Interface Signaling Simulation And Inter-Cell Interference Coordination (ICIC) Scheme For LTE System

LTE is a wireless broadband technology designed to support high data rate service. The interfaces have been standardized, which allow terminals from different vendors to interoperate in LTE network. Therefore, the protocol conformance testing is needed to ensure product performance, which is much significant to LTE deployment. The interactive simulation platform of LTE S1and X2interface signaling has been implemented by TTCN3language, protocol conformance testing can easily be taken once the eNB is connected to this simulation platform. The author finds that the SFR ICIC scheme can be improved by improving X2-AP message exchange. Based on this, an improved SFR ICIC scheme is proposed in this thesis.The protocol stack and application protocol procedures of LTE S1and X2interface have been emphatically analyzed in this thesis. The eNB and MME simulators are established by TTCN3respectively, then, S1and X2interfaces signaling interaction is achieved using test cases. The protocol conformance testing has been carried out by simulation platform connected to eNB. Meanwhile, a C/C++version simulation platform is established, which has achieved the simulation of signaling interaction.In the process of protocol analysis and conformance testing, the author finds that adjacent eNBs can share resource allocation information by adding information element to LOAD INFORMATION message. In SFR scheme, the new accessed cell-edge users will increase the power ratio, when the cell-edge users are saturated, and the new accessed inner-cell users will be allocated with primary sub-carriers, resulting in wasting of power. To solve those problems, an SFR improvement scheme based on the X2interface is proposed in this thesis. On the condition that the cell-edge users are saturated and the new accessed cell-edge users are less than the defined threshold, the new accessed cell-edge user will be allocated with suitable second sub-carriers, and when the cell-center users are saturated and the new accessed cell-center users are more than the defined threshold. The system will reduce the power ratio respectively. The added signaling message is designed and the ASN.l description is given. The proposed scheme can improve cell-edge users’throughput, compared with SFR scheme.Finally, a simulation model is established in Matlab, on which the performance of FFR and SFR ICIC scheme is analyzed. According to the simulation results, the FFR scheme shows a better performance when the users are uniformly distributed and the SFR scheme can provide a better performance when the users are distributed non-uniformly. Based on the results attained above, the author suggests that FFR and SFR could be used in uniformly distributed and non-uniformly distributed scenarios respectively.