# Next-Generation Dual Transceiver FSO Communication System for High-Speed Trains in Neon Smart City
## 1 Introduction  
Smart cities are urban environments that harness the power of technology and data to create sustainable, efficient, and livable communities. These cities integrate cutting-edge digital infrastructure, advanced technologies, and intelligent systems to optimize various aspects of urban life. Through the use of sensors, connected devices, and data analytics, smart cities collect real-time information about transportation, energy usage, waste management, public safety, and more. This wealth of data enables city planners and administrators to make informed decisions and implement targeted strategies to improve the quality of life for residents. Furthermore, smart cities are not just limited to technological advancements but also emphasize social innovation and sustainability. They strive to create equitable communities by focusing on affordable housing, accessible healthcare, education, and social services for all residents. By fostering collaboration between government, businesses, academia, and citizens, smart cities foster innovationand entrepreneurship, attracting investments and creating job opportunities in emerging industries [1]. The effective and eco-friendly advancement of cities and their surrounding urban areas has emerged as a critical and widely discussed matter, with a key focus on establishing a transportation system that ensures intelligent and sustainable mobility. According to the United Nations, an astounding three million individuals relocate from rural regions to cities around the globe each week, resulting in an anticipated doubling of urban populations by the year 2050. This rapid urban growth raises significant concerns regarding the capacity of urban areas to accommodate this influx in the forthcoming decades, encompassing the challenges of housing, energy, traffic infrastructure, and deteriorating air quality. The pursuit of sustainable and intelligent solutions for urban transportation aligns with the United Nations' Sustainable Development Goals (SDGs). With the endorsement of the 2030 Agenda, the United Nations has outlined 17 SDGs aimed at addressing global sustainability challenges related to poverty, inequality, and environmental degradation. In 2015, these SDGs were embraced by all 193 member countries of the United Nations, recognizing that attaining these ambitious sustainability objectives necessitates both financial and non-financial commitments from policymakers, entrepreneurs, consumers, and society at large [2]. Urban mobility in smart cities is pivotal for sustainable and efficient urban development. By leveraging advanced technologies and data-driven solutions, smart cities aim to optimize transportation systems, enhance connectivity, and improve residents' quality of life. From intelligent traffic management to shared mobility services, these cities deploy diverse tools to streamline mobility and reduce carbon emissions. Integration of emerging technologies like autonomous vehicles and electric mobility promises to transform urban transportation further. Through innovative policies and partnerships, smart cities strive to create vibrant, accessible, and environmentally sustainable urban environments [3]. High-speed railways (HSRs) play a crucial role in the development of smart cities, offering rapid and efficient transportation solutions for urban residents and visitors alike. With their ability to connect distant urban centers seamlessly, HSRs facilitate mobility and promote economic growth within smart city networks. These advanced transportation systems leverage cutting-edge technology to ensure safety, reliability, and sustainability. By reducing travel times and congestion, HSRs contribute to improved urban mobility and enhance overall accessibility within smart cities. Furthermore, their integration with other modes of transportation, such as metro systems and autonomous vehicles, creates a comprehensive and interconnected urban mobility ecosystem [4].