用于二维光址多分址系统的代数同余码研究

Research of Algebraic Congruent Codes Used in Two-Dimensional Code Division Multiaddress System

总结了线性、二次和双曲等有限域内的代数同余运算在光码分多址系统中的应用 ,将代数同余码分为三类 :跳频码、扩时码和跳频扩时码 ,并给出它们的构造公式。提出了一种同时采用这三类编码分别用以提供不同类型用户服务的二维光码分多址方案 ,该系统方案尤其适合于大量用户需要常规服务 ,而少部分用户需要高速或高服务质量 (QoS)服务的情况 ,具有对速率和服务质量的强适应能力。为了证明该系统方案的可行性 ,首先证明了三种码字的互相关常数 ,然后推导了达到各种互相关值的概率 ,最后得出混合系统中不同类型干扰对系统误码率的影响 ,并进行了数值分析与讨论。

After summarizing the application of linear, quadratic and hyperbolic operators in CDMA system, a generalized algebraic congruent code is given out by its construction formula in three different categories, which are frequency-hop (FH), time-spread (TS) and FH-TS codes. A novel two-dimensional optical CDMA system is given out, in which different categories of codes are used to provide different types of service. Such a OCDMA system is very fit for the case that a small part of services are with high bit rate or high quality of service, while great amount of services are common one. In order to prove the possibility of such a hybrid system, the cross-correlation constants between those three codes are given firstly, the probabilities to attend those cross-correlation values are calculated secondly, system's BER performances under several different types of interferences are provided at last. Numerical analysis and discussion is also given.