Lijia Zhang

Secure OFDM-PON Based on Chaos Scrambling

This letter proposes and experimentally demonstrates a secure orthogonal frequency-division-multiplexing passive optical network (OFDM-PON) based on the chaos scrambling in the OFDM frequency domain. The Logistic map is adopted for the chaos mapping. The chaos scrambling algorithm can dynamically allocate the scrambling matrices for different OFDM frames according to the initial condition, which enhance the confidentiality of the physical layer. It achieves a secure transmission at physical layer in OFDM-PON for data encryption. The experiment successfully transmits 8.37-Gb/s OFDM data with Logistic mapped chaos scrambling over 25-km single-mode fiber (SMF), and the results indicate the robustness against eavesdropping.

Physical Layer Security in OFDM-PON Based on Dimension-Transformed Chaotic Permutation

A physical layer security enhanced orthogonal frequency division multiplexing (OFDM) passive optical network based on dimension-transformed chaotic permutation is proposed and experimentally demonstrated. In this scheme, a large key space is obtained by multidomain jointed Rossler permutation, and the corresponding complexity scale caused by multidomain encryption can be reduced through dimension-transformed permutation. An experiment with 10.61-Gb/s encrypted optical OFDM access system is performed to demonstrate the proposed method.

Theory and Performance Analyses in Secure CO-OFDM Transmission System Based on Two-Dimensional Permutation

Security in optical orthogonal frequency division multiplexing (OFDM) network has traditionally been considered to be addressed in higher layers of the network, while the physical layer is vulnerable to various attacks. As the dramatic increase of network capacity and secret sensitivity, the issue of physical layer security becomes more and more important. This paper proposes a novel physical-enhanced chaotic secure strategy for optical OFDM system based on two-dimensional (2-D) permutation. A controlled Logistic map is adopted for the chaotic mapping. The 2-D secure algorithm jointly utilizes frequency subcarriers and time-slots permutation to guarantee the secure of physical layer security of optical OFDM transmission system. This method performs dynamic permutations over frequency and time dimensions, resulting in a robust protection on transmitted information. Experiment is performed to confirm the good effectiveness of the proposed method.

A Novel MAMSK-OFDM Technology for Next-Generation Optical Access Networks

We propose and experimentally demonstrate a novel MAMSK-OFDM-PON. 5-Gb/s MAMSK-OFDM signal and 2.5-Gb/s upstream OOK signal is transmitted over 20km fiber successfully. The results show the prospect of this technology in future optical access networks.

MAMSK-OFDM Signal for RoF Access With Increased Tolerance Toward Frequency Offset

A novel multi-amplitude minimum shift keying (MAMSK) orthogonal frequency division multiplexing (OFDM) signal is proposed for 60-GHz radio-over-fiber (RoF) access system. It can increase the tolerance toward frequency offset of an OFDM signal due to the faster roll-off side-lobe. In the experiment, a 3.21-Gb/s 2AMSK-OFDM signal is transmitted over 22 km single mode fiber (SMF) and 5 m air link successfully. Compared with a conventional 8QAM-OFDM signal, the signal-to-interference ratio (SIR) of 2AMSK-OFDM is improved by 11.5 dB at a frequency offset of 0.15. The performance is improved by 1.7 dB under a normalized frequency offset (FO) of 0.2.

LDPC-coded A×M-DAPPM systems for simulation of turbulent free-space optical communication system

A LDPC coded DAPPM (4×4 & 4×8) modulated scheme for both strong and weak turbulent free-space optical communication is proposed and its BER performance is analyzed by Monte Carlo simulation. Results prove its well reliability especially for weak turbulent channel, and calls for advanced forward error control means to deal with strong turbulent channel.

A novel super-orthogonal modulation scheme for high speed optical OFDM system

High speed optical communication is one of the research hotspot in optical communication field at present. A novel super-orthogonal modulation method based on quadrature amplitude modulation (QAM) and frequency shift key (FSK) is proposed for high speed optical orthogonal frequency division multiplexing (OFDM) system. The coding-modulation and demodulation-decoding scheme is designed. The principle and transmission performance of optical OFDM system with proposed super-orthogonal modulation method is simulated and analyzed. The research result will lay the foundation of optical communication realizing with high speed, large capacity and high efficiency transmission.