The Research And Implementation Of S1-MME Interface In LTE Network

With the development of mobile internet, the demand of high-speed data transmissionservice increases very quickly. For further development,3GPP began to work out thestandardization of both radio access network and core network. LTE mainly specifies thedirection of radio access network development and the key technology, while SAE defines thewhole structure of the future core network. LTE/SAE technology improves the mobilenetwork performance and realizes the full IP-based core network. At the same time, its flatnetwork architecture lessens the number of network elements. MME, one of the core networkelements, is the most important signaling processer, and its S1-MME interface is the corecommunication interface in the control plane between E-UTRAN and EPC. S1-MMEinterface transmit the signaling information by S1AP protocol in principal. According to thedemand of the prototype system required by business equipment, this dissertation analyzesand designs an implementation for S1-MME interface in MME, and focuses on the realizationof S1AP protocol functions.This dissertation, firstly, analyzes the network architecture of LTE, the function of MME,SCTP protocol, S1AP protocol, and discusses the basic working principle of S1-MMEinterface. Secondly, it proposes the implementation of S1-MME interface and thecorresponding functions based on the analysis of protocol stack. Meanwhile, it discusses thesoftware implementation combined with the hardware and software architecture of MME.Last but not least, it verifies the feasibility of the implementation through functional tests.According to different kinds of signaling information processing mode, this dissertationproposes two implementations of S1-MME interface. The first one is based on centralizationprocessing mode and the second one is based on distributed processing mode. After someanalysis and comparison, the centralization processing mode is chosen to deal with signalingprocess. In that mode, the signaling information which is received in the S1-MME interface isrepacked as the internal information and stored into the queue. The module of S1-MMEinterface is separated into SCTP sub module and S1AP sub module. This dissertationintensively discusses the software implementation of two sub modules. Finally, series of testcases based on LTE signaling flow are designed for the functional test of S1-MME interface. The test data has been collected and analyzed in detail. The result of the tests shows that thesoftware implementation of S1-MME interface in this dissertation is feasible and practical.