Opt Express. 2023 Feb 27;31(5):7425-7439. doi: 10.1364/OE.483799.
In this paper, we propose a performance improvement of non-orthogonal multiple access (NOMA) with a three-dimensional (3D) constellation and a two-dimensional Inverse Fast Fourier Transform IFFT modulator (2D-IFFT) for the passive optical network (PON). Two kinds of 3D constellation mapping are designed for the generation of a three-dimensional NOMA (3D-NOMA) signal. Higher-order 3D modulation signals can be obtained by superimposing signals of different power levels by pair mapping. Successive interference cancellation (SIC) algorithm is implemented at the receiver to remove interference from different users. Compared with the traditional two-dimensional NOMA (2D-NOMA), the proposed 3D-NOMA can increase the minimum Euclidean distance (MED) of constellation points by 15.48%, which enhances the bit error rate (BER) performance of the NOMA. The peak-to-average power ratio (PAPR) of NOMA can be reduced by 2 dB. A 12.17 Gb/s 3D-NOMA transmission over 25 km single-mode fiber (SMF) is experimentally demonstrated. The results show that at the bit error rate (BER) of 3.8 × 10, the sensitivity gain of the high-power signals of the two proposed 3D-NOMA schemes is 0.7 dB and 1 dB compared with that of 2D-NOMA under the condition of the same rate. Low-power level signal also has 0.3 dB and 1 dB performance improvement. Compared with 3D orthogonal frequency-division multiplexing (3D-OFDM), the proposed 3D-NOMA scheme could potentially expand the number of users without obvious performance degradation. Due to its good performance, 3D-NOMA is a potential method for future optical access systems.
在本文中，我们提出了一种在无源光网络（PON）中使用三维（3D）星座和二维逆快速傅里叶变换调制器（2D-IFFT）来提高非正交多址（NOMA）性能的方法。为了生成三维 NOMA（3D-NOMA）信号，设计了两种 3D 星座映射方法。通过对不同功率水平的信号进行对映，可以获得更高阶的 3D 调制信号。在接收器端实现了连续干扰消除（SIC）算法，以消除来自不同用户的干扰。与传统的二维 NOMA（2D-NOMA）相比，所提出的 3D-NOMA 可以将星座点的最小欧式距离（MED）提高 15.48%，从而提高 NOMA 的误码率（BER）性能。NOMA 的峰均功率比（PAPR）可以降低 2dB。在 25km 单模光纤（SMF）上进行了 12.17Gb/s 的 3D-NOMA 传输实验。结果表明，在误码率（BER）为 3.8×10-3 的条件下，与 2D-NOMA 相比，两种所提出的 3D-NOMA 方案的高功率信号的灵敏度增益分别提高了 0.7dB 和 1dB，而低功率水平信号的性能也分别提高了 0.3dB 和 1dB。与 3D 正交频分复用（3D-OFDM）相比，所提出的 3D-NOMA 方案可以在不明显降低性能的情况下增加用户数量。由于其良好的性能，3D-NOMA 是未来光接入系统的一种潜在方法。
