Polarization code building method capable of resisting atmospheric turbulence decline based on Gaussian approximation theory

Abstract

The invention provides a polarization code building method capable of resisting atmospheric turbulence decline based on a Gaussian approximation theory. Polarization code coding is applied to a free space optical communication system, a polarization sub-channel with relatively low atmospheric turbulence gain error probability is selected to be applied to transmitting an information bit sequence, and a polarization sub-channel with relatively high atmospheric turbulence gain error probability is selected to be applied to transmitting a known fixed bit sequence. The method provided by the invention comprises the specific steps of initializing a probability density distribution of a received signal log-likelihood ratio according to a signal transient gain caused by atmospheric turbulence; performing iteration computing on log-likelihood ratio probability density distribution of the polarization channels; computing the error probability of each polarization sub-channel; and selecting the polarization sub-channel with the relatively low error probability to be applied to transmitting the information bit sequence. According to the method provided by the invention, the problem of buildingthe polarization code under the atmospheric turbulence decline channel is mainly solved, decrease of the system performance caused by atmospheric turbulence decline can be effectively suppressed, andthe stability of the free space optimal communication system is improved.

Description

technical field [0001] The invention relates to the field of information coding and free space optical communication, in particular to a construction method of polar codes against atmospheric turbulence attenuation. Background technique [0002] With the continuous increase of communication capacity, the spectrum resource of traditional radio frequency communication is gradually becoming saturated, and the Free Space Optical communication system (Free Space Optical, FSO) communication system has been widely concerned. Compared with the traditional radio frequency communication system, the free space optical communication system has the advantages of high transmission rate, large transmission bandwidth, no electromagnetic interference, and no frequency license. Therefore, the free space optical communication system is being widely used in the last mile access, campus and enterprise interconnection, video surveillance stream transmission, wireless backhaul, disaster recovery e...

AI Technical Summary

Problems solved by technology

[0007] When polar codes are used in free-space optical communication systems, since the atmospheric turbulence effect will produce random fluctuations in the strength of the received signal, the traditional polar code construction scheme for additive Gaussian white noise channels will face the influence of atmospheric turbulence , the most reliable polar sub-channel cannot be accurately selected for the transmission of information bits, which limits the decoding performance of polar codes for free-space optical communication systems

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