基于码分多址(CDMA)和非对称限幅光(ACO)正交频分复用,提出了非对称限幅光多载波码分多址系统。在视线传播和散射传播信道中,采用正交恢复合并(ORC)、最大比合并(MRC)和等增益合并(EGC)算法,推导了受限幅噪声影响时系统的信噪比,建立了蒙特卡罗误比特率(BER)仿真模型。研究结果表明,通过增大扩频序列长度可以提高BER性能。随着用户数增多,多用户间干扰增大,MRC算法性能变差,ORC算法保持了用户间的正交性,BER性能最好。所提系统的性能比反转多载波CDMA和单极性多载波CDMA系统的更好。

An asymmetrically clipped optical (ACO) multi-carrier (MC) code division multiple access (CDMA) system is proposed based on CDMA and ACO orthogonal frequency division multiplexing. The theoretical expression of signal-to-noise ratio for the system affected by clipping noises is derived with the orthogonality restoring combining (ORC), maximum ratio combining (MRC) and equal gain combining (EGC) algorithms in the sight and sattering propagation channels. The model for Monte Carlo bit-error-ratio (BER) simulation is established. The reasearch results show that the BER performance can be improved with an increase in the length of spreading codes. As the number of users increases, the MRC algorithm deteriorates due to the muli-user disturbance, however the ORC algorithm maintains the orthogonality among different users and demonstrates the best BER performance. The proposed system outperforms the Flip-MC-CDMA and the unipolar multi-carrier CDMA (U-MC-CDMA) systems.