Interoperation programme design and performance test on LTE-M integrated bearing system

For the problem that when the commercial public network of long term evolution (LTE) was used to bear the urban rail transit, the reliability and real-time performance of interoperation crossing core network could not meet the service demands, the service demands of long term evolution for the metro (LTE-M) integrated bearing system were analyzed. The demands of interoperability and the data service connectivity of LTE-M integrated bearing system were put forward. The connectivity operating mechanism of LTE-M integrated bearing system was studied. The method of reliability assurance was designed, including the route reestablishment and failure switch between core networks, and the single plate switch of core network. The interoperation system architecture of LTE-M integrated bearing system was presented. The interoperation test environment for LTE-M integrated bearing system was established in laboratory. The signaling and data were analyzed to verify whether the system meet the application requirements. The hand-off test and route test between core networks, failure switch test of core network, reliability test and interoperability performance test on LTE-M integrated bearing system were conducted. Research result shows that to meet the demands of urban rail trains operating cross-line, it should realize the interoperations among the reference points between LTE-M terminal and base station, between the serving gateway of core network and packet data network gateway, between mobility management entities, and between home subscriber server and mobility management entity. The hand-off time between core networks of LTE-M integrated bearing system is less than 1 s, the route reestablishment time between core networks is less than 1 s, the failure switch time of single plate of core network is less than 2 s, and the failure switch time between core networks is less than 31 s. The transmission delay for LTE-M integrated bearing system interoperability service is less than 0.15 s, and the packet loss rate is less than 1%. When the LTE-M integrated bearing system works at a 10 MHz bandwidth, it can simultaneously transmit one path 100 kb·s^-1 communication based train control service, two path 2 Mb·s^-1 closing circuit TV service and one path 4 Mb·s^-1 passenger information system service. Thus, the interoperation performance of LTE-M integrated bearing system can meet the service demands for the cross-line operation of urban rail transit.