherein the phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q;
and performing peak clipping processing on the first digital signal according to the third digital signal.
2. The method of claim 1, wherein the peak reduction processing of the first digital signal according to the third digital signal comprises:
searching points with the amplitude value larger than or equal to a first threshold value and points with the amplitude value smaller than the first threshold value from the third digital signal;
setting the amplitude of the point smaller than the first threshold value to be 0, and reducing the amplitude of the point larger than or equal to the first threshold value by the first threshold value to obtain a fourth digital signal;
and performing peak clipping processing on the first digital signal by using the fourth digital signal, wherein the peak clipping processing is used for reducing the amplitude of a point in the first digital signal, which corresponds to the point which is greater than or equal to the first threshold value.
3. The method of claim 2, wherein the peak reduction processing of the first digital signal using the fourth digital signal comprises:
subtracting the fourth digital signal from the first digital signal to obtain a peak-clipped fifth digital signal; or,
and filtering the fourth digital signal to obtain a sixth digital signal, and subtracting the sixth digital signal from the first digital signal to obtain a seventh digital signal after peak clipping.
4. The method of claim 1,
the interpolating the first digital signal with N points to obtain the second digital signal includes: setting an i-th point in the first digital signal as an ((i-1) × M +1) th point in the second digital signal, setting a (M-1) th point generated by interpolating the i-th point in the first digital signal between the ((i-1) × M +1) th point and the ((i) × M +1) th point in the second digital signal, wherein i is more than or equal to 1 and less than or equal to N;
said sequentially dividing N M points in said second digital signal into N packets comprises: setting 1 st to P th points in the second digital signal as a 1 st packet of the N packets, wherein P ≦ 2 ≦ M-1; setting the (P +1) + (j-2) × M) th to ((P +1) + (j-1) × M-1) th points in the second digital signal as the jth grouping, wherein, j is more than or equal to 2 and less than or equal to N.
5. The method of claim 4, wherein the step of determining the target position is performed by a computer
6. The method of claim 1, wherein selecting a point of maximum magnitude from each of the N packets to obtain a third digital signal comprises:
obtaining the amplitude and phase of each point in each of the N groups;
obtaining the amplitude of the point with the maximum amplitude from each group;
and generating a point in the third digital signal according to the acquired amplitude value and the corresponding phase of the point with the maximum amplitude value.
7. A digital signal processing apparatus, comprising:
the interpolation module is used for interpolating a first digital signal with N points to obtain a second digital signal, wherein each point in the first digital signal is interpolated into M points, both N and M are greater than or equal to 2, and the phase difference between two adjacent points in the M points is Q;
a dividing module, configured to sequentially divide N × M points in the second digital signal into N packets, where the N points in the first digital signal are located at positions other than two end points in the corresponding packets;
a selecting module, configured to select a point with a largest amplitude from each of the N packets to obtain a third digital signal, where a phase difference between each point in the third digital signal and a corresponding point in the N points is less than (M-1) × Q;
and the processing module is used for carrying out peak clipping processing on the first digital signal according to the third digital signal.
8. The apparatus of claim 7, wherein the processing module comprises:
a searching unit configured to search for a point whose amplitude is equal to or greater than a first threshold value and a point whose amplitude is less than the first threshold value from the third digital signal;
a setting unit, configured to set an amplitude of a point smaller than the first threshold to 0, and reduce the amplitude of the point greater than or equal to the first threshold by the first threshold to obtain a fourth digital signal;
and the processing unit is used for performing peak clipping processing on the first digital signal by using the fourth digital signal, wherein the peak clipping processing is used for reducing the amplitude of a point, corresponding to the point which is greater than or equal to the first threshold, in the first digital signal.
9. The apparatus of claim 8, wherein the processing unit comprises:
the processing subunit is configured to subtract the fourth digital signal from the first digital signal to obtain a peak-clipped fifth digital signal; or,
and the filtering subunit is configured to filter the fourth digital signal to obtain a sixth digital signal, and subtract the sixth digital signal from the first digital signal to obtain a seventh digital signal after peak clipping.
10. The apparatus of claim 7,
the interpolation module is configured to interpolate the first digital signal to obtain the second digital signal by: setting an i-th point in the first digital signal as an ((i-1) × M +1) th point in the second digital signal, setting a (M-1) th point generated by interpolating the i-th point in the first digital signal between the ((i-1) × M +1) th point and the ((i) × M +1) th point in the second digital signal, wherein i is more than or equal to 1 and less than or equal to N;
the dividing module is configured to sequentially divide N × M points in the second digital signal into N groups by: setting 1 st to P th points in the second digital signal as a 1 st packet of the N packets, wherein P ≦ 2 ≦ M-1; setting the (P +1) + (j-2) × M) th to ((P +1) + (j-1) × M-1) th points in the second digital signal as the jth grouping, wherein, j is more than or equal to 2 and less than or equal to N.
11. The apparatus of claim 10, wherein the apparatus is a portable device
12. The apparatus of claim 7, wherein the selecting module comprises:
a first obtaining unit configured to obtain an amplitude and a phase of each point in each of the N packets;
a second obtaining unit configured to obtain an amplitude value of a point having a maximum amplitude value from each of the packets;
and the generating unit is used for generating the point in the third digital signal according to the acquired amplitude value and the corresponding phase of the point with the maximum amplitude value.
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