5. Radio Communications Systems in Railways

This chapter explores the essential role of wireless communication systems in modern railway operations, with a particular focus on train-to-ground (T2G) systems. It begins by distinguishing wireless systems from wired communications, emphasizing the importance of T2G systems in railway infrastructure. The chapter delves into the foundational aspects of mobile communications, including the physical layer and the impact of the radio channel on signal propagation. It discusses key factors such as data rate, range, number of users, mobility, energy consumption, and spectrum use, which are crucial for designing effective railway communication systems. The text also covers the challenges posed by the diverse environments in railway settings, such as tunnels, viaducts, and cuttings, and the high speeds of trains. It provides an overview of various wireless technologies, including GSM-R, WiFi, and LTE, highlighting their applications and limitations in railway communications. The chapter also explores the concept of spectrum, its allocation, and the implications for railway operations. It discusses the use of antennas in railway scenarios, both onboard trains and wayside, and the integration of multiantenna technologies like MIMO and beamforming. The evolution of mobile communications generations, from 1G to 5G, is examined, with a focus on their relevance to railway communications. The chapter concludes with a detailed look at GSM-R, its history, standardization, and future evolutions, providing a comprehensive understanding of its role in modern railway operations.