Research on quasi-orthogonal space-time block coding for free space optical communication system based on mimo technology.Author(s): Huiying Zhang
Due to the free space optical communication severely affected by atmospheric turbulence, this paper studies the atmospheric channel characteristics and analyzes the advantage of the space time block coding, a MIMO scheme and an improved quasi-orthogonal spacetime block coding (QOSTBC) are proposed in order to improve the performance of free space optical communication system. This scheme uses the method of matrix diagonalization to eliminate the non-orthogonal items and for four transmit antenna systems,it can solve the limitations of the Alamouti Code. Using Monte Carlo simulation method,the channel capacity and BER of the system are numerically examined. The results show that by using new QOSTBC for the FSO system, it can effectively resist fading and the capacity of system is increased, he high spectral efficiency can be achieved, the error performance is improved effectively.