Physical-Layer Security Scheme for 32QAM OFDM-PON Using Geometric Probabilistic Shaping and Chaos

A 32QAM OFDM-PON physical-layer security scheme using geometric probability shaping (G/PS) and chaos is proposed in order to enhance transmission security and reliability. The encrypted signals are validated on a net bit rate of 42.74 Gb/s 32 quadrature amplitude modulation (QAM) OFDM-PON system, which is transmitted over 20km SSMF fiber. The simulation results show the scheme can effectively expand the key space to 10¹²⁷, achieves about 1.8 dB gain at a BER of 10⁻² and maintains generalized mutual information (GMI) gain up to 0.58 bits/symbol, thus achieving good transmission security reliability.

I. Introduction

With the rapid development of the 5G era and the deployment of novel modern technologies, the traffic demand of communication networks increases dramatically [1], and numerous researches related to optical communication technologies have been derived accordingly. Next-generation passive optical networks (PONs), characterized by high flexibility, low power consumption, and high bandwidth, have attracted attention and are widely used in practice [2]–[4]. Orthogonal Frequency Division Multiplexing (OFDM) technology has the advantages of strong dispersion resistance, high spectral efficiency, and flexible modulation format [5]–[8], which is considered as the one of the effective solutions to realize PON.