CN104243379B

CN104243379B - The suppressing method and transmitter of ofdm signal peak power in wireless communication system

Info

Publication number: CN104243379B
Application number: CN201310227545.1A
Authority: CN
Inventors: 黄煌; 王光健
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2013-06-08
Filing date: 2013-06-08
Publication date: 2019-04-26
Anticipated expiration: 2033-06-08
Also published as: WO2014194697A1; CN104243379A

Abstract

The embodiment of the present invention provides the suppressing method and transmitter of ofdm signal peak power in a kind of wireless communication system.The suppressing method of orthogonal frequency-division multiplex singal peak power in wireless communication system of the present invention, comprising: determine clipping parameter corresponding with data-signal to be sent；The data-signal after amplitude clipping obtains clipping is carried out respectively according to real and imaginary parts of the clipping parameter to the data-signal to be sent；Data-signal after sending the clipping.The embodiment of the present invention carries out the technical solution of clipping by the real and imaginary parts to signal to be sent respectively, reduces the complexity of slicing operation, realizes low complex degree and inhibits orthogonal frequency-division multiplex singal peak power in wireless communication system.

Description

Method for suppressing peak power of OFDM signal in wireless communication system and transmitter

Technical Field

The embodiment of the invention relates to the communication technology, in particular to a method for suppressing the peak power of an OFDM signal in a wireless communication system and a transmitter.

Background

With the development of broadband wireless communication systems, frequency selective fading channels will inevitably be encountered. And a high spectrum efficiency technique is required in order to satisfy various integrated service demands from voice to multimedia.

Orthogonal Frequency Division Multiplexing (OFDM) is a kind of multi-carrier narrowband transmission, and subcarriers thereof are Orthogonal to each other, so that spectrum resources can be efficiently utilized, adverse effects caused by multipath effect and Frequency selective fading can be overcome, and high reliability of signal transmission can be realized. Therefore, OFDM is the mainstream technology for communication at present, and is adopted by many standards, such as IEEE802.11, IEEE802.16, IEEE802.15, and the like.

One of the main problems of using OFDM for carrier modulation is that the Peak to Average power ratio (PAPR) is too high. The peak-to-average ratio is the ratio of the peak power to the average power of the transmitted signal. If the peak power of the transmitted signal is much higher than the average power, i.e. the power of the transmitted signal varies over a large range, it requires a large enough dynamic range for the amplifier and other components of the OFDM system, otherwise the transmitted power is limited.

The prior art utilizes some reserved sub-carriers in OFDM systems to eliminate the peaks of the OFDM signal. The amplitude limiting operation is carried out on the OFDM signal according to the amplitude limiting sequence transmitted by the reserved subcarrier, operations such as modulus value operation, division operation, complex multiplication operation and the like are required, and the complexity of the amplitude limiting calculation method is high.

Disclosure of Invention

The embodiment of the invention provides a method for inhibiting the peak power of an OFDM signal in a wireless communication system and a transmitter, which aim to solve the problem of high complexity of an amplitude limiting scheme in the prior art.

In a first aspect, an embodiment of the present invention provides a method for suppressing a peak power of an orthogonal frequency division multiplexing signal in a wireless communication system, including:

determining a clipping parameter corresponding to a data signal to be transmitted;

respectively carrying out amplitude limiting on the real part and the imaginary part of the data signal to be sent according to the amplitude limiting parameters to obtain the data signal after amplitude limiting;

and transmitting the limited data signal.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the determining a slicing parameter corresponding to a data signal to be transmitted includes:

determining a time domain discrete data signal corresponding to the data signal to be transmitted after Inverse Fast Fourier Transform (IFFT);

determining the amplitude limiting parameter according to the time domain discrete data signal;

then, the performing amplitude limiting on the real part and the imaginary part of the data signal to be transmitted respectively according to the amplitude limiting parameter to obtain the data signal after amplitude limiting includes:

amplitude limiting is carried out on the real part and the imaginary part of each data in the time domain discrete data signal according to the amplitude limiting parameters;

and D/A conversion DAC is carried out on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the determining the slicing parameter according to the time-domain discrete data signal includes:

determining a real maximum absolute value and an imaginary maximum absolute value in the time-domain discrete data signal;

judging the magnitude of the real part maximum absolute value, the imaginary part maximum absolute value and the amplitude threshold;

if the real part maximum absolute value is larger than or equal to the imaginary part maximum absolute value and the real part maximum absolute value is larger than the amplitude threshold, calculating a first amplitude limiting parameter according to data corresponding to the real part maximum absolute value;

and if the maximum absolute value of the imaginary part is greater than or equal to the maximum absolute value of the real part and the maximum absolute value of the imaginary part is greater than the amplitude threshold, calculating a second amplitude limiting parameter according to data corresponding to the maximum absolute value of the imaginary part.

With reference to the second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the calculating a first clipping parameter according to the data corresponding to the maximum absolute value of the real part includes:

the first clipping parameter is calculated according to the following formula:

wherein v is₁And a is the first amplitude limiting parameter, a is the amplitude threshold, l is the serial number of the data corresponding to the maximum absolute value of the real part, l is greater than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, x (l) is the data corresponding to the maximum absolute value of the real part, and Re { x (l) } is the real part numerical value of the data corresponding to the maximum absolute value of the real part.

With reference to the second possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the calculating a second clipping parameter according to the data corresponding to the maximum absolute value of the imaginary part includes:

the second clipping parameter is calculated according to the following formula:

wherein v is₂And as the first amplitude limiting parameter, a is the amplitude threshold, m is the serial number of the data corresponding to the maximum absolute value of the imaginary part, m is greater than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, x (m) is the data corresponding to the maximum absolute value of the imaginary part, and Im { x (m) } is the numerical value of the imaginary part of the data corresponding to the maximum absolute value of the imaginary part.

With reference to any one of the second to fourth possible implementation manners of the first aspect, in a fifth possible implementation manner of the first aspect, the performing amplitude limiting on the real part and the imaginary part of each data in the time-domain discrete data signal according to the amplitude limiting parameter respectively includes:

if the real maximum absolute value is greater than or equal to the imaginary maximum absolute value and the real maximum absolute value is greater than the amplitude threshold, amplitude limiting is performed on the real part of each data in the time domain discrete data signal according to the following formula:

if the maximum absolute value of the imaginary part is greater than or equal to the maximum absolute value of the real part, and the maximum absolute value of the imaginary part is greater than the amplitude threshold, amplitude limiting is performed on the imaginary part of each data in the time domain discrete data signal according to the following formula:

wherein,for the limited time-domain discrete data signal, x (n) is the time-domain discrete data signal, v₁Is said first clipping parameter, v₂For the second clipping parameter, l is the serial number of the data corresponding to the maximum absolute value of the real part, l is greater than or equal to 0 and is less than or equal to N-1, m is the serial number of the data corresponding to the maximum absolute value of the imaginary part, m is greater than or equal to 0 and is less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, p is a clipping sequence with a period of N, j is an imaginary unit, i.e., j is²＝-1。

With reference to the first possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, the determining the slicing parameter according to the time-domain discrete data signal includes:

determining a real part maximum value and a real part minimum value of the time domain discrete data signal, and calculating an average value of the real part maximum value and the real part minimum value;

determining imaginary maximum and minimum values of the time domain discrete data signal and calculating an average value of the imaginary maximum and minimum values;

and taking the average value of the real part maximum value and the real part minimum value as the real part of the clipping parameter, and taking the average value of the imaginary part maximum value and the imaginary part minimum value as the imaginary part of the clipping parameter.

With reference to the sixth possible implementation manner of the first aspect, in a seventh possible implementation manner of the first aspect, the performing amplitude limiting on the real part and the imaginary part of the time-domain discrete data signal according to the limiting parameter respectively includes:

amplitude limiting is respectively carried out on the real part and the imaginary part of each data in the time domain discrete data signal according to the following formula:

wherein,for the time domain discrete data signal after amplitude limiting, x (N) is the time domain discrete data signal, e is the average value of the real part maximum value and the real part minimum value, f is the average value of the imaginary part maximum value and the imaginary part minimum value, N is the product of the number of subcarriers and the up-sampling multiple, j is an imaginary unit, namely j²＝-1。

With reference to the first aspect and any one of the first to seventh possible implementation manners of the first aspect, in an eighth possible implementation manner of the first aspect, the sending the limited data signal includes:

judging whether the amplitude limiting times reach a preset total amplitude limiting times or not, and if so, sending the data signal after amplitude limiting; otherwise, returning to the step of determining the amplitude limiting parameter corresponding to the data signal to be sent.

In a second aspect, an embodiment of the present invention provides a transmitter in a wireless communication system, including:

the device comprises a determining module, a determining module and a processing module, wherein the determining module is used for determining an amplitude limiting parameter corresponding to a data signal to be sent;

the processing module is used for respectively carrying out amplitude limiting on the real part and the imaginary part of the data signal to be sent according to the amplitude limiting parameters to obtain the data signal after amplitude limiting;

and the sending module is used for sending the data signal after amplitude limiting.

With reference to the second aspect, in a first possible implementation manner of the second aspect, the determining module includes:

a first determining unit, configured to determine a time-domain discrete data signal corresponding to the data signal to be transmitted after an Inverse Fast Fourier Transform (IFFT);

a second determining unit, configured to determine the clipping parameter according to the time-domain discrete data signal;

the processing module comprises:

the amplitude limiting unit is used for respectively carrying out amplitude limiting on the real part and the imaginary part of each data in the time domain discrete data signal according to the amplitude limiting parameters;

and the conversion unit is used for performing digital-to-analog conversion (DAC) on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting.

With reference to the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, the second determining unit includes:

a first determining subunit, configured to determine a real maximum absolute value and an imaginary maximum absolute value in the time-domain discrete data signal;

the judgment subunit is used for judging the magnitude of the real part maximum absolute value, the imaginary part maximum absolute value and the amplitude threshold;

a first calculating subunit, configured to calculate a first clipping parameter according to data corresponding to the real maximum absolute value if the real maximum absolute value is greater than or equal to the imaginary maximum absolute value and the real maximum absolute value is greater than the amplitude threshold;

and the second calculating subunit is configured to calculate a second clipping parameter according to the data corresponding to the imaginary maximum absolute value if the imaginary maximum absolute value is greater than or equal to the real maximum absolute value and the imaginary maximum absolute value is greater than the amplitude threshold.

With reference to the second possible implementation manner of the second aspect, in a third possible implementation manner of the second aspect, the first calculating subunit is specifically configured to:

the first clipping parameter is calculated according to the following formula:

With reference to the second possible implementation manner of the second aspect, in a fourth possible implementation manner of the second aspect, the second calculating subunit is specifically configured to:

the second clipping parameter is calculated according to the following formula:

wherein v is₂Is the first clipping parameter, A is the amplitude threshold, m is the imaginary partThe serial number of the data corresponding to the maximum absolute value is more than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, x (m) is the data corresponding to the maximum absolute value of the imaginary part, and Im { x (m) } is the numerical value of the imaginary part of the data corresponding to the maximum absolute value of the imaginary part.

With reference to any one of the second to fourth possible implementation manners of the second aspect, in a fifth possible implementation manner of the second aspect, the amplitude limiting unit includes:

a first processing subunit, configured to perform amplitude clipping on the real part of each data in the time-domain discrete data signal according to the following formula if the real part maximum absolute value is greater than or equal to the imaginary part maximum absolute value and the real part maximum absolute value is greater than the amplitude threshold:

a second processing subunit, configured to perform amplitude clipping on an imaginary part of each data in the time-domain discrete data signal according to the following formula if the imaginary part maximum absolute value is greater than or equal to the real part maximum absolute value and the imaginary part maximum absolute value is greater than the amplitude threshold:

wherein,for the limited time-domain discrete data signal, x (n) is the time-domain discrete data signal, v₁Is said first clipping parameter, v₂L is the serial number of the data corresponding to the maximum absolute value of the real part, l is more than or equal to 0 and less than or equal to N-1, m is the serial number of the data corresponding to the maximum absolute value of the imaginary part, m is more than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple,p is a slicing sequence of period N and j is an imaginary unit, i.e. j²＝-1。

With reference to the first possible implementation manner of the second aspect, in a sixth possible implementation manner of the second aspect, the second determining unit includes:

a second determining subunit, configured to determine a real maximum value and a real minimum value of the time-domain discrete data signal, and calculate an average value of the real maximum value and the real minimum value;

a third determining subunit, configured to determine an imaginary maximum value and an imaginary minimum value of the time-domain discrete data signal, and calculate an average value of the imaginary maximum value and the imaginary minimum value;

and the fourth determining subunit is used for taking the average value of the real part maximum value and the real part minimum value as the real part of the clipping parameter and taking the average value of the imaginary part maximum value and the imaginary part minimum value as the imaginary part of the clipping parameter.

With reference to the sixth possible implementation manner of the second aspect, in a seventh possible implementation manner of the second aspect, the clipping unit is specifically configured to:

With reference to the second aspect and any one of the first to seventh possible implementation manners of the second aspect, in an eighth possible implementation manner of the second aspect, the sending module is specifically configured to determine whether the number of times of amplitude limiting reaches a preset total number of times of amplitude limiting, and if so, send the data signal after amplitude limiting; and if not, returning to the determining module to execute the determination of the amplitude limiting parameter corresponding to the data signal to be sent.

The method for suppressing the peak power of the OFDM signal in the wireless communication system and the transmitter provided by the embodiment of the invention respectively carry out amplitude limiting on the real part and the imaginary part of the signal to be transmitted, thereby realizing low-complexity reduction of the peak power of the signal to be transmitted.

Drawings

Fig. 1 is a flowchart illustrating a first method for suppressing peak power of an OFDM signal in a wireless communication system according to an embodiment of the present invention;

FIG. 2 is an exemplary graph of amplifier input voltage and output voltage relationships;

fig. 3 is a flowchart illustrating a second method for suppressing peak power of an OFDM signal in a wireless communication system according to an embodiment of the present invention;

fig. 4 is a flowchart illustrating a third method for suppressing peak power of an OFDM signal in a wireless communication system according to a third embodiment of the present invention;

fig. 5 is a flowchart illustrating a fourth method for suppressing peak power of an OFDM signal in a wireless communication system according to an embodiment of the present invention;

fig. 6 is a schematic diagram of subcarrier allocation according to a fifth embodiment of the method for suppressing peak power of an OFDM signal in a wireless communication system of the present invention;

FIG. 7 is a schematic diagram of a WiFi network using OFDM signals in the method for suppressing peak power of OFDM signals in a wireless communication system according to the present invention;

FIG. 8 is a schematic diagram of an LTE network using OFDM signals in the method for suppressing peak power of OFDM signals in a wireless communication system according to the present invention;

fig. 9 is a schematic diagram illustrating CCDF performance comparison of a seventh embodiment of the method for suppressing peak power of an OFDM signal in a wireless communication system according to the present invention;

fig. 10 is a schematic diagram of a transmitter in a wireless communication system according to a first embodiment of the present invention;

fig. 11 is a schematic structural diagram of a second embodiment of a transmitter in a wireless communication system according to the present invention;

fig. 12 is a schematic structural diagram of a third embodiment of a transmitter in a wireless communication system according to the present invention.

Detailed Description

Example one

Fig. 1 is a flowchart illustrating a method for suppressing peak power of an OFDM signal in a wireless communication system according to a first embodiment of the present invention. The embodiment of the invention provides a method for suppressing the peak power of an OFDM signal in a wireless communication system, which can be executed by a transmitter and is realized by software and/or hardware. As shown in fig. 1, the method of the present embodiment includes:

step 101, determining a clipping parameter corresponding to a data signal to be transmitted.

Specifically, in the embodiment of the present invention, the data signal to be sent is a frequency domain discrete data signal generated by the OFDM system according to the number of subcarriers and an upsampling multiple, and the length of the frequency domain discrete data signal is a product of the number of subcarriers and the upsampling multiple. In practical applications, the frequency domain discrete data signal needs to be converted into a time domain discrete data signal, and the time domain discrete data signal is converted into a time domain continuous signal through Digital-to-Analog Conversion (DAC) so as to facilitate transmission. In order to reduce the loss of the signal in the transmission process, an amplifier is adopted at a signal transmitting end to process the time domain continuous signal so as to increase the signal-to-noise ratio of the time domain continuous signal.

FIG. 2 is a diagram illustrating an example of the relationship between the input voltage and the output voltage of the amplifier, as shown in FIG. 2, the input voltage is in millivolts, the output voltage is in volts, and the dashed line represents the ratio of the output voltage to the input voltage in the amplifier under an ideal condition, and it can be seen that the ratio of the input voltage to the output voltage is a fixed value, which is illustrated as 100, but not limited thereto; the solid line represents the relation between the output voltage and the input voltage in the amplifier in the practical application scene, and it can be seen that, due to the nonlinear effect of the amplifier, the ratio between the output voltage of the amplifier and the corresponding input voltage is gradually reduced along with the increase of the input voltage, that is, if the peak power of the data signal to be transmitted is too large, the data signal to be transmitted will undergo nonlinear distortion at the peak part, thereby reducing the signal-to-noise ratio of the signal. Therefore, it is necessary to perform clipping processing on the data signal to be transmitted to reduce the PAPR of the data signal to be transmitted.

The PAPR of the OFDM signal, that is, the PAPR of the time-domain continuous signal, may be calculated by the following formula:

wherein | x (t) circuitry²The square value of the amplitude value of each time in one period of the OFDM signal is obtained, and T is the period of the OFDM signal.

In general, the average power of a signal is relatively stable and does not change much, and the PAPR of the signal is reduced by performing clipping processing on the signal because the PAPR of the signal is in a direct proportional relationship with the peak power of the signal as can be seen from equation (1). Therefore, the embodiment of the present invention is used for performing amplitude limiting processing on the data signal to be transmitted.

And 102, respectively carrying out amplitude limiting on the real part and the imaginary part of the data signal to be sent according to the amplitude limiting parameters to obtain the data signal after amplitude limiting.

Specifically, in the prior art, the complex signal to be transmitted is entirely limited according to the limiting parameter, modulo arithmetic, division arithmetic, complex multiplication arithmetic and the like are required, and the calculation process is complex. In the embodiment of the invention, the real part and the imaginary part of the data signal to be sent are subjected to amplitude limiting respectively according to the amplitude limiting parameters to obtain the data signal after amplitude limiting, so that the calculation process is simplified.

And 103, sending the limited data signal.

According to the embodiment of the invention, the real part and the imaginary part of the data signal to be transmitted are respectively subjected to amplitude limiting so as to realize reduction of the PAPR of the data signal to be transmitted, thereby improving the transmission quality of the data signal to be transmitted.

Example two

Fig. 3 is a flowchart illustrating a second method for suppressing peak power of an OFDM signal in a wireless communication system according to an embodiment of the present invention. As shown in fig. 3, the embodiment of the present invention is further refined on the basis of the above embodiment, and the method may include:

step 301, determining a corresponding time domain discrete data signal after the inverse fast fourier transform of the data signal to be transmitted.

Specifically, the data signal to be transmitted is subjected to Inverse Fast Fourier Transform (IFFT) processing, and the data signal to be transmitted is converted from a frequency domain discrete data signal to a time domain discrete data signal.

Step 302, determining the clipping parameter according to the time domain discrete data signal.

Wherein, the steps 301 and 302 are further detailed for the step 101 in the above embodiment.

And 303, respectively carrying out amplitude limiting on the real part and the imaginary part of each data in the time domain discrete data signal according to the amplitude limiting parameter.

And step 304, performing digital-to-analog conversion on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting.

Specifically, through the operations of steps 301 to 303, a slice processing on the data signal to be transmitted is completed, and the data signal needs to be converted from a time-domain discrete data signal to a time-domain continuous data signal, so as to facilitate transmission. Further, the operations of step 301 to step 304 may be repeatedly executed, and the PAPR performance may be improved through multiple iterations.

Wherein, the steps 303 and 304 are further refinements of the step 102 in the above embodiment.

Step 305, transmitting the limited data signal.

EXAMPLE III

Fig. 4 is a flowchart illustrating a third method for suppressing peak power of an OFDM signal in a wireless communication system according to a third embodiment of the present invention. As shown in fig. 4, the method may include the steps of:

step 401, determining a time domain discrete data signal corresponding to the data signal to be transmitted after IFFT.

Specifically, the description will be given by taking N-point data as an example, where N is the product of the number of subcarriers and the upsampling multiple. The time domain discrete data signal is x (N), N is more than or equal to 0 and less than or equal to N-1.

Step 402, determining a real maximum absolute value and an imaginary maximum absolute value in the time domain discrete data signal.

Specifically, the real absolute value and the imaginary absolute value of each data in the time-domain discrete data signal may be obtained first, the real absolute values are compared to obtain a real maximum absolute value, and the imaginary absolute values are compared to obtain an imaginary maximum absolute value, which is not limited herein.

Wherein the real maximum absolute value is:

the maximum absolute value of the imaginary part is:

step 403, determining a slicing sequence corresponding to the data signal to be transmitted.

Specifically, when the slicing sequence corresponds to the frequency domain, only the values on the reserved subcarriers are provided, so that the slicing sequence and the sending data signal do not interfere with each other in the transmission process. It should be noted that, in the embodiment of the present invention, the above limitation may not be performed on the clipping sequence, that is, the clipping sequence may be arbitrary. In addition, the timing relationship of this step in the embodiment of the present invention is arbitrary, and it is only necessary to perform this step before the clipping process.

Step 404, judging the magnitude of the real part maximum absolute value, the imaginary part maximum absolute value and the amplitude threshold, if the real part maximum absolute value is larger than or equal to the imaginary part maximum absolute value, and the real part maximum absolute value is larger than the amplitude threshold, executing step 405 and step 406; if the imaginary maximum absolute value is greater than or equal to the real maximum absolute value and the imaginary maximum absolute value is greater than the magnitude threshold, then step 407 and step 408 are performed.

Specifically, the amplitude threshold is preset, and if both the real part maximum absolute value and the imaginary part maximum absolute value are smaller than the amplitude threshold, the process is ended, that is, the data signal to be transmitted does not need to be subjected to amplitude limiting processing. Otherwise, the subsequent steps are executed.

In the one-time clipping process, the steps between step 404 and step 409 perform the case: only step 405 and step 406 may be executed, only step 407 and step 408 may be executed, or steps 405 to 408 may be executed, and are selected according to actual situations, and are not limited herein. Wherein, steps 402 to 404, 405 and 407 are further refinements of step 302 in the above embodiment.

And 405, calculating a first amplitude limiting parameter according to the data corresponding to the maximum absolute value of the real part.

Specifically, the first clipping parameter is calculated according to the following formula:

And 406, amplitude limiting is performed on the real part of each data in the time domain discrete data signal.

Specifically, amplitude clipping is performed on the real part of each data in the time domain discrete data signal according to the following formula:

wherein,for the limited time-domain discrete data signal, x (n) is the time-domain discrete data signal, v₁For the first amplitude limiting parameter, l is the serial number of the data corresponding to the maximum absolute value of the real part, l is more than or equal to 0 and is less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, p is an amplitude limiting sequence with the period of N, j is an imaginary number unit, namely j²＝-1。

Step 407, calculating a second clipping parameter according to the data corresponding to the maximum absolute value of the imaginary part.

Specifically, the second clipping parameter is calculated according to the following formula:

And step 408, amplitude limiting is carried out on the imaginary part of each data in the time domain discrete data signal.

Specifically, amplitude clipping is performed on the imaginary part of each data in the time-domain discrete data signal according to the following formula:

wherein,for the limited time-domain discrete data signal, x (n) is the time-domain discrete data signal, v₂M is the serial number of the data corresponding to the maximum absolute value of the imaginary part, m is more than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, p is an amplitude limiting sequence with the period of N, j is an imaginary number unit, namely j²＝-1。

Wherein step 406 and step 408 are further refinements of step 303 in the above embodiment.

And 409, performing DAC on the time domain discrete data signal after amplitude limiting of the amplitude to obtain the data signal after amplitude limiting.

Specifically, steps 401 to 409 are a complete clipping process flow. After the primary amplitude limiting processing is completed, whether the amplitude limiting processing is continued or not can be judged by any one of the following two ways:

1. whether the amplitude limiting times reach the preset total amplitude limiting times or not can be judged;

2. or calculating whether the PAPR of the clipped data signal reaches the target peak-to-average ratio according to the formula (1).

In the embodiment of the present invention, the determination is performed in the manner 1.

If yes, go to step 410; otherwise, returning to the step 401, and repeatedly executing the steps 401 to 409 until the number of amplitude limiting times reaches a preset total number of amplitude limiting times, so that the data signal to be sent meets a target peak-to-average ratio.

And step 410, sending the limited data signal.

According to the embodiment of the invention, the calculation formula of the amplitude limiting parameter in the prior art is improved, the complexity of the system is simplified through the calculation formula of the first amplitude limiting parameter and the second amplitude limiting parameter, the sending end is not required to send extra information, in addition, the data signal to be sent is subjected to amplitude limiting according to the formula (5) and the formula (7), the data signal to be sent is not damaged, and the sudden change of the data signal to be sent is not caused.

Example four

Fig. 5 is a flowchart illustrating a fourth method for suppressing peak power of an OFDM signal in a wireless communication system according to the present invention. In the embodiment of the invention, the maximum absolute value and the minimum absolute value of the real part of the time domain discrete data signal are ensured to be equal by adjusting the direct current component of the time domain discrete data signal, and the maximum absolute value and the minimum absolute value of the imaginary part of the time domain discrete data signal are equal, so that the PAPR performance of the OFDM system is improved. The specific process is as follows:

step 501, determining a time domain discrete data signal corresponding to the data signal to be transmitted after the IFFT.

Specifically, the description is still given by taking N-point data as an example, where N is the product of the number of subcarriers and the upsampling multiple. The time domain discrete data signal is x (N), N is more than or equal to 0 and less than or equal to N-1.

Step 502, determining a real part maximum value and a real part minimum value of the time domain discrete data signal, and calculating an average value of the real part maximum value and the real part minimum value.

Step 503, determining the imaginary maximum and minimum values of the time domain discrete data signal, and calculating the average value of the imaginary maximum and minimum values.

Specifically, the maximum value and the minimum value of the real part and the maximum value and the minimum value of the imaginary part, namely x (N),0 ≦ N ≦ N-1 are determined

Wherein a is the maximum real part of x (N) and N is more than or equal to 0 and less than or equal to N-1; b is the real part minimum value of x (N) and N is more than or equal to 0 and less than or equal to N-1; c is the imaginary minimum value of x (N) and N is more than or equal to 0 and less than or equal to N-1; d is the minimum value of the imaginary part of the x (N) and N is more than or equal to 0 and less than or equal to N-1.

Calculating the average value of the real part maximum value and the real part minimum value and the average value of the imaginary part maximum value and the imaginary part minimum value according to the a, b, c and d determined in the step, wherein e is the average value of the real part maximum value and the real part minimum value, and f is the average value of the imaginary part maximum value and the imaginary part minimum value.

The calculation formula of e and f is:

wherein, the sequence of step 502 and step 503 is arbitrary, and step 502 can be executed first, and then step 503 can be executed; step 503 may be performed first, and then step 502 may be performed.

Step 504, the average value of the real part maximum value and the real part minimum value is used as the real part of the clipping parameter, and the average value of the imaginary part maximum value and the imaginary part minimum value is used as the imaginary part of the clipping parameter.

Specifically, the clipping parameters are: (e + j · f).

Wherein, the steps 502 to 504 are further detailed for the step 302 in the above embodiment.

And 505, respectively carrying out amplitude limiting on a real part and an imaginary part of each data in the time domain discrete data signal.

Specifically, amplitude clipping is performed on the real part and the imaginary part of each data in the time domain discrete data signal according to the following formula:

Step 506, performing DAC on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting.

Specifically, steps 501 to 506 are a complete clipping process flow. After the primary amplitude limiting processing is completed, whether the amplitude limiting processing is continued or not can be judged by any one of the following two ways:

If yes, go to step 507; otherwise, returning to the step 501, and repeatedly executing the steps 501 to 506 until the number of amplitude limiting times reaches a preset total number of amplitude limiting times, so that the data signal to be sent meets a target peak-to-average ratio.

And step 507, sending the data signal after amplitude limiting.

The embodiment of the invention improves the calculation formula of the amplitude limiting parameter in the prior art, simplifies the complexity of the system by determining the direct current subcarrier of the data signal to be sent, does not need the sending end to send extra information, and in addition, carries out amplitude limiting on the data signal to be sent according to the formula (10) so as not to cause sudden change of the data signal to be sent.

EXAMPLE five

The embodiments of the present invention illustrate the above embodiments.

Assume that there are 4 subcarriers in the OFDM system, wherein two subcarriers are used as data subcarriers, one subcarrier is used as reserved dc subcarrier, and one subcarrier is used as reserved subcarrier, as shown in fig. 6. In this embodiment, only two data subcarriers are used to transmit data. The data signal to be transmitted adopts single-time up-sampling, so after IFFT, the length of the obtained time-domain discrete data signal is: n is 4.

Assuming that the slicing sequence is represented by p (n), n is 0,1,2,3, where p (0) is 1, p (1) is-0.2-j 0.4, p (2) is 1, and p (3) is-0.2-j 0.4, it should be noted that when p (n) corresponds to the frequency domain, there is no value on the data subcarrier, and therefore transmission of the data subcarrier is not affected.

Assuming that a time-domain discrete data signal of a data signal to be transmitted after IFFT is represented by x (n), x (0) — 0.2182-j0.2182, x (1) — 1.3193-j0.4464, x (2) — 0.2182+ j0.2182, and x (3) — 0.8+ j 0.4364. The amplitude of clipping a is 1.3.

The invention discloses an implementation mode, and the flow of a low-complexity amplitude limiting scheme is as follows:

1. finding the real part maximum absolute value a of x (n) and the sequence number l corresponding to a, and the imaginary part maximum absolute value b and the sequence number m corresponding to b, that is:

2. because a is greater than or equal to b and a is greater than a, real part clipping is performed.

3. Calculating a first clipping parameter according to equation (4): v. of₁＝0.0193。

4. Clipping said x (n) according to equation (5), i.e.

In the embodiment of the present invention, before clipping, the absolute value of the real part of x (n) is 1.3193, and the absolute value of the imaginary part of x (n) is 0.4464; after the clipping is performed,the absolute value of the real part of (a) is 1.3000,the absolute value of the imaginary part of (c) is 0.4464. From the calculation results before and after the amplitude limiting, the peak value of the data signal to be transmitted is reduced after the amplitude limiting.

5. And judging whether the amplitude limiting times reach the preset total amplitude limiting times or not. And if so, performing DAC conversion on the data signal after amplitude limiting and then sending the data signal, otherwise, returning to the processing of 1.

In another implementation manner of the present invention, the flow of reducing PAPR by using dc subcarriers is as follows:

1. finding the real part maximum value a and minimum value b, imaginary part maximum value c and minimum value d of said x (n), namely:

2. determining the mean of the real and imaginary maxima and minima of said x (n), i.e. the mean of the real and imaginary maxima and minima

3. Amplitude clipping is performed on the real and imaginary parts of x (n), respectively.

In particular, the real and imaginary parts of x (n) are respectively translated to make the x (n) to be parallel-shiftedThe absolute values of the maximum and minimum values of the real part of (a) and the absolute values of the maximum and minimum values of the imaginary part of (b) are equal.

The scheme of reducing PAPR by adopting direct current sub-carrier wave is adopted, after amplitude limiting,the absolute values of the maximum and minimum values of the real part of (a) are equal, are both 1.05965,the absolute values of the maximum and minimum values of the imaginary part of (b) are equal and are all 0.4414. Before and after the amplitude limiting, the maximum absolute value of the real part is reduced from 1.3193 to 1.05965.

4. And judging whether the amplitude limiting times reach the preset total amplitude limiting times or not. And if so, sending the data signal after amplitude limiting after DAC conversion, otherwise, returning to the step 1 for processing.

EXAMPLE six

Assume that there are 4 subcarriers in the OFDM system, wherein two subcarriers are used as data subcarriers, one subcarrier is used as reserved dc subcarrier, and one subcarrier is used as reserved subcarrier, as shown in fig. 6. In this embodiment, only two data subcarriers are used to transmit data. Since 2 times up-sampling is adopted for the data signal to be transmitted, the length of the corresponding time-domain discrete data signal after IFFT is 8.

It is assumed that the slicing sequence is represented by p (n), n is 0,1,2,3,4,5,6,7, where p (0) is 1, p (1) is 0.6-j0.8, p (2) is-0.2-j 0.4, p (3) is 0.2+ j0.4, p (4) is 1, p (5) is 0.6-j0.8, p (6) is-0.2-j 0.4, and p (7) is 0.2+ j0.4, and it should be noted that p (n) corresponds to a frequency domain, where there is no value on the data subcarrier, and therefore transmission of the data subcarrier is not affected.

It is assumed that a time-domain discrete data signal corresponding to a data signal to be transmitted after IFFT is represented by x (n), n is 0,1,2,3,4,5,6,7, x (0) is-0.6447-j 1.2993, x (1) is-0.2986-j 0.6072, x (2) is 0.2282+ j0.4464, x (3) is 0.6272+ j1.2444, x (4) is 0.6647+ j1.3193, x (5) is 0.3186+ j0.6272, x (6) is-0.2082-j 0.4264, and x (7) is-0.6072-j 1.2244. The amplitude of clipping a is 1.3.

2. because b is greater than or equal to a and b is greater than a, imaginary amplitude clipping is performed.

3. Calculating a second clipping parameter according to equation (6): v. of₂＝-0.0193。

4. Clipping said x (n) according to equation (7), i.e.

In the embodiment of the present invention, before clipping, x (n), n is 0, and the serial numbers corresponding to the real maximum absolute value and the imaginary maximum absolute value of 0,1,2,3,4,5,6,7 are both 4, and the real absolute value of x (4) is 0.6647, and the imaginary absolute value of x (4) is 1.3193; after the clipping is performed,the absolute value of the real part of (a) is 0.6647,1.3000, and the data peak value corresponding to sequence number 4 is reduced after the clipping. In addition, as can be seen from equation (17):the serial numbers corresponding to the real part maximum absolute value and the imaginary part maximum absolute value of (1) are both 0, andthe absolute value of the real part of (a) is 0.6647,1.3186, the imaginary maximum absolute value is reduced from 1.3193 to 1.3186 compared to the real maximum absolute value and the imaginary maximum absolute value of the data before slicing, i.e., the peak value of the discrete data signal after slicing is reduced.

Note that the divide-by-2 operation does not require any operation in actual implementation, and only needs to artificially shift the binary point to the left by one bit.

Specifically, the real part and imaginary part of x (n) are respectively shifted so that the absolute value of the maximum and minimum values of the real part of x (n) are equal, and the absolute value of the maximum and minimum values of the imaginary part of x (n) are equal.

The scheme of reducing PAPR by adopting direct current sub-carrier wave can be known from the calculation results before and after amplitude limiting,the absolute values of the maximum and minimum values of the real part are equal to 0.6547, and the absolute values of the maximum and minimum values of the imaginary part are equal to 1.3093. Before and after the clipping, the maximum absolute value of the imaginary part is reduced from 1.3193 to 1.3093.

It should be noted that any embodiment of the present invention may be applied to all OFDM communication systems, such as a Wireless Fidelity (WiFi) network shown in fig. 7 and a Long Term Evolution (LTE) network shown in fig. 8. As shown in fig. 7, VoIP represents a Voice over internet protocol (VoIP) phone, and the transmitter of the present invention may be disposed in a WiFi phone; as shown in fig. 8, MME represents a Mobility Management Entity (MME), PDN represents a Public Data Network (PDN), and eNodeB represents a base station in the LTE Network.

EXAMPLE seven

As shown in FIG. 9, the peak-to-average-ratio Complementary Cumulative Distribution Function (CCDF) performance of various schemes is compared, i.e. Pr { PAPR ≧ PAPR₀I.e. PAPR greater than or equal to PAPR₀Wherein the PAPR₀The PAPR for the purpose, known as the PAPR threshold value.

Wherein, the original OFDM signal is data corresponding to each subcarrier of the data signal to be transmitted before amplitude limiting processing, namely x (n); the existing clipping scheme directly clips the amplitude of the complex signal x (n) according to the following formula (21):

in the formula, a is a clipping threshold, and y (n) is a clipped signal, that is, data corresponding to each subcarrier of a data signal to be transmitted after clipping; the first scheme only adopts the scheme of reducing the PAPR by utilizing the direct current subcarrier provided by the invention; the second scheme only adopts the low-complexity amplitude limiting scheme provided by the invention; the third scheme combines the low-complexity amplitude limiting scheme provided by the invention with the scheme of utilizing the direct current subcarrier, and particularly adopts the low-complexity amplitude limiting scheme firstly and then adopts the direct current subcarrier scheme. It can be seen from the figure that the performance of the present invention is far superior to the existing scheme, wherein the performance of the two schemes (low complexity clipping and utilization of dc sub-carriers) provided by combining the present invention is optimal.

The specific parameters are set as follows: 128 sub-carriers, 12 reserved sub-carriers, 2-time IFFT upsampling plus 2-time zero padding upsampling, that is, 4-time upsampling in total, a digital intermediate frequency scheme, 16 Quadrature Amplitude Modulation (QAM) data signals, the total number of amplitude limiting is 10 times, and the amplitude limiting threshold is 9.3 decibels (dB for short).

It should be noted that, in the embodiment of the present invention, a low-complexity amplitude limiting scheme may be performed on a data signal to be transmitted first, and then an amplitude limiting process may be performed on a dc subcarrier scheme; or, the direct current subcarrier scheme can be executed for the data signal to be sent first, then the low-complexity amplitude limiting scheme is executed for amplitude limiting processing, and the execution sequence of the two schemes is not limited; it is also possible to perform one of the two schemes separately.

Example eight

Fig. 10 is a schematic structural diagram of a first embodiment of a transmitter in a wireless communication system according to the present invention, where the transmitter may be disposed in a WiFi phone as shown in fig. 7, or disposed in an eNodeB as shown in fig. 8. As shown in fig. 10, the transmitter 100 of the present embodiment includes a determining module 1001, a processing module 1002, and a transmitting module 1003.

The determining module 1001 is configured to determine an amplitude limiting parameter corresponding to a data signal to be sent; the processing module 1002 is configured to perform amplitude limiting on the real part and the imaginary part of the data signal to be transmitted according to the amplitude limiting parameter, respectively, to obtain an amplitude-limited data signal; the sending module 1003 is configured to send the limited data signal.

The transmitter in the wireless communication system of this embodiment may be used in the technical solution of the first embodiment of the method for suppressing the peak power of the OFDM signal in the wireless communication system, and the implementation principle and the technical effect are similar, which are not described herein again.

Example nine

Fig. 11 is a schematic structural diagram of a second embodiment of a transmitter in a wireless communication system according to the present invention. As shown in fig. 11, on the basis of the above embodiment, the determining module 1001 may include a first determining unit 1101 and a second determining unit 1102, where the first determining unit 1101 is configured to determine a time-domain discrete data signal corresponding to the data signal to be transmitted after IFFT, and the second determining unit 1102 is configured to determine the clipping parameter according to the time-domain discrete data signal; the processing module 1002 may include a clipping unit 1103 and a converting unit 1104, where the clipping unit 1103 is configured to clip the real part and the imaginary part of each data in the time-domain discrete data signal according to the clipping parameter; the conversion unit 1104 is configured to perform DAC on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting.

The transmitter in the wireless communication system of this embodiment may be used to implement the technical solution of the method for suppressing the peak power of the OFDM signal in the wireless communication system provided in any embodiment of the present invention, and the implementation principle and the technical effect are similar, which is not described herein again

Further, the second determining unit 1102 may include:

Further, the first calculating subunit is specifically configured to:

the first clipping parameter is calculated according to the following formula:

Further, the second calculating subunit is specifically configured to:

the second clipping parameter is calculated according to the following formula:

Further, the clipping unit may include:

Example ten

Embodiment of the present invention is based on the above embodiment, and the second determining unit may include a second determining subunit, a third determining subunit, and a fourth determining subunit.

The second determining subunit is configured to determine a real maximum value and a real minimum value of the time-domain discrete data signal, and calculate an average value of the real maximum value and the real minimum value; a third determining subunit, configured to determine an imaginary maximum value and an imaginary minimum value of the time-domain discrete data signal, and calculate an average value of the imaginary maximum value and the imaginary minimum value; and the fourth determining subunit is used for taking the average value of the real part maximum value and the real part minimum value as the real part of the clipping parameter and taking the average value of the imaginary part maximum value and the imaginary part minimum value as the imaginary part of the clipping parameter.

The transmitter in the wireless communication system of this embodiment may be used to implement the technical solution of the method for suppressing the peak power of the OFDM signal in the wireless communication system provided in any embodiment of the present invention, and the implementation principle and the technical effect are similar, and are not described herein again.

Further, the clipping unit is specifically configured to:

Further, the sending module is specifically configured to determine whether the number of amplitude limiting times reaches a preset total number of amplitude limiting times, and if so, send the data signal after amplitude limiting; and if not, returning to the determining module to execute the determination of the amplitude limiting parameter corresponding to the data signal to be sent.

EXAMPLE eleven

Fig. 12 is a schematic structural diagram of a third embodiment of a transmitter in a wireless communication system, as shown in fig. 12, the transmitter 200 includes: a processor 121 and a transmitter 122, wherein the processor 121 is configured to determine a slicing parameter corresponding to a data signal to be transmitted; and respectively carrying out amplitude limiting on the real part and the imaginary part of the data signal to be sent according to the amplitude limiting parameters to obtain the data signal after amplitude limiting. Transmitter 122 is configured to transmit the sliced data signal.

Further, the processor 121 is specifically configured to determine a time-domain discrete data signal corresponding to the data signal to be transmitted after the IFFT; determining the amplitude limiting parameter according to the time domain discrete data signal; amplitude limiting is carried out on the real part and the imaginary part of each data in the time domain discrete data signal according to the amplitude limiting parameters; and D/A conversion DAC is carried out on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting.

Still further, the processor 121 may be configured to determine a real maximum absolute value and an imaginary maximum absolute value in the time-domain discrete data signal; and judging the magnitude of the real part maximum absolute value, the imaginary part maximum absolute value and the amplitude threshold.

If the real part maximum absolute value is larger than or equal to the imaginary part maximum absolute value and the real part maximum absolute value is larger than the amplitude threshold, calculating a first amplitude limiting parameter according to data corresponding to the real part maximum absolute value, and carrying out amplitude limiting on the real part of each data in the time domain discrete data signal; if the maximum absolute value of the imaginary part is greater than or equal to the maximum absolute value of the real part and the maximum absolute value of the imaginary part is greater than the amplitude threshold, calculating a second amplitude limiting parameter according to the data corresponding to the maximum absolute value of the imaginary part, and carrying out amplitude limiting on the imaginary part of each data in the time domain discrete data signal.

It should be noted that, the first clipping parameter is calculated according to the following formula:

wherein v is₁Is the first amplitude limiting parameter, A is the amplitude threshold, l is the serial number of the data corresponding to the maximum absolute value of the real part, l is more than or equal to 0 and less than or equal to N-1, and N is the subcarrierThe product of the number of waves and the up-sampling multiple, x (l) is the data corresponding to the maximum absolute value of the real part, and Re { x (l) } is the real part numerical value of the data corresponding to the maximum absolute value of the real part.

The second clipping parameter is calculated according to the following formula:

Amplitude limiting is carried out on the real part of each data in the time domain discrete data signal according to the following formula:

amplitude limiting is carried out on the imaginary part of each data in the time domain discrete data signal according to the following formula:

wherein,for the limited time-domain discrete data signal, x (n) is the time-domain discrete data signal, v₁Is said first clipping parameter, v₂For the second amplitude limiting parameter, l is the serial number of the data corresponding to the maximum absolute value of the real part, l is more than or equal to 0 and less than or equal to N-1, and m is the number corresponding to the maximum absolute value of the imaginary partAccording to the serial number, m is more than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, p is an amplitude limiting sequence with the period of N, j is an imaginary number unit, namely j²＝-1。

Further, the processor 121 may be further specifically configured to determine a real maximum value and a real minimum value of the time-domain discrete data signal, and calculate an average value of the real maximum value and the real minimum value; determining imaginary maximum and minimum values of the time domain discrete data signal and calculating an average value of the imaginary maximum and minimum values; and taking the average value of the real part maximum value and the real part minimum value as the real part of the clipping parameter, and taking the average value of the imaginary part maximum value and the imaginary part minimum value as the imaginary part of the clipping parameter.

Still further, the processor 121 may be further configured to amplitude-clip the real part and the imaginary part of each data in the time-domain discrete data signal according to the following formula:

Further, the transmitter 122 may be configured to determine whether the number of times of amplitude limiting reaches a preset total number of times of amplitude limiting, and if so, transmit the data signal after amplitude limiting; otherwise, the return processor 121 performs the step of determining the clipping parameter corresponding to the data signal to be transmitted.

The transmitting end device of this embodiment may be configured to implement the technical solution of the method for suppressing the peak power of the OFDM signal in the wireless communication system provided in any embodiment of the present invention, and the implementation principle and the technical effect are similar, which are not described herein again.

Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing peak power of an ofdm signal in a wireless communication system, comprising:

determining a time domain discrete data signal corresponding to a data signal to be transmitted after Inverse Fast Fourier Transform (IFFT);

determining a clipping parameter according to the real part maximum absolute value and the imaginary part maximum absolute value;

amplitude limiting is carried out on the real part and the imaginary part of each data in the time domain discrete data signal according to the real part maximum absolute value, the imaginary part maximum absolute value and the limiting parameter;

performing digital-to-analog conversion (DAC) on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting;

transmitting the limited data signal;

the determining the clipping parameter according to the real maximum absolute value and the imaginary maximum absolute value includes:

if the maximum absolute value of the imaginary part is greater than or equal to the maximum absolute value of the real part and the maximum absolute value of the imaginary part is greater than the amplitude threshold, calculating a second amplitude limiting parameter according to data corresponding to the maximum absolute value of the imaginary part;

the amplitude limiting is respectively performed on the real part and the imaginary part of each data in the time domain discrete data signal according to the real part maximum absolute value, the imaginary part maximum absolute value and the limiting parameter, and the amplitude limiting method includes:

2. The method of claim 1, wherein the calculating a first clipping parameter from the data corresponding to the absolute maximum real part comprises:

the first clipping parameter is calculated according to the following formula:

3. The method of claim 1, wherein said calculating a second clipping parameter based on the data corresponding to the imaginary maximum absolute value comprises:

the second clipping parameter is calculated according to the following formula:

wherein v is₂And as the second amplitude limiting parameter, a is the amplitude threshold, m is the serial number of the data corresponding to the maximum absolute value of the imaginary part, m is greater than or equal to 0 and less than or equal to N-1, N is the product of the number of subcarriers and the up-sampling multiple, x (m) is the data corresponding to the maximum absolute value of the imaginary part, and Im { x (m) } is the numerical value of the imaginary part of the data corresponding to the maximum absolute value of the imaginary part.

4. The method of claim 1, wherein said transmitting said limited data signal comprises:

judging whether the amplitude limiting times reach a preset total amplitude limiting times or not, and if so, sending the data signal after amplitude limiting; otherwise, returning to the step of determining the clipping parameters.

5. A transmitter in a wireless communication system, comprising:

a first determining unit, configured to determine a time-domain discrete data signal corresponding to a data signal to be transmitted after an Inverse Fast Fourier Transform (IFFT);

a second determining unit, configured to determine a clipping parameter according to the time-domain discrete data signal;

the second determination unit includes:

the second determining unit is specifically configured to determine the clipping parameter according to the real maximum absolute value and the imaginary maximum absolute value;

the amplitude limiting unit is used for respectively carrying out amplitude limiting on the real part and the imaginary part of each data in the time domain discrete data signal according to the real part maximum absolute value, the imaginary part maximum absolute value and the amplitude limiting parameter;

the conversion unit is used for performing digital-to-analog conversion (DAC) on the time domain discrete data signal after amplitude limiting to obtain the data signal after amplitude limiting;

a sending module, configured to send the data signal after amplitude limiting;

the second determination unit includes:

a second calculating subunit, configured to calculate a second clipping parameter according to data corresponding to the imaginary maximum absolute value if the imaginary maximum absolute value is greater than or equal to the real maximum absolute value and the imaginary maximum absolute value is greater than the amplitude threshold;

the clipping unit includes:

6. The transmitter according to claim 5, wherein the first calculating subunit is specifically configured to:

the first clipping parameter is calculated according to the following formula:

7. The transmitter according to claim 5, wherein the second calculating subunit is specifically configured to:

the second clipping parameter is calculated according to the following formula:

wherein v is₂As the second amplitude limiting parameter, A is the amplitude threshold, m is the serial number of the data corresponding to the maximum absolute value of the imaginary part, m is more than or equal to 0 and less than or equal to N-1, and N is the sum of the number of subcarriers and the number of the upper subcarriersAnd the product of sampling multiples, x (m) is data corresponding to the maximum absolute value of the imaginary part, and Im { x (m) } is the numerical value of the imaginary part of the data corresponding to the maximum absolute value of the imaginary part.

8. The transmitter of claim 5, wherein the sending module is specifically configured to determine whether the number of slicing times reaches a preset total number of slicing times, and if so, send the sliced data signal; otherwise, returning to the second determining unit to determine the clipping parameter according to the time-domain discrete data signal.