Method for calculating average channel capacity of FTN transmission system on the condition of double Gamma turbulence channels

Abstract

The invention discloses a method for calculating the average channel capacity of an FTN transmission system on the condition of double Gamma turbulence channels, and aims to introduce an FTN technology into a Gamma-Gamma turbulence channel, so that the symbol rate is greater than the Nyquist rate, the average capacity of the system is effectively improved, and the performance of an atmospheric transmission system is improved. The FTN signal is formed by performing QPSK mapping on input bit information an and then generating the FTN signal through an FTN shaping filter. The system channel capacity is obtained by using a received signal transmission model, and then normalizing the period of the channel capacity to obtain the average capacity of the FTN system. On the basis, an expression ofthe average capacity of the super-Nyquist optical transmission system under a Gamma-Gamma turbulence channel under a QPSK modulation format is derived according to QPSK modulation characteristics. Theconstruction of the super-Nyquist optical transmission system effectively improves the spectral efficiency of the system.

Description

Technical field [0001] The invention relates to a method for calculating the average capacity of an FTN transmission system under a Gamma-Gamma turbulence channel, and belongs to the technical field of wireless optical communication. Background technique [0002] In recent years, free space optical communication (FSO, Free Space Optical) has become a significant research hotspot due to the advantages of large communication capacity, high transmission rate, and good confidentiality. With the development of 5G and 6G and the increasing demand for large-capacity and high-spectrum efficiency technologies in information networks, more technologies need to be developed to improve the transmission performance of wireless optical communications. Researchers have done a lot of research on this issue, such as the use of wavelength division multiplexing, high modulation format and other methods. However, as the modulation order increases, the sensitivity of the system will decrease. Faste...

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Problems solved by technology

[0003] Although FSO has many advantages, when the laser signal is transmitted in the atmospheric channel, the signal is easily affected by atmospheric turbulence, which will lead to spot drift of the transmitted beam, light intensity fluctuations (flickering), and the scattering caused by aerosols in the atmosphere. And refraction may also cause signal delay and pulse broadening, further causing problems such as increased bit error rate and reduced channel capacity of wireless optical communication systems, thus affecting the application of FTN technology in free space optical communication systems

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