Optical space-time trellis code coding method applicable to intensity modulation/direct detection type

Abstract

The invention discloses an optical space-time trellis code coding method applicable to an intensity modulation / direct detection type. Through utilization of the symmetry of fast inverse Fourier transform, a PSK / QAM signal output by a space-time trellis code coder is transformed into a link transmission signal applicable to intensity modulation / direct detection (IM / DD). Compared with an uncoded scheme, the scheme has the advantages that the bit error rate performance is greatly improved, a communication bit rate and the system information traffic are improved, and influences of atmosphere random channels on a wireless optical communication system are reduced.

Description

technical field [0001] The design method of space-time lattice coding in wireless optical communication multiple-input multiple-output (MIMO) system, the method of realizing quadrature amplitude modulation (QAM) or phase keying (PSK) by light intensity modulation, belongs to wireless optical communication (FSO) technology field. Background technique [0002] It has the advantages of high bandwidth, large capacity, low cost, and no need for frequency license. It is an effective means to build triple play, solve the "last mile" bottleneck, and realize global high-speed and real-time communication. Optical signals are subject to various interferences such as loss, attenuation, background radiation and atmospheric turbulence when transmitted in the atmosphere. Among them, atmospheric turbulence has the most serious impact on optical signals, especially in the case of strong turbulence, which can achieve a fading greater than 30dB, resulting in serious interference or even off-t...

AI Technical Summary

Problems solved by technology

[0006] The present invention is an optical space-time trellis code encoding method suitable for intensity modulation / direct detection, and its goal is to convert the PSK or QAM output by the space-time trellis code encoder into a positive real number signal, thereby solving the problem of the original space-time The problem that the complex signal output by the trellis code encoder cannot be directly transmitted in the optical communication link; the receiving end adopts the opposite process, through real / complex conversion, to obtain the signal input to the space-time trellis code decoder, and finally Complete the decoding; the steps are:

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