GSM-R Communication Quality Analysis In CTCS-3

CTCS-3 is a train protection system for Chinese high-speed railway. CTCS-3 uses GSM-R radio channel to exchange data between the trackside Radio Block Center (RBC) and the trains. RBC generates the correct movement authorities (MA) for the trains. Signal quality of mobile station is affected by signal fading and multipath fading on the wireless channel. Especially, the linear coverage of GSM-R network and frequent handover are two important factors which impact the transmission of train control information. Therefore, to provide the design basis for the construction of GSM-R network and assure the train operation safety at high-speed movement, this paper analyses the quality of service in GSM-R via the aspects of field strength, channel, handover and so on. These aspects of research are as follows:According to the test results of electromagnetic field strength on Beijing-Tianjin high-speed railway, this paper provides an empirical formula by the method of least squares curve fitting based on Okumura-Hata and COST-231-Walfish-Ikegami path loss model. The empirical formula is practical in guiding GSM-R network cell planning and network maintenance.Bit error rate caused by Doppler effect and SNR in multipath channel are analyzed and simulated. Suggestions for the selection of base station sites are also provided.An advanced handover algorithm for GSM-R network is proposed based on the studies of handover process. Handover delay and its impact on CTCS-3 are also analyzed. The algorithm can reduce the handover delay effectively and avoid the ping-pong handover.