多噪音背景下引入光硬限幅器及并行干扰抑制器的光码分多址系统

为了抑制光码分多址中的多址干扰及多噪音,提出了一种引入光硬限幅器及基于最大值判决的并行干扰抑制器的光码分多址系统.在系统中存在APD噪音及热噪音的情况下,研究了系统对多址干扰的抑制作用.系统采用光正交码作为地址码,APD作为光电检测器,分析推导了系统的误码率表达式.根据所得的误码率表达式,进行了数值仿真,比较了该方法与其他方法的多址干扰抑制效果.研究结果表明:与现有其他有效方法(单比特引入一个光硬限幅器、单比特引入两个光硬限幅器、多比特传输、多比特引入光硬限幅器、基于最大值判决的并行干扰抑制器等)相比,本系统对多址干扰的抑制作用优于并行干扰抑制器、多比特传输、多比特引入光硬限幅器方法|当接收功率较低时,该系统优于引入双光硬限幅器的方法,因此可以有效的抑制多址干扰及多噪音.

Optical Code Division Multiple Access System with Optical Hard-limiter and Parallel Interference Cancellers under Multiple Noise Background

To suppress multiple access interference and multiple noises existing in optical code division multiple access system,a system with hard-limiter and parallel interference canceller based on maximal value decision is presented.The effect of suppress multiple access interference is examined while APD noise and thermal noise exist.Optical orthogonal code is applied as address code,APD is used as opto-electro detector,and bit error rate of the system is derived and analyzed.Simulations based on the expression are done and comparison with other multi-user interference suppressing methods is made.Compared with other effective methods such as single bit with single hard-limiter,single bit with double hard-limiters,multiple-bit transmitted method,multiple-bit transmitted with hard-limiter method,parallel interference canceller(without hard-limiter) based maximal value decision method and so on,simulation results show that the effect of suppress multiple access interference of the system is superior to parallel interference canceller without hard-limier and multiple-bit transmitted method with or without hard-limiter.If the received power is low,the system is also superior to double hard-limiters method.So,it is effective for suppressing multiple access interference and multiple noises.