Constellation shaping is a research area in the field of digital signal processing, specifically in the design and optimization of communication systems. It involves designing non-uniform signal constellations that can improve the performance of communication systems, such as increasing data rates, reducing power consumption, and improving error rates. By shaping the constellation points in a non-uniform manner, it is possible to increase the distance between the points closest to each other, which can help to mitigate the effects of noise and interference in the communication channel. This can result in more reliable and efficient communication systems. Researchers in the field of constellation shaping explore various techniques to optimize the design of constellations, such as probabilistic shaping, geometric shaping, and adaptive shaping. These techniques aim to maximize the performance of communication systems while taking into account practical constraints such as hardware limitations and channel conditions. Overall, constellation shaping is a key research area in improving the performance and efficiency of communication systems, particularly in high-speed data transmission applications such as optical communication and wireless communication.