阅读说明：本技术 一种适用于多载波频域调制信号的擦除方法及装置 (Erasing method and device suitable for multi-carrier frequency domain modulation signals ) 是由 张旭 杨超 罗鸣 江风 孟令恒 于 2020-11-30 设计创作，主要内容包括：一种适用于多载波频域调制信号的擦除方法及装置,涉及光通信系统中的多载波频域调制领域,包括步骤：从多载波频域信号的传输链路分离出部分信号进行数据采样,采样后的数字信号进行FFT,按照频谱位置对应关系解映射恢复出加载的信号；选择需要做时钟恢复的频点,通过相邻两次FFT后该频点的相位差评估相位漂移,取相邻多次相位漂移结果的平均值来调整本地参考时钟的频率；当调整后的参考时钟与发端时钟同步时,在需要擦除子载波的频点产生一个强度相同、且相位相反的子载波信号,进行IFFT,得到的结果与传输链路的多载波频域信号叠加。本发明实现光标签数据从1到0的修改,使得多载波频域调制信号可以根据需要灵活修改。(An erasing method and device suitable for multi-carrier frequency domain modulation signals relates to the field of multi-carrier frequency domain modulation in an optical communication system, and comprises the following steps: separating partial signals from a transmission link of the multi-carrier frequency domain signals to perform data sampling, performing FFT on the sampled digital signals, and demapping and recovering the loaded signals according to the corresponding relation of the frequency spectrum positions; selecting a frequency point needing clock recovery, evaluating phase drift through the phase difference of the frequency point after two adjacent FFT, and taking the average value of the phase drift results of the adjacent FFT to adjust the frequency of a local reference clock; when the adjusted reference clock is synchronous with the originating clock, a subcarrier signal with the same strength and opposite phase is generated at the frequency point where the subcarrier needs to be erased, IFFT is carried out, and the obtained result is superposed with the multicarrier frequency domain signal of the transmission link. The invention realizes the modification of the optical label data from 1 to 0, so that the multi-carrier frequency domain modulation signal can be flexibly modified according to the requirement.)

1. An erasure method for a multi-carrier frequency domain modulated signal, comprising the steps of:

s1, separating partial signals from the transmission link of the multi-carrier frequency domain signals to perform data sampling, performing Fast Fourier Transform (FFT) on the sampled digital signals, and demapping and recovering the loaded signals according to the corresponding relation of the frequency spectrum positions;

s2, selecting a frequency point needing clock recovery, evaluating phase drift through the phase difference of the frequency point after two adjacent FFT, and taking the average value of the phase drift results of the adjacent FFT to adjust the frequency of the local reference clock;

s3, judging whether the adjusted reference clock is synchronous with the originating clock, if so, entering S4; if not, the process goes to S1;

and S4, generating a subcarrier signal with the same intensity and opposite phase at the frequency point where the subcarrier needs to be erased, performing Inverse Fast Fourier Transform (IFFT), and overlapping the obtained result with the multicarrier frequency domain signal of the transmission link, namely erasing the signal of the corresponding frequency point.

2. The method according to claim 1, wherein after FFT in S1, a mapping relation between data and spectrum in the multicarrier frequency domain modulation signal is generated according to the FFT result, showing whether the frequency points have subcarriers, and obtaining which frequency points need to be erased by recovering the loaded subcarrier signals.

3. The method of claim 1, wherein the step of averaging the phase shift results of the adjacent multiple times in step S2 comprises:

wherein, l represents the serial number of a group of results output by one FFT, delta theta (n) is the average value of the adjacent multiple phase drift results, m is the number of the phase drift results for solving the average value, m is more than or equal to 1, and n is the frequency point serial number for clock recovery; θ (n) is a phase calculated from the complex result of the FFT output.

4. The method according to claim 3, wherein in step S2, the vco adjusts the frequency of the local reference clock, and the input voltage V of the vco is updated according to the formula:

V＝V-μΔθ(n)

wherein mu is an update coefficient and the value range is 0.01 to 0.0001.

5. The method of claim 1, wherein according to the FFT result, the obtained strength and phase of the corresponding frequency point are:

FFT_output(x)＝Re(x)+j*IM(x)

wherein, FFT_output(x) For the result of FFT calculation, x isThe frequency point sequence number of the subcarrier needs to be erased;

in step S4, the subcarrier signals having the same intensity and opposite phases are generated as follows:

IFFT_input(x)＝-Re(x)-j*IM(x)。

6. an erasure apparatus for a multi-carrier frequency domain modulated signal, comprising:

the data sampling module is used for separating partial signals from a transmission link of the multi-carrier frequency domain signals to perform data sampling;

an FFT module for performing FFT on the sampled digital signal;

the data mapping module is used for obtaining a mapping relation graph of data in the multi-carrier frequency domain modulation signal and the frequency spectrum according to the output result of the FFT module;

the clock recovery module is used for recovering the loaded signal by demapping according to the frequency spectrum position corresponding relation, selecting a frequency point needing to erase the subcarrier from the data and frequency spectrum mapping relation graph, calculating phase drift through the phase difference of the frequency point after two adjacent FFT, and taking the average value of the phase drift results of the adjacent FFT;

the voltage-controlled crystal oscillator calculates the input voltage by adopting the average value, adjusts the frequency of the local reference clock and synchronizes the adjusted reference clock with the originating clock;

the signal generation module is used for generating a subcarrier signal with the same intensity and opposite phase at a frequency point where the subcarrier needs to be erased;

an IFFT module for performing IFFT on the subcarrier signal generated by the signal generation module;

and the data sending module sends the output result of the IFFT module to a transmission link, and the output result is superposed with the multi-carrier frequency domain signal, namely the corresponding frequency point signal is erased.

7. Erasing apparatus for multi-carrier frequency domain modulated signals according to claim 6,

and after the voltage-controlled crystal oscillator is adjusted, the reference clock is not synchronous with the originating clock, the data sampling module performs data sampling again, the FFT module performs FFT on the sampled digital signal, the clock recovery module calculates the average value again, and the voltage-controlled crystal oscillator is adjusted again until the adjusted reference clock is synchronous with the originating clock.

8. Erasing apparatus for multi-carrier frequency domain modulated signals according to claim 7,

the average value delta theta (n) of adjacent multiple phase drift results obtained by the recovery module is as follows:

wherein, l represents the serial number of the FFT output result, delta theta (n) is the average value of the phase drift results of multiple adjacent times, m is the number of the phase drift results of the average value, m is more than or equal to 1, and n is the frequency point serial number for clock recovery; θ (n) is a phase calculated from the complex result of the FFT output.

9. The apparatus of claim 7, wherein the vco adjusts the frequency of the local reference clock, and the input voltage V of the vco is updated according to the following formula:

V＝V-μΔθ(n)

wherein mu is an update coefficient and the value range is 0.01 to 0.0001.

10. The erasure apparatus for multi-carrier frequency domain modulated signals as set forth in claim 6, wherein the erasure apparatus is coupled to a transmission link of a multi-carrier frequency domain modulated communication system.

Technical Field

The present invention relates to the field of multi-carrier frequency domain modulation in an optical communication system, and in particular, to an erasing method and an erasing device suitable for multi-carrier frequency domain modulation signals.

Background

Currently, optical communication networks are continuously developing towards higher speed, larger capacity and longer distance. The multiple modulation formats exert their own advantages in different scenarios, wherein the multicarrier frequency domain modulation signal is more and more widely valued because of its high spectral efficiency and the ability to achieve higher rate and bandwidth. Meanwhile, as the capacity and the speed of the network are greatly improved, the management and the maintenance of different channels are very important.

In an optical network system, an optical label based on a multi-carrier frequency domain modulation signal is an effective method for facilitating management. It can load management information, such as source address, destination address, modulation format, etc. by using idle frequency band and by means of multicarrier frequency domain modulation. With this information, the operator can identify the signal and perform management functions, such as all-optical switching, signal quality evaluation, etc., at the network node. The optical label signal is separated from the high-speed signal, the multi-carrier frequency domain modulation is used in the idle frequency band, the signal extraction can be completed without demodulating the high-speed optical signal, the cost of an algorithm and a device is reduced, the processing efficiency is improved, and the unified management and maintenance are facilitated.

However, in the existing optical label system implemented based on the multi-carrier frequency domain modulation method, the carried optical label data is fixed, and a flexible solution is also lacking for a scene that the optical label data needs to be modified at a network node. Although the modification of data from 0 to 1 can be realized by using the same method of loading the optical tag signal as the originating terminal based on the prior art, the modification of data from 1 to 0 cannot be realized.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an erasing method and an erasing device suitable for a multi-carrier frequency domain modulation signal, which are used for modifying optical label data from 1 to 0, so that the multi-carrier frequency domain modulation signal is not fixed any more and can be flexibly modified according to requirements.

In order to achieve the above object, in one aspect, an erasing method for a multi-carrier frequency domain modulation signal is adopted, which includes the steps of:

s1, separating partial signals from the transmission link of the multi-carrier frequency domain signals to perform data sampling, performing Fast Fourier Transform (FFT) on the sampled digital signals, and demapping and recovering the loaded signals according to the corresponding relation of the frequency spectrum positions;

s2, selecting a frequency point needing clock recovery, evaluating phase drift through the phase difference of the frequency point after two adjacent FFT, and taking the average value of the phase drift results of the adjacent FFT to adjust the frequency of the local reference clock;

s3, judging whether the adjusted reference clock is synchronous with the originating clock, if so, entering S4; if not, the process goes to S1;

and S4, generating a subcarrier signal with the same intensity and opposite phase at the frequency point where the subcarrier needs to be erased, performing Inverse Fast Fourier Transform (IFFT), and overlapping the obtained result with the multicarrier frequency domain signal of the transmission link, namely erasing the signal of the corresponding frequency point.

Preferably, after the FFT in S1, a mapping relation between data in the multi-carrier frequency domain modulation signal and the frequency spectrum is generated according to the FFT result, and whether a frequency point has a subcarrier is shown, and which frequency points need to be erased is obtained by combining the recovered loaded subcarrier signal.

Preferably, in S2, the averaging of the results of the phase shifts of the adjacent multiple times includes:

wherein, l represents the serial number of a group of results output by one FFT, delta theta (n) is the average value of the adjacent multiple phase drift results, m is the number of the phase drift results for solving the average value, m is more than or equal to 1, and n is the frequency point serial number for clock recovery; θ (n) is a phase calculated from the complex result of the FFT output.

Preferably, in S2, the frequency of the local reference clock is adjusted by using a voltage controlled crystal oscillator, and the update formula of the input voltage V of the voltage controlled crystal oscillator is as follows:

V＝V-μΔθ(n)

wherein mu is an update coefficient and the value range is 0.01 to 0.0001.

Preferably, according to the FFT result, the strength and phase of the corresponding frequency point are obtained as follows:

FFT_output(x)＝Re(x)+j*IM(x)

wherein, FFT_output(x) X is the frequency point sequence number of the subcarrier needing to be erased as the result of FFT calculation;

in step S4, the subcarrier signals having the same intensity and opposite phases are generated as follows:

IFFT_input(x)＝-Re(x)-j*IM(x)。

in another aspect, an erasing apparatus for a multi-carrier frequency domain modulation signal is further provided, including:

the data sampling module is used for separating partial signals from a transmission link of the multi-carrier frequency domain signals to perform data sampling;

an FFT module for performing FFT on the sampled digital signal;

the data mapping module is used for obtaining a mapping relation graph of data in the multi-carrier frequency domain modulation signal and the frequency spectrum according to the output result of the FFT module;

the clock recovery module is used for recovering the loaded signal by demapping according to the frequency spectrum position corresponding relation, selecting a frequency point needing to erase the subcarrier from the data and frequency spectrum mapping relation graph, calculating phase drift through the phase difference of the frequency point after two adjacent FFT, and taking the average value of the phase drift results of the adjacent FFT;

the voltage-controlled crystal oscillator calculates the input voltage by adopting the average value, adjusts the frequency of the local reference clock and synchronizes the adjusted reference clock with the originating clock;

the signal generation module is used for generating a subcarrier signal with the same intensity and opposite phase at a frequency point where the subcarrier needs to be erased;

an IFFT module for performing IFFT on the subcarrier signal generated by the signal generation module;

and the data sending module sends the output result of the IFFT module to a transmission link, and the output result is superposed with the multi-carrier frequency domain signal, namely the corresponding frequency point signal is erased.

Preferably, after the voltage-controlled crystal oscillator is adjusted, if the reference clock is not synchronous with the originating clock, the data sampling module performs data sampling again, the FFT module performs FFT on the sampled digital signal, the clock recovery module calculates the average value again, and the voltage-controlled crystal oscillator is adjusted again until the adjusted reference clock is synchronous with the originating clock.

Preferably, the average value Δ θ (n) of the adjacent multiple phase drift results obtained by the recovery module is:

wherein, l represents the serial number of the FFT output result, delta theta (n) is the average value of the phase drift results of multiple adjacent times, m is the number of the phase drift results of the average value, m is more than or equal to 1, and n is the frequency point serial number for clock recovery; θ (n) is a phase calculated from the complex result of the FFT output.

Preferably, the frequency of the local reference clock is adjusted by using a voltage-controlled crystal oscillator, and the update formula of the input voltage V of the voltage-controlled crystal oscillator is as follows:

V＝V-μΔθ(n)

wherein mu is an update coefficient and the value range is 0.01 to 0.0001.

Preferably, the erasing device is connected to a transmission link of a multi-carrier frequency domain modulation communication system.

One of the above technical solutions has the following beneficial effects:

aiming at the scene that the multi-carrier frequency domain modulation signal needs to be modified at the middle node of the transmission link, firstly, the multi-carrier signal is obtained on the transmission link, and the local reference clock is synchronized with the originating clock through clock recovery. Then, determining the target subcarrier needing to be erased, which may be one or more, and generating a signal with the same strength as the target subcarrier and opposite phase to load the signal on a transmission link to implement the erasure of the target subcarrier, i.e. the modification of data from 1 to 0. The method is combined with a mode of loading signals at the transmitting end, so that the flexible modification function of data is realized.

Drawings

FIG. 1 is a diagram illustrating a mapping relationship between data and spectrum in a multi-carrier frequency domain modulated signal according to an embodiment of the present invention;

fig. 2 is a block diagram of an erasing system for a multi-carrier frequency domain modulated signal according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In a multi-carrier frequency domain modulation communication system, there is usually a fixed frequency band, which is composed of multiple sub-carriers, and signals are loaded and transmitted on different sub-carriers respectively. At the transmitting end, the transmission data is first mapped into a multicarrier sequence, and then converted into a time-domain signal by IFFT (Inverse Fast Fourier Transform) and transmitted. In the aspect of signal reception, after time domain data is sampled, the time domain data is converted into a frequency domain signal through Fast Fourier Transform (FFT), modulated signals are detected at a plurality of subcarrier frequency points, and then data is obtained by demapping according to a carrier sequence.

The erasing method of the invention is mainly aimed at the scene that the multi-carrier frequency domain modulation signal needs to be erased at the intermediate node of the transmission link in the communication system, namely the data 1 to 0 in the mapping relation between the data in the multi-carrier frequency domain modulation signal and the frequency spectrum.

The embodiment of the invention discloses an erasing method suitable for a multi-carrier frequency domain modulation signal, which comprises the following steps:

s1, separating partial signals from the transmission link of the multi-carrier frequency domain signals to perform data sampling, performing Fast Fourier Transform (FFT) on the sampled digital signals, and demapping and recovering the loaded signals according to the corresponding relation of the frequency spectrum positions;

s2, selecting a frequency point needing clock recovery, evaluating phase drift through the phase difference of the frequency point after two adjacent FFT, and taking the average value of the phase drift results of the adjacent FFT to adjust the frequency of the local reference clock;

s3, judging whether the adjusted reference clock is synchronous with the originating clock, if so, entering S4; if not, the process goes to S1;

and S4, generating a subcarrier signal with the same intensity and opposite phase at the frequency point where the subcarrier needs to be erased, performing Inverse Fast Fourier Transform (IFFT), and overlapping the obtained result with the multicarrier frequency domain signal of the transmission link, namely erasing the signal of the corresponding frequency point.

Specifically, in step S1, after 5% of the signals are separated and data sampling is performed, an FFT is performed on the obtained digital signals to complete the conversion from a group of time domain data to frequency domain data, so as to obtain the spectrum of the multicarrier frequency domain modulation signal transmitted in the channel. Further, the output result of the FFT can be expressed as:

FFT_output(i)＝Re(i)+j*IM(i)

wherein, Re represents the real part of the FFT output result, IM represents the imaginary part of the FFT output result, and i is the serial number of all frequency points in a group of results output by one FFT. The mapping relationship between the data and the frequency spectrum in the multi-carrier frequency domain modulation signal can be obtained from the output result of the FFT, as shown in fig. 1. In fig. 1, the data band is composed of a plurality of subcarriers, and the presence or absence of a subcarrier signal is generally denoted by 1 or 0, the subcarrier-present signal is denoted by 1, and the subcarrier-absent signal is denoted by 0. According to fig. 1, which frequency points have subcarrier signals and which frequency points do not have subcarrier signals can be judged, and the loaded signals are recovered by demapping in combination with the corresponding relation of the frequency spectrum positions.

In step S2, a frequency point with any subcarrier being 1 is selected from all frequency points of the FFT output result, and the phase can be calculated from the complex result of the FFT output to obtain θ.

For example, the subcarrier of the nth frequency point is 1, n ∈ i, the frequency point is used for clock recovery, and the phase is:

θ(n)＝phase[FFT_output(n)]

selecting the sub-carrier on the frequency point, evaluating the phase drift by comparing the phase difference of the frequency point after two adjacent groups of FFT, and calculating the average value of the adjacent multiple phase drift results:

wherein, l represents the serial number of the FFT output result, and each FFT output is a group of complete results; m is the number of the phase drift results of the average value, and m is more than or equal to 1; n is a frequency point sequence number for clock recovery; Δ θ (n) is the average of the results of adjacent multiple phase shifts.

In this embodiment, the frequency of the local reference clock is adjusted by the vcxo, and the input voltage V of the vcxo is updated according to the average value:

V＝V-μΔθ(n)

wherein, mu is a tiny updating coefficient, and the value is taken according to the clock convergence speed of the system, and the value range is 0.01 to 0.0001. And feeding back the phase drift result to the input voltage of the voltage controlled crystal oscillator in a certain proportion to adjust the local reference clock.

Preferably, m is 50, and μ is 0.0001.

The steps S1 and S2 are iterated until the adjusted reference clock and the originating clock are synchronized.

In step S4, after the clock synchronization is completed, a subcarrier signal with the same intensity and opposite phase is generated for the frequency points where the subcarriers need to be erased. From the output of the FFT, the strength and phase of the bin are known:

FFT_output(x)＝Re(x)+j*IM(x)

wherein, x is the frequency point sequence number of the subcarrier to be erased, that is, the frequency point sequence number needs to be changed from 1 to 0. Generating real and imaginary signals inverse to the FFT output as inputs to the IFFT:

IFFT_input(x)＝-Re(x)-j*IM(x)

the output of the IFFT is sent back to a transmission link and is superposed with the multi-carrier frequency domain signal of the separated part of the signal on the transmission link, so that the signal of the corresponding frequency point can be erased.

The procedure is the same for the case where there are multiple subcarriers to be suppressed.

As shown in fig. 2, an embodiment of an erasing apparatus for a multi-carrier frequency domain modulated signal is provided, which is connected to a transmission link of the multi-carrier frequency domain signal, and is used for implementing the above method. The device comprises a data sampling module, an FFT module, a clock recovery module, a voltage control crystal oscillator, a data mapping module, an IFFT module and a data sending module.

And the data sampling module is used for separating partial signals from the transmission link of the multi-carrier frequency domain signals to perform data sampling.

And the FFT module is used for carrying out FFT on the sampled digital signal.

The data mapping module is used for generating a mapping relation graph of data in the multi-carrier frequency domain modulation signal and the frequency spectrum according to the output result of the FFT module;

and the clock recovery module is used for recovering the loaded signal by demapping according to the frequency spectrum position corresponding relation, selecting a frequency point needing to erase the subcarrier from the data and frequency spectrum mapping relation graph, calculating phase drift through the phase difference of the frequency point after two adjacent FFT (fast Fourier transform), and taking the average value of the phase drift results of multiple adjacent times.

And the voltage-controlled crystal oscillator calculates the input voltage by adopting the average value, and adjusts the frequency of the local reference clock so as to synchronize the adjusted reference clock with the originating clock.

And the signal generating module generates a subcarrier signal which has the same strength as the FFT result and is opposite in phase with the FFT result at the frequency point where the subcarrier needs to be erased.

And an IFFT module for performing IFFT on the subcarrier signal generated by the signal generation module.

And the data sending module sends the output result of the IFFT module to a transmission link, and the output result is superposed with the multi-carrier frequency domain signal (the superposition can be realized by an adder), namely the corresponding frequency point signal is erased.

After the voltage-controlled crystal oscillator is adjusted, the reference clock is not synchronous with the originating clock, the data sampling module performs data sampling again, the FFT module performs FFT on the sampled digital signal, the clock recovery module calculates the average value again, and the voltage-controlled crystal oscillator is adjusted again until the adjusted reference clock is synchronous with the originating clock.

In the above embodiment, the number of the subcarriers to be erased may be one or multiple, the erasure of the target subcarrier is realized by modifying data from 1 to 0, and if the generation of data from 0 to 1 at the transmitting end is combined, the flexible data modification function may be realized.

The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.