Capacity Research of Asynchronous OCDMA System
异步OCDMA系统信道容量研究

To research the information capacity of the Asynchronous Optical Code Division Multiple Access(OCDMA) system,the system model and its implementation under ideal channel and AWGN channel optical communications are presented. We modeled a discrete memoryless channel OCDMA system and evaluated the aggregate capacity from the probability of the output signal at the chip level. On the condition that the information capacity limited by 1 bit per chip,the results show that the interference caused by asynchronism reduces the capacity limit as the number of users increases,but for a sufficiently large number of users,both the ideal and the AWGN channel throughput limit varies slowly and the limit is around 0.71-0.75 bit/chip. With less number of users of the ideal channel,the more the input probability is lower than 0.50,the lower the largest capacity limit will be. With low noise variance of the AWGN channel,the system with smaller users can attain higher capacity limit. So the information capacity of the asynchronous OCDMA is gotten.