WO2009089753A1

WO2009089753A1 - A method and device for peak-to-average ratio suppression in multi-carrier orthogonal frequency division multiplexing system

Info

Publication number: WO2009089753A1
Application number: PCT/CN2008/073803
Authority: WO
Inventors: Zhiqiang Zou; Jie Wu; Binbin Zhang; Erni Zhu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-12-28
Filing date: 2008-12-27
Publication date: 2009-07-23
Also published as: CN101222468A; CN101222468B

Abstract

The invention provides a method for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing OFDM method. The method comprises that: baseband frequency-domain signals of each carrier are combined into a time-domain multi-carrier combination channel signal on each OFDM symbol; clipping noise corresponding to each carrier is obtained from the multi-carrier combination channel signal, the length of the clipping noise is a symbol length; a frequency-domain response of the clipping noise corresponding to each carrier and symbol length is obtained and reversely superposed to the baseband frequency-domain signal after the corresponding carrier has a time delay on the OFDM symbol to make the peak-to-average ratio suppression. The invention also provides a device for peak-to-average ratio suppression in a multi-carrier OFDM system. Application of the invention can make an effective suppression to the peak-to-average ratio in the multi-carrier OFDM system.

Description

The present invention claims to be submitted to the Chinese Patent Office on December 28, 2007, the application number is 200710306951. 1, and submitted on January 31, 2008. The Chinese Patent Office, Application No. 200810007101. 6, the title of the invention is the priority of the Chinese Patent Application for "Method and Apparatus for Peak-to-Average Ratio Reduction in Multi-Carrier Orthogonal Frequency Division Multiplexing Systems", the entire contents of which are incorporated by reference. In this application. Technical field

The present invention relates to Orthogonal Frequency Division (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, 0F Li technology becomes the first with its high frequency utilization rate, strong Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI). The key technology of 4th generation mobile communication.

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 Fouri er Transform) converts the frequency domain signal into the time domain. The length of the NIFF output is N time-domain sample symbols, called 0FDM symbols. To eliminate interference between symbols, a cyclic prefix (CP, Cycl ic Prefix) can be inserted between user data to form a cyclically extended OFDM symbol. At the receiving end of the 0FDM signal, the CP is 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 (PAPR) of the signal at the transmitting end increases accordingly. 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. Power amplifiers have a certain linear region. Signals with peak-to-average ratios reduce the efficiency of the power amplifier and increase power consumption. Therefore, the suppression of 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 sub-carriers. Wave. 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 is more More, the PAPR 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 matching filtering clipping scheme for the multi-carrier system, and FIG. 1 shows a block diagram of the multi-match filtering clipping scheme. The forming 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, and the encoder performs coding according to a predetermined coding scheme and then performs corresponding constellation mapping according to the modulation mode. Then, CP is added after IFFT processing, and time domain windowing (ramp) is performed, and the interpolated value is filtered to the high-speed time domain signal after framing, and modulated by a numerically controlled oscillator (NC0, Numeri c Control Osc il lator ) After the frequency points, 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 multi-carrier combined time domain signal to form a clipped multi-carrier combined time domain signal. The matched filter coefficients here are obtained by accumulating the source filter coefficients after NC0 modulation, and the same filter coefficients are used for each stage of matched filtering.

Although the prior art scheme 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, that is, the clipped multi-carrier combining channel can be obtained. The signal has a lower peak-to-average ratio, but the scheme is mainly for CDMA systems. The clipping scheme implemented by matched filtering shown in Figure 1 cannot be directly applied to multi-carrier OFDM systems, but currently there is no multi-carrier. The 0FDM system achieves an effective peak-to-average ratio suppression scheme. Summary of the invention

Embodiments of the present invention provide a method for peak-to-average ratio suppression of a multi-carrier 0FDM system, which can effectively suppress a peak-to-average ratio in a multi-carrier ◦F leg system.

Embodiments of the present invention provide a device for peak-to-average ratio suppression of a multi-carrier 0FDM system, which is capable of multi-carrier

The peak-to-average ratio in the 0F leg system is effectively suppressed.

The technical solution 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:

Generating the baseband frequency domain signal of each carrier into a time domain multi-carrier combined channel signal on each orthogonal frequency division multiplexing 0FDM symbol; Obtaining, from the multi-carrier combining channel signal, clipping noise corresponding to each carrier, where the length of the clipping noise is a symbol length;

The frequency domain response of the clipping noise corresponding to each carrier is obtained, and is inversely superimposed to the baseband frequency domain signal of the corresponding carrier on the OFDM symbol, and the peak-to-average ratio suppression is performed.

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 multi-carrier combined channel signal on each orthogonal frequency division multiplexing OFDM symbol;

a delay module, configured to delay a baseband frequency domain signal of each carrier;

a clipping noise acquisition module, configured to acquire, from the multi-carrier combining channel signal, clipping noise corresponding to each carrier, where the length of the clipping noise is a symbol length;

The peak-to-average ratio suppression module is configured to acquire the frequency domain response of the clipped noise corresponding to each carrier and symbol length, and inversely superimpose the baseband frequency domain signal after the corresponding carrier delay to perform peak-to-average ratio suppression.

It can be seen that, in the method and device for peak-to-average ratio suppression in a multi-carrier OFDM system according to an embodiment of the present invention, a baseband frequency domain signal of each carrier is combined into a time-domain multi-carrier combined channel signal on each OF 丽 symbol, In the multi-carrier combined channel signal, the clipping noise corresponding to each carrier is obtained, the length of the clipping noise is a symbol length, and the frequency domain response corresponding to the clipping noise of each carrier is inversely superimposed to the corresponding carrier. The frequency domain signal is delayed in the OFDM symbol, thereby achieving effective suppression of the peak-to-average ratio in the multi-carrier OFDM system by superposing additional frequency domain noise on each carrier. DRAWINGS

1 is a schematic block diagram of a multi-match filter clipping scheme in a multi-carrier system in the prior art;

2 is a schematic block diagram of a method for suppressing a peak-to-average ratio in a multi-carrier 0FDM system according to an embodiment of the present invention; FIG. 3 is a flowchart of a method for suppressing a peak-to-average ratio in a multi-carrier 0FDM system according to an embodiment of the present invention;

4 is a flowchart of realizing a frequency domain signal transmitted by each carrier in an 0FDM symbol in a peak-to-average ratio suppression method in a multi-carrier 0FDM system according to an embodiment of the present invention;

FIG. 5 is a flowchart of implementing a multi-carrier combined channel signal in a peak-to-average ratio suppression method in a multi-carrier 0FDM system according to an embodiment of the present invention; FIG.

6 is a flow chart of index evaluation in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention; FIG. 7 is a schematic diagram of clipping noise extraction in a peak-to-average ratio suppression method in a multi-carrier ΟΚΰΜ system according to an embodiment of the present invention; Schematic diagram

8a~b are clipped noise interception methods in a peak-to-average ratio suppression method in a multi-carrier OFDM system according to an embodiment of the present invention; Schematic diagram of the principle;

FIG. 9 is a schematic diagram showing the principle of amplitude phase adjustment of a frequency domain response 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 structural diagram of a peak-to-average ratio suppression apparatus in a multi-carrier OFDM system according to an embodiment of the present invention; FIG. 11 is a first embodiment of a clipping noise acquisition module in a peak-to-average ratio suppression apparatus in a multi-carrier OFDM system according to an embodiment of the present invention; Schematic diagram of the structure;

12 is a second schematic structural diagram of a clipping noise acquisition module in a peak-to-average ratio suppression apparatus in a multi-carrier OFDM system according to an embodiment of the present invention;

13 is a schematic structural diagram of a multi-carrier combining channel signal module in a peak-to-average ratio suppression apparatus in a multi-carrier OFDM system according to an embodiment of the present invention;

14 is a schematic diagram showing a first structure of a peak-to-average ratio suppression module in a peak-to-average ratio suppression apparatus in a multi-carrier 0FDM system according to an embodiment of the present invention;

FIG. 15 is a second schematic structural diagram of a peak-to-average ratio suppression module in a peak-to-average ratio suppression apparatus in a multi-carrier 0FDM system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION In the process of implementing the present invention, the inventors discovered that:

If the scheme shown in Figure 1 is directly applied to the OFDM system, the modulation and coding modes, carrier power, etc. of the subcarriers on different OFDM symbols may be different, and the permissible performance loss may be different. The symbols use the same filter coefficients for matched filtering. For example, the filter coefficients are designed in a high-order modulation mode. The clipping ability of the matched filter will be very limited. The peak-to-average ratio of the matched filtered multi-carrier 0FDM system is still high. The filter coefficients are selected with a large error vector magnitude (EVM, Error Vector Magni tude) loss, which inevitably causes the high-order modulation subcarriers to fail to meet the EVM requirements specified by the protocol, which seriously affects the link performance of the system.

Even if the matching filtering in Figure 1 is properly modified, for example, using different filter coefficients on each OFDM symbol, a large portion of the sampling points between the two OFDM symbols will be severely distorted, resulting in more serious out-of-band leakage and Inter-symbol interference, which significantly deteriorates the EVM of the high-order modulation subcarriers in the 0FDM carrier, and the out-of-band leakage also makes the peak-to-average channel signal unable to satisfy the protocol-defined spectrum template.

The embodiments of the present invention will be 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. In FIG. 2, taking two carriers as an example, the baseband frequency domain signal 1 of carrier 1 and carrier 2 and the baseband frequency domain signal 2 are first multi-carrier combined. The road, after forming the multi-carrier combined channel signal, performs index evaluation. If the indicator evaluation is passed, it is directly sent to the intermediate frequency channel for subsequent processing. If the index evaluation fails, the clipping noise is extracted from the multi-carrier combined channel signal, and the extraction will be extracted. The clipping noise is intercepted by the symbol length and then assigned to carrier 1 and carrier 2. For carrier 1, obtain the frequency domain response of the allocated clipping noise, use the amplitude phase adjustment factor to adjust the amplitude and phase response of the obtained clipping noise, and inversely superimpose the adjusted frequency domain response to the corresponding carrier in the OFDM symbol. The baseband frequency domain signal after the upper delay is subjected to peak-to-average ratio suppression, and the operation of the carrier 2 is the same as that of the carrier 1. The new baseband frequency domain signal using carrier 1 and carrier 2 described above can continue to perform the operation of multi-carrier combining.

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. The process includes: Step 301: Combining baseband frequency domain signals of each carrier on each OF symbol Time domain multi-carrier combined channel signal.

Step 302: Acquire, from the multi-carrier combining channel signal, clipping noise corresponding to each carrier and symbol length.

Step 303: The frequency domain response corresponding to the clipping noise of each carrier and symbol length is inversely superimposed to the baseband frequency domain signal after the carrier delay, and the peak-to-average ratio suppression is performed.

In the method for suppressing peak-to-average ratio in a multi-carrier OFDM system according to an embodiment of the present invention, a baseband frequency domain signal of each carrier is combined into a time-domain multi-carrier combined channel signal on each OFDM symbol, and the multi-carrier combined signal is combined In the channel signal, the clipping noise corresponding to the length of each carrier and symbol is obtained, and then the frequency domain response of the clipping noise corresponding to each carrier and symbol length is inversely superimposed to the frequency domain signal corresponding to the carrier delay, thereby Effective suppression of the peak-to-average ratio in a multi-carrier 0F system is achieved by superimposing additional frequency domain noise on each carrier.

The method provided by the embodiment of the present invention is described in detail below in terms of multi-carrier combining channel signal formation, index evaluation, clipping noise acquisition, and peak-to-average ratio suppression.

1) Multi-carrier combined channel signal formation.

First, the frequency domain signal sent by each carrier in the 0FDM symbol is obtained. The implementation process is as shown in FIG. 4, and the process includes:

Step 401: On each 0FDM symbol of the multi-carrier 0FDM system, the data signal on each carrier is coded according to a predetermined coding mode.

Step 402: Perform constellation mapping on the encoded data signals of each carrier according to a predetermined modulation manner. Step 403: Insert control information such as a pilot signal for the data signal of each carrier after the constellation mapping. Step 404: Set the idle (', Tone Reservation) subcarrier and the left and right protection subcarriers of each carrier to 0 to generate a baseband frequency domain signal of each carrier.

Secondly, the baseband frequency domain signals of each carrier are combined into a multi-carrier combined channel signal, that is, a multi-carrier combined channel The implementation process of the signal is as shown in FIG. 5 . Taking the baseband frequency domain signal combining of two carriers as an example, the process includes: Step 501: On each OF leg symbol, the baseband frequency domain signal of each carrier is used. High-speed IFFT processing, forming a time domain signal.

Step 502: Add CP to the IFFT processed time domain signal to form a channel signal for each carrier.

Step 503: modulate the channel signals of each carrier obtained in step 502 to respective frequency points by using NC0, which may 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 OF匪 carrier after frequency modulation are accumulated one by one to obtain the multi-carrier combined channel signal _y(«) in the multi-carrier OFDM system, which can be expressed by:

L

y{n) = _j x _l (n)e ² ^ ^n+N o ^l ')^, n = Q ...,Sym _L + CI —1.

1=1

A ( / = 1,2,.., ) in the above equation is the frequency modulation frequency of each OFDM carrier, the frequency difference between carriers satisfies the configuration requirement, and is the number of carriers; N is the frequency modulation signal of the first carrier in the 0FDM symbol The phase of the 0th sampling point, through which the phase of the FM signal between the 0F匪 symbols is continuous; ΔΓ is the sampling point interval of the multi-carrier combining channel signal; CP _ _L is the CP region in the multi-carrier combined channel signal釆The number of samples is the number of samples in the symbol area of the multi-carrier combined channel signal; x, («) is the channel signal before each carrier is combined.

2) Indicator evaluation.

For the multi-carrier combined channel signal formed by the frequency domain signal, before the peak-to-average ratio suppression is performed, the index evaluation may be firstly used to determine whether the multi-carrier combining channel signal needs to perform peak-to-average ratio suppression, and specifically, a clipping algorithm may be set. Stop criteria, including: maximum iterations and target peak-to-average ratio. Figure 6 shows the flow of the above indicator evaluation, which includes:

Step 601: Determine whether the peak-to-average ratio suppression iteration number of the multi-carrier combining channel signal is greater than the maximum number of iterations. If the step 604 is directly performed, otherwise step 602 is performed.

Step 602: Determine whether the peak-to-average ratio of the multi-carrier combining channel signal is smaller than the target peak-to-average ratio. If yes, go to step 604, otherwise go to step 603.

Step 603: Continue to perform the step of performing clipping noise extraction on the multi-carrier combining channel signal.

In this step, if the result of the index evaluation still needs to perform peak-to-average ratio suppression for the multi-carrier combined channel signal, the clipping noise extraction of the multi-carrier combined channel signal is continued, and subsequent clipping is performed after the clipping noise extraction is performed. Noise interception and other steps.

Step 604: Send the multi-carrier combined channel signal to the intermediate frequency channel.

The above steps 601 and 602 have no strict order relationship. The above process gives one of the order relationships. It is also possible to first determine whether the peak-to-average ratio of the multi-carrier combined channel signal is smaller than the target peak-to-average ratio, and then judge the multi-load. The peak-to-average ratio of the wave-pass channel signal is greater than the maximum number of iterations.

3) Clipping noise acquisition.

In the method provided by the embodiment of the present invention, the clipping noise acquisition is divided into two specific implementation manners.

The first type is a peak preset threshold Gate of the multi-carrier combined channel signal, determining a portion of the multi-carrier combined channel signal whose peak value is greater than the extraction threshold, and calculating a portion exceeding the preset threshold and a signal of the multi-carrier combined channel The amplitude ratio, the multi-carrier combining channel signal is multiplied by the amplitude ratio, as the clipping noise of the multi-carrier combining channel signal, in the clipping noise of the multi-carrier combining channel signal, the length of the truncated symbol is cut The wave noise is then distributed to the respective carriers by the clipping noise of the intercepted symbol length. Fig. 7 shows the implementation principle of the above-mentioned extraction multi-carrier combining channel signal being larger than the preset threshold portion.

The above process can be implemented in the following manner. Each sample point of the multi-carrier combined channel signal is represented as ^ = + 'x W, where is the I input signal, which is the Q input signal, and the calculated signal amplitude ^rapO) and the clipping ratio γ(η) are as follows As shown in the formula:

Then the clipping noise of the multi-carrier combined channel signal is as follows:

Noise(n) = (1 - Y{n))y(n), t = 0,1, ...,Sym _L + CP _L - 1.

It can be seen that the clipping noise length of the multi-carrier combining channel signal is the channel length 3⁄4^- + ^.

Since the frequency domain structure can only process clipping noise of length symbol length at a time, it is necessary to intercept the clipping noise of the above multi-carrier combined channel signal. A simple and feasible strategy is to deal with the peak-to-average ratio suppression of different levels, and to handle the clipping noise at different positions in the multi-carrier combined channel signal. The level here refers to the current peak-to-average ratio suppression of the multi-carrier combined channel signal. The number of iterations, for example, when the multi-carrier combining channel signal is currently performing the first iteration, is the first level; when the multi-carrier combining channel signal is currently performing the second iteration, it is the second level.

At odd-numbered iterations, the symbol-length noise signal is intercepted from the end of the multi-carrier combining channel signal, and at even-numbered iterations, the symbol-length noise signal is intercepted from the front of the multi-carrier combining channel signal. The implementation principle of the above-mentioned two-stage clipping noise interception is as shown in Fig. 8, where a shows the processing mode in an odd number of iterations, and b shows the processing mode in an even number of iterations. The clipping noise intercepted by different iterative processes is different in the channel, so that after multiple iterations of the multi-carrier combined channel signal, it is beneficial to suppress the peak-to-average ratio of the entire channel signal.

After the clipping noise interception process, the clipping noise of the output symbol length is as follows: ί(1 - Y{n+CP _L ))y{n+CP _L ), odd iterations

Noise{n) = \ _ n i e 1

{{l - Y{n))y{n\ even iterations, "2 ¹ '...^)^— - ^1. After the clipping noise is intercepted, the intercepted clipping noise is distributed to each carrier, which can be based on The frequency domain response of the wave noise is used to perform the above-mentioned clipping noise distribution, and the clipping noise of the multi-carrier combined channel signal can be distributed by the NC0 conjugate at the time of complex multiplication.

If the clipping noise is an odd number of iterations, the clipping noise of the / ( / = 1,..., Z, £ is the number of carriers) after the assignment is as follows:

Noisej (n) = (1 _ r(n+ CP _L ))x(n+ CP _L , _e - ' ^+N . ^+CP , _n = 0,\, ... ,Sym _L - 1 If clipping noise is intercepted For even iterations, the assigned clipping noise is as follows - .

Secondly, extracting a portion of the multi-carrier combining channel signal whose peak value exceeds a preset threshold, and calculating an amplitude ratio of the portion exceeding the preset threshold and the signal of the multi-carrier combining channel, and multiplying each by using the amplitude ratio The channel signal of the carrier, as the clipping noise of each carrier, intercepts the clipping noise of the symbol length from the clipping noise of each carrier.

The second method described above can be implemented as follows. Still calculating the clipping ratio γ(η) according to the method in the first implementation manner above, and multiplying the calculated channel signal of each carrier by the calculated clipping ratio, as shown in the following equation - noise, ( n) = (I - γ(η))χ, (η),

After the above equation has been calculated, the clipping noise of each carrier has been obtained, and the clipping noise of the symbol length can be directly extracted for each carrier according to the rule of clipping the clipping noise in the first implementation method described above.

4) Peak-to-average ratio suppression.

For each carrier and symbol length clipping noise, the frequency domain response in the band is obtained by high-speed FFT processing, and then inversely superimposed to the frequency domain signal of each carrier after delay after appropriate amplitude and phase adjustment. Thereby achieving peak-to-average ratio suppression in a multi-carrier OFDM system. Alternatively, the frequency domain response of obtaining the carrier clipping noise of each carrier may be implemented in another manner, that is, the frequency domain response of the out-of-band portion of each carrier clipping noise is first filtered by using a filter, and the low-frequency extraction is performed after the low-speed extraction. The frequency domain response of each carrier clipping noise is obtained by a single-speed FFT process.

Fig. 9 is a schematic diagram showing the implementation of amplitude phase adjustment for each of the above-described carrier frequency domain responses.

The amplitude and phase adjustment of the above-mentioned frequency domain response are controlled by the amplitude and phase adjustment factors, and the amplitude and phase adjustment factors are determined by considering the subcarrier parameters and the TR subcarrier parameters. Subcarrier parameters can be derived from link performance Considering, including coding rate, constellation modulation mode, subcarrier power, EVM loss, spectrum template, etc., and peak-to-average ratio performance and implementation complexity also restrict the configuration of the above adjustment factors, so the above factors should be fully considered to select the appropriate range. , phase adjustment factor.

For the TR subcarriers in each OFDM symbol, these TR subcarriers do not carry any useful signals, and theoretically allow arbitrary amplitude and phase adjustment factors to be configured, but excessive superimposed noise on the TR subcarriers not only affects the receiver data. The demodulation of the carrier also reduces the power of the transmitter. Therefore, the TR subcarrier parameters may include appropriate suppression of the amplitude and phase adjustment factors to attenuate the adverse effects. It can be seen that the embodiment of the present invention allows the TR subcarriers in the OFDM symbol to participate in the peak-to-average ratio suppression, fully utilizes the system physical resources, and can obtain a better peak-to-average ratio suppression effect, and the amplitude on the TR subcarriers. The limitation of the phase adjustment factor also enables the noise energy superimposed on the TR subcarrier to be effectively controlled, which not only facilitates the demodulation of the terminal data subcarrier, but also indirectly improves the efficiency of the transmitter.

Since the frequency domain subcarriers of each carrier may have different characteristics on each OFDM symbol, the amplitude and phase factors configured on different OF symbols are also different.

In combination with the principle of determining the amplitude and phase adjustment factors given in the above embodiments of the present invention, how to determine the amplitude and phase adjustment factors is not described herein.

The amplitude, the phase adjustment factor, and the frequency domain clipping noise of each carrier are multiplied, and the result of the complex multiplication can also be referred to as cancellation noise. When performing peak-to-average ratio suppression, the frequency domain of each of the above carriers is directly canceled and inversely superimposed on the baseband frequency domain signal of each carrier after the corresponding delay, and the peak-to-average ratio suppression is completed.

FIG. 10 is a schematic structural diagram of an apparatus for suppressing peak-to-average ratio in a multi-carrier 0FDM system according to an embodiment of the present invention, where 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 multi-carrier combined channel signal on each 0FDM symbol.

The delay module 12 is configured to delay the baseband frequency domain signal of each carrier.

The clipping noise acquisition module 13 is configured to acquire, from the multi-carrier combining channel signal, clipping noise corresponding to each carrier, where the length of the clipping noise is a symbol length.

The peak-to-average ratio suppression module 14 is configured to obtain the frequency domain response of the clipping noise corresponding to each carrier, and inversely superimpose the signal to the baseband frequency domain signal after the carrier delay, and perform peak-to-average ratio suppression.

In the multi-carrier 0FDM system of the embodiment of the present invention, the multi-carrier combining channel signal module 1 1 combines the frequency domain signals of each carrier on the 0FDM symbol into a time domain multi-carrier combined channel signal. The clipping noise acquisition module 13 obtains clipping noise corresponding to each carrier from the multi-carrier combining channel signal, and the peak-to-average ratio suppression module 14 inversely superimposes the frequency domain response of the clipping noise corresponding to each carrier. Delay to the corresponding carrier on the 0FDM symbol The latter frequency domain signal, thereby effectively suppressing the peak-to-average ratio in the multi-carrier OFDM system by superimposing additional frequency domain noise on each carrier.

In the apparatus provided by the embodiment of the present invention, the clipping noise acquisition module 13 may include two internal structures, which will be described below with reference to FIGS. 11 and 12.

The clipping noise acquisition module 13 may include:

The indicator evaluation unit 131 is configured to determine whether the peak-to-average ratio of the multi-carrier combining channel signal is greater than the maximum number of iterations, and if yes, send the multi-carrier combining channel signal to the intermediate frequency channel, otherwise continue to determine the multi-carrier combination Whether the peak-to-average ratio of the channel channel signal is smaller than the target peak-to-average ratio, and if so, transmitting the multi-carrier combining channel signal to the intermediate frequency channel, otherwise transmitting the multi-carrier combining channel signal to the clipping noise acquisition performing unit 132 Or determining whether the peak-to-average ratio of the multi-carrier combining channel signal is smaller than a target peak-to-average ratio ratio, and if yes, transmitting the multi-carrier combining channel signal to the intermediate frequency channel, otherwise continuing to determine the multi-carrier combined channel signal The peak-to-average ratio is suppressed whether the number of iterations is greater than the maximum number of iterations. If yes, the multi-carrier combining channel signal is sent to the intermediate frequency channel, otherwise the multi-carrier combining channel signal is sent to the clipping noise acquisition performing unit 132.

The clipping noise acquisition performing unit 132 is configured to acquire, from the multi-carrier combining channel signal output by the index evaluating unit 131, clipping noise corresponding to each carrier, and the length of the clipping noise is a symbol length.

The above-described clipping noise acquisition execution unit 132 has two configurations.

First, referring to FIG. 1, the clipping noise acquisition execution unit 132 includes:

The first extraction execution sub-unit 1321 is configured to extract a portion of the multi-carrier combining channel signal whose peak value exceeds a preset threshold, and calculate an amplitude ratio of the portion exceeding the preset threshold and the multi-carrier combining channel signal, and use The amplitude ratio multiplies the multi-carrier combining channel signal as clipping noise of the multi-carrier combining channel signal.

a first intercepting execution sub-unit 1322, configured to intercept a symbol length from a clipping noise tail of the multi-carrier combining channel signal when the current peak-to-average ratio of the multi-carrier combining channel signal is an odd number of times Clipping noise; when the current peak-to-average ratio of the multi-carrier combining channel signal is an even number of times, the clipping noise of the symbol length is intercepted from the front part of the clipping noise of the multi-carrier combining channel signal .

The allocation execution sub-unit 1323 is configured to multiply the clipping noise of the symbol length and the conjugate of the frequency-modulated signal of the corresponding carrier to obtain clipping noise corresponding to each carrier, and the clipping noise is a symbol length.

Second, referring to FIG. 12, the clipping noise acquisition unit 132 may include:

a second extraction execution sub-unit 1324, configured to extract a portion of the multi-carrier combining channel signal whose peak value exceeds a preset threshold, and calculate an amplitude ratio of a part of the multi-carrier combining channel signal that exceeds the preset threshold, The amplitude ratio is multiplied by the channel signal of each carrier as the clipping noise of each carrier.

a second intercepting execution sub-unit 1325, configured to intercept each of the clipped noises of each of the carriers The clipping noise of the wave, which is the symbol length.

FIG. 13 is a schematic structural diagram of a multi-carrier combining channel signal module 11 in a peak-to-average ratio suppression apparatus in a multi-carrier OFDM system according to an embodiment of the present invention, as shown in FIG. 13, based on the structure of the clipping noise acquiring module 13 described above. The multi-carrier combining channel signal module 11 may include:

The frequency domain signal unit 111 is configured to acquire a baseband frequency domain signal of each carrier on each OF匪 symbol.

The IFFT unit 112 is configured to perform high-speed IFFT processing on the baseband frequency domain signal of each carrier.

The CP unit 113 is configured to add CP to the frequency domain signal sent by the high-speed IFFT processed carrier in the corresponding OFDM symbol.

The NC0 unit 114 is configured to modulate signals of each carrier after the CP is added to respective frequency points.

The first accumulating unit 115 is configured to accumulate the channel signals of each carrier modulated to respective frequency points to obtain a multi-carrier combining channel signal.

Based on the structure of the clipping noise acquisition module 13, the above-described peak-to-average ratio suppression module 14 has two configurations.

First, referring to Figure 14, the peak-to-average ratio suppression module 14 includes:

The high-speed FFT unit 141 is configured to perform high-speed FFT processing on the clipping noise corresponding to each carrier to obtain a corresponding frequency domain response;

a first phase adjustment unit 142, configured to perform amplitude and phase adjustment on the frequency domain response using a configured amplitude and phase adjustment factor;

The second accumulating unit 143 is configured to inversely superimpose the baseband frequency domain signal of each carrier after the delay and the frequency domain response of the corresponding carrier output by the first phase adjustment unit 142, and perform peak-to-average ratio inhibition.

Second, referring to Figure 15, the peak-to-average ratio suppression module 14 includes:

The filtering unit 144 is configured to filter the clipping noise corresponding to each carrier, and filter out the frequency domain response of the out-of-band portion.

The double-speed FFT unit 145 is configured to perform a double-speed FFT processing on the clipping noise of each carrier output by the filter unit 144 to obtain a corresponding frequency domain response.

The second phase adjustment unit 146 is configured to perform amplitude and phase adjustment on the frequency domain response output by the one-speed FFT unit 145 using the configured amplitude and phase adjustment factors.

The third accumulating unit 147 is configured to inversely superimpose the frequency domain signal of each carrier baseband after the delay and the corresponding carrier frequency domain response output by the second phase adjustment unit 146 to perform peak-to-average ratio suppression. .

A method and apparatus for peak-to-average ratio suppression in a multi-carrier OFDM system according to an embodiment of the present invention, wherein each baseband frequency domain signal of each carrier is combined into a time-domain multi-carrier combined channel signal from each of the OFDM symbols In the carrier combined channel signal, the clipping noise corresponding to each carrier and symbol length is obtained, and then the frequency domain response of the clipping noise corresponding to each carrier and symbol length is inversely superimposed to the corresponding carrier delay on the 0FDM symbol. After the frequency domain signal, thus passing in each The additional frequency domain noise is inversely superimposed on the carriers to achieve effective suppression of the peak-to-average ratio in the multi-carrier OFDM system. It should be noted that, in the foregoing device embodiment, each unit included is only divided according to functional logic, but is not limited to the above division, as long as the corresponding function can be implemented; in addition, the specific name of each functional unit It is also for convenience of distinguishing from each other and is not intended to limit the scope of protection of the present invention.

In addition, those skilled in the art can understand that all or part of the steps in the method provided by the embodiments of the present invention can be completed by using hardware related to program instructions. For example, it can be done by computer running. The program can be stored on a readable storage medium such as a random access memory, a magnetic disk, an optical disk, or the like.

In conclusion, the above is only the 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 scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

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

Obtaining, from the multi-carrier combining channel signal, clipping noise corresponding to each carrier, where the length of the clipping noise is a symbol length;

Obtaining the frequency domain response of the clipping noise corresponding to each carrier, and superimposing the signal to the baseband frequency domain signal delayed by the corresponding carrier on the OFDM symbol, and performing peak-to-average ratio suppression.

2. The method according to claim 1, wherein the clipping algorithm stopping criterion is preset, comprising: a maximum number of iterations and a target peak-to-average ratio; and the combining is after the time domain multi-carrier combining channel signal, acquiring Before corresponding to the clipping noise of each carrier, further includes:

Determining whether the peak-to-average ratio of the multi-carrier combining channel signal is greater than the maximum number of iterations, and if not, continuing to determine whether the peak-to-average ratio of the multi-carrier combining channel signal is smaller than the target peak-to-average ratio, and if not, continue Performing a step of acquiring clipping noise corresponding to each carrier from the multi-carrier combining channel signal;

Or determining whether the peak-to-average ratio of the multi-carrier combining channel signal is smaller than the target peak-to-average ratio, and if not, continuing to determine whether the peak-to-average ratio of the multi-carrier combining channel signal is greater than the maximum number of iterations, if no And continuing to perform the step of acquiring clipping noise corresponding to each carrier from the multi-carrier combining channel signal.

The method according to claim 2, wherein the combining into a time domain multi-carrier combining channel signal is: acquiring a baseband frequency domain signal transmitted by each carrier in an OF匪 symbol;

After the baseband frequency domain signal is subjected to high-speed inverse Fourier transform IFFT processing, adding a cyclic prefix CP;

The channel signals of each carrier after the CP is modulated to respective frequency points and accumulated to obtain a time domain multi-carrier combined channel signal.

The method according to claim 2, wherein the peak value of the multi-carrier combining channel signal is preset; and the clipping noise corresponding to each carrier is obtained from the multi-carrier combining channel signal:

And extracting, in the multi-carrier combining channel signal, a portion whose peak value exceeds the preset threshold, and calculating an amplitude ratio of the portion exceeding the preset threshold and the multi-carrier combining channel signal;

Multiplying the multi-carrier combining channel signal by the amplitude ratio as a clipping noise of the multi-carrier combining channel signal; intercepting the clipping noise of the symbol length in the clipping noise of the multi-carrier combining channel signal;

Clipping noise of the intercepted symbol length is assigned to each carrier.

The method according to claim 4, wherein the number of iterations of the multi-carrier combining channel signal currently performing peak-to-average ratio suppression is more than one time; the clipping noise of the intercepted symbol length is: at a time In the iteration of peak-to-average ratio suppression, The clipping noise of the symbol length is intercepted at different positions.

The method according to claim 5, wherein if the number of iterations of the current multi-carrier combining channel signal currently performing peak-to-average ratio suppression is an odd number, the clipping noise of the symbol length intercepted at different positions is : intercepting the clipping noise of the symbol length from the tail of the clipping noise;

Or, if the number of iterations of the multi-carrier combining channel signal currently performing peak-to-average ratio suppression is an even number of times, the clipping noise of the symbol length intercepted at different positions is: from the front part of the extracted clipping noise, the symbol length is intercepted Clipping noise.

7. The method according to claim 4, wherein the allocating the clipping noise of the truncated symbol length to each carrier is:

The clipping noise of the intercepted symbol length is multiplied by the conjugate of the frequency modulated signal corresponding to each carrier to obtain clipping noise assigned to each carrier.

The channel signal before each carrier combination is multiplied by the amplitude ratio as the clipping noise of each carrier; in the clipping noise of each carrier, the clipping noise of the symbol length is intercepted.

The method according to claim 2, wherein the frequency domain response corresponding to the clipping noise of each carrier is inversely superimposed to a frequency domain signal after the delay of the corresponding carrier on the OFDM symbol, further Includes:

Performing high-speed Fourier transform FFT processing on the clipping noise corresponding to each carrier to obtain a corresponding frequency domain response; using amplitude and phase adjustment factors configured on the frequency domain subcarriers of each carrier to perform corresponding frequency domain response Amplitude and phase adjustment.

The method according to claim 2, wherein the frequency domain response corresponding to the clipping noise of each carrier is inversely superimposed to the delayed frequency domain signal of the corresponding carrier, and further includes:

Filtering the clipping noise corresponding to each carrier and symbol length, filtering out the frequency domain response of the out-of-band portion of the clipping noise, and performing low-speed extraction and then performing FFT processing to obtain a corresponding frequency domain response;

The amplitude and phase adjustment factors configured on the frequency domain subcarriers of each carrier are used to perform amplitude and phase adjustment for the corresponding frequency domain response.

The method according to claim 9 or 10, wherein the amplitude and phase adjustment factors are configured according to subcarrier parameters and idle 'subcarrier parameters;

The subcarrier parameters include: a coding rate, a constellation modulation mode, a subcarrier power, an error vector magnitude EVM loss, a frequency template, a peak-to-average ratio performance, and an implementation complexity; The TR subcarrier parameters include: suppressing the amplitude and phase of the TR subcarrier.

12. A device for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing system, characterized in that the apparatus comprises a multi-carrier combining channel signal module for multiplexing OFDM symbols in each orthogonal frequency division. Upper, combining the baseband frequency domain signals of each carrier into a multi-carrier combined channel signal;

The peak-to-average ratio suppression module is configured to acquire the frequency domain response of the clipping noise corresponding to each carrier and symbol length, and inversely superimpose the signal to the baseband frequency domain signal corresponding to the carrier delay, and perform peak-to-average ratio suppression.

The device according to claim 12, wherein the clipping noise acquisition module comprises: an index evaluation unit, configured to determine whether a peak-to-average ratio of the multi-carrier combining channel signal is greater than a maximum iteration Number of times, if not, continue to determine whether the peak-to-average ratio of the multi-carrier combining channel signal is smaller than the target peak-to-average ratio, and if not, send the multi-carrier combining channel signal to the clipping noise acquiring unit; or for judging the multi-carrier Whether the peak-to-average ratio of the combined channel signal is smaller than the target peak-to-average ratio, if not, continuing to determine whether the peak-to-average ratio of the multi-carrier combining channel signal is greater than the maximum number of iterations, and if not, combining the multiple carriers The channel signal is sent to the clipping noise acquisition execution unit;

And a clipping noise acquisition execution unit configured to acquire, from the multi-carrier combining channel signal output by the index evaluating unit, clipping noise corresponding to each carrier, wherein the length of the clipping noise is a symbol length.

The apparatus according to claim 13, wherein the multi-carrier combining channel signal module comprises: a frequency domain signal unit, configured to acquire a baseband frequency domain signal of each carrier on each OFDM symbol; An inverse Fourier transform IFFT unit, configured to perform high-speed IFFT processing on the baseband frequency domain signal of each carrier;

a cyclic prefix CP unit, configured to add a signal of each carrier after the high-speed IFFT processing to form a channel signal of each carrier;

a numerically controlled oscillator NC0 unit, configured to modulate channel signals of each carrier to respective frequency points; a first accumulating unit, configured to accumulate channel signals of each carrier modulated to respective frequency points, to obtain multi-carrier combination Road channel signal.

The apparatus according to claim 13, wherein the clipping noise acquisition execution unit comprises: a first extraction execution subunit, configured to extract a peak value of the multi-carrier combining channel signal that exceeds a preset threshold And calculating an amplitude ratio of the portion exceeding the preset threshold and the multi-carrier combining channel signal, and multiplying the multi-carrier combining channel signal by the amplitude ratio as the clipping noise of the multi-carrier combining channel signal; a first intercepting execution subunit, configured to intercept a symbol length from a clipping noise tail of the multi-carrier combining channel signal when the current peak-to-average ratio of the multi-carrier combining channel signal is an odd number of times Clipping noise; when the current peak-to-average ratio of the multi-carrier combining channel signal is an even number of times, the clipping noise of the symbol length is intercepted from the front part of the clipping noise of the multi-carrier combining channel signal;

And an allocation execution subunit, configured to multiply the clipping noise of the symbol length and the conjugate of the frequency modulated signal of the corresponding carrier to obtain clipping noise corresponding to each carrier, where the length of the clipping noise is a symbol length.

The apparatus according to claim 13, wherein the clipping noise acquisition execution unit comprises: a second extraction execution subunit, configured to extract a peak value of the multi-carrier combining channel signal that exceeds a preset threshold And calculating an amplitude ratio of the portion exceeding the preset threshold and the multi-carrier combining channel signal, and multiplying the amplitude ratio by a channel signal of each carrier as a clipping noise of each carrier;

And a second intercepting execution unit, configured to intercept, from the clipping noise of each carrier, clipping noise corresponding to each carrier, where the length of the clipping noise is a symbol length.

The apparatus according to claim 13, wherein the peak-to-average ratio suppression module comprises:

a high-speed Fourier transform FFT unit for performing high-speed FFT processing on the clipping noise corresponding to each carrier to obtain a corresponding frequency domain response;

a first phase adjustment unit, configured to perform amplitude and phase adjustment on the frequency domain response by using a configured amplitude and phase adjustment factor;

The second accumulating unit is configured to inversely superimpose the baseband frequency domain signal of each carrier after the delay and the frequency domain response of the corresponding carrier output by the first phase adjustment unit to perform peak-to-average ratio suppression.

18. The apparatus of claim 13, wherein the peak-to-average ratio suppression module comprises:

a filtering unit, configured to filter the clipping noise corresponding to each carrier, and filter out a frequency domain response of the outband portion, where the length of the clipping noise is a symbol length;

a double-speed FFT unit, configured to perform a double-speed FFT processing on the clipping noise of each carrier output by the filter unit, to obtain a corresponding frequency domain response;

a second phase adjustment unit, configured to perform amplitude and phase adjustment on a frequency domain response of the output of the one-speed FFT unit by using a configured amplitude and phase adjustment factor;

The third accumulating unit is configured to inversely superimpose the baseband frequency domain signal of each carrier after the delay and the corresponding carrier frequency domain response of the second phase adjustment unit to perform peak-to-average ratio suppression.