Chaotic Constellation Shaping Synchronization Header Assistance Cognate Coherence OFDM-FSO Communication

We propose an orthogonal frequency division multiplexing - free space optical - chaotic constellation shaping (OFDM-FSO-CCS) scheme based on synchronization header assistance. The redundant information of constellation shaping is converted into a binary bit stream. The bit stream is encrypted by using a pseudo-random binary sequence (PRBS) generated by the 1-dimensional chaotic map amplifier (1-DCMA). This encrypted redundant information is inserted into the synchronization header. The proposed scheme enhances transmission security and reduces the bandwidth occupation of redundant information. Experimental results demonstrate an approximate 0.8dB bit error ratio (BER) performance improvement at 3.8×10⁻³, compared with the original model.

I. Introduction

Free space optical (FSO) communication has advantages including high bandwidth, free spectrum resources, low cost, flexible deployment, high security, and resistance to electromagnetic interference [1]–[3]. These qualities make FSO highly valuable in both civilian and military applications. However, the transmission performance of FSO systems can be hindered by unpredictable atmospheric conditions including absorption, scattering, and turbulence. Among these factors, atmospheric turbulence is a primary contributor to the significant degradation of transmission performance. Improving the communication performance of FSO links in turbulent atmospheres is a major current challenge.