Effect Of GSM-R Handover On CTCS-3 And Model Analysis In High-speed Railway Environment

ABSTRACT:As a special digital mobile communication system designed for railway, GSM-R provides a high safety data transmission for China Train Control System-Level 3. GSM-R is responsible for transmitting two-way train control messages for automatic train control system. So the reliability of GSM-R is directly related to the safety of moving trains. As a key technology of GSM-R system, a hard handoff process may cause a short link interruption accordingly, which might be more frequent as train runs faster. The increasing handover rate may cause a relative high bit error rate and probability of call failures. So the handover failure rate is nevertheless crucial in determine the Quality-of-Service of GSM-R network especially on high-speed railways. Taking all above into consideration, this thesis studies the impact of handover factor on CTCS-3 system, and proposes a reliability analysis model of handover process, as well as the advanced strategy to enhance system reliability, hopefully provide a reference for the future system construction.This thesis deeply analyzes the handover process following two ways, namely the theoretical calculation and the modeling simulation.This thesis studies the impacts of handover processes to CTCS-3, mainly a successful handover to the delay caused by train control message generation, and a failed handover to train delays. Finally, this thesis proposes a reliability model for handover based on Markov model, and a systematic improvement for this model.Based on the analysis above, the innovations of this thesis are listed as follows:First, it is possible to deduct the impact of time delay caused by transmit interference in a successful handover to movement authority in train control system, and then analyze the factors that may affect the delayed time.Second, a failed handover may cause onboard-trackside link expires in train control system. By comparing train deceleration after link expired and train acceleration after link re-established, it is possible to calculate related delay time of trains by specific scenarios and typical parameters.Third, this thesis proposes a handover reliability analysis model through MATLAB simulations under 250km/h,350km/h,500km/h speeds, which further verify the relation between handover reliability and train speeds.Last, this thesis proposes a related solution to improve handover reliability, that is, to adopt dual-terminal radio station instead of single terminal radio station, and then evaluates this improved solution.