二维光码分多址的地址码及干扰估计接收机

Address Code and Interference Estimate Receiver of 2D-OCDMA

阐述了自相关旁瓣为0,互相关值小于等于1的二维光正交码(2D-OOC)的新构造方法及非同步频域跳频时域扩频二维光码分多址(2D-OCDMA)系统中的干扰估计接收机模型。二维光正交码的新构造方法以两个单极性码分别作为频域跳频模式和时域扩频模式。用作频域跳频模式的地址码是自相关旁瓣及互相关值小于等于1的一维光正交码(1D-OOC),用作时域扩频模式的地址码其码长为素数或码长与码中任意两个非零码元的位置差值互质。将一个没有分配给任何用户并且和接收用户地址码正交的地址码用作干扰估计码来得到多用户干扰(MUI)估计值,从而得到最佳的判决门限。系统误码率(BER)的分析显示干扰估计接收机系统的性能要优于传统的接收机系统。

The new construction scheme of two dimensional optical orthogonal codes (2D-OOCs), of which autocorrelation side lobes are 0 and the cross-correlation side lobes are at most 1, and the interference estimate receiver of asynchronous frequency-hopping time-spreading two-dimensional optical code division multiple access (2D-OCDMA) system are presented. For constructing the 2D-OOCs, two unipolar codes are used as the frequency-hopping pattern and the time-spreading pattern, respectively. The unipolar codes used as frequency-hopping patterns are OOCs of which auto-correlation side lobes and the cross-correlation one are at most 1, for the unipolar codes used as the time-spreading patterns, the restriction is that their code lengths are a prime number or their code length and displacement difference between any two non-zero chips in the same code are co-prime number. By using one 2D-OOC as multi-user interference (MUI) estimation code, which is not assigned to any user, the asynchronous MUI estimate can be realized. According to the estimating of MUI, the optimum decision threshold can be obtained. The analysis of bit error rate (BER) indicates that the system with interference estimate receiver has advantage over traditional system.