多用户检测技术在光码分多址系统中的应用

在分析光码分多址（OCDMA）系统的多址复用光纤传输信道模型的同时,从最长似然检测的角度出发,推导了基于该模型的DCDMA最佳多用户检测器。该检测器可通过维特比（Viterbi）算法实现,在此基础之上,利用相关检测的原理,研究了一种较实用的次佳多用户检测器-多级检测器,在抑制多址干扰的同时,尽量降低检测器实现的复杂度,并分析了它对系统性能的影响,结果表明,由于传输环境的不同,DCDMA系统具有与无线CDMA系统不同的最佳多用户检测判决准则,而作为一种非线性多用户检测技术,多级检测器可以较理想地改善DCDMA系统的误码率性能。

Multi-User Detection for Optical Code Division Multiple Access Systems

The both optimal and sub optimal multi user detectors for optical code division multiple access (OCDMA) systems were studied. A suitable multi access fiber optic channel model was proposed firstly, which was then utilized to derive the optimal multi user detector for OCDMA systems under the criteria of maximum likelihood (ML) detection. This optimal detector can be accomplished by Viterbi algorithm. A new sub optimal multi stage detector was also proposed for practical usage, with both low complexity and the suppression of multi access interference (MAI). The effect of this multi stage detector on system performance was investigated. The analytical results reveal that OCDMA systems have different optimal multi user detection criteria from electronic CDMA systems, and the proposed multi stage detector can improve system performance satisfyingly.