CN108243139A - Adaptive orthogonal frequency division multiplexing multi-carrier modulation method and system - Google Patents
Adaptive orthogonal frequency division multiplexing multi-carrier modulation method and system 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
- H04L27/2601—Multicarrier modulation systems
- H04L27/2614—Peak power aspects
- H04L27/2618—Reduction thereof using auxiliary subcarriers
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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
- H04L27/2601—Multicarrier modulation systems
- H04L27/2614—Peak power aspects
- H04L27/2621—Reduction thereof using phase offsets between subcarriers
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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
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
- H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
- H04L27/3854—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
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Abstract
The present invention proposes a kind of adaptive orthogonal frequency division multiplexing multicarrier modulation system.The system is on the basis of traditional Orthogonal Frequency Division Multiplexing (OFDM) multicarrier modulation system, is obtained by introducing Adaptive Signal Processing.It is different from ofdm system, sub-carrier number in AD ofdm systems in each signal frame is changed with characteristics of signals, the sub-carrier number of transmitting terminal handles the size variation of power PAR (PAPR) value of signal according to every frame, by calculating PAPR values come the sub-carrier number of decision systems, so as to effectively reduce the PAPR values of system and power consumption.It is compared with the method for PAPR values in other reduction ofdm systems, AD ofdm systems can not only keep the superiority of ofdm system, and reduce the more efficient of PAPR values.The transmitting terminal of AD ofdm systems needs the sub-carrier number of every frame to be dealt into receiving terminal as side information.
Description
Technical field
The present invention relates to multi-carrier modulation technology, more particularly to a kind of adaptive orthogonal frequency division multiplexing multicarrier modulation system
(AD-OFDM)。
Background technology
Orthogonal Frequency Division Multiplexing (OFDM) is that most representative multi-carrier modulation technology is compared with single-carrier modulated, OFDM
Modulating system has the advantages that strong antijamming capability, especially in wireless channel caused by Multipath Transmission frequency selectivity
Attenuation has apparent resistivity, therefore OFDM technology is selected as uniquely modulating by current almost all of wireless communication standard
Scheme is the core technology in the 4th generation wireless broadband network standard LTE.Other than wireless communication, OFDM technology is also widely used
In the Voice and Video field of broadcast type and wired communication system, such as asymmetric digital subscriber line (ADSL), number
The systems such as video broadcasting (DVB), high-definition television (DVB) and WLAN (WLAN).
The OFDM multi-carrier modulation technologies used at present belong to non-adaptive OFDM modulation techniques, that is to say, that its subcarrier
Number, the points of FFT transform are changeless in communication process in other words.The ofdm system of fixed sub-carrier number, which has, to be realized
The advantages of simple, because the length of FFT is changeless.But non-adaptive OFDM has the defects of some are intrinsic, such as
Power PAR (PAPR) value is high, and temporal frequency resolution ratio is low etc..PAPR value height means that the power consumption of terminal device increases, and when
Low efficiency of transmission and the quality reduction meaned in system of frequency division resolution.Time frequency resolution refers to frequency in different time periods point
Resolution, for weighing balance of the system between temporal resolution and frequency resolution.Ideally, modulating system should have
The frequency resolution changed over time, that is to say, that system can adjust frequency resolution according to the quality of channel, such as when
When channel quality is good, we can increase number of subchannels, improve the frequency resolution of system, so as to improve efficiency of transmission, work as letter
We can reduce number of subchannels when road quality reduces, and the frequency resolution of system be reduced, so as to improve the anti-interference energy of system
Power.Non-adaptive OFDM does not have ideal time frequency resolution, because non-adaptive OFDM sub-channels number is changeless.
In addition, adaptive OFDM can also reduce the PAPR values of system, so as to reduce the power consumption of terminal device.In an ofdm system, it is high
For PAPR values since IFFT operations are brought, IFFT operation length is longer, and the probability for generating big PAPR values is bigger, therefore from
For the angle for reducing PAPR values, the length of IFFT should be as short as possible, that is to say, that sub-carrier number is preferably adaptive.It is comprehensive
Upper described, adaptive OFDM (AD-OFDM) systems are more preferable than the performance of non-adaptive ofdm system.
There are many forms of expression by adaptive OFDM, and traditional adaptive OFDM is to select to send by the bit error rate of channel
The sub-carrier code method at end, so as to adaptively adjust the transmission rate of sub-carrier signal, to reach the optimal bit error rate of system.
Be not much with adaptive OFDM to reduce the scheme of PAPR, a kind of method that can be found in the literature be by PAPR thresholdings come
The adaptively selected companding algorithm for reducing PAPR is selected, and the method for the invention to be introduced and other methods are different, this hair
Bright is to reduce PAPR by the signal processing frame length of Adaptive Modulation OFDM, and this method can not only reduce PAPR, moreover it is possible to
The signal resolution of ofdm system is provided, improves the error ratio characteristic of system.
Invention content
The technical problems to be solved by the invention are to carry out signal tune using non-adaptive ofdm system for the prior art
System does not have ideal time frequency resolution, and the PAPR values of system are excessive, the problem of so as to increase terminal device power consumption,
Invention provides a kind of adaptive orthogonal frequency division multiplexing multi-carrier modulation method and its system.
Technical proposal that the invention solves the above-mentioned problems is as follows：
A kind of adaptive orthogonal frequency division multiplexing multi-carrier modulation method, this method include the following steps：Transmitting terminal is to input
Signal sequence carries out baseband modulation processing, and the signal length M of every frame of baseband modulation signal is fixed；According to the power of system
Peak-to-average force ratio PAPR values determine sub-carrier number N (m), and as the operation length of present frame IFFT, the m frame numbers of m expressions here
According to；The sub-carrier number N (m) of current demand signal frame is sent into channel as side information and modulated signal together and is sent to receiving terminal,
Signal needs prefixing before sending；Receiving terminal removes prefix to modulated signal, then removes channel disturbance by frequency domain equalizer；
Receiving terminal is according to side information demodulated signal.
Further, determine that sub-carrier number N (m) is specifically included according to the PAPR values of system：Initialization takes N (m)=M, Q
(m)=M/N (m) carries out M point baseband modulations output signal secondary N (m) the point IFFT of Q (m) and operates, then IFFT is exported and is synthesized
The data for being M for a frame length, and its PAPR value is calculated, by obtained PAPR values and given threshold value PAPR0It makes comparisons, if
PAPR values are less than given threshold value PAPR0, then sub-carrier number be maintained as original M, i.e. N (m)=M, otherwise, sub-carrier number
The points of N (m)=M/2, i.e. IFFT operation are kept to M/2, and so on, circulate operation, until the PAPR values of the symbolic frame are little
In given threshold value PAPR0。
In receiving terminal, prefix process is first carried out to the side information and modulated signal that receive, then carries out M points
FFT (Fourier transformation) is operated, and signal, which is transformed to frequency domain, obtains frequency domain data, then carry out frequency domain equalization operation to frequency domain data
After removing channel disturbance, IFFT (Fourier's anti-change) operation of M points is carried out, obtains M point baseband modulation reconstruction signals；It will
M point baseband modulation signals are by with after the corresponding base band demodulating of transmitting terminal, recovering transmitting terminal data sequence.
The present invention also proposes a kind of adaptive orthogonal frequency division multiplexing multicarrier modulation system, and system includes transmitting terminal and reception
End, the transmitting terminal carry out input signal sequence baseband modulation processing, and the signal length M of every frame of baseband modulation signal is solid
Fixed；Transmitting terminal determines sub-carrier number N (m), and as present frame IFFT's according to the power PAR PAPR values of system
Operation length；Using the sub-carrier number N (m) of current demand signal frame as side information and modulated signal, believed by being sent into after prefixing
Road is sent to receiving terminal；Receiving terminal removes modulated signal prefix first, then removes channel disturbance by frequency domain equalizer；It connects
Receiving end is according to side information demodulated signal.
It proposes to determine the carrier number of multicarrier system using the PAPR values of system as parameter index in invention, this method is not
The adaptive of OFDM multicarrier systems is only realized, improves the time frequency resolution of system, and this adaptive modulation system
Method can also improve the defects of multicarrier system is intrinsic, i.e., excessive system PAPR values.It is disclosed by the invention this adaptive
OFDM modulating systems are answered, while improving system time frequency resolution ratio, reducing system PAPR values, improvement system performance, and can be subtracted
The design difficulty of the subsequent high power amplifier of few transmitting terminal.Compared with the existing methods, method proposed by the present invention, can not only
PAPR values are reduced, while can also keep the superiority of OFDM modulating systems, and realize that difficulty is small.
Description of the drawings
Figure 1A D-OFDM systems transmit symbol generating process schematic diagram；
Fig. 2A D-OFDM system structure diagrams；
Fig. 3 signal processing flow figures of the present invention
Fig. 4 signal frame structures；
Fig. 5 sub-carrier number search process schematic diagrames.
Specific embodiment
OFDM has excellent possessed by frequency domain multicarrier modulation system as a kind of special frequency domain multicarrier modulation system
Point while realizing large-capacity data transmission by mutually orthogonal multiple subcarriers, also improves the availability of frequency spectrum of system.
Similary OFDM modulating systems also have the defects of frequency domain multicarrier system, particularly have higher peak to average power ratio, this obstruction
The development of OFDM technology.Since OFDM technology proposes till now, there have been many methods for reducing ofdm system PAPR, but mesh
Preceding all methods are required for changing modulation output signal (output of IFFT), the property for the destruction ofdm system that this can be different degrees of
Energy.
High papr values in ofdm system are caused by the modulation scheme of ofdm system, in the transmission of ofdm system
End, the modulation of signal are to operate to realize by IFFT, although this simplifies the complexity of ofdm system realization, are also carried simultaneously
The high PAPR values of signal.The reason is that because IFFT is superimposed and obtains after being multiplied by input signal with the complex exponential of different frequency
, and the input signal of IFFT comes from baseband modulation, these signals are the complex values of random distribution.When these random complex and again
After index is multiplied, the phase of product will change, when the phase of all products is identical, at this moment and reach maximum, generate peak
Value.Therefore, the probability of the PAPR values more larger than original signal generation of the signal after IFFT is converted is big, that is to say, that by IFFT
PAPR values afterwards can become larger.The methods for reducing PAPR values all at present are all based on this mechanism, by changing IFFT output letters
Number change the distribution of phase, so as to reduce PAPR values, but the influence OFDM modulation system that the output for changing IFFT can be different degrees of
The characteristic of system.
Pass through the analysis to OFDM overloading frequency modulating systems, it has been found that in overloading frequency modulating system, work as sub-carrier number
Become hour, the probability for high papr values occur can become smaller, this discovery let us is contemplated is to reduce by changing sub-carrier number
The method of system PAPR.The advantages of this method is the output signal characteristics for not needing to change modulating system, so as to maintain overloading
The advantages of frequency modulating system.Thus modulating system obtained from is called adaptive overloading frequency modulating system by we, because it is sub
Carrier number changes over time.
Fig. 1 transmits symbol generating process schematic diagram for AD-OFDM systems, describes the generation transmission of AD-OFDM modulating systems
The process of symbol.Input data sequence s (n) carries out deblocking, current by baseband modulation to baseband modulation signal X (n)
The data block of m frames is divided into N (m) sub-block X (n, m), and then carrying out N (m) point IFFT to deblocking X (n, m) converts, during acquisition
Domain signal x (n, m).Input data sequence passes through baseband modulation to generate the complex signal easily transmitted, while base band tune first
Mode processed also directly affects the transmission rate of system.The same with ofdm system, the baseband modulation mode of AD-OFDM systems can be
QPSK, 16QAM and 64QAM.Twice faster than QPSK of 16QAM, and twice faster than 16QAM of 64QAM, therefore baseband modulation mode is not
Together, the transmission rate of system is also different.Then signal after baseband modulation is converted by IFFT, the purpose of IFFT transformation is
Being transmitted in signal modulation to sub- carrier frequency, if the output after baseband modulation is regarded as frequency-region signal by we, then IFFT
Signal after transformation is time-domain signal.The length of IFFT is change of variable at any time, in the present invention, by current demand signal frame
PAPR determine.
Fig. 2 gives the realization block diagram of AD-OFDM systems, and top half is transmitting terminal, and lower half portion is receiving terminal.In figure
The expression of symbol is similar with Fig. 1, and in transmitting terminal, s (n) represents input signal series, and X (n) represents the symbol after baseband modulation
Number, Xi(n, m) (0≤i≤Q (m) -1) represents i-th sub-blocks of the m frame symbol data X (n) after piecemeal, wherein Q
(m) number of sub-block is represented, x (n) represents sub-block after Fourier's anti-change (IFFF), and by Data Synthesis
Output series afterwards.N (m) represents the length of sub-block in m frame symbol datas, if the signal length of symbol data frame is
The relationship of M, N (m), M and Q (m) are N (m)=M/Q (m), and N (m) need to pass to receiving terminal as side information.The symbol of receiving terminal
It is corresponding with the symbol of transmitting terminal, represent after channel receiving terminal recover with the corresponding signal of receiving terminal.
In fig. 2, signal sequence is handled in a manner of frame, base band output symbol series of X (n) the elder generation a length of M of configuration frame
Signal frame, the value of M determines, not with change of variable between 64 to 2048 according to system requirements.The value of M once it is determined that after,
All it is fixed number in entire transmission.
The adaptive variation (m represents m frames symbol data) for being embodied in sub-frame data length N (m) of system, N in Fig. 3
(m) value is the PAPR values by current data frame come determining.Since N (m) is changed with frame Coefficient m, each frame number
It is also what is changed with frame Coefficient m according to the middle number Q (m) for carrying out IFFF.After N (m) is determined, Q (m) is true by formula Q (m)=M/N (m)
It is fixed.After N (m) and Q (m) is waited to determine, data frame is divided into a subframes of Q (m) that length is N (m), then carries out the secondary IFFT fortune of Q (m)
It calculates, after the completion of IFFT operations, subframe one signal length of composition that a length of Q (m) is N (m) is that the signal frame of M etc. is to be transmitted.
It is illustrated in figure 3 signal processing flow figure of the present invention.
Transmitting terminal carries out baseband modulation processing to input signal sequence, and the signal length M of every frame of baseband modulation signal is
It is fixed；Sub-carrier number N (m) is determined, and as the operation of present frame IFFT according to the power PAR PAPR values of system
Length；It is sent using the sub-carrier number N (m) of current demand signal frame as being sent into channel after side information and modulated signal together prefixing
To receiving terminal；Receiving terminal removes prefix to modulated signal, and channel disturbance is gone by frequency domain equalizer, is demodulated and believed according to side information
Number.
In transmitting terminal, first have to determine sub-carrier number (subsignal frame length) N (m) of current demand signal frame, basic operation is first
First take N (m)=M, then carry out the secondary IFFT variations of Q (m)=M/N (m), PAPR (m) values of current frame signal are obtained, then
PAPR (m) and threshold value PAPR0Compare.If PAPR (m)>PAPR0, show that PAPR is unsatisfactory for requiring, need to reduce sub-carrier number
N(m).N (m)=M/2 is taken, continue PAPR evaluations and is compared, until meeting PAPR (m)<PAPR0, N (m) at this moment is
The sub-carrier number to be found.Detailed description will be later to providing in the explanation of Fig. 5.
After sub-carrier number N (m) is determined, so that it may IFFF operations are carried out to each sub-frame data, finally Q (m) subframes
IFFT outputs synthesize a M point output signal, and the output signal of synthesis can be sent to channel after prefixing.Prefixing
Purpose be allow Finite Length Signal frame by after channel and channel transfer function formed cyclic convolution relationship, to receive
End can remove channel disturbance using frequency-domain equilibrium method.Meanwhile sub-carrier number N (m) also must be in the form of side information
It is sent to receiving terminal.In receiving terminal, the signal frame received removes prefix first, is then done using balanced device removal channel
It disturbs.We use frequency domain equalizer in the present invention, since frequency domain equalization is carried out in frequency domain, so first having to receive
Removal prefix data by FFT transform to frequency domain, as shown in Figure 3.Frequency domain equalization operation is very simple, need to only carry out simple
Division arithmetic, i.e.,WhereinRepresent the reception data of removal prefix,Represent balanced
Device exports, and H (n) represents the FFT transform of channel transfer function.By the data after balanced device using obtaining time domain weight after IFFT
Signal is built, is the subframe that a length of Q (m) is N (m) M point signal decompositions, then to each number of sub frames then according to side information
According to FFT operations are carried out, obtain rebuilding baseband signal after synthesizing a FFT output points of Q (m).Then by being obtained after base band demodulating
Output signal is rebuild, arrives this, the data processing of a frame finishes.
It is compared with non-adaptive OFDM multicarrier modulation systems, in the receiving terminal of AD-OFDM, passes through the number after equilibrium treatment
According to also need carry out an IFFT operation.But in non-adaptive OFDM, this IFFT is not needed to, because being connect in non-adaptive OFDM
FFT operations before receiving end balanced device have double function：One is balancing operational, detaches signal and transfer function；The second is to hair
The IFFT of sending end carries out inverse transformation, restores baseband modulation signal.But in adaptive OFDM multicarrier modulation systems, due to
Transmitting terminal data frame is divided into multiple subframes, and each subframe carries out IFFT operations respectively, so the FFT operations before balanced device exist
Dual function in non-adaptive OFDM modulating systems, can not embody in AD-OFDM modulating systems.Therefore, in AD-
In OFDM modulating systems, the FFT operations of M points need to first be carried out by receiving data, therein dry by being eliminated after balancing operational
Signal is disturbed, then carries out transform frequency domain data after IFFT operation handlebar equilibriums to time domain.
It is illustrated in figure 4 signal frame structure schematic diagram.In figure, X (0) to X (M-1) represents a frame M of baseband modulation symbol
Glyph number, N (m) represent sub-carrier number (subframe lengths), Xi(n, m) (0≤i≤Q (m) -1) represents i-th of sub-frame signals.
Time-domain signal x (n), x are obtained after carrying out IFFF variations to each subframei(n, m) and (Xi(n, m) forms a FFT variation pair.
The present invention can be used following method and determine sub-carrier number, the method that Fig. 5 show determining sub-carrier number, according to system
PAPR values determine that sub-carrier number N (m) is specific as follows：：
Initialization takes N (m)=M, carries out deblocking according to formula Q (m)=M/N (m), point input data X (n) is divided
Block data is point per block length, and Q (m) secondary N (m) point IFFT operations are carried out to M point baseband modulations output signal, then
IFFT outputs synthesize a frame length and are the data of M, and calculate its PAPR value, by obtained PAPR values and given threshold value
PAPR0It makes comparisons, if PAPR values are less than given threshold value PAPR0, then sub-carrier number be maintained as original M, i.e. N (m)=M,
Otherwise, the points of sub-carrier number N (m)=M/2, i.e. IFFT operation are kept to M/2, and so on, circulate operation, until the symbolic frame
PAPR values no more than given threshold value PAPR0, the signal frame coefficient of m expressions here.PAPR (m) is calculated by formula below：
In formula, PAPR (m) represents the PAPR values of m frame symbol datas, and x (kN (m)+n, m) is the output of transmitting terminal IFFF,
Q (m) is IFFT number of operations.Threshold value PAPR0It is determined by the requirement of design system, generally 6<PAPR0<8(dB)。
A kind of adaptive OFDM overloadings frequency modulating system based on system PAPR values proposed by the present invention can effectively drop
The power consumption of low system.It is compared with existing non-adaptive OFDM, AD-OFDM systems can control the PAPR values of whole system
Threshold value PAPA0Within value, this characteristic is advantageous to the design of transmitting terminal power amplifier.By setting threshold value PAPA0
We can be the lower power consumption of terminal device to desired value.In addition to this, the adaptive of system also improves modulating system
Time frequency resolution and transmission quality.
Claims (10)
1. a kind of adaptive orthogonal frequency division multiplexing multi-carrier modulation method, which is characterized in that this method includes the following steps：It sends
End carries out baseband modulation processing to input signal sequence, obtains signal length M of the baseband modulation signal per frame and fixes；According to system
Power PAR PAPR values determine sub-carrier number i.e. subframe lengths N (m), and using sub-carrier number Q (m) as current demand signal frame
The operation length of IFFT carries out Q (m) secondary IFFT operations, and after the completion of IFFT operations, the subframe that a length of Q (m) is N (m) forms one
A signal length is the signal frame of M；Again using the sub-carrier number N (m) of current demand signal frame as side information and modulated signal together
Prefixing is then fed into channel and is sent to receiving terminal；Receiving terminal removes prefix to modulated signal, is then gone by frequency domain equalizer
Except channel disturbance, receiving terminal is according to side information demodulated signal.
2. modulator approach according to claim 1, it is characterised in that：Sub-carrier number N (m) is determined according to the PAPR values of system
It specifically includes：The number that N (m)=M, Q (m)=M/N (m), Q (m) represents sub-block is initialized, M points baseband modulation is exported
Signal carries out secondary N (m) the point IFFT operations of Q (m), IFFT outputs is then synthesized the data that a frame length is M, and according to public affairs
Formula：Its PAPR value is calculated, PAPR values are made comparisons with given threshold value PAPR0, if PAPR values are less than given threshold value
PAPR0, then sub-carrier number, that is, subframe lengths be maintained as original M, i.e. N (m)=M, otherwise, sub-carrier number N (m)=M/2, i.e.,
The points of IFFT operations are kept to M/2, and so on, circulate operation, until the PAPR values of the symbolic frame are no more than given thresholding
Value PAPR0.
3. modulator approach according to claim 1, it is characterised in that：Threshold value PAPR0 determines by the requirement of design system,
Generally 6<PAPR0<8(dB).
4. modulator approach according to claim 1, it is characterised in that：In receiving terminal, to the side information and tune received
Signal processed carries out the Fourier transformation FFT operations of M points, and signal, which is transformed to frequency domain, obtains frequency domain data, then to frequency domain data into
After the balancing operational of line frequency domain, Fourier's anti-change IFFT operations of M points are carried out, obtain M point baseband modulation signals；By M points
Baseband modulation signal is by with after the corresponding base band demodulating of transmitting terminal, recovering transmitting terminal data sequence.
5. modulator approach according to claim 1, it is characterised in that：The baseband modulation mode of system be QPSK, 16QAM or
64QAM。
6. a kind of adaptive orthogonal frequency division multiplexing multicarrier modulation system, system includes transmitting terminal and receiving terminal, which is characterized in that
The transmitting terminal carries out baseband modulation processing to input signal sequence, and the signal length M of every frame of baseband modulation signal is fixed
's；Transmitting terminal determines sub-carrier number N (m), and as the fortune of present frame IFFT according to the power PAR PAPR values of system
Length is calculated, carries out Q (m) secondary IFFT operations, after the completion of IFFT operations, the subframe that a length of Q (m) is N (m) forms a Chief Signal Boatswain
Spend the signal frame for M；Again using the sub-carrier number N (m) of current demand signal frame as side information and modulated signal, pass through transmitting terminal frequency
Domain balanced device is sent to receiving terminal by channel is sent into after modulated signal prefixing；The receiving terminal removes prefix to modulated signal,
According to side information demodulated signal.
7. modulating system according to claim 6, it is characterised in that：Sub-carrier number N (m) is determined according to the PAPR values of system
It specifically includes：Initialization takes N (m)=M, Q (m)=M/N (m), and Q (m) secondary N (m) point is carried out to M point baseband modulations output signal
IFFT is operated, and IFFT outputs is then synthesized the data that a frame length is M, and according to formula：Its PAPR value is calculated, will be obtained
PAPR values make comparisons with given threshold value PAPR0, if PAPR values are less than given threshold value PAPR0, sub-carrier number is still
Original M, i.e. N (m)=M are remained, otherwise, the points of sub-carrier number N (m)=M/2, i.e. IFFT operation are kept to M/2, with such
It pushes away, circulate operation, until the PAPR values of the symbolic frame are no more than given threshold value PAPR0.
8. modulator approach according to claim 7, it is characterised in that：Threshold value PAPR0 determines by the requirement of design system,
Generally 6<PAPR0<8(dB).
9. modulating system according to claim 6, it is characterised in that：In receiving terminal, to the side information and tune received
Signal processed carries out the Fourier transformation FFT operations of M points, and signal, which is transformed to frequency domain, obtains frequency domain data, then to frequency domain data into
After the balancing operational of line frequency domain, Fourier's anti-change IFFT operations of M points are carried out, obtain M point baseband modulation signals；By M points
Baseband modulation signal is by with after the corresponding base band demodulating of transmitting terminal, recovering transmitting terminal data sequence.
10. modulating system according to claim 6, it is characterised in that：The baseband modulation mode of system is QPSK, 16QAM
Or 64QAM.
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| CN111654462A (en) * | 2020-06-03 | 2020-09-11 | 珠海中慧微电子有限公司 | Method for reducing peak-to-average ratio of OFDM (orthogonal frequency division multiplexing) signal based on symbol splitting |
| CN116996543A (en) * | 2023-09-27 | 2023-11-03 | 之江实验室 | Vehicle-mounted Ethernet communication method and device based on orthogonal frequency division multiplexing |
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| CN103297379A (en) * | 2013-07-01 | 2013-09-11 | 重庆邮电大学 | Time-varying orthogonal frequency division multiplexing (TV-OFDM) multi-carrier modulation system and modulation method |
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| CN103297379A (en) * | 2013-07-01 | 2013-09-11 | 重庆邮电大学 | Time-varying orthogonal frequency division multiplexing (TV-OFDM) multi-carrier modulation system and modulation method |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111654462A (en) * | 2020-06-03 | 2020-09-11 | 珠海中慧微电子有限公司 | Method for reducing peak-to-average ratio of OFDM (orthogonal frequency division multiplexing) signal based on symbol splitting |
| CN111654462B (en) * | 2020-06-03 | 2022-11-11 | 珠海中慧微电子有限公司 | Method for reducing peak-to-average ratio of OFDM (orthogonal frequency division multiplexing) signals based on symbol splitting |
| CN116996543A (en) * | 2023-09-27 | 2023-11-03 | 之江实验室 | Vehicle-mounted Ethernet communication method and device based on orthogonal frequency division multiplexing |
| CN116996543B (en) * | 2023-09-27 | 2024-01-09 | 之江实验室 | Vehicle-mounted Ethernet communication method and device based on orthogonal frequency division multiplexing |
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