Study Of High-capacity Wireless Optical Cdma System, Multi-user Detection Techniques

Wireless optical communications has many advantages such as high data rate, good security, small dimension of device. Because CDMA(Code Division Multiple Access) has great bandwidth, strongly combating interference, achieving message privacy, it becomes one of the hot research areas. Applying optical in CDMA can use not only the characteristics of CDMA such as combating interference, message privacy, soft capacity, but also the huge wideband of optical.Wireless optical CDMA has good potential.This paper is a part of "The principle and realization of high-capacity wireless optical CDMA communications". It is a topic of National Natural Science Foundation of China(NSFC). I am mainly in charge of solving the multiuser detection. After researching the channel of wireless optical CDMA, we classify in freespace, atmosphere and indoor. The decorrelating detection of multiuser detection is employed. The influence of background noise to the communications is considered in freespace channel. Besides the influence of background noise, the scintillation effect is considered in atmospheric channel. Besides the influence of background noise, the multipath effect is considered in indoor channel. Decorrelating detection is employed for the three channels.With the Gaussian model, we analyse the system performance of decorrelation detection and get the figure of probability of error and also simulate the system. These results we got prove that the decorrelating detection in three channels is feasible and get the anticipating object. For the optical coder, we advance optical delay lines. By working hard, we have accomplished establishing channel models, advancing the scheme of multiuser detection,computer analysis and simulation, and experiment. At last, we bring up new hope of thewireless optical communicatons.