WO2009089733A1 - Peak-average-ratio restraining method and device for multi-carrier orthogonal frequency division multiplexing system - Google Patents

Abstract

A peak-average-ratio restraining method for a multi-carrier orthogonal frequency division multiplexing (OFDM) system, pre-generating a lengthened kernel wave, includes: base band frequency domain signals of each carrier are combined into time domain multi-carrier combination channel signals on each orthogonal frequency division multiplexing symbol (S301); clipped noises are extracted from the multi-carrier combination channel signals, and impulse-like signals with a channel length are intercepted from the lengthened kernel wave according to the position of the clipped noises in the multi-carrier combination channel signals (S302); the impulse-like signals are multiplied by the extracted clipped noises to obtain cancellation noises (S303); the cancellation noises are inversely superposed on the delayed multi-carrier combination channel signals to carrying out peak-average-ratio restrain (S304). Also a peak-average-ratio restraining device for OFDM system is provided.

Description

 The present invention claims to be submitted to the Chinese Patent Office on December 28, 2007, and the application number is

200710306945.6, the entire disclosure of which is incorporated herein by reference in its entirety in its entirety the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all

 This application is submitted to the Chinese Patent Office on January 31, 2008. The application number is

200810006699.7, the entire disclosure of which is hereby incorporated by reference in its entirety in its entirety in its entirety in the the the the the the the the the the the the TECHNICAL FIELD The present invention relates to Orthogonal Frequency Division Multiplexing (OFDM) technology, and more particularly to a method and apparatus for peak-to-average ratio suppression in a multi-carrier OFDM system. Background technique

 Among the existing communication technologies, OFDM technology has become the fourth generation mobile communication with its high frequency utilization, strong inter-symbol interference (ISI) and inter-carrier interference (ICI) capabilities. Key technology.

 For the single carrier technology, at the transmitting end of the OFDM signal, if the single carrier includes N subcarriers, the high speed data stream is serially converted and divided into N parallel substreams for inverse Fourier transform (IFFT, Inverse). Fast Fourier Transform) converts the frequency domain signal into the time domain. The length of the IFFT output is a time domain sample signal called OFDM symbol. To eliminate interference between symbols, a cyclic prefix (CP, Cyclic Prefix) can be inserted between user data to form a cyclically extended OFDM symbol. At the receiving end of the OFDM signal, the CP is first removed from the received time domain signal, and then Fourier transform (FFT, Fast Fourier Transform), digital demodulation, and the like are performed to correctly receive the data.

When the number of subcarriers in the OFDM system increases, the peak-to-average ratio of the signal at the transmitting end (PAPR, Peak) To Average Power Ratio ) will also increase the force. It is well known that a transmitter of a wireless base station in a mobile communication system uses a power amplifier to transmit a signal to compensate for signal attenuation due to propagation distance. The power amplifier has a certain linear region. The signal with peak-to-average ratio will reduce the efficiency of the power amplifier and increase the power consumption. Therefore, the suppression of the peak-to-average ratio is an urgent problem to be solved.

 Further, since the advent of the 3rd generation mobile communication system, in order to effectively reduce the volume of the base station and reduce the cost of the base station, multi-carrier technology is generally adopted, that is, the system includes multiple carriers, and each carrier includes multiple subcarriers. Compared with the single carrier technology, since the transmission of the multi-carrier information can be completed by one transmitter and one power amplifier, the volume and cost of the base station can be greatly reduced, but the number of sub-carriers in the multi-carrier OFDM system More, the peak-to-average ratio of the channel signal after the combination is larger, which puts higher requirements on the multi-carrier peak-to-average ratio suppression.

 In order to suppress the high peak-to-average ratio of the multi-carrier system, the prior art proposes a multi-stage matched filtering clipping scheme for the multi-carrier system, and FIG. 1 shows a block diagram of the multi-stage matched filtering clipping scheme. The formation of the multi-carrier combined time domain signal may be briefly described as: the transmission data and the control data bits of each single carrier on each symbol are encoded by the encoder according to a predetermined coding scheme, and then subjected to corresponding constellation mapping according to the modulation mode. Then, after CP processing, add CP, and perform time domain windowing (ram), after framing, filtering to high-speed time domain signal by interpolation value, and modulating to different frequency points by digital oscillator (NCO, Numeric Control Oscillator) The multi-carrier combined channel signals are obtained one by one. The multi-carrier combining channel signal formed above enters the clipping processing process shown in FIG. 1, first extracting clipping noise higher than a predetermined threshold in the channel signal, and then removing the out-of-band portion of the clipping noise through the multi-stage matched filtering module. The noise on some important subcarriers is finally superimposed by the matched filtered clipping noise on the delayed multicarrier combined time domain signal to form a clipped multicarrier combined time domain signal. The matched filter coefficients here are obtained by accumulating the source filter coefficients after NCO modulation, and the same filter coefficients are used for each level of matched filtering.

Although the scheme given above can achieve better clipping effect under the condition of satisfying the same error vector magnitude, peak code domain error and adjacent channel power leakage ratio, the clipped multi-carrier combined channel signal can be obtained. The lower peak-to-average ratio, but the scheme is mainly for Code-Division Multiple Access (CDMA) systems. If the scheme shown in Figure 1 is directly applied to OFDM In the system, the modulation and coding modes and carrier power of the frequency domain subcarriers on different OFDM symbols may be different, and the allowed performance loss may be different. If the same filter coefficients are used for matched filtering for each OFDM symbol, for example, the filter coefficients are designed in a high-order modulation manner, the clipping capability of the matched filter will be very limited, and the peak-to-average ratio of the matched filtered multi-carrier OFDM system will be very limited. Still 4 艮 high, and the choice of filter coefficients with a large error vector magnitude (EVM, Error Vector Magnitude) loss, will inevitably lead to high-order modulation subcarriers can not meet the EVM requirements specified by the protocol, seriously affecting the system chain Road performance.

 Even if the matching filtering in Figure 1 is properly modified, for example, using different filter coefficients on each OFDM symbol, a part of the sample points between the two OFDM symbols are severely distorted, resulting in more serious out-of-band leakage. Inter-symbol interference, which significantly deteriorates the EVM of the high-order modulation subcarriers in the OFDM carrier, and the out-of-band leakage also makes the peak-to-average channel signal not satisfy the protocol-defined spectrum template.

 It can be seen from the above analysis that the clipping scheme implemented by matched filtering shown in Figure 1 cannot be directly applied to multi-carrier OFDM systems, and there is currently no scheme for achieving effective peak-to-average ratio suppression for multi-carrier OFDM systems. Summary of the invention

 Embodiments of the present invention provide a method for peak-to-average ratio suppression in a multi-carrier OFDM system, which can effectively suppress peak-to-average ratio in a multi-carrier OFDM system.

 Embodiments of the present invention provide a device for peak-to-average ratio suppression in a multi-carrier OFDM system, which is capable of effectively suppressing a peak-to-average ratio in a multi-carrier OFDM system.

 The technical solution of the embodiment of the present invention is implemented as follows:

 A method for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing system, the method comprising: combining baseband frequency domain signals of each carrier into a time domain on each orthogonal frequency division multiplexing OFDM symbol Multi-carrier combined channel signal;

Extracting clipping noise from the multi-carrier combining channel signal, and intercepting a channel from the pre-generated extended core kernel waveform according to the position of the clipping noise in the multi-carrier combining channel signal a pulse-like signal of length;

 Using the pulse signal of the type and multiplying the extracted clipping noise to obtain cancellation noise;

 The cancellation noise is inversely superimposed on the delayed multi-carrier combining channel signal to perform peak-to-average ratio suppression.

 A device for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing system, the device comprising: a multi-carrier combining channel signal module, configured to baseband frequency domain signals of each carrier on each OFDM symbol, Combining into a time domain multi-carrier combined channel signal;

 a delay module, configured to delay the signal of the multi-carrier combined channel;

 a cancellation noise acquisition module, configured to extract clipping noise from the multi-carrier combining channel signal; according to the position of the clipping noise in the multi-carrier combining channel signal, a pre-generated extended kernel waveform Extracting a pulse-like signal of a channel length; using the pulse signal of the type and multiplying the extracted clipping noise to obtain cancellation noise;

 The peak-to-average ratio suppression module is configured to inversely superimpose the cancellation noise on the delayed multi-carrier combining channel signal to perform peak-to-average ratio suppression.

 It can be seen that the method and device for peak-to-average ratio suppression in the multi-carrier OFDM system according to the embodiment of the present invention extracts clipping noise from the multi-carrier combining channel signal, and according to the position of the clipping noise in the channel, the pre-generated lengthening is performed. The pulse waveform of the channel length is intercepted on the kernel waveform, and then the cancellation noise is obtained by multiplying the pulse signal with the extracted clipping noise, and is inversely superimposed to the delayed multi-carrier combined channel signal. Since the extended kernel waveform is generated in advance, when the pulse-like signal of the channel length is intercepted, the CP region and the symbol region in the multi-carrier combining channel signal are simultaneously considered, and the cancellation noise calculated using the intercepted pulse-like signal is also At the same time, for the CP area and the symbol area, after the reverse superposition cancels the noise, the peak-to-average ratio suppression is performed on the multi-carrier combined channel signal over the entire channel length, thereby effectively suppressing the peak-to-average ratio. DRAWINGS

1 is a schematic block diagram of a multi-match filter clipping scheme in a multi-carrier system in the prior art; FIG. 2 is a schematic block diagram of a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention; Figure

 3 is a flowchart of a method for suppressing a peak-to-average ratio in a multi-carrier OFDM system according to an embodiment of the present invention; FIG. 4 is a flowchart showing a method for implementing a single-carrier baseband frequency-domain signal in a method for suppressing a peak-to-average ratio in a multi-carrier OFDM system according to an embodiment of the present invention; Figure

 FIG. 5 is a flowchart of implementing a two-carrier baseband frequency domain signal combining method in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention; FIG.

 6 is a flow chart of a time-domain in the peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention;

 7 is a schematic diagram of extracting clipping noise by a single threshold in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention;

 FIG. 8 is a flowchart of generating a lengthened kernel waveform in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention; FIG.

 FIG. 9 is a schematic diagram showing waveform changes of a period-like extension of a pulse-like signal in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention; FIG.

 10 is a schematic diagram of intercepting a channel length type pulse signal in an extended kernel waveform according to a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention;

 11 is a flowchart of an indicator evaluation in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention;

 12 is a schematic diagram of a peak-to-average ratio suppression apparatus in a multi-carrier OFDM system according to an embodiment of the present invention; FIG. 13 is a schematic diagram showing a structure of a kernel waveform generation module in a multi-carrier OFDM system according to an embodiment of the present invention;

 14 is a schematic structural diagram of a signal module of a multi-carrier combining channel in a multi-carrier OFDM system according to an embodiment of the present invention;

FIG. 15 is a structural diagram of a cancellation noise acquisition module in a multi-carrier OFDM system according to an embodiment of the present invention; detailed description

 In order to make the objects and advantages of the embodiments of the present invention more comprehensible, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

 2 is a schematic block diagram of a method for suppressing a peak-to-average ratio in a multi-carrier OFDM system according to an embodiment of the present invention. FIG. 2 shows an example of two carriers, and the baseband frequency domain signal 1 corresponds to carrier 1. The baseband frequency domain signal 2 corresponds to carrier 2. The baseband frequency domain signals of carrier 1 and carrier 2 are first multi-carrier combined to form a multi-carrier combined channel signal; then the peak detection of the multi-carrier combined channel signal is performed, and the specific implementation can be performed on the multi-carrier combined channel signal. The sampling points are sorted according to the power from large to small, and the preset number of clipping noises are sorted; the position of the extracted clipping noise in the multi-carrier combining channel signal is intercepted from the extended kernel waveform. The pulse-like signal of the channel length multiplies the extracted clipping noise and the pulse-like signal to obtain cancellation noise; and the obtained cancellation noise is inversely superimposed to the delayed multi-carrier combined channel signal, after the inverse superposition The result is evaluated by the indicator. If the indicator is passed, it is directly sent to the IF channel for subsequent processing. If the indicator evaluation fails, the peak detection of the multi-carrier combined channel signal after the reverse superposition cancellation noise is performed.

 FIG. 3 is a flowchart of a method for suppressing a peak-to-average ratio in a multi-carrier OFDM system according to an embodiment of the present invention. Before the process shown in Figure 3, an extended kernel waveform is generated in advance. The flow shown in Figure 3 includes:

 Step 301: Combine the baseband frequency domain signals of each carrier into a time domain multi-carrier combining channel signal on each OFDM symbol.

 Step 302: Extract clipping noise from the multi-carrier combining channel signal, and intercept a channel-like pulse from the extended kernel waveform according to the position of the clipping noise in the multi-carrier combining channel signal. signal.

 Step 303: Multiply the pulse signal with the extracted clipping noise to obtain a noise cancellation noise.

Step 304: Reversely superimpose the cancellation noise on the delayed multi-carrier combining channel signal to perform peak-to-average ratio suppression. The method for suppressing the peak-to-average ratio in the multi-carrier OFDM system according to the embodiment of the present invention extracts clipping noise from the signal of the multi-carrier combining channel, and according to the position of the clipping noise in the channel, from the pre-generated extended kernel waveform The pulse-like signal of the channel length is intercepted, and then the cancellation noise is obtained by multiplying the pulse-like signal with the extracted clipping noise, and is inversely superimposed to the delayed multi-carrier combined channel signal. Since the extended kernel waveform is generated, when the pulse-like signal of the channel length is intercepted, the CP region and the symbol region in the multi-carrier combining channel signal are simultaneously considered, and the cancellation noise calculated by using the intercepted pulse-like signal is simultaneously For the CP area and the symbol area, after the reverse superposition cancels the noise, the peak-to-average ratio suppression is performed on the multi-channel combined channel signal over the entire channel length, thereby effectively suppressing the peak-to-average ratio.

 The following provides a detailed description of the method provided by the embodiment of the present invention from the aspects of multi-carrier combining channel signal formation, extraction of clipping noise, lengthened kernel waveform generation, generation of cancellation noise, and index evaluation.

 1) Multi-carrier combined channel signal formation.

 First, on each OFDM symbol, the baseband frequency domain signal sent by each carrier is obtained, and the implementation process is as shown in FIG. 4, and the process includes:

 Step 401: The data signal sent by each carrier on each OFDM symbol of the multi-carrier OFDM system is coded according to a predetermined coding manner.

 Step 402: Perform constellation mapping on the encoded data signal of each carrier according to a predetermined modulation manner. The modulation mode may be Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (Quarature Amplitude Modulation). 16QAM) and so on.

 Step 403: Insert control information such as a pilot signal for the data signal of each carrier after the constellation mapping.

 Step 404: Set a space (TR, Tone Reservation) subcarrier and a left and right protection subcarrier of each carrier to 0, and generate a baseband frequency domain signal sent by each carrier on each OFDM symbol.

Secondly, the baseband frequency domain signals of each carrier are combined into a time domain multi-carrier combined channel signal, and the implementation process thereof is as shown in FIG. 5, taking the baseband frequency domain signal combining of two carriers as an example, the process includes: Step 501: The baseband frequency domain signal on each OFDM symbol is processed by a low-speed IFFT, for example. Time domain signals are formed as processed by 1x speed IFFT.

 Step 502: Add CP to the time domain signal after the IFFT processing.

 Step 503: The time domain signal after adding the CP is sampled to form a high-speed channel signal of each carrier.

 The signal in this step is too much, and can be realized by interpolation filtering at one or more levels. Taking the 4x speed as an example, the specific process can be as shown in Figure 6. The process shown in Figure 6 includes:

 Step 601: Interval interpolation 0 is performed on the time domain signal after adding the CP.

 Step 602: Perform a finite impulse response (FIR, Finite Impulse Response) filtering on the time domain signal after the interval interpolation 0.

 Step 603: Repeat step 601.

 Step 604: Perform a half-band filtering (HBF, Half Band Filter) processing on the time domain signal after the interpolation of step 603.

 After the above steps 601 ~ 604, a time domain signal of 4 times speed can be obtained. Of course, the time domain signal of the higher speed can be implemented by using multiple HBFs in series, which will not be described here.

 Step 504: The NCO is used to modulate the high-speed channel signals of each carrier obtained in step 503 to respective frequency points, which can be digitally realized by directly multiplying the frequency modulation signals, and the phase of the frequency modulation signals between the OFDM symbols is continuous. Finally, the channel signals of each OFDM carrier after frequency modulation are accumulated one by one to obtain a multi-carrier combined channel signal of each multi-carrier OFDM system on each OFDM symbol, and the multi-carrier combined channel signal can be expressed by the following formula:

 L

= _x ( .201+0. , n = l,...,Sym _L + CP _L

 1=1

 X» in the above formula is the high-speed channel signal of each carrier, / is the carrier mark, and the value is 1 to L, L is the carrier number, which is the frequency modulation frequency of each carrier, and the frequency difference between carriers satisfies the configuration requirement; W is the phase of the first frequency of the frequency modulated signal of the first carrier in the current OFDM symbol, and is used to ensure that the phase of the frequency modulated signal between the OFDM symbols is continuous; It is the sampling point interval of the multi-carrier combined channel signal; O ^ is the number of sampling points in the CP area of the channel, which is the number of points in the symbol area in the channel.

2) Extract clipping noise. In each OFDM symbol, peak detection is performed on the multi-carrier combined channel signal, and the number of extracted clipping noises N (N ≥ 0) is preset. You can first sort the sample points of the channel signal in ascending order according to the power, and then extract the N pieces of clipping noise noised ) ( = 1,2,.., N ). Figure 7 shows Ν = 3 as an example. The principle of extracting clipping noise is realized.

 The above-mentioned power is sorted in ascending order, and then the clipping noise of the maximum peak exceeding the preset threshold is extracted, which can be realized by the following specific methods:

上上式式中中

,, GGaatete表表示示预预定定门门限限值值。。 上上述述检检测测出出的的 NN个个最最大大峰峰值值为为前前 NN个个 )) << 11 (( == 11,,22,, ......,, NN ))的的釆釆样样点点。。这这里里，，如如果果通通道道中中 γγ((ηη)) << 11 的的个个数数不不超超过过 ΝΝ ,,补补充充 ««)) == ll的的釆釆样样点点使使每每次次峰峰值值检检测测都都输输出出 ΝΝ个个噪噪声声峰峰值值 位位置置，， 相相应应的的削削波波噪噪声声 nnooiisseeii^^可可以以表表示示为为：： The multi-carrier combined channel signal is written as a complex number «« = yj («) + jx _e («) , where y: (n) is the I input signal, («) is the Q input signal, and the signal amplitude is calculated. Ampin) and clipping ratio θ), ^ as shown in the following equation:

Upper middle and upper middle

,, GGaatete table indicates the pre-determined threshold threshold value. . The maximum and maximum peak-to-peak values of the NN measured by the above-mentioned detection and detection are the former NN and the first NN)) << 11 (( == 11,,22,,...,, NN ) ) A little bit of something. . Here, if the number of γγ((ηη)) << 11 in the channel of the fruit passage is not more than the excess, the complement is filled with ««)) == ll The sample point is such that each time the peak value is detected and outputted, the peak value of the noise peak is set, and the corresponding wave noise noise nnooisseeii^^ can be The table representation is shown as:

Nnooiissee ((ss _tt )) == ηη χχ ((\\ -- ((s _ii )))) xxyy((ss _ii )) , , ii == \\,,22,,...... ,, NN. .

 In the above formula, middle; , ;; is to cut the wave noise noise factor, and use it for controlling the control to extract and extract the amplitude of the wave noise noise, mark Record the wave noise of the clipping noise in the position of the channel in the pass channel. .

 33)) Add a long kkeerrnneell wave shape to generate. .

 For the subcarrier carrier wave in each of the carrier waves, the corresponding predistortion distortion coefficient number, and the number of the predistortion distortion coefficient The configuration of the configuration needs to consider the special characteristics of the subcarrier carrier wave and the TTRR subcarrier carrier wave. .

Considering the performance of the system from the system, the number of pre-distortion distortion coefficients is subject to the coded rate rate, the constellation modulation method, and the subcarrier carrier wave function. The power rate, the EEVVMM loss loss sum, and the frequent utterance template board, etc., and the peak-to-peak average performance and the actual complex complexity are also limited. The arrangement of the number of pre-distortion distortion coefficients is, therefore, when the number of pre-distortion distortion coefficients is set for the carrier wave of the OOFFDDMM sub-carrier, it should be fully considered. Considering the influence of the above-mentioned factor factors, choose the appropriate number of pre-predistortion distortion coefficients to obtain a better system performance. . Test Considering the above factors affecting the subcarrier, the signal distortion on the subcarrier can be effectively controlled, so that the performance loss on each subcarrier is effectively controlled.

 For the TR subcarriers in the carrier within each OFDM symbol, these TR subcarriers do not carry any useful signals, theoretically allowing arbitrary predistortion coefficients to be configured, but excessively large clipping noise on the TR subcarriers not only affects The modulation of adjacent subcarriers at the receiving end also significantly reduces the efficiency of the transmitter. Therefore, the predistortion coefficient on the TR subcarrier needs to be appropriately suppressed to reduce the adverse effects. Considering the above factors of suppressing the TR subcarrier, the noise energy superimposed on the TR subcarrier is appropriately suppressed, which not only facilitates the demodulation of the terminal data subcarrier, but also indirectly improves the efficiency of the transmitter.

 In combination with the principle of predistortion coefficient configuration given in the foregoing embodiment of the present invention, how to configure the predistortion coefficient is specifically described herein.

 On each OFDM symbol, the extended kernel waveform is obtained by the predistortion coefficient of each carrier on the frequency domain subcarrier, and the generated pulse signal waveform is cyclically extended and combined, taking a two-cycle extension as an example. The process is shown in Figure 8, which includes:

 Step 801: On each OFDM symbol, each carrier is configured with a predistortion coefficient for the frequency domain subcarrier, and a high-speed IFFT processing is performed to obtain an over-type pulse signal k^ (/= l, 2, . .., J, J is the number of carriers). This type of pulse signal is a periodic signal and the maximum real peak is at the first sample point.

 Step 802: Repeat the cycle-like pulse signal obtained in step 801 for one cycle to form a two-cycle pulse-like signal.

 Step 803: Complement the left and right CPs on the two-cycle type pulse signals obtained in step 802, and obtain a pulse-like signal of two-cycle extension of each OFDM carrier, which can be expressed by:

Kerneh (Sym_ _L - CP _ _L + m) \ < m < CP _ _L

k^h (m) = ( -5 ^p — CP_ _L + l≤m≤ CP—L + Sym_ _L

Kerneh (m - CP _ _L - Sym_ _L ) CP _ _L + Sym_ _L + _l ≤ m ≤ CP _ _L + 2Sym_ _L kernel (m - 2Sym_ _L - CP _ _L ) CP: _L + 2Sym_ _L + \≤m≤ 2CP_ _L + 2Sym_ _L in FIG. 9 shows a waveform of the pulse signal period variation class step 801 to step 803 described continuation. Step 804: Modulating the twice-channel signal length to the respective frequency points by using the NCO, specifically by multiplying the frequency modulation signal of each carrier, and finally accumulating the extended kernel waveform kernel (m) = ^kernel ι {m eMi -cp , \ < m < 2CP _ _L + 2Sym _ _L where is the frequency modulation frequency of the carrier, and the carrier frequency of the multi-carrier signal combining is the same; t. It is the sampling interval of the combined channel signal.

 The kernel waveform is always 0 phase and is at the maximum at the C3⁄4 + 1 sample point. In order to facilitate future amplitude and phase adjustment, the extended kernel waveform can be normalized.

 In addition to the above-described manner of generating the extended kernel waveform, the steps of oversampling by interpolation filtering may be added between step 803 and step 804.

 4) Generate cancellation noise.

 Align the clipping noise of each carrier with the maximum peak value of the extended kernel waveform, and use the alignment point as the reference point to intercept the channel-like pulse signal from the kernel waveform, so that the maximum peak position and clipping of the intercepted pulse-like signal are obtained. The noise is in the same position in the channel signal.

 Figure 10 shows a schematic diagram of intercepting channel length-like pulse signals in an extended kernel waveform. Appropriate phase and amplitude adjustment for the above-mentioned pulse-like signals, so that the maximum value of the adjusted pulse-like signal and the phase of the noise peak are the same, and the amplitude is equivalent. In the specific implementation, the pulse of the normalized channel length can be pulsed. The signal and channel clipping noise are multiplied to obtain superimposed cancellation noise.

 On each OFDM symbol, the corresponding N cancellation noises are accumulated and inversely superimposed to the delayed multi-carrier combined channel signal to form a multi-carrier combined channel signal obtained after clipping noise cancellation.

 5) Indicator evaluation.

For the evaluation of the multi-carrier combined channel signal obtained after the clipping noise cancellation, the clipping algorithm stopping criterion needs to be set in advance. The clipping algorithm standard may include the target peak-to-average ratio and the target calculation number, when the clipping noise is cancelled. The peak-to-average ratio of the multi-carrier combined channel signal obtained later is smaller than the target peak-to-average ratio, or the peak-to-average ratio of the multi-carrier combined channel signal obtained after the clipping noise cancellation is greater than the target peak-to-average ratio, but the number of calculations has been More than the maximum number of calculations, it is considered that the peak-to-average ratio has been suppressed Comply with the clipping algorithm to stop the standard.

 Figure 11 shows the flow of the indicator evaluation, which includes:

 Step 1101: Determine whether the peak-to-average ratio of the multi-carrier combining channel signal is greater than the target calculation number. If yes, go directly to step 1104, otherwise go to step 1102.

 Step 1102: Determine whether the peak-to-average ratio of the signal of the multi-carrier combining channel is smaller than the target peak-to-average ratio. If yes, go directly to step 1104. Otherwise, go to step 1103.

 Step 1103: Return to perform the step of extracting clipping noise from the multi-carrier combining channel signal. In this step, the steps of delaying the multi-carrier combining channel signal, performing the extraction of the clipping noise, intercepting the kernel waveform, obtaining the cancellation noise, and inversely superimposing the cancellation noise are all implemented in the foregoing. the same.

 Step 1104: Send the multi-carrier combined channel signal to the intermediate frequency channel for further processing. The method provided by the embodiment of the present invention can be used for the number of carriers and any multi-carrier frequency spacing, and an arbitrary modulation mode can be configured for each frequency carrier subcarrier of each carrier on each OFDM symbol.

 FIG. 12 is a schematic structural diagram of an apparatus for peak-to-average ratio suppression in a multi-carrier OFDM system according to an embodiment of the present invention, the apparatus includes:

 The multi-carrier combining channel signal module 11 is configured to combine the baseband frequency domain signals of each carrier into a time domain multi-carrier combined channel signal on each OFDM symbol.

 The delay module 12 is configured to delay the multi-carrier combining channel signal.

 Denoising noise acquisition block 13 for extracting clipping noise from the multi-carrier combining channel signal; according to the position of the clipping noise in the multi-carrier combining channel signal, in a pre-generated A pulse-like signal of a channel length is intercepted on the extended kernel waveform; and the canceled noise is obtained by multiplying the extracted pulse noise with the extracted clipping noise.

 The peak-to-average ratio suppression module 14 is configured to inversely superimpose the cancellation noise on the multi-carrier combining channel signal after the delay, and perform peak-to-average ratio suppression.

The apparatus for suppressing the peak-to-average ratio in the multi-carrier OFDM system according to the embodiment of the present invention, the cancellation noise acquisition module 13 extracts the multi-carrier combined channel signal generated by the multi-carrier combining channel signal module 11 Clipping noise, and according to the position of the clipping noise in the channel, intercept the pulse-like signal of the channel length from the extended kernel waveform, and then multiply the extracted pulse noise to obtain the cancellation noise, and then the peak The average ratio suppression module 14 inversely superimposes the cancellation noise obtained by the cancellation noise acquisition module 13 to the delayed multi-carrier combination channel signal. Since the extended kernel waveform is generated, the cancellation noise acquisition module 13 simultaneously considers the CP region and the symbol region in the multi-carrier combining channel signal when intercepting the pulse-like signal of the channel length, and uses the intercepted pulse-like signal to calculate The cancellation noise is also applied to the CP area and the symbol area at the same time, so that the peak-to-average ratio is inversely superimposed on the suppression module 14 to cancel the noise, and the peak-to-average ratio is suppressed for the entire channel length of the multi-carrier combined channel signal, thereby realizing effective peak-average Than suppression.

 The device also includes a kernel waveform generation module 15 for generating an extended kernel waveform. FIG. 13 is a schematic structural diagram of a kernel waveform generating module 15 in a multi-carrier OFDM system according to an embodiment of the present invention. As shown in FIG. 13, the kernel waveform generating module 15 may include:

 The first inverse Fourier transform IFFT unit 151 is configured to perform high-speed I F F T processing on the pre-distortion coefficients of the frequency domain sub-carriers of each carrier to obtain a pulse-like pulse signal of each carrier.

 The first cyclic prefix CP unit 152 is configured to periodically extend the over-type pulse signal of each carrier, and supplement the left and right CPs for the cyclically extended pulse-like signal to obtain a periodic extension class of each carrier. Pulse signal.

 The first numerically controlled oscillator NCO unit 153 is configured to modulate the cyclic extension type pulse signals of each of the carriers to respective frequency points.

 The first accumulating unit 154 is configured to accumulate the cyclic extension type pulse signals of each carrier modulated to respective frequency points to obtain an extended kernel waveform.

 FIG. 14 is a schematic structural diagram of a multi-carrier combining channel signal module 11 in a multi-carrier OFDM system according to an embodiment of the present invention. As shown in FIG. 14, the multi-carrier combining channel signal module 11 may include:

 The baseband frequency domain signal unit 111 is configured to acquire a baseband frequency domain signal transmitted by each carrier on each OFDM symbol.

a second inverse Fourier transform IFFT unit 112, configured to perform the baseband frequency domain signal low Double speed IFFT processing.

 The second cyclic prefix CP unit 113 is configured to add the time domain signal obtained by the low-speed IFFT processing to the CP.

 The over-sampling unit 114 is configured to perform the time-domain signal after the CP is added to obtain a high-speed channel signal of each carrier.

 The second numerically controlled oscillator NCO unit 115 is configured to modulate the high-speed channel signals of each of the carriers to respective frequency points.

 The second accumulating unit 116 is configured to accumulate the high-speed channel signals of each carrier modulated to respective frequency points to obtain a multi-carrier combining channel signal.

 FIG. 15 is a schematic structural diagram of a cancellation noise acquisition module 13 in a multi-carrier OFDM system according to an embodiment of the present invention. As shown in FIG. 15, the cancellation noise acquisition module 13 includes:

 The peak detecting unit 131 is configured to extract, from the multi-carrier combining channel signal, a peak whose peak value is higher than a preset threshold and meet the number of extracted clipping noises.

 The kernel waveform intercepting unit 132 is configured to align the position of each of the clipping noises with the maximum peak value of the extended kernel waveform, and respectively use the alignment point as a reference point to intercept the pulse of the channel length corresponding to each clipping noise. signal.

 The cancellation noise calculation unit 133 is configured to multiply the intercepted each type of pulse signal and the corresponding clipping noise, and accumulate the multiplication result as cancellation noise.

 The device provided by the embodiment of the present invention may further include an indicator evaluation module 16 configured to determine whether the peak-to-average ratio of the multi-carrier combined channel signal after the reverse superimposition cancellation noise is greater than the target calculation number, and if so, Transmitting the multi-carrier combining channel signal after the noise cancellation to the intermediate frequency channel, otherwise continuing to evaluate whether the peak-to-average ratio of the multi-carrier combining channel signal of the reverse superimposed cancellation noise is smaller than the target peak-to-average ratio, and if so, Transmitting the anti-noise multi-carrier combining channel signal to the intermediate frequency channel, otherwise transmitting the reverse superimposed cancellation noise multi-carrier combining channel signal to the delay module 12 and the cancellation noise acquiring module 13 continue processing;

Or it is used to determine whether the peak-to-average ratio of the multi-carrier combining channel signal after the reverse superposition cancellation noise is smaller than the target peak-to-average ratio value, and if so, the multi-carrier combining channel signal after the anti-noise cancellation is superimposed Send to the intermediate frequency channel, otherwise continue to judge whether the peak-to-average ratio of the multi-carrier combined channel signal after the reverse superimposition cancellation noise is greater than the target calculation number, and if so, the multi-carrier combination after the inverse cancellation of the cancellation noise The channel channel signal is sent to the intermediate frequency channel, otherwise the reverse superimposed cancellation noise multi-carrier combining channel signal is sent to the delay module 12 and the cancellation noise acquisition module 13 to continue processing.

 The method and apparatus for peak-to-average ratio suppression in a multi-carrier OFDM system according to an embodiment of the present invention extracts clipping noise from a multi-carrier combining channel signal, and according to the position of the clipping noise in the channel, from the pre-generated extended kernel The pulse-like signal of the channel length is intercepted on the waveform, and the cancellation noise is obtained by multiplying the pulse-like signal with the extracted clipping noise, and is inversely superimposed to the delayed multi-carrier combined channel signal. Since the extended kernel waveform is generated in advance, when the pulse-like signal of the channel length is intercepted, the CP region and the symbol region in the multi-carrier combining channel signal are simultaneously considered, and the cancellation noise calculated using the intercepted pulse-like signal is also At the same time, for the CP area and the symbol area, after the reverse superposition cancels the noise, the peak-to-average ratio suppression is performed on the multi-carrier combined channel signal over the entire channel length, thereby effectively suppressing the peak-to-average ratio. Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by hardware, or can be implemented by means of software plus necessary general hardware platform, and the technical solution of the present invention. It can be embodied in the form of a software product that can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including a number of instructions for making a computer device (may It is a personal computer, a server, or a network device, etc.) that performs the methods described in various embodiments of the present invention.

 In conclusion, the above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim  A method for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing system, characterized in that the method comprises:  Performing, on each orthogonal frequency division multiplexing OFDM symbol, a baseband frequency domain signal of each carrier into a time domain multicarrier combining channel signal;  Extracting clipping noise from the multi-carrier combining channel signal, and extracting a channel length class from the pre-generated extended core kernel waveform according to the position of the clipping noise in the multi-carrier combining channel signal Pulse signal;  Using the pulse signal of the type and multiplying the extracted clipping noise to obtain cancellation noise;  The cancellation noise is inversely superimposed on the delayed multi-carrier combining channel signal, and peak-to-average ratio suppression is performed.  2. The method according to claim 1, wherein the process of generating the extended kernel waveform is:  Predistortion coefficients are configured for frequency domain subcarriers of each carrier on each OFDM symbol; high frequency multiplication inverse Fourier transform IFFT processing is performed on the predistortion coefficients of the frequency domain subcarriers, and each carrier is obtained. Pulse signal  Performing a periodic extension of the over-type pulse signal of each carrier, and supplementing the left and right cyclic prefixes CP to obtain a periodic extension type pulse signal of each carrier;  The cyclic extension type pulse signals of each carrier are modulated to respective frequency points and accumulated, and a kernel waveform with a long strength is generated.  The method according to claim 2, wherein the predistortion coefficients are configured for frequency domain subcarriers of each carrier, which are configured according to factors affecting subcarriers and factors for suppressing TR subcarriers; The factors affecting the subcarriers include: a coding rate, a constellation modulation mode, a frequency domain subcarrier power, an error vector magnitude EVM loss, a spectrum template, a desired peak-to-average ratio performance, and an implementation complexity; the factor of suppressing the TR subcarrier Including: suppressing the predistortion coefficient on the TR subcarrier. 4. The method according to claim 2, wherein the modulating the cyclic extension type pulse signal of each carrier to the respective frequency points is:  The period extension type pulse signal of each carrier is multiplied with a respective frequency modulation signal.  5. The method according to claim 1, wherein the combining into a time domain multi-carrier combining channel signal is:  Passing the baseband frequency domain signal of each carrier through low-speed IFFT processing, adding CP;  Performing a time domain signal after adding CP to each carrier to obtain a high power rate channel signal of each carrier;  The high-speed channel signals of each carrier are modulated to respective frequency points and accumulated to obtain a multi-carrier combined channel signal.  6. The method according to claim 5, wherein the time domain signal after adding CP to each carrier is performed as follows:  The time domain signal after each carrier plus CP is subjected to one-level interpolation filtering.  7. The method according to claim 5, wherein the modulating the high-speed channel signals of each carrier to respective frequency points is:  The high-speed channel signals of each carrier are multiplied with respective FM signals.  8. The method according to claim 1, wherein the number of extracted clipping noises N is preset; and the clipping noise is extracted from the multi-carrier combining channel signals:  The sample points in the multi-carrier combined channel signal are sorted according to their power from large to small, and the N pieces of clipping noise in the previous order are extracted as the clipping noise extracted from the multi-carrier combined channel signal.  9. The method of claim 8, wherein the pulse-like signal that intercepts the length of the channel from the extended kernel waveform is:  The position of each extracted clipping noise is aligned with the maximum peak value of the extended kernel waveform, and the alignment point is used as a reference point, and the pulse-like signal of the channel length corresponding to each clipping noise is intercepted, so that the intercepted pulse-like pulse is obtained. The maximum peak position of the signal and the corresponding clipping noise are in the same position in the channel signal. 10. The method according to claim 9, wherein the multiplicative use of the pulse-like signal and the extracted clipping noise results in cancellation noise as: a class of each of the clipping noise and a corresponding channel length Multiplying the pulse signal to obtain corresponding cancellation noise;  The inverse superimposing cancellation noise on the delayed multi-carrier combining channel signal is: superimposing the accumulated sum of the cancellation noise on the delayed multi-carrier combining channel signal.  The method according to claim 1, wherein the clipping algorithm stopping criterion is set in advance, comprising: a target calculation number and a target peak-to-average ratio; and the performing the peak-to-average ratio suppression further comprises: determining the reverse superposition pair Whether the peak-to-average ratio of the multi-carrier combining channel signal after noise cancellation is greater than the target calculation number, and if not, whether to judge whether the peak-to-average ratio of the multi-carrier combining channel signal after the reverse superposition cancellation noise is smaller than the target peak Average ratio, if not, returns to perform the step of extracting clipping noise from the multi-carrier combining channel signal;  Or determining whether the peak-to-average ratio of the multi-carrier combining channel signal after the reverse superimposition cancellation noise is smaller than the target peak-to-average ratio value, and if not, continuing to determine the peak value of the multi-carrier combining channel signal after the reverse superimposition cancellation noise cancellation Whether the number of times of suppression calculation is greater than the number of times of calculation of the target, and if not, returns to perform the step of extracting clipping noise from the signal of the multi-carrier combining channel.  12. A device for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing system, the device comprising:  a multi-carrier combining channel signal module, configured to combine the baseband frequency domain signals of each carrier into a time domain multi-carrier combined channel signal on each orthogonal frequency division multiplexing OFDM symbol;  a delay module, configured to delay the signal of the multi-carrier combined channel;  a cancellation noise acquisition module, configured to extract clipping noise from the multi-carrier combining channel signal; according to the position of the clipping noise in the multi-carrier combining channel signal, in a pre-generated extended core kernel A pulse-like signal of a channel length is intercepted on the waveform; and the pulse-like signal is multiplied with the extracted clipping noise to obtain cancellation noise;  The peak-to-average ratio suppression module is configured to inversely superimpose the cancellation noise on the multi-carrier combining channel signal after the delay, and perform peak-to-average ratio suppression.  The apparatus of claim 12, further comprising: a kernel waveform generating module, configured to generate an extended kernel waveform; the kernel waveform generating module includes: a first inverse Fourier transform IFFT unit for each OFDM symbol, for each The predistortion coefficient of the frequency domain subcarrier configuration of the wave is subjected to high-speed IFFT processing to obtain a pulse-like pulse signal of each carrier;  a first cyclic prefix CP unit, configured to periodically extend the over-type pulse signal of each carrier, and supplement the left and right CPs for the cyclically extended pulse signal to obtain a periodic extension class of each carrier Pulse signal;  a first numerically controlled oscillator NCO unit, configured to modulate the cyclic extension type pulse signals of each of the carriers to respective frequency points;  And a first accumulating unit, configured to accumulate the cyclic extension type pulse signals of each carrier modulated to respective frequency points, to obtain an extended kernel waveform.  The device of claim 12, wherein the multi-carrier combining channel signal module comprises:  a baseband frequency domain signal unit, configured to acquire, on each OFDM symbol, a baseband frequency domain signal transmitted by each carrier;  a second inverse Fourier transform IFFT unit, configured to perform the low-speed IFFT processing on the baseband frequency domain signal;  a second cyclic prefix CP unit, configured to add the time domain signal obtained by the low-speed IFFT processing to the CP;  a sampling unit, configured to perform the time domain signal after the CP is added to obtain a high-speed channel signal of each carrier;  a second numerically controlled oscillator NCO unit, configured to modulate the high-speed channel signals of each of the carriers to respective frequency points;  And a second accumulating unit, configured to accumulate the high-speed channel signals of each carrier modulated to respective frequency points, to obtain a multi-carrier combining channel signal. The device according to claim 12, wherein the cancellation noise acquisition module comprises: a peak detection unit, configured to scan a sample point in the multi-carrier combination channel signal according to its power from large to large Sorting small, extracting the preset N pieces of clipping noise as the clipping noise extracted from the multi-carrier combining channel signal; a kernel waveform intercepting unit, configured to align a position of each of the extracted clipping noises with a maximum peak value of the elongated kernel waveform, and respectively intercept the pulse of the channel length corresponding to each clipping noise with the alignment point as a reference point signal;  The cancellation noise calculation unit is configured to multiply the intercepted each type of pulse signal and the corresponding clipping noise, and accumulate the multiplication result as cancellation noise.  The device according to claim 12, further comprising an indicator evaluation module, configured to determine whether a peak-to-average ratio of the multi-carrier combining channel signal after the inverse superimposition cancellation noise is greater than a suppression calculation time The number of target calculations, if not, continue to determine whether the peak-to-average ratio of the inverse superimposed cancellation noise multi-carrier combining channel signal is smaller than the target peak-to-average ratio, and if not, the reverse-superimposed cancellation noise multi-carrier combining channel The signal is sent to the delay module and the cancellation noise acquisition module to continue processing; or is used to determine whether the peak-to-average ratio of the multi-carrier combined channel signal after the reverse superposition cancellation noise is smaller than the target peak-to-average ratio, and if not, continue Determining whether the peak-to-average ratio of the multi-carrier combining channel signal after the reverse superposition cancellation noise is greater than the target calculation number, and if not, transmitting the reverse-superimposed cancellation noise multi-carrier combining channel signal to the The delay module and the cancellation noise acquisition module continue to process.