The Research On Interoperability Test Of LTE-M System With Integrated Services

With the rapid development of urban rail transit,the train speed becomes higher.More stable and reliable technology is required by the train-ground communication system.As a new generation wireless communication technology of urban rail transit communications system,LTE-M for train-ground communication systems is gradually studied by many research groups.In order to verify whether the LTE-M can meet the needs of urban rail transit business,an indoor testing environment is set up.The features of the LTE-M system are the ability to transmit integrated services while guaranteeing the reliable transmission of CBTC service.In addition,in order to achieve the cross-line/parallel operation among different subway lines in the same city or region,the interoperability of LTE-M system in different lines is required.The test cases of LTE-M system are designed according to the field test,however,they are lack of the support of the theoretical methods.In this paper,we study the testing methods of LTE-M with integrated services,and the interoperability between LTE-M systems.The specific research contents of the thesis are as follows.(1)In order to simulate the real wave propagation environment and different services,the detailed analysis of the channel fading model and the service models are given.(2)A simulative environment of radio waves based on the wave propagation model is established in the laboratory.Moreover,the receive signal level collected in the laboratory test and in the field test are compared and analyzed.(3)The test methods of LTE-M interoperation are studied.In this paper,we describe two methods to generate test cases.One is Equivalence Class Division and the other is generating interoperability test set by Finite State Machine.Then,the combined finite state machine is presented based on the Finite State Machine.First,we use the formal method to establish a combined finite state machine model.Then,a test suite of NAS layer interoperability is generated based on the method of generating test cases by combined finite state machine.The results show that the communication environment can be simulated accurately by COST231-HATA model and the ITU-VA model.The RSRP values tested in the laboratory and the RSRP values collected in the field are basically the same.There are two methods of generating LTE-M interconnection test cases presented in this paper.The Equivalence Class Division method can be applied to all black box tests,but the function cannot be covered completely.Combined Finite State Machine can do a comprehensive coverage of the test cases.We can follow the test case generation algorithm to generate test cases.