Peak power optimization method and emission system in ofdm system
Technical field
The disclosure belongs to peak power optimization method and hair in digital communication technology field more particularly to a kind of ofdm system
Penetrate system.
Background technique
Orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) is a kind of nothing
The data-signal of high speed is converted into the Multicarrier Transmission Technology that low speed subcarrier data is handled under thread environment.It is grasped substantially
It is exactly that given channel is divided into multiple mutually orthogonal subchannels in frequency domain as principle, then by the data of high-speed transfer
Stream is assigned in each sub-channels of low speed by serioparallel exchange port, then orthogonal with one on each sub-channels
Subcarrier is modulated.Therefore, OFDM technology can be converted into high-speed data signal low speed data information by it and be transmitted
This feature shows very big advantage in some respects, such as: information processing, anti-multipath fading and anti-narrowband interference multiple access access
Etc..As the advantages of OFDM technology is exploited, which is gradually widely applied in each application of mobile communication,
Such as: European digital audio/video broadcast, wireless MAN IEEE802.16a system, digital video broadcasting etc..
Emission port in an ofdm system, for used phase-shift keying (PSK) (Phase Shift Keying, PSK) or
The data-signal symbol obtained after quadrature amplitude modulation method (Quadrature Amplitude Modulation, QAM) modulation
Sequence, by inverse fast Fourier transform (Inverse Fast Fourier Transform, IFFT) operation after obtain from
Time-domain signal { x [n] } is dissipated to be expressed as follows:
It that is to say, N number of discrete time-domain signalPhase Calais obtains discrete time signal { x [n] }, wherein each
The corresponding different orthogonal sub-carriers of a signal, k-th of subcarrier are modulated by data-signal symbol X [k].Here N represents son
The quantity of carrier wave.
By expression above it is found that ofdm signal is got by N number of mutually orthogonal sub-carrier signal addition.Cause
This, when the initial phase of subcarrier is same or similar, the signal being added is exactly by the signal with identical initial phase
Modulation, according to central-limit theorem it is found that the signal of synthesis is there is a high likelihood that generate biggish instantaneous power peak value.
In addition, peak-to-average power ratio (Peak-To-Average Power Ratio, PAPR) is defined as: peak power and mean power
Ratio, expression formula is as follows.Again because the mean power of signal is constant, biggish instantaneous power in transmission process
Peak value will increase the peak-to-average power ratio of signal.
Wherein, E { } represents the expectation of data-signal { x [n] }.
In fact, the quality of the PAPR performance about ofdm signal, we are generally retouched using its probabilistic statistical characteristics
State it.We use complementary cumulative distribution function (Complementary Cumulative Distribution under normal conditions
Function, CCDF) the peak-to-average power ratio performance of ofdm signal described, it may be expressed as:
CCDF=Pr (PAPR > PAPR0)
=1- (1-exp (- PAPR0))N
Wherein, PAPR0It is a threshold value.
For OFDM technology, height power ratio is one of major defect of OFDM technology.Therefore, 90 years 20th century
Generation, people just have begun working on the PAPR performance for how simply and efficiently improving ofdm system.Currently, for having mentioned
The method of improvement PAPR out, can substantially be divided into two major classes: have the PAPR suppression technology of signal distortion and no signal to distort
PAPR suppression technology.The former is realized by simply cutting ofdm signal, cutting the result is that increasing the mistake of system
Code rate and out-of-band distortion, but out-of-band distortion can be improved by repeating filtering.The latter is to be converted into original waveform
The new waveform of one group of PAPR better performances, but most of reduction with bandwidth.The PAPR restrainable algorithms packet of no signal distortion
Include selected mapping method, optimization algorithm, planisphere expansion etc..
Selective mapping is more excellent an one of technology in numerous technologies.The basic principle is that: first defeated
The signal data block X=[X entered0,X1,…,XN-1] and U different phase sequencesIt is weighted processing, obtains U modified signal data blocksWhereinV=0,1 ..., N-
1, u=1,2 ..., U.Then to U mutually independent X(u)It carries out IFFT and obtains U OFDM candidate signal x(u)(u=1,2 ...,
U).Finally, selecting the best signal of PAPR performance from these candidate ofdm signals to transmit.In addition, we in order to
Guarantee that original input signal data block is not changed, should must include one complete 1 sequence in this U phase sequence.Cause
This, we generally set first phase sequence and are all 1, i.e. P1=[1,1 ..., 1].
Although selected mapping method technology improves the PAPR performance of ofdm system, transmission signal is not also distorted, but
It is that the introducing of the technology but substantially increases the complexity of system.
Summary of the invention
To overcome above-mentioned the deficiencies in the prior art, present disclose provides peak power optimization method in a kind of ofdm system and
Emission system, this method can not only obtain PAPR performance similar with original selected mapping method method, but also can be big
The earth reduces the computation complexity of system.
To achieve the above object, one or more other embodiments of the present disclosure provide following technical solution:
Peak power optimization method in a kind of ofdm system, comprising the following steps:
It receives original binary and transmits signal, carry out phase-shift keying (PSK) modulation, obtain modulated signal;
Two groups of different phase factor rotatable sequences are respectively adopted, processing is weighted to the modulated signal;
Inverse fast Fourier transform is carried out to the modulated signal of weighted processing, obtains two groups of time-domain signal sequences;
Deformation parameter collection is selected, place is weighted to two groups of time-domain signal sequences respectively using the deformation parameter collection
Reason, obtains two groups of OFDM candidate signal sequences, is respectively stored in the first cluster and the second cluster;
Two groups of OFDM candidate signal sequences are added and are normalized, new OFDM candidate signal sequence is obtained
Column, are stored in third cluster;
The signal sequence of PAPR best performance is selected to be used for transmission from three cluster candidate signals.
Further, described two groups different phase factor rotatable sequence generation methods are as follows:
Two phase factor set are selected, one for generating a length and ofdm system number of subcarriers
Equal phase factor rotatable sequence, another is equal with ofdm system number of subcarriers for generating b length
Phase factor rotatable sequence;Wherein, the element in each rotatable sequence is from the element of corresponding phase factor set
It is randomly selected.
Further, being weighted processing to modulated signal using phase factor rotatable sequence includes:
The phase factor rotatable sequence and the modulated signal are subjected to dot product processing.
Further, the phase-shift keying (PSK) modulation is using QPSK modulation or BPSK modulation.
Further, it is modulated according to QPSK, selects deformation parameter collection W={ w1, w2, wherein w1And w2Meet following item
Part:
(1) whenWhen, w2Value isIn one;
(2) whenWhen, w2Value isIn one.
Further, being weighted processing to any group of time-domain signal sequence using deformation parameter collection includes:
Time-domain signal sequence in the group is subjected to combination of two;
Being all made of the deformation parameter for each combination concentrates element to be weighted processing.
Further, it is modulated according to BPSK, selects deformation parameter collection W={ w1, w2, w3, w4, wherein w1、w2、w3And w4
Meet the following conditions:
The amplitude of any two parameter absolute value in (1) four parameter is all 1, the amplitude of remaining two parameter absolute values
It is all 2;
(2) phase of all parameters is selected from phase sets
Further, being weighted processing to any group of time-domain signal sequence using deformation parameter collection includes:
Four different time domain signal sequences every in the group are combined;
Being all made of the deformation parameter for each combination concentrates element to be weighted processing.
One or more embodiments provide a kind of computer system, including server, the server include memory,
Processor and storage on a memory and the computer program that can run on a processor, when the processor execution described program
Realize peak power optimization method in the ofdm system.
One or more embodiments provide a kind of computer readable storage medium, are stored thereon with computer program, should
Peak power optimization method in the ofdm system is realized when program is executed by processor.
The above one or more technical solution there are following the utility model has the advantages that
Traditional selected mapping method method one OFDM candidate signal of every generation just needs to carry out an IFFT operation, thus
The computation complexity of system is caused to increase, and when disclosure generation part OFDM candidate signal, it does not need to carry out IFFT operation, from
And reduce computation complexity, but also peak-to-average power ratio similar with traditional selected mapping method technology can be obtained
Can, to improve the overall performance of ofdm system.
Detailed description of the invention
The Figure of description for constituting a part of this disclosure is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is the technical principle block diagram of peak power optimization method in the ofdm system of method in the embodiment of the present disclosure one;
Fig. 2 is in an ofdm system, to generate 80 OFDM candidate signal sequences, a=b=2, J=2, when N difference, with
Conventional selective reflection method is compared, and the present invention program calculates complicated reduction chart of percentage comparison.
Fig. 3 is in an ofdm system, to generate 48 OFDM candidate signal sequences, a=b=4, J=4, when N difference, with
Conventional selective reflection method is compared, and the present invention program calculates complicated reduction chart of percentage comparison.
Fig. 4 is to generate 80 OFDM candidate signal sequences, a=b=2, J in the ofdm system with 128 subcarriers
In the case where=2, the PAPR performance map of the present invention program.
Fig. 5 is to generate 48 OFDM candidate signal sequences, a=b=4, J in the ofdm system with 128 subcarriers
In the case where=4, the PAPR performance map of the present invention program.
Specific embodiment
It is noted that described further below be all exemplary, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field
The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
In the absence of conflict, the features in the embodiments and the embodiments of the present application can be combined with each other.
Embodiment one
Present embodiment discloses peak power optimization methods in a kind of ofdm system, as shown in Figure 1, comprising the following steps:
(1) PSK modulation is carried out to the binary transmissions signal data of input;
(2) with two groups of different phase factor set P1And P2Two groups of different phase factor rotatable sequences are generated respectively;
Wherein, two groups of different phase factor rotatable sequences are generated method particularly includes:
Select two phase factor set P1={ ± 1 } and P2={ ± j }, with set P1Generate a length and orthogonal frequency
The equal phase factor rotatable sequence of multiplex system number of subcarriers;With set P2Generate b length and orthogonal frequency division multiplexing system
The equal phase factor rotatable sequence of number of subcarriers of uniting;Element in each rotatable sequence is from corresponding phase factor collection
It is randomly selected in the element of conjunction.
(3) signal data that step (1) generates is weighted with the phase factor rotatable sequence that step (2) generate respectively
Processing, and inverse fast Fourier transform (IFFT) operation is carried out to weighting treated data respectively, generate two groups of PSK modulation
Time-domain signal sequence;
Wherein, the modulated signal data generated to step (1) are weighted processing, specifically:
Each of the two groups of rotatable sequences generated in step (2) phase factor rotatable sequence is produced with step (1)
Raw psk modulation signal data carry out dot product processing.
(4) deformation parameter collection is introduced, element will be concentrated with the time-domain signal sequence deformation parameter of PSK modulation in first group
The OFDM candidate signal sequence obtained after weighting processing is stored in the first cluster, the time-domain signal sequence that second group is modulated with PSK
The OFDM candidate signal sequence that column obtain after being handled with deformation parameter weighting is stored in the second cluster;
Wherein, when selecting deformation parameter, it is divided into following two situation:
The first chooses J=2, i.e. deformation parameter collection W={ w when step (1) uses QPSK to modulate1, w2}.This
When w1And w2Meet condition: 1. whenWhen, w2There are four types of possibilities:②
WhenWhen, w2There are four types of possibilities:At this point, what is generated in step (2) is each
Phase factor rotatable sequence number all has to be larger than equal to 2 in group.
Second, when step (1) uses BPSK to modulate, choose J=4, i.e. deformation parameter collection W={ w1, w2, w3,
w4}.Deformation parameter meets condition at this time: 1. the amplitude of any two parameter absolute value in four parameters is all 1, remaining
The amplitude of two parameter absolute values is all 2;2. the phase of all parameters is selected from phase setsAt this point, step
Suddenly phase factor rotatable sequence number all has to be larger than equal to 4 in each group generated in (2).
Correspondingly, element weighting processing, tool will be concentrated with the time-domain signal sequence deformation parameter of PSK modulation in first group
Body are as follows:
1. when selecting the first deformation parameter collection, in will generate in the step (3) first group with QPSK modulation when
Domain signal sequence combination of two, each combination all concentrates element to be weighted processing with deformation parameter, so that each is combined
Available 8 OFDM candidate signal sequences after weighting;
2. when selecting second of deformation parameter collection, in will generate in the step (3) first group with BPSK modulation when
Every 4 different signal sequences in the signal sequence of domain form a combination, each combination all concentrates element with deformation parameter
It is weighted processing, at most obtain the different OFDM candidate signal sequence of 48 PAPR after each combined weighted.
The OFDM candidate signal sequence obtained after weighting processing is stored in the first cluster, by OFDM candidate signal in the first cluster
Sequence is denoted asM1For the number of signal sequence in the first cluster.
The time-domain signal sequence that PSK in second group is modulated concentrates element weighting processing with deformation parameter, specifically:
1. when selecting the first deformation parameter collection, in will generate in the step (3) second group with QPSK modulation when
Domain signal sequence combination of two, each combination all concentrates element to be weighted processing with deformation parameter, so that each is combined
Available 8 OFDM candidate signal sequences after weighting;
2. when selecting second of deformation parameter collection, in will generate in the step (3) second group with BPSK modulation when
Every 4 different signal sequences in the signal sequence of domain form a combination, each combination is all weighted with deformation parameter
Processing, at most obtain the different OFDM candidate signal sequence of 48 PAPR after each combined weighted.
The OFDM candidate signal sequence obtained after weighting processing is stored in the second cluster, by OFDM candidate signal in the second cluster
Sequence is denoted asM2For the number of signal sequence in set 2.
(5) it is made at normalization of each of the first cluster signal sequence and each signal sequence phase adduction in the second cluster
Reason generates one group of new OFDM candidate signal sequence, is stored in third cluster;
The OFDM candidate signal sequence generated in the step (5), i.e. signal sequence in third cluster, specifically: first
Each of cluster signal sequence is added and is normalized with each signal sequence in the second cluster respectively, obtains M1×
M2A new alternative signal sequence.
OFDM candidate signal sequence in third cluster is denoted asI.e.
Alternative signal sequence in third cluster includes:
(6) signal sequence that PAPR best performance is selected from this three clusters candidate signal is transmitted.
Next in order to verify the performance of this embodiment scheme, following experiment is carried out.
Simulated conditions: MATLAB emulation platform is used, is randomly generated 105A ofdm signal, using 4 times of over-samplings.
First of all for illustrating the present embodiment method feature low relative to traditional selected mapping method method computation complexity,
Fig. 2 and 3 gives in the case where the OFDM candidate signal of different sub-carrier quantity quantity identical with generation, with conventional selective
Mapping method is compared, and the computation complexity of the present embodiment method lowers chart of percentage comparison.From Fig. 2 and 3 as can be seen that the present embodiment side
Case can largely reduce the computation complexity of ofdm system.Furthermore it can be obtained and tradition in order to illustrate the present embodiment
The similar PAPR performance of selected mapping method method, Figure 4 and 5 give the OFDM in different modulating mode quantity identical with generation
In the case where candidate signal, the PAPR performance map of traditional selected mapping method method and the present embodiment.From Fig. 4 and Fig. 5, can see
PAPR performance similar with traditional selected mapping method technology may be implemented in the present embodiment out.
In conclusion compared with traditional selective mapping, this embodiment scheme can not only obtain with it is traditional
The similar PAPR performance of selected mapping method method, and can largely reduce the computation complexity of system.
Embodiment two
The purpose of the present embodiment is to provide a kind of computer system.
A kind of computer system can be run on a memory and on a processor including memory, processor and storage
Computer program, the processor realize following steps when executing described program, comprising:
It receives original binary and transmits signal, carry out phase-shift keying (PSK) modulation, obtain modulated signal;
Two groups of different phase factor rotatable sequences are respectively adopted, processing is weighted to the modulated signal;
Inverse fast Fourier transform is carried out to the modulated signal of weighted processing, obtains two groups of time-domain signal sequences;
Deformation parameter collection is selected, place is weighted to two groups of time-domain signal sequences respectively using the deformation parameter collection
Reason, obtains two groups of OFDM candidate signal sequences, is respectively stored in the first cluster and the second cluster;
Two groups of OFDM candidate signal sequences are added and are normalized, new OFDM candidate signal sequence is obtained
Column, are stored in third cluster;
The signal sequence of PAPR best performance is selected to be used for transmission from three cluster candidate signals.
Embodiment three
The purpose of the present embodiment is to provide a kind of computer readable storage medium.
A kind of computer readable storage medium, is stored thereon with computer program, execution when which is executed by processor
Following steps:
It receives original binary and transmits signal, carry out phase-shift keying (PSK) modulation, obtain modulated signal;
Two groups of different phase factor rotatable sequences are respectively adopted, processing is weighted to the modulated signal;
Inverse fast Fourier transform is carried out to the modulated signal of weighted processing, obtains two groups of time-domain signal sequences;
Deformation parameter collection is selected, place is weighted to two groups of time-domain signal sequences respectively using the deformation parameter collection
Reason, obtains two groups of OFDM candidate signal sequences, is respectively stored in the first cluster and the second cluster;
Two groups of OFDM candidate signal sequences are added and are normalized, new OFDM candidate signal sequence is obtained
Column, are stored in third cluster;
The signal sequence of PAPR best performance is selected to be used for transmission from three cluster candidate signals.
Each step involved in above embodiments two and three is corresponding with embodiment of the method one, and specific embodiment can be found in
The related description part of embodiment one.Term " computer readable storage medium " is construed as including one or more instruction set
Single medium or multiple media;It should also be understood as including any medium, any medium can be stored, encodes or be held
It carries instruction set for being executed by processor and processor is made either to execute in the disclosure method.
The above one or more embodiment has following technical effect that
It will be understood by those skilled in the art that each module or each step of above-mentioned the application can be filled with general computer
It sets to realize, optionally, they can be realized with the program code that computing device can perform, it is thus possible to which they are stored
Be performed by computing device in the storage device, perhaps they are fabricated to each integrated circuit modules or by they
In multiple modules or step be fabricated to single integrated circuit module to realize.The application be not limited to any specific hardware and
The combination of software.
The foregoing is merely preferred embodiment of the present application, are not intended to limit this application, for the skill of this field
For art personnel, various changes and changes are possible in this application.Within the spirit and principles of this application, made any to repair
Change, equivalent replacement, improvement etc., should be included within the scope of protection of this application.
Although above-mentioned be described in conjunction with specific embodiment of the attached drawing to the application, model not is protected to the application
The limitation enclosed, those skilled in the art should understand that, on the basis of the technical solution of the application, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within the protection scope of the application.