对光码分多址接入系统中由于各个用户距离和发射功率不同导致的远近效应进行研究。结果表明，远近效应显著劣化了小功率用户的误码率和掉线率。而且，系统中用户的信号功率方差越大，各个用户的误码率和掉线率的劣化也越严重。提出了一种应用光硬限幅器消除远近效应的方法，该方法还极大地降低了多用户干扰。

This paper investigates the near-far effect stemming from different signal power of users in OCDMA system. Based on the assumption that user′s signal power is Gauss-distributed, the impacts of near-far effect on system performance are presented. Results show that near-far effect significantly degrades the probability for the error and outage probability for the power-less users. Furthermore, increase of user′s signal power variance degrades both probability of error and outage probability for all users in the system. A method of coping with near-far effect, i.e. using an optical hard-limiter in the ODN, is proposed. Additively, the optical hard-limiter alleviates the multiple access interference.