The Analysis And Design Of The Internet Short Message Gateway

In GSM network, point-to-point short message service supports message transmission without traffic channel (TCH) for mobile subscribers. Now the service application is very extensive due to low costs and convenient usage. On the other hand, Internet service develops swiftly, and information resources are very rich. In order to make mobile subscriber share these rich resources, implementing communication between GSM and Internet is the first problem. Internet short message gateway (ISMG) is just a kernel entity to resolve it, which lies between two networks and is responsible for transferring, inspecting and recording message. So, with increasing of users and information, the performance of ISMG is the key factor of Internet short message application.According to Monternet Short Message Service Signaling Flow Specification, Linux C language is adopted to implement ISMG software system in this thesis. Capacity and expansibility have also been resolved to enhance the performance of ISMG with emphasis.This thesis first discusses Short Message Transmission Protocol which is used for sending and receiving short messages in PLMN, especially analyzes two protocols related to ISMG: CMPP (used to access GSM network) and SMPP (used to access Internet network). Then the functions of ISMG are confirmed, namely protocol conversion, routing, store-and-forward, feeing and so on. Finally according to Short Message Service Signaling Flow Specification, this thesis focuses on thedesign of the software structure, which completes ISMG basic functions. This gateway software consists of five parts as follows: package handling module, communication agent module, routing module, store-and-forward module and feeing module. Package handling module (package_server) is responsible for assigning all received messages, which can advance real time capability; communication agent module (sp_agent & smc_agent) is responsible for communicating with external entities, but doesn't identify message contents, which can lighten burden of Package handling module; store-and-forward module (store_server) completes store-and-forward mechanism by setting up timer, and implements overtime retransferring and failure handling; routing module (route_server) is responsible for maintaining the links with the other ISMGs to implement routing; feeing module only consists of some functions which can be called to record message items. All modules (except feeing module) communicate with each other by queue flat, which can enhance expansibility of software. In a word, the software design resolves capacity and expansibility of ISMG well. Finally, the thesis also points to some aspects need to be improved in the software system.