Research On Handover Failure And Optimization Of GSM-R Network

Dedicated communication system for railway~GSM-R plays a more and more important role in the development of the railway and is directing the railway communication. As the basic technology, handover is the important matter of radio resource management and is the essential requirement in wireless engineering, network deployment and optimization. Moreover, different from public mobile network, GSM-R network requires higher reliability and safety. So severe rules will be required in handover realization and optimization.The paper researches on the normal handover process and sumarizes the signaling flow on each interface. According to the stages of handover process, six categories of handover failure situations are analysed with the optimization methods in the duration of engineering operation discussed.Because of the linear coverage for railway, there are only two neighbor cells under single layer coverage in handover process. If the running direction of the train is known, the target cell BCCH list can be simplifyed. Then the Ping-pong handover can be avoided and this method can improve the efficiency and makes sure the handover reliability. Three methods of judging the train running direction are introduced:running function nunber discriminance, BSC handover record statistical discriminance and Doppler shift discriminance.Last, lots of timers are working in handover communication process, the paper analyses the setting rules and propositional values of these timers. Specially, the radio link timeout timer ralated to maintaining and releasing radio resource and is applied in DaQin and Tibet lines.So, the paper calculates the appropriate range of the RLTO timer value according to the special use in practice.