A frame synchronization method in a digital coherent optical fiber communication system
A technology of optical fiber communication system and frame synchronization, applied in the direction of digital transmission system, transmission system, synchronization device, etc., can solve the problems of large timing deviation, large influence of frequency offset, and large influence of Gaussian noise, etc., and achieve strong resistance, frequency offset Effect of insensitivity and small number of code elements
Active Publication Date: 2019-06-18
HUAZHONG UNIV OF SCI & TECH
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[0003] Aiming at the defects of the existing frame synchronization technology, the purpose of the present invention is to provide a frame synchronization method in a digital coherent optical fiber communication system, which aims to solve the problem of large timing deviation, large influence by Gaussian noise and large influence by frequency offset in the traditional frame synchronization method The problem
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[0026] In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.
[0027] In the field of signal processing, convolution operation is a widely used mathematical tool. The convolution operation can calculate the sum of products in reverse order for the data of the same size window in different time periods in a set of data. If the data in this window has the property of conjugate symmetry with respect to its central time point, then the timing metric obtained by the convolution operation can obtain a sharp peak. At the same time, since the phase change brought by the frequency offset is a process of linear accumulation over time, each item of the reverse produc...
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The invention discloses a frame synchronization method for a digital coherent optical fiber communication system. The method comprises the following steps: designing a conjugate symmetric quadrature phase shift keying data sequence that is used for frame synchronization; performing convolution operation and power normalization operation for received optical communication signals in a sliding window mode to obtain a convolution value sequence M(d) of a signal string; and finding a maximum value of M(d) by using a size comparison method, wherein the location of the maximum value is a time slot location of a frame synchronization sequence in the received optical communication signals. According to the frame synchronization method disclosed by the invention, the designed conjugate symmetric quadrature phase shift keying data sequence may have a sharp peak in the convolution operation, but ordinary transmission signals do not have the same phenomenon, the peak can be found out by insertingthe designed frame synchronization sequence at a sending end and performing the convolution operation at a receiving end, and thus the frame synchronization can be achieved; and the frame synchronization method is accurate in positioning, less in time consumption and low in power consumption, adopts fewer code elements, is insensitive to frequency offset, and has strong robustness to chromatic dispersion and Gaussian noise.
Description
technical field [0001] The invention belongs to the technical field of optical fiber communication, and more specifically relates to a frame synchronization method in a digital coherent optical fiber communication system. Background technique [0002] Frame synchronization means to accurately find the starting position of a certain data frame. Frame synchronization is an essential step for practical communication systems. Many algorithms that require training symbol assistance have been proposed and used in existing single-carrier digital coherent optical fiber communication systems, such as training symbol-assisted equalization algorithms, frequency offset estimation algorithms, and carrier phase estimation algorithms. For such a training sequence-assisted algorithm, a certain amount of training symbols will be inserted at the beginning of the data frame or inserted at intervals in the data frame. We must precisely locate such training symbols. Even for the blind operati...
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IPC IPC(8): H04B10/556H04B10/61H04L7/00
Inventor 付松年陆佳宁唐明刘德明
Owner HUAZHONG UNIV OF SCI & TECH