| Summary: | 碩士 === 國立宜蘭大學 === 電機工程學系碩士班 === 103 === In this thesis, the investigation for improving performance in optical code division multiple access (OCDMA) system is proposed, where the transmission characteristic and throughput analysis are discussed. With the increasing demand of bandwidth in high-speed internetworking OCDMA technique is a preferable way to
be as the platform, which has the merits of scalability, asynchronous transmission, security, low cost, and low complexity.
Since OCDMA is an interference-limited system, the system performance is dominated by MAI (multiple access interference) and beat noise. We propose three
countermeasures to alleviate such adverse impact, which are applied to different system architectures. First of all, the duobinary signaling scheme and LDPC (low
density parity check) code are employed to further reduce the error floor. In the second approach, we utilize coded modulation scheme and LDPC code, where the
laser chirping effect and fiber dispersion are taken into consideration. Finally, the OHL (optical hard-limiter) and Reed-Solomon code are exploited in unslotted
ALOHA network. Our proposed schemes can effectively improve system performance, and can allow more users accommodated in the network.
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