Research On Wireless Optical Communication System With Photon Counting Based On Laguerre Model

Optical wireless communication or Free-Space Optical (FSO) communication has many advantages, such as broad bandwidth, effective anti-interference, high data transfer rate and so on. Therefore more and more attention both in China and abroad is paid on this important research.Despite its merits, the inevitable factors which severely degrade the error rate performance such as atmospheric turbulence, background noise, thermal noise and so on. This paper firstly focuses on the principles and key technical problems of FSO systems. We model the photon counting technology in FSO system with consideration of thermal radiation, background radiation and atmospheric turbulence. The bit error rate (BER) expression with modulation of On-Off Keying (OOK) and Pulse Position Modulation (PPM) in different turbulence channels is deduced based on the Laguerre model. By using Monte-Carlo simulation, we prove the validity of the proposed algorithm. In addition, the simulation results show that atmospheric turbulence and noise is the main influence.Then we propose a space diversity scheme to improve the system performance and derive the BER expression of transmit diversity system, receive diversity system and Multiple-Input Multiple-Output (MIMO) system respectively in strong turbulence channel. Numerical results and Monte Carlo simulation results are presented to evaluate the improvement of the performance by achieving space diversity.Moreover, we investigate the iterative detection of Interleave-Division Multiple-Access (IDMA) multiuser system in Laguerre FSO links and propose the multiuser detection (MUD) scheme based on the optimum Bayesian (OB) algorithm. The results of computer simulations in different environments show that IDMA can obviously eliminate multiple access interference (MAI) and OB algorithm is capable of providing the obvious performance gain with fast Convergence rate.