CN112637098A - Method and device for reducing peak-to-average power ratio of OFDM (orthogonal frequency division multiplexing) system, signal sending end and receiving end - Google Patents
Method and device for reducing peak-to-average power ratio of OFDM (orthogonal frequency division multiplexing) system, signal sending end and receiving end Download PDFInfo
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Abstract
The invention provides a method and a device for reducing the peak-to-average power ratio of an OFDM (orthogonal frequency division multiplexing) system, a signal sending end and a signal receiving end, and belongs to the technical field of communication. The method comprises the following steps: grouping the frequency domain signals, performing phase rotation on each group of grouped signals to obtain a group frequency domain signal, or performing phase rotation on the frequency domain signals, and grouping the phase-rotated signals to obtain a group frequency domain signal; transforming the group frequency domain signal to obtain a group time domain signal; traversing the weighting factor groups in the weighting factor set to determine the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group; selecting an optimal weighting factor group according to the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group; and combining the group time domain signals according to the optimal weighting factor set to obtain a signal to be sent, wherein the weighting factors in the weighting factor set are real numbers. The weighting factor of the scheme is a real number, the weighting process is realized through bit flipping and superposition, and the space for searching the weighting factor is small and easy to realize.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a method and a device for reducing the peak-to-average power ratio of an OFDM system, a signal sending end and a signal receiving end.
Background
An IEEE 802.15.4g intelligent public network (SUN) is suitable for low-power consumption, low-cost and long-distance transmission application and supports a multi-frequency multi-region orthogonal frequency division multiplexing physical layer scheme. Orthogonal Frequency Division Multiplexing (OFDM) technology distributes a high-speed data stream to a plurality of Orthogonal sub-carrier channels with lower rates through serial-to-parallel conversion and transmits the data stream. OFDM has a high spectral efficiency and can provide efficient transmission. The OFDM signal is a superposition of a plurality of orthogonal subcarrier signals, and thus when the in-phase subcarriers are added by a Peak value, the OFDM signal generates a maximum Peak value, which brings a high Peak to Average Power Ratio (PAPR), resulting in a performance degradation of the OFDM system.
Methods for improving the peak-to-average power ratio of OFDM can be divided into three categories: pre-distortion techniques, coding-class techniques, and probability-class techniques. The predistortion technology carries out preprocessing such as amplitude limiting on a transmitted signal, is easy to realize, but has the defect that signal nonlinearity is caused to influence the performance of the error rate of a system. The coding technology introduces redundant coding, selects signal transmission with smaller peak-to-average ratio, does not cause signal distortion, but has high complexity of searching the optimal code group and is difficult to realize. The probability method reduces the autocorrelation of the signal by scrambling the transmitted signal data, thereby reducing the probability of high peak-to-average ratio, and the processing process does not cause signal distortion and has lower realization complexity.
In order to reduce PAPR of a spread spectrum OFDM system, the prior art often changes signal characteristics by means of phase code scrambling, and the IEEE 802.15.4g MR-OFDM physical layer adopts a frequency domain spreading technology, such as CAZAC (constant Amplitude Zero Auto-correlation) sequence with good correlation characteristics, a specified form of newmann phase twiddle factor, and the like as a frequency domain spreading code. These sequences are complex sequences, and the spreading process has a certain computational complexity. In addition, if multiple cyclic shifts or multiple phase sequences are adopted, the phase sequence selected by the transmitting end needs to be transmitted to the receiving end as auxiliary information, and overhead is increased. If the selective mapping mode is adopted, after scrambling and IFFT conversion are carried out on a plurality of preset phase codes one by one symbol, a sequence with the minimum PAPR is selected as a time domain signal, and the operation complexity of a sending end is high. The receiving end needs to obtain the best sequence information transmitted by the transmitting end so as to perform de-spreading.
The maximum spreading multiple of the MR-OFDM frequency domain is 4 times, repeated information on the frequency domain is subjected to phase rotation, and a phase rotation factor is related to a spreading coefficient and is a specific phase complex number. The spread spectrum OFDM technology repeatedly spreads the modulation symbols on different carriers, thereby improving the reliability of signal transmission. If the repeated sequence is directly used as the data after the frequency spreading, the peak-to-average ratio of the transmission signal is higher.
Disclosure of Invention
An object of the embodiments of the present invention is to provide a method and an apparatus for reducing a peak-to-average power ratio of an OFDM system, a signal transmitting end and a signal receiving end, so as to solve the above technical problems or at least partially solve the above technical problems.
In order to achieve the above object, an embodiment of the present invention provides a method for reducing a peak-to-average ratio of an OFDM system, where the method includes: grouping the frequency domain signals, performing phase rotation on each group of grouped signals to obtain a group of frequency domain signals, or performing phase rotation on the frequency domain signals, and grouping the phase-rotated signals to obtain the group of frequency domain signals; transforming the set of frequency domain signals to obtain a set of time domain signals; traversing the weighting factor groups in the weighting factor set to determine the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group; selecting an optimal weighting factor group according to the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group; and combining the group of time domain signals according to the optimal weighting factor group to obtain a signal to be sent, wherein the weighting factors in the weighting factor set are real numbers.
Optionally, the weighting factor is 1 and/or-1.
Optionally, the phase code used for the phase rotation is a Hadamard sequence.
Optionally, performing phase rotation on each group of grouped signals includes: and performing phase rotation on each group of signals by adopting the same phase code.
Optionally, the transforming the set of frequency domain signals to obtain a set of time domain signals includes: and performing inverse fast Fourier transform on each set of frequency domain signals of the set of frequency domain signals respectively to obtain the set of time domain signals composed of time domain signals respectively corresponding to each set of frequency domain signals.
Optionally, the method includes: acquiring a spreading factor, and grouping the frequency domain signals based on the spreading factor or grouping the phase-rotated signals based on the spreading factor.
Optionally, the grouping manner used for grouping the frequency domain signals is as follows: block grouping, comb grouping, or random grouping.
In another aspect, the present invention provides an apparatus for reducing a peak-to-average power ratio of an OFDM system, the apparatus comprising: the first processing module is used for grouping the frequency domain signals, performing phase rotation on each group of grouped signals to obtain a group of frequency domain signals, or performing phase rotation on the frequency domain signals, and grouping the phase-rotated signals to obtain the group of frequency domain signals; a transform module for transforming the set of frequency domain signals into a set of time domain signals; the traversing module is used for traversing the weighting factor groups in the weighting factor set to determine the peak-to-average ratio of the group time domain signals corresponding to each weighting factor group; a selecting module, configured to select an optimal weight factor group according to a peak-to-average ratio of a group time domain signal corresponding to each weight factor group; and the second processing module is used for combining the group of time domain signals according to the optimal weighting factor group to obtain a signal to be sent, wherein the weighting factors in the weighting factor set are real numbers.
In another aspect, the present invention provides a signal transmitting end, where the transmitting end is configured to perform the following operations: and transmitting the signal to be transmitted and the optimal weight factor set corresponding to the signal to be transmitted.
In another aspect, the present invention provides a signal receiving end, where the receiving end is configured to perform the following operations: receiving a signal to be transmitted and an optimal weight factor set corresponding to the signal to be transmitted, wherein the signal to be transmitted is any one of the signals; and recovering the signal to be transmitted according to the optimal weighting factor group and a preset phase code.
According to the scheme provided by the embodiment of the invention, the real number is used as the weighting factor, the weighting process can be completed through bit flipping and superposition, and the advantages of small space for searching the weighting factor and low complexity in implementation are achieved.
Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:
fig. 1 is a schematic flowchart of a method for reducing a peak-to-average ratio of an OFDM system according to an embodiment of the present invention;
FIG. 2 is a diagram of different grouping of the same frequency domain signal;
FIG. 3 is a flowchart illustrating a method for traversing weighting factor groups in a weighting factor set according to an embodiment of the present invention;
FIG. 4 is a diagram of a simulation result of peak-to-average power ratio of a signal provided by an embodiment of the present invention;
fig. 5 is a block diagram of an apparatus for reducing a peak-to-average ratio of an OFDM system according to an embodiment of the present invention.
Description of the reference numerals
51 first processing module 52 transformation module
53 traverse module 54 select module
55 second processing module
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.
Fig. 1 is a flowchart illustrating a method for reducing a peak-to-average ratio of an OFDM system according to an embodiment of the present invention. As shown in fig. 1, the method for reducing the peak-to-average ratio of the OFDM system includes steps S110 to S150.
In step S110, the frequency domain signals are subjected to grouping and phase rotation processing to obtain group frequency domain signals.
The grouping of the frequency domain signals refers to mapping the signals onto a plurality of groups. For the scheme provided by the embodiment of the present invention, the frequency domain signals to be processed may be grouped in any existing grouping manner, for example, in a grouping manner such as block grouping, comb grouping, or random grouping.
FIG. 2 is a schematic diagram of different grouping manners for the same frequency domain signal, and the frequency domain signals in FIG. 2 are all divided into V groups, and the group numbers include i0、i1…iV-1. The block grouping is shown in the figure, and the grouped data information in each group keeps continuous and occupies partial subcarriers; (b) the data information in each group after grouping is uniformly distributed in a subcarrier space; (c) after being grouped randomlyThe grouped data information of each group randomly occupies a plurality of subcarriers. Considering that each grouping mode has respective advantages and disadvantages, a user can select a proper grouping mode according to actual requirements.
The spreading factor may be obtained prior to grouping the frequency domain signals, and the frequency domain signals may be grouped based on the spreading factor. The specific value of the spreading factor can be determined according to the actually required data rate.
The phase rotation of the signal includes selecting a phase code and performing phase rotation on the corresponding signal according to the phase code. The phase code is preferably a code sequence with good autocorrelation in order to reduce the complexity of data processing, for example, a Hadamard sequence may be used as the phase code.
In the case of phase-rotating a signal using a fixed code sequence, the order of the step of grouping processing the signal and the step of phase-rotating the signal is arbitrarily switched without affecting the subsequent signal processing.
Specifically, the grouping and phase rotating the frequency domain signals may include the following two ways:
(1) firstly, grouping the frequency domain signals to obtain a plurality of groups of grouped signals, and then performing phase rotation on each group of grouped signals by adopting corresponding phase codes to obtain a group frequency domain signal; or
(2) Firstly, the group frequency domain signals are subjected to phase rotation, and then the signals after the phase rotation are grouped, so that the group frequency domain signals formed by a plurality of groups of signals can be obtained.
The scheme provided in step S110 will now be explained in detail by using a specific embodiment, which processes the frequency domain signals in a way of grouping before phase rotation.
Specifically, the frequency domain signals are grouped to obtain V group signals. And performing zero padding processing on each group signal in the V group signals, namely, padding the signal length to a length N, wherein N is the depth of Inverse Fast Fourier Transform (IFFT).
And selecting a phase code with the length of N, and respectively carrying out phase rotation on the V group signals to obtain a group frequency domain signal.
In order to further simplify the data processing procedure, a Hadamard sequence with dimension N may be preferred. The Hadamard sequence only takes values in {1, -1}, so that when phase rotation processing is carried out, phase rotation can be completed only by carrying out inversion of positive and negative values of bits on each group of signals. Namely, the Hadamard sequence is adopted as the phase code, so that the complexity of data processing can be effectively reduced.
In step S120, the group frequency domain signal is transformed to obtain a group time domain signal.
The frequency domain transformation of the signal proposed by this embodiment of the present invention to the time domain may employ Inverse Fast Fourier Transform (IFFT). Specifically, each group of frequency domain signals in the group frequency domain signals is subjected to IFFT to obtain a corresponding time domain signal, that is, a group time domain signal composed of a plurality of time domain signals can be obtained, and the length of the time domain signal is the same as the length of the corresponding frequency domain signal.
In step S130, the weighting factor groups in the weighting factor set are traversed to determine the peak-to-average ratio of the set time domain signal corresponding to each weighting factor group.
The weighting coefficient set comprises a plurality of elements formed by weighting factor groups, the number of the elements is related to the selected value of the weighting factor, and the number of the weighting factors in each weighting factor group is the same as the number of the time domain signal groups in the group time domain signals. In the traversing process, the peak-to-average ratio of the group time domain signal corresponding to each element needs to be determined, and after the traversing is completed, the number of the obtained group time domain signal peak-to-average ratios is the same as the number of the elements in the weighting coefficient set.
The weighting factor is preferably a real value, which effectively reduces the complexity of signal processing. For example, the weighting factors may be 1 and-1, and thus the weighting process may be accomplished by only bit flipping superposition.
The embodiment of the present invention further provides a method for traversing the weighting factor groups in the weighting factor set to determine a peak-to-average ratio of the group time domain signal corresponding to each weighting factor group, where a flow chart of the method is shown in fig. 3.
In this embodiment, the group of time-domain signals includes V time-domain signals, each time-domain signal has a length of N, and each group of weighting vectors has V weighting factors.
In step 1: firstly, each group of time domain signals in the group of time domain signals is respectively associated with a weighting vector W0Multiplying the V weighting factors to determine a weighting vector W0Corresponding to the V weighted time domain data. In case the weighting factor has a value of 1 or-1, the multiplication can be performed by bit flipping superposition.
In step 2: adding and combining the V weighted time domain data obtained in the step 1 to obtain a weighted vector W0And the corresponding signal to be selected with the length of N.
In step 3: and (4) calculating the PARR of the signal to be selected obtained in the step (2).
In step 4: and selecting the next weighting vector in the weighting coefficient set, and repeating the process until the selection of the elements in the weighting coefficient set is completed. In the case of a weighting factor of 1 or-1, a total of 2 is obtainedVPARR of the candidate signal.
This step will be explained in detail by taking an example in which the group timing signal includes V group signals and the weighting factor is ± 1.
In this embodiment, if the weighting factor is ± 1, the weighting coefficient set S has 2 in totalVAn element, i.e.
Each element is a coefficient vector with V factors, and V peak-to-average ratios are obtained after traversing all elements in the weighting coefficient set S for the group of time domain signals determined through the above steps.
For example, taking V ═ 4 as an example, the elements in the weighting coefficient set S are W respectively0＝[-1,-1,-1,-1]，W1＝[-1,-1,-1,1]，W2＝[1,1,1,1]，W3＝[1,-1,1,1]，W4＝[1,1,-1,-1]… …, 16 in total. After weighting the group time domain signal by the weighting factor in each element, the weighting factor is obtainedSince the peak-to-average ratio values correspond to the elements, a total of 16 peak-to-average ratio values can be obtained.
In step S140, an optimal weight factor set is selected according to the peak-to-average ratio of the set time domain signal corresponding to each weight factor set.
Comparing the multiple peak-to-average ratios obtained after traversing the weighting factor groups in the weighting coefficient set in step S130, and selecting the weighting factor group corresponding to the smallest of the multiple peak-to-average ratios as the optimal weighting factor group.
The comparison method of the peak-to-average ratios can be implemented by any existing algorithm. Considering that different algorithms have different time complexity, a user can select a proper sorting algorithm or a proper comparison algorithm according to the product processing capacity and the time requirement to determine the minimum value in the plurality of peak-to-average ratios.
In the embodiment provided in connection with fig. 3, in the case that the weighting factor is 1 and/or-1, after traversing the weighting factor group in the weighting factor set, a total of 2 is obtainedVPARR of a signal to be selected, and then the 2 s are comparedVSelecting the PARR of each signal to be selected, wherein the group time domain signal record serial number with the minimum PARR is p, and the weighting factor group corresponding to the group time domain signal with the minimum PARR is WpI.e. the set of weighting factors WpIs the optimal weight factor set.
In step S150, the group time domain signals are combined according to the optimal weight factor group to obtain a signal to be transmitted.
The scheme provided by the embodiment of the invention can effectively reduce the calculated amount in the process of obtaining the signal with the lower peak-to-average ratio by comparing the signals obtained by weighting and combining the group time domain signals, can avoid the complex multiplication spread spectrum process and avoid the increase of the calculated amount caused by searching a large number of spread spectrum code words, can solve the problem of overhigh PARR of the OFDM system with lower complexity, and has the advantage of wide application range.
In addition, the scheme provided by the embodiment of the invention provides that the fixed code sequence can be adopted to carry out phase rotation on the signal, so that the fixed code sequence corresponding to the signal does not need to be transmitted in the subsequent signal transmitting process, and the utilization rate of the frequency band can be effectively improved.
The solution provided by the present invention will now be explained in detail with a specific embodiment, as shown in fig. 4. Fig. 4 shows the simulation result of the signal peak-to-average ratio where N is 32(N is the depth of IFFT) and V is 4(V is the number of groups into which frequency domain signals are grouped). The frequency domain signal is divided in a block form, and the signal is processed by a phase rotation weighting method which is partially mapped and takes a Hadamard sequence as a phase code.
The horizontal axis in fig. 4 represents values above the average power of the signal and the vertical axis represents the percentage of time that the signal is actually above the power level corresponding to the horizontal axis. The peak-to-average ratio CCDF of 10 can be achieved at a signal-to-noise ratio SNR of 8.7dB as shown in fig. 4-3. Compared with the original scheme of not performing weighting optimization in spread spectrum, the PAPR performance is effectively improved.
Fig. 5 is a block diagram of an apparatus for reducing a peak-to-average ratio of an OFDM system according to an embodiment of the present invention. As shown in fig. 5, the apparatus includes: a first processing module 51, a transformation module 52, a traversal module 53, a selection module 54 and a second processing module 55. The first processing module 51 is configured to perform grouping processing and phase rotation processing on frequency domain signals to obtain group frequency domain signals, the transforming module 52 is configured to transform the group frequency domain signals into time domain signals, the traversing module 53 is configured to traverse weighting factor groups in weighting factor combination to determine a peak-to-average ratio of a group time domain signal corresponding to each weighting factor group, the selecting module 54 is configured to select an optimal weighting factor group according to the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group, and the second processing module 55 is configured to combine the group time domain signals according to the optimal weighting factor group to obtain signals to be transmitted.
For the first processing module 51, in the case of performing the phase rotation processing by using the fixed phase code, the sequence of the grouping processing and the phase rotation processing may be interchanged, that is, the frequency domain signals may be grouped first, and then each group of signals after grouping is subjected to the phase rotation to obtain a group of frequency domain signals, or the frequency domain signals may be subjected to the phase rotation first, and then the signals after phase rotation are grouped to obtain a group of frequency domain signals.
In order to reduce the amount of calculation of the first processing module 51, the phase code preferably uses a code sequence with better autocorrelation. For example, a Hadamard sequence can be adopted, which takes values in {1, -1}, so that only the positive and negative values of a bit need to be inverted in the phase rotation process, and the method has the advantage of simple implementation process.
For transform module 52, it may transform the set of frequency domain signals into a set of time domain signals using an IFFT transform.
The weighting factors in the weighting coefficient set mentioned in the embodiment of the present invention are all selected from real numbers, preferably 1 or-1, so that the complexity of the algorithm can be effectively reduced by implementing the inversion and superposition of bits during the weighting process.
For the selection module 54, the optimal set of weighting factors may be determined by: and comparing the peak-to-average ratio of the group time domain signals corresponding to each weighting factor group in the weighting coefficient set, and selecting the weighting factor group corresponding to the group time domain signal with the lowest peak-to-average ratio as the optimal weighting factor group.
For specific details and benefits of the apparatus for reducing the peak-to-average power ratio of the OFDM system according to the above embodiments of the present invention, reference may be made to the above description of the method for reducing the peak-to-average power ratio of the OFDM system provided by the present invention, and details are not described herein again.
The embodiment of the present invention further provides a signal transmitting end, which is suitable for signal transmitting operation of an OFDM system, and can be specifically configured to perform the following operations: and transmitting a signal to be transmitted and an optimal weight factor group corresponding to the signal to be transmitted.
The signal to be transmitted is the signal to be transmitted with probabilistically lower peak-to-average ratio determined by the method for reducing the peak-to-average ratio of the OFDM system provided by the embodiment of the invention. The optimal weight factor set is determined by traversing the weight factor set in the method for reducing the peak-to-average power ratio of the OFDM system provided by the embodiment of the invention.
The signal to be transmitted received at the signal transmitting end is a signal with a probabilistically low peak-to-average ratio determined by the method for reducing the peak-to-average ratio of the OFDM system provided by the embodiment of the present invention, and in the process of processing the frequency domain signal into the signal to be transmitted, the same phase code sequence is used as the frequency domain spreading code, so that only the preset spreading code is set at the corresponding signal receiving end, and the repeated spreading code is not required to be transmitted while the signal to be transmitted is transmitted, thereby effectively improving the frequency band utilization rate.
Correspondingly, an embodiment of the present invention further provides a signal receiving end, where the signal receiving end is applicable to a signal receiving operation of an OFDM system, and can be specifically configured to perform the following operations: receiving a signal to be sent by a sending end and an optimal weight factor group corresponding to the signal to be sent; and recovering the signal to be transmitted according to the optimal weighting factor group and a preset phase code.
Because the same spread spectrum sequence is adopted in the process of generating the signal to be processed, only the spread spectrum sequence is pre-stored at the signal receiving end, and the data after spread spectrum does not need to be pre-stored.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.
Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.
Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solutions of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications all belong to the protection scope of the embodiments of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention do not describe every possible combination.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. A method for reducing a peak-to-average ratio in an OFDM system, the method comprising:
grouping the frequency domain signals, performing phase rotation on each group of grouped signals to obtain a group of frequency domain signals, or performing phase rotation on the frequency domain signals, and grouping the phase-rotated signals to obtain the group of frequency domain signals;
transforming the set of frequency domain signals to obtain a set of time domain signals;
traversing the weighting factor groups in the weighting factor set to determine the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group;
selecting an optimal weighting factor group according to the peak-to-average ratio of the group time domain signal corresponding to each weighting factor group; and
combining the set of time domain signals according to the optimal weighting factor set to obtain a signal to be transmitted,
wherein the weighting factors in the weighting coefficient set are real numbers.
2. The method of claim 1, wherein the weighting factor is 1 and/or-1.
3. The method of claim 1, wherein the phase rotation uses a phase code that is a Hadamard sequence.
4. The method of claim 1, wherein phase rotating each group of grouped signals comprises:
and performing phase rotation on each group of signals by adopting the same phase code.
5. The method of claim 1, wherein transforming the set of frequency domain signals to obtain a set of time domain signals comprises:
and performing inverse fast Fourier transform on each set of frequency domain signals of the set of frequency domain signals respectively to obtain the set of time domain signals composed of time domain signals respectively corresponding to each set of frequency domain signals.
6. The method according to claim 1, characterized in that it comprises:
acquiring a spreading factor, and
grouping the frequency domain signals based on the spreading factor or grouping the phase rotated signals based on the spreading factor.
7. The method of claim 1, wherein the frequency domain signals are grouped in a manner of: block grouping, comb grouping, or random grouping.
8. An apparatus for reducing a peak-to-average ratio of an OFDM system, the apparatus comprising:
the first processing module is used for grouping the frequency domain signals, performing phase rotation on each group of grouped signals to obtain a group of frequency domain signals, or performing phase rotation on the frequency domain signals, and grouping the phase-rotated signals to obtain the group of frequency domain signals;
a transform module for transforming the set of frequency domain signals into a set of time domain signals;
the traversing module is used for traversing the weighting factor groups in the weighting factor set to determine the peak-to-average ratio of the group time domain signals corresponding to each weighting factor group;
a selecting module, configured to select an optimal weight factor group according to a peak-to-average ratio of a group time domain signal corresponding to each weight factor group; and
a second processing module, configured to combine the set of time domain signals according to the optimal weighting factor group to obtain a signal to be sent,
wherein the weighting factors in the weighting coefficient set are real numbers.
9. A signal transmitting end, wherein the transmitting end is configured to perform the following operations:
transmitting a signal to be transmitted according to any one of claims 1 to 7 and an optimal set of weighting factors corresponding to the signal to be transmitted.
10. A signal receiving end, wherein the receiving end is configured to perform the following operations:
receiving a signal to be transmitted according to any one of claims 1 to 7 and an optimal weight factor set corresponding to the signal to be transmitted; and
and restoring the signal to be transmitted according to the optimal weighting factor group and a preset phase code.
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