Frequency domain dispersion search method based on training sequences

Abstract

The invention discloses a frequency domain dispersion search method based on training sequences. The frequency domain dispersion search method comprises the following steps: performing frequency domain dispersion search on modulation symbol sequences obtained through modulating the training sequences; performing frequency domain maximum cost function-based dispersion search on received continuous sampling signals by a receiving end by adopting shift factors OmegaCT, wherein OmegaCT is equal to NFFT / 2<K+2>, and K is an integer not smaller than 0; meanwhile, correspondingly performing the following preprocessing on modulation symbol sequences of a sending end: enabling 2<K> modulation symbol sequences for one group, setting all modulation symbols to be 0 every two groups, and keeping the rest modulation symbols constant, and thus, not only is the problem that amplitude of a frequency domain maximum cost function is changed along with the ADC sampling time changes solved but also the dispersion search can be performed by adopting a larger dispersion search step, and therefore, the search time is reduced, the algorithm complexity is lowered, and system resources are saved.

Description

technical field [0001] The invention belongs to the technical field of frequency domain dispersion search, and more specifically relates to a training sequence-based frequency domain dispersion search method. Background technique [0002] With the development of optical fiber coherent communication technology, the coherent detection receiver including digital equalization technology can compensate for all linear channel losses or low nonlinear optical fiber channels, which makes it possible to correct the chromatic dispersion at the receiving end during transmission. (CD, Chromatic Dispersion) performs digital equalization without compensating in the optical domain through a dispersion compensating fiber (DCF, Dispersion Compensating Fiber). There are two ways of time-domain equalization and frequency-domain equalization in commonly used digital equalization methods. Since frequency domain equalization has very low computational complexity and good parallelism, it is compat...

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Problems solved by technology

[0011] However, in the above-mentioned dispersion search algorithm based on the maximum cost function in the frequency domain, there are two problems: first, under the most commonly used double-rate sampling, the use of Ω CT =N FFT / 2, however, in this case, the magnitude of the frequency-domain maximum cost function will change with the change of the ADC sampling point, resulting in a large performance difference, and even causing the dispersion search module to fail to work properly

In the traditional dispersion search algorithm, it is necessary to use a very small dispersion search step size ΔL to ensure that the correct dispersion estimation value can be obtained. In the actual processing process, multiple sets of frequency domain dispersion compensation functions are required to achieve the required dispersion range. The search, which is a waste of resources in hardware implementation

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