Key Technology And System Realization Of VoLTE-SMSC Under High-Loading

As the 5G era approaches,the short message business system is migrating to the packet-switched network.China Telecom’s SMSC(Short Message Service Center)system is facing construction of evolution from CDMA(Code Division Multiple Access)to VoLTE(Voice over Long-Term Evolution)system.Compared with the CDMASMSC,the VoLTE-SMSC has to face unprecedented high-loading pressure in terms of system,specification,and business.In this case,the technical performance of the original CDMA-SMSC is not sufficient to deal with this situation.In this paper,the three high-loading technical problems faced in the VoLTE-SMSC construction project were solved separately,and the overall system design and development were realized.The main work includes the following four parts:(1)The massive concurrent user ownership query process in the VoLTE system is based on the DNS protocol over UDP.Due to the unreliability of UDP,it is impossible to detect DNS query failures caused by external faults in real time.Therefore,there is a systematic defect what a large number of short messages cannot be delivered by this situation.This paper uses the ordinary least squares method to design and implement a curve fitting algorithm and optimize it.This method is used to fit the curve function with real-time statistical response rate data for predicting future values.And then,a mechanism is designed to determine the fault tendency based on the predicted response rate data,and then to avoid the fault by the distributing load strategy,and verify its effectiveness.(2)Because the VoLTE short message protocol specification requires all user terminals to periodically send a registered message for notifying the online status,a huge amount of registered messages continue to flood into SMSC,causing serious system load.This paper applies Redis as a cache to this massive data processing scene.And based on the principle of Redis data structure to make storage optimization,use pipeline characteristics to improve performance,and analyze the optimal configuration scheme of data persistence and other parameters.Finally,the performance of the scheme was verified and compared using simulated real data under various conditions and framework.(3)According to the business requirement of the real-time control and filter largescale group-send messsage through gateway by similarity strategy,introduce the similarity calculation based on the Levinstein distance.And use the dynamic programming idea to design the algorithm of realization.According to the high-loading characteristics of large-scale group-send data sources and large-scale samples,for great optimizing the dynamic programming process,introduce the early exit matrix mechanism.Finally constructing and implementing the similarity discrimination strategy based on this algorithm.(4)On the basis of solving the above three main key points of high-loading,inherit the inherent business through the converged framework,develop the protocol stack of the VoLTE-related communication protocol,and realize the specific process and business requirements of the China Telecom’s VoLTE short message business in SMSC,construct the development plan of VoLTE-SMSC.Based on the above technical solutions,this paper successfully solved the technical difficulties faced by VoLTE-SMSC construction under high-loading,and realized the development of all system based on software engineering specifications.The system passed the network access test of China Telecom Research Institute with high standards,and was successfully put into working in four provinces including Fujian.