Research On The Interoperability Testing For The Safety Communication Protocol Of Train Control System Based On TTCN-3

In recent years, there has been vigorous development for high-speed railway in China, with the advantages of high speed, better safety, large transport volume, low pollution and so on. Currently, CTCS-3(Chinese Train Control System level3) train control system, used by Chinese high-speed railway, is a safety-critical system and relies on a large-capacity transmission system for data transmission. Railway Signal Safety Protocol-I (RSSP-I) is made by Ministry of Railways and used as a safety data transmission protocol for the high-speed railway, it is an effective means to ensure the transmission of the real-time safety data between the related railway signal safety equipments and plays a vital role in ensuring the safety of the train running control system. Therefore, before the protocol implementation is put into use, it's necessary to test it completely.Among the protocol testing, the interoperability testing is to check whether the protocol implementations of the same protocol or the same type protocol can interoperate correctly to provide the desired service. Since most of the protocols are described in nature language with selectable options, and the conformance testing can not be exhaustive, it is of great significance to take the interoperability testing. So this paper researches on the interoperability testing of the safety communication protocol in the train control system, using RSSP-1as an example.For interoperability testing, its process is divided into three phases:test generation, test realization and test execution. Test generation is the generation of interoperability test sequence, this paper analyzed the states and the events of RSSP-I, built the finite state machine models for RSSP-I sending party and receiving party, then made the description and validation for them using SDL, then generated the test sequence. For test realization, this paper introduced the standard test language TTCN-3, set up the interoperability testing system and realized the components of the system, then described the test sequence. Finally this paper ran the test system, executed the test sequence, got and analyzed the message sequence chart and test log.The interoperability testing system based on TTCN-3has a good capacity of test configuration and test description, and it can make the entire testing process clear and in order. In addition, the testing process can be reflected in the MSC diagram and test log, which makes the test process visible, so we can understand the test behaviors described well. Also the MSC and test log provide the detailed data support for the debugging and testing of the test platform, which can make the test result available, so the entire test activity gets a good result and realizes the desired test objectives.