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正交四相序列编码相比于二相序列具有更大的码字容量和更好的互相关特性,因此更适用于光码分多址(OCDMA)无源光接入网。提出并实现了一种基于超结构光纤光栅的正交四相光码分多址编/解码器。该编/解码器采用A族四相序列作为地址码,在制作的过程中仅需一个均匀相位掩模板即可实现编码功能,并且在性能上与传统工艺制作的编码器相当。为了与不同波长信道相匹配,提出了变信道编码技术,仿真结果表明采用该技术的编码器具有更高频谱效率,因此得到更好的编/解码性能。对一个码长63,长度4.1cm的正交四相编/解码器进行了信息速率为2.5Gb/s,码片速率为156Gchip/s的编/解码实验,取得了较好的编/解码效果。
Orthogonal four-phase sequence coding is more suitable for optical code division multiple access (OCDMA) passive optical access networks than two-phase sequences because of its larger codebook size and better cross-correlation performance. An orthogonal quadrature optical code division multiple access encoder / decoder based on superstructured fiber grating is proposed and implemented. The encoder / decoder uses A group of four-phase sequence as the address code, in the production process requires only a uniform phase mask to achieve coding, and performance comparable with the traditional process encoder. In order to match different wavelength channels, a variable channel coding technique is proposed. The simulation results show that the encoder using this technique has higher spectral efficiency and hence better coding / decoding performance. An orthogonal four-phase encoder / decoder with a code length of 63 and a length of 4.1 cm was compiled / decoded with an information rate of 2.5 Gb / s and a chip rate of 156 Gchip / s, and a better encoding / decoding effect was achieved .