Analysis about impact of GSM-R cell handoff on data transfer delay in China Train Control System

China Train Control System level 3 (CTCS-3) transmits bi-directional track-train data via Global System Mobile for Railway (GSM-R) network, and GSM-R network should provide secure wireless environment to ensure train operation safety. GSM-R network handoff will cause a brief interruption of communication. If a train control message is on transmission during this interruption time, some message data units may be erroneously transmitted during the transmission interference and must be corrected by re-transmission. These re-transmissions result in a delay. This paper analysis´s the message transfer mechanism, summarizes some factors influence on the message of Movement Authority (MA) transfer delay during a handoff interference, obtains values of transfer delay of MA affected by handoff, and at last verifies that recovery period of GSM-R network required in QoS specification can meet the needs of train control data transmission.