A Geometric Constellation Shaping Optimization Method Based on the Sparrow Search Algorithm

A geometric constellation shaping optimization method based on the sparrow search algorithm is proposed. This method employs the bit error rate as the fitness function as well as utilizes the sparrow search mechanism to adjust the positions of the constellation points, achieving the optimal distribution after several iterations. Simulation results indicate that the sparrow-optimized constellation provides a greater optical signal-to-noise ratio gain compared to the uniform quadrature amplitude modulation constellation. Furthermore, the sparrow-optimized geometric shaping constellation enables longer transmission distances in the coherent optical communication system compared to the uniform constellation. Therefore, the proposed scheme has certain development prospects in long-distance, high-speed optical fiber communication.

I. Introduction

With the advent of technologies like virtual reality, self-driving car diagnostics, and cloud computing, higher requirements are placed on exchanging and transmitting information [1]. To attain the improvement for high-capacity, high-speed, constellation shaping has become a focal point as it enables optical communication systems close to the Shannon limit. [2]. Geometric shaping can adjust constellation distribution based on the transmission channel characteristics, improving bandwidth utilization efficiency and symbol reception. By optimizing the geometric constellation distribution, geometric shaping can enhance the capacity of optical transmission systems and improve transmission distances [3]. Therefore, research on shaping geometric constellations is crucial to enhance optical fiber communication systems.