An adaptive wireless communications method design for rail transportation systems

Among the rail transportation systems, various difficulties may be experienced in meeting the wireless communication needs of passengers in the train on the routes of high-speed trains. As passengers' wireless communication needs increase, these difficulties bring about more problems. Due to the high speeds of high-speed trains and the difficult terrain conditions on the routes of these trains, the negative effects of the wireless communication channel may increase. New generation communication infrastructures, such as "Fifth Generation" (5G) systems, tend to bring more flexible and adaptable solutions to communication problems. In this study, a unique adaptive modulation method is proposed to be environmentally aware, taking into account the wireless communication needs of passengers in high-speed trains. Within the scope of the method, the most appropriate technique from a set of modulations is automatically suggested, depending on environmental conditions and user needs. Therefore, the modulation type and degree can be selected with the method developed in this study. As system input, passenger density, usage density, weather conditions, terrain conditions and instantaneous speed of the high-speed train are used. From these inputs, basic features are extracted in response to two questions: how much spectral efficiency should be achieved and how much uninterrupted communication should be provided. Ultimately, the type and degree of modulation are determined adaptively using the two features and the signal-to-noise ratio (SNR) measurement value information. QPSK, 16-QAM and 64-QAM modulation types and degrees were tested within the scope of the developed method. The results show that the most appropriate modulation type and degree can be successfully determined, according to environmental factors and wireless communication needs of the active passengers users in the train. Keywords: 5G, Environmental awareness, Flexible system design, Wireless communication, Uninterrupted communication, Rail transportation systems, Adaptive modulation