阅读说明：本技术 一种适用于多载波频域调制信号的检测方法及装置 (Detection method and device suitable for multi-carrier frequency domain modulation signal ) 是由 张旭 杨超 罗鸣 孟令恒 江风 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检测方法及装置,涉及光通信系统中的多载波频域调制领域,接收多载波频域调制信号采样后进行快速傅立叶变换FFT,根据一次FFT结果获得对应载波频段内各频点的相位,基于相邻两次FFT结果计算各频点的相位差,再计算各频点多次连续FFT相位差的平均值；在需要解析的频段内,各频点采用对应的平均值进行相位补偿后,再进行多次FFT结果的累加,对累加后得到的结果取模,模值增强的频点为有子载波的频点。本发明可以提高长距离光纤传输后多载波频域调制信号的检测准确率。(A detection method and apparatus suitable for the frequency domain modulation signal of multi-carrier, relate to the frequency domain modulation field of multi-carrier in the optical communication system, carry on fast Fourier transform FFT after receiving the modulation signal sampling of frequency domain of multi-carrier, obtain the phase place of every frequency point in the frequency band of the corresponding carrier according to FFT result of one time, calculate the phase difference of every frequency point on the basis of FFT result of two adjacent times, calculate the mean value of multiple consecutive FFT phase difference of every frequency point; and in the frequency band to be analyzed, after each frequency point adopts the corresponding average value to perform phase compensation, accumulating FFT results for multiple times, and performing modulus on the result obtained after accumulation, wherein the frequency point with enhanced modulus is the frequency point with subcarriers. The invention can improve the detection accuracy of the multi-carrier frequency domain modulation signal after long-distance optical fiber transmission.)

1. A method for detecting a multi-carrier frequency domain modulated signal, comprising:

receiving a multi-carrier frequency domain modulation signal, sampling, performing Fast Fourier Transform (FFT), obtaining the phase of each frequency point in a corresponding carrier frequency band according to a primary FFT result, calculating the phase difference of each frequency point based on two adjacent FFT results, and calculating the average value of multiple continuous FFT phase differences of each frequency point;

and in the frequency band to be analyzed, after each frequency point adopts the corresponding average value to perform phase compensation, accumulating FFT results for multiple times, and performing modulus on the result obtained after accumulation, wherein the frequency point with enhanced modulus is the frequency point with subcarriers.

2. The method as claimed in claim 1, wherein a single FFT outputs a set of results, and the frequency band to be analyzed is an interval within the length of the single FFT result.

3. The method as claimed in claim 1, wherein the phase θ of each frequency point is calculated based on FFT results^(f)The method comprises the following steps:

wherein the content of the first and second substances,and generating a mapping relation between data in the multi-carrier frequency domain modulation signal and the frequency spectrum according to the output result of the FFT, wherein f is the serial number of the FFT frequency point.

4. The method as claimed in claim 3, wherein the average Δ θ of the multiple continuous FFT phase differences at each frequency point is calculated^(f)The method comprises the following steps:

wherein i represents the serial number of the output result of one continuous FFT, m is the number of continuous FFT, and m is more than or equal to 2.

5. The method as claimed in claim 4, wherein the step of performing phase compensation on each frequency point by using the corresponding average value comprises:

for each frequency point, use exp (j (i-1) × Δ θ^(f)) And carrying out phase compensation.

6. The method of claim 5, wherein the accumulating the FFT results comprises:

wherein the content of the first and second substances,for the accumulated result, n represents the number of accumulated FFTs.

7. The method according to claim 1, wherein the frequency points with relatively no significant change in modulus values are frequency points without subcarriers, modulo the result obtained by accumulation.

8. The method as claimed in claim 1, wherein the detection method is performed at a receiving end of the multicarrier frequency-domain modulation link, a transmitting end of the multicarrier modulation link maps data into a sequence of subcarriers of the multicarrier signal, and the receiving end de-maps the modulo data according to the sequence of the subcarriers.

9. A detection apparatus for a multi-carrier frequency domain modulated signal, comprising:

the data sampling module is used for carrying out data sampling on the received multi-carrier frequency domain modulation signal;

the FFT module is used for carrying out FFT on the data sampled signal;

the phase offset estimation module is used for obtaining the phase of each frequency point in the corresponding carrier frequency band according to the FFT result of one time, calculating the phase difference of each frequency point based on the adjacent two FFT results, and then calculating the average value of the multiple continuous FFT phase differences of each frequency point;

the phase offset compensation module is used for performing phase compensation on each frequency point by adopting a corresponding average value in a frequency band needing to be analyzed;

and the data accumulation module is used for accumulating the frequency points after phase compensation after multiple times of FFT and performing modulus operation on the accumulation result, and the frequency points with enhanced modulus values are frequency points with subcarriers.

10. The detection apparatus for a multi-carrier frequency domain modulated signal as set forth in claim 9, wherein the detection apparatus further comprises:

and the data demapping module is used for demapping the modulo data according to the carrier sequence.

Technical Field

The present invention relates to the field of multi-carrier frequency domain modulation in an optical communication system, and in particular, to a method and an apparatus for detecting a multi-carrier frequency domain modulation signal.

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, multi-carrier frequency domain modulation is used in an idle frequency band, and signal extraction can be completed without demodulating the high-speed optical signal.

However, in the conventional optical label system implemented based on the multi-carrier frequency domain modulation method, in order to reduce the influence of the optical label signal on the original high-speed channel, the modulation amplitude as small as possible is inevitably adopted. Meanwhile, in the existing wavelength division multiplexing network, there may be 80-120 channels with different wavelengths, and after the optical label signal is multiplexed at the transmitting end, the signal-to-noise ratio on the transmission link may be greatly reduced. After long-distance optical fiber transmission, errors may occur in detection of the multicarrier frequency domain modulation signal by the receiving end, and there is a possibility that the frequency point corresponding to the multicarrier frequency domain modulation signal cannot be detected.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a method and a device for detecting a multi-carrier frequency domain modulation signal, which are used for improving the detection accuracy of the multi-carrier frequency domain modulation signal after long-distance optical fiber transmission.

In order to achieve the above object, in one aspect, a method for detecting a multi-carrier frequency domain modulation signal is adopted, including:

receiving a multi-carrier frequency domain modulation signal, sampling, performing Fast Fourier Transform (FFT), obtaining the phase of each frequency point in a corresponding carrier frequency band according to a primary FFT result, calculating the phase difference of each frequency point based on two adjacent FFT results, and calculating the average value of multiple continuous FFT phase differences of each frequency point;

and in the frequency band to be analyzed, after each frequency point adopts the corresponding average value to perform phase compensation, accumulating FFT results for multiple times, and performing modulus on the result obtained after accumulation, wherein the frequency point with enhanced modulus is the frequency point with subcarriers.

Preferably, a group of results is output by one FFT, and the frequency band to be analyzed is an interval within the length of the result of one FFT.

Preferably, the phase θ of each frequency point is calculated based on the FFT result^(f)The method comprises the following steps:

wherein the content of the first and second substances,and generating a mapping relation between data in the multi-carrier frequency domain modulation signal and the frequency spectrum according to the output result of the FFT, wherein f is the serial number of the FFT frequency point.

Preferably, the average value delta theta of the multiple continuous FFT phase differences of each frequency point is calculated^(f)The method comprises the following steps:

wherein i represents the serial number of the output result of one continuous FFT, m is the number of continuous FFT, and m is more than or equal to 2.

Preferably, each frequency point performs phase compensation by using a corresponding average value, including:

for each frequency point, use exp (j (i-1) × Δ θ^(f)) And carrying out phase compensation.

Preferably, the accumulating of the FFT results is performed a plurality of times, including:

wherein the content of the first and second substances,for the accumulated result, n represents the number of accumulated FFTs.

Preferably, the result obtained after the accumulation is subjected to modulus operation, and the frequency points with relatively no obvious change of modulus values are the frequency points without subcarriers.

Preferably, the detection method is performed at a receiving end of a multi-carrier frequency domain modulation link, a transmitting end of the multi-carrier modulation link maps data into a sub-carrier sequence of a multi-carrier signal, and the receiving end de-maps the modulo data according to the carrier sequence.

In another aspect, a detection apparatus for a multi-carrier frequency domain modulation signal is further provided, including:

the data sampling module is used for carrying out data sampling on the received multi-carrier frequency domain modulation signal;

the FFT module is used for carrying out FFT on the data sampled signal;

the phase offset estimation module is used for obtaining the phase of each frequency point in the corresponding carrier frequency band according to the FFT result of one time, calculating the phase difference of each frequency point based on the adjacent two FFT results, and then calculating the average value of the multiple continuous FFT phase differences of each frequency point;

the phase offset compensation module is used for performing phase compensation on each frequency point by adopting a corresponding average value in a frequency band needing to be analyzed;

and the data accumulation module is used for accumulating the frequency points after phase compensation after multiple times of FFT and performing modulus operation on the accumulation result, and the frequency points with enhanced modulus values are frequency points with subcarriers.

Preferably, the detection device further comprises:

and the data demapping module is used for demapping the modulo data according to the carrier sequence.

The technical scheme has the following beneficial effects:

because the noise phase is random, the phase of the signal loaded by the sending end is fixed, and the phase deviation of the receiving end is mainly an offset which is asynchronously introduced by the clock of the receiving end and the sending end, the invention carries out phase deviation compensation on each frequency point, and can eliminate the offset; and then accumulating the compensated multiple continuous FFT (Fast Fourier Transform) results and then performing modulus extraction, so that the modulus of the signal can be enhanced, the modulus of the noise can not be obviously changed, namely the SNR (signal to noise ratio) is improved, whether the frequency point has the subcarrier can be accurately judged, and the detection accuracy of the multicarrier frequency domain modulation signal is improved.

Drawings

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

FIG. 2 is a schematic diagram of phase offset compensated summation of multicarrier frequency domain modulation signals in accordance with an embodiment of the present invention;

fig. 3 is a schematic diagram of a detection apparatus for a multi-carrier frequency domain modulation 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.

As shown in fig. 1, in a multi-carrier frequency domain modulation communication system, there is usually a fixed frequency band used to load data. The frequency band is composed of a plurality of subcarriers, and each subcarrier carries respective fixed bit information to form a segment of data. At a signal transmitting end, data to be transmitted is firstly mapped to a subcarrier sequence of a multicarrier signal in a frequency domain, where a subcarrier represents 1 and no subcarrier represents 0, and then converted into a time domain signal through IFFT (Inverse Fast Fourier Transform) and transmitted. At a signal receiving end, time domain data received from a link is sampled and converted into a frequency domain signal through FFT, whether a subcarrier modulation signal exists or not is detected in a corresponding carrier frequency band, and then data is obtained through demapping according to a carrier sequence.

Based on the above system, this embodiment provides a detection method suitable for a multi-carrier frequency domain modulation signal, mainly aiming at a scene of demodulating the multi-carrier frequency domain modulation signal at a signal receiving end, for determining a frequency point with a subcarrier, and the detection method includes the steps of:

firstly, data sampling is carried out on a received signal, then FFT is carried out on the sampled digital signal, the frequency spectrum of a multi-carrier frequency domain modulation signal transmitted in a channel is obtained, and the output result of the FFT is as follows:

wherein, Re represents the real part of the FFT output result, IM represents the imaginary part of the FFT output result, a mapping relationship between data in the multi-carrier frequency domain modulation signal and the frequency spectrum can be obtained according to the FFT output result, one FFT outputs a group of results, and f is the frequency number of the FFT output result, i.e. the frequency point number.

And secondly, performing phase offset estimation on each frequency point based on the FFT result. And obtaining the phase of each frequency point in the corresponding carrier frequency band according to the output result of the FFT of one time, calculating the phase difference of each frequency point based on the adjacent FFT results of two times, and calculating the average value of the repeated continuous FFT phase difference of each frequency point, wherein the average value is the estimated phase deviation.

Specifically, the phase of each frequency point in the frequency band to be detected is calculated according to the following formula:

wherein the content of the first and second substances,the frequency band to be detected for the output result of the FFT is an interval within the length of one FFT, for example, the length of the output result of one FFTThe degree is 10000, and the frequency band to be analyzed is 3000-4000 frequency points. Then, based on the multiple groups of continuous FFT output results of each frequency point, calculating the phase change of each frequency point:

where i represents the serial number of the one-time FFT output continuous result, θ^(f)(i)-θ^(f)(i +1) is the phase difference of two adjacent FFT output results of the frequency point f, m is the number of continuous FFT, and m is more than or equal to 2; mean value Delta theta^(f)Is the phase change of the frequency point. The more times m, the higher the accuracy, but the longer the calculation time, preferably m is selected to be 8.

Then, in the frequency band to be analyzed, after each frequency point adopts the corresponding average value to perform phase compensation, the FFT result is accumulated for a plurality of times:

wherein the content of the first and second substances,for the accumulated result, n represents the number of accumulated FFTs. Since the output result of FFT isCompensating the output result to be exp (j (i-1) × Delta theta^(f)) After each compensation, the sum is accumulated, the first time is the compensation 0 x delta theta^(f)The second time is to compensate for 1 x Δ θ^(f)And the third time is 2 × Δ θ^(f)The more the number of accumulation times, the better the effect, the better the trade-off effect and the efficiency, and the number of accumulation times n is preferably 50.

Finally, the accumulated result is subjected to modulus taking, and the modulus value is enhanced due to the frequency point of the subcarrier; the module value is relatively not obviously changed without the frequency points of the sub-carriers, and the overall signal-to-noise ratio is enhanced, so that the 0 and 1 of the data can be more accurately judged according to the obvious difference. By means of the method, the problem that the signal-to-noise ratio of the remote transmission is reduced and then 0 and 1 images are not obvious is solved, and the detection result is more accurate.

As shown in fig. 2, the left spectrum is the FFT result after phase compensation before accumulation, the phase corresponding to each frequency point is represented by an arrow in a circle, the thick arrow represents a signal, the phase directions of which in the group spectrum are consistent, and the thin arrows below two sides 0 represent noise, and the phase directions are still random. The right frequency spectrum is the frequency spectrum obtained after the accumulation of the left side, and the amplitude of the signal is obviously improved relative to the noise, namely the SNR is improved.

At the receiving end, the data after the modulus is extracted is subjected to demapping according to the carrier sequence to obtain the data sent by the sending end.

As shown in fig. 3, an embodiment of a detection apparatus for a multi-carrier frequency domain modulation signal is provided, which can implement the above method, and the apparatus includes a data sampling module, an FFT module, a phase offset estimation module, a phase offset compensation module, and a data accumulation module.

The data sampling module is used for carrying out data sampling on the received multi-carrier frequency domain modulation signal;

the FFT module is used for carrying out FFT on the signal after the data sampling;

the phase offset estimation module is used for obtaining the phase of each frequency point in the corresponding carrier frequency band according to the FFT result of one time, calculating the phase difference of each frequency point based on the adjacent two FFT results, and then calculating the average value of the multiple continuous FFT phase differences of each frequency point;

the phase offset compensation module is used for performing phase compensation on each frequency point by adopting a corresponding average value in a frequency band needing to be analyzed;

and the data accumulation module is used for accumulating the frequency points after phase compensation after multiple times of FFT and performing modulus taking on the accumulation result, wherein the frequency points with enhanced modulus values are the frequency points with subcarriers.

Preferably, the detection apparatus may further include a data demapping module, configured to demap the modulo data according to the carrier sequence.

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.