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Cascaded compensation method in coherent light OFDM communication system

A communication system and coherent optical technology, applied in the field of optical communication systems to achieve the effect of improving the transmission performance of the system

Active Publication Date: 2017-06-13
UNIV OF SCI & TECH OF CHINA
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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for cascade compensation in a coherent optical OFDM communication system, which solves the influence of laser phase noise on signal demodulation in the coherent optical OFDM system, estimates and compensates the IQ imbalance factor at the transmitting end, Improved system transmission performance

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  • Cascaded compensation method in coherent light OFDM communication system
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  • Cascaded compensation method in coherent light OFDM communication system

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Embodiment Construction

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0035] Firstly, the impact of the IQ imbalance at the transmitting end and the IQ imbalance at the receiving end on the received signal in the coherent optical communication system is explained:

[0036] Assume that there is a transmitter phase mismatch factor θ t and magnitude mismatch factor ε t , after the optical IQ modulator, the output electric field intensity expression is:

[0037]

[0038] in, is the electric field strength of the i...

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Abstract

The invention discloses a cascaded compensation method in a coherent light OFDM communication system. The method comprises the following steps: firstly designing a pilot frequency sub-carrier distribution sachem at a transmitting terminal of a coherent light OFDM communication system; compensating the laser phase noise of the transmitting terminal at a receiving terminal of the coherent light OFDM communication system by use of a phase conjugated pilot frequency assisting method; further estimating the IQ amplitude and a phase imbalance factor of the transmitting terminal at the receiving terminal by use of a frequency domain second-order estimation algorithm; further eliminating the system performance deterioration callused by the IQ mismatching at the transmitting terminal, thereby improving the signal to noise ratio of a receiving signal. By use of the cascade compensation method disclosed by the invention, the influence on the signal demodulation by the laser phase noise in the coherent light OFDM system can be solved, the IQ imbalance factor of the transmitting terminal is estimated and compensated, and the transmission system performance is improved.

Description

technical field [0001] The invention relates to the technical field of optical communication systems, in particular to a cascade compensation method in a coherent optical OFDM communication system. Background technique [0002] At present, coherent detection has become the first choice for high-speed long-distance optical transmission systems. Single-carrier 100G coherent reception has been commercialized. Coherent optical OFDM communication technology is a powerful alternative for future 400G and 1T optical transmission systems. OFDM technology has a high tolerance to fiber chromatic dispersion (CD) and polarization mode dispersion (PMD), and is easy to combine with high-order modulation formats (such as m-QAM and m-PSK) to obtain high spectral efficiency. However, coherent detection is particularly sensitive to the phase noise caused by the laser linewidth, especially because OFDM signals have long symbol periods, phase noise will seriously affect and deteriorate system pe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/38H04L27/26H04B10/61
CPCH04B10/6165H04L27/2695H04L27/3854
Inventor 李超徐正元
Owner UNIV OF SCI & TECH OF CHINA
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