Physical Layer Encryption of OFDM-PON Based on Quantum Noise Stream Cipher with Polar Code

Orthogonal frequency division multiplexing passive optical network(OFDM-PON) has superior anti-dispersion property to operate in the C-band of fiber for increased optical power budget. However,the downlink broadcast exposes the physical layer vulnerable to the threat of illegal eavesdropping. Quantum noise stream cipher(QNSC) is a classic physical layer encryption method and well compatible with the OFDM-PON. Meanwhile, it is indispensable to exploit forward error correction(FEC) to control errors in data transmission. However, when QNSC and FEC are jointly coded, the redundant information becomes heavier and thus the code rate of the transmitted signal will be largely reduced. In this work, we propose a physical layer encryption scheme based on polar-code-assisted QNSC. In order to improve the code rate and security of the transmitted signal, we exploit chaotic sequences to yield the redundant bits and utilize the redundant information of the polar code to generate the higher-order encrypted signal in the QNSC scheme with the operation of the interleaver.We experimentally demonstrate the encrypted 16/64-QAM, 16/256-QAM, 16/1024-QAM, 16/4096-QAM QNSC signals transmitted over 30-km standard single mode fiber. For the transmitted 16/4096-QAM QNSC signal, compared with the conventional QNSC method, the proposed method increases the code rate from 0.1 to 0.32 with enhanced security.

Modeling Impact of ROADM Intra-Node Add/Drop Contention on a Single Node Lightpath Blocking Performance

We propose an analytical model to evaluate the lightpath blocking performance for a single ROADM node with intra-node add/drop contention,in which the number of lightpaths that can be added/dropped with the same wavelength is limited by the add/drop contention factor.Different models of traffic load per nodal degree are considered to validate the effectiveness of the analytical model.The simulation results show that the proposed analytical model is effective in predicting the performance for different values of add/drop contention factor C and for variable offered loads at the node.The add/drop contention factor shows an important impact on the lightpath blocking performance and properly raising the contention factor can significantly improve the lightpath blocking performance.When the add/drop contention factor C exceeds a certain level,the performance of a ROADM with intra-node contention is close to that of a contentionless ROADM.

车载网络发展趋势和车载光纤传输研究进展

随着智能网联汽车的发展,车载网络作为汽车内传感器、处理器和执行器间的信息共享平台,逐步向简化架构和更高带宽方向发展。通过对智能网联汽车上几种主要新型车载传感器的工作原理介绍和带宽需求分析,分析了车载网络的带宽需求趋势。同时,本文根据对传统车载网络的网络架构和主流协议的回顾,以及对当前车载网络发展的追踪,指出了车载网络在汽车智能化趋势下面临的带宽瓶颈,光纤传输是未来车载网络的发展方向。最后,通过车载网络对光纤要求的分析和对塑料光纤传输技术的行业现状和最新研究进展的调研,说明了车载光纤传输技术亟须进一步研究。

面向中短距应用的差分自相干光纤传输系统

基于4电平脉冲幅度调制(PAM4)的强度调制直接检测(IMDD)是目前中短距应用的主要解决方案之一。然而,基于高阶脉冲调制的IMDD方案检测灵敏度明显下降。另一方面,拥有更高灵敏度的标准相干检测技术又面临成本和复杂度方面的挑战。因此,自零差相干检测(SHCD)和差分检测等自相干检测方案,因其优于PAM4的性能和低于标准相干检测的硬件成本而在新一代中短距应用中具备优势。本文综述和比较自零差相干以及差分自相干检测(DSCD)系统各自的特征、优点和挑战。文中进一步针对光功率受限和光信噪比受限的不同传输场景,分析比较基于SHCD-正交相移键控(QPSK)和DSCD-差分正交相移键控(DQPSK)方案的系统性能,展示了DSCD-DQPSK系统相较其他方案在硬件成本和系统性能方面的综合优势。