Research On Space-time Coding Based On MIMO In Optical Communication

With the development and requirement of all-optic access network technology, free space optics as one of the advanced means of communication develops rapidly. It not only makes up for the wireless communication to meet the pressing demand for spectrum resources, but also does not need to complete fiber cabling required by optical fiber communication. Free-space optics with the laser beam as an information carrier, can realize the linear transmission in the atmosphere or in space directly, and can simultaneously achieve two-way transmission of information such as sound and data, and has great development space.Single input single output (SISO) for free space optics has been replaced by multiple input multiple output (MIMO), to satisfy its large volume and strong ability of anti-fading demand. MIMO technology can be used for signal processing in the two-dimensional space, namely the time dimension and spatial dimension, and can increase the channel capacity, improve the system capability against fading. Space-time coding on account of transmit diversity can enhance the ability of anti-fading of channels, and can provide diversity gain and coding gain at the same time. As the mature development between these two kinds technologies in modern wireless communication, MIMO technology and space time coding technology used in free space optical communication are some promising attempt and exploration. The paper firstly carries on the detailed introduction of the effects of atmospheric turbulence, the MIMO diversity and space-time coding, and then on the basis of some comparative analysis, it looks for technology widely used in free space optics.