The Design And Implementation Of USSD Access Scheme Of CRBT System

Unstructured Supplementary Service Data (USSD) is a new type of data service based on Global System for Mobile Communications (GSM). It is a mechanism to transfer information and instructions between mobile sets and network-side applications, which provides text-based interfaces for mobile users. Compared with Short Message Service (SMS), USSD has advantages of fast response, strong interaction ability and high reliability. With USSD, wireless data srvices can be provided in a fast and convenient way in GSM, and supporting multiple interactions in a session as well.Color Ring Back Tone (CRBT) is a service subscribed by the called party, providinig the calling party with a customized music before he/she answers the call, instead of the traditional dull ring back tone. CRBT can provide different music for different callers.Now there are three access ways to CRBT system: Voice, SMS and Wireless Application Protocol (WAP). But, they all have inevitable defects, which have become a bottle-neck to the growth of CRBT service. It is necessary to develop a novel access scheme to keep CRBT market expanding. Consequently, USSD has become the focus.In this thesis, it is discussed in detail how to design and implement USSD access scheme of CRBT system. And, the discussion is based on a project that deploys Independent Intelligent Peripheral (IIP) platform to provide CRBT service. The structure of this thesis goes as follows.In charter one, the concept of USSD is introduced, together with its three phases. Then USSD services are compared with SMS services. Furthermore, the architecture and framework of USSD are also introduced.Charter two is the introduction of Intelligent Network (IN) and CRBT services. IN Concept Model (INCM) is emphatically recommended. Subsequently, the architecture of Customized Applications for Mobile Network Enhanced Logic (CAMEL) are presented. In the end, CRBT services based on mobile IN are introduced briefly.Charter three is the research on current CRBT system and the requirement analysis for USSD access schemes. The CRBT system based on IIP is firstly described. The structure and implementation of CRBT system is analyzed. Then comparison of the existing access ways of CRBT service is stated. At last, the advantage of USSD access scheme is summarized.Charter four discusses the design and implementation of USSD access scheme of CRBT system. Firstly, it presents the general design, and the design of architecture and USSD Application Daemon (UAPD) use cases. Secondly, the detailed design is illuminated, including UAPD design, Control Node (CN) modification, communication scheme between processes and the load balance algorithm designed for UAPD to dispatch messages to CNs. Finally, the service scripts are implemented and verified.Charter five describes the progress of the project. And future works are discussed.