Design And Implementation Of Call Handling Of AP Part Of A New BSS

As the the most important equipment of mobile communication system, base station is undergoing profound changes. Based on the GSM system and referenced the design idea of soft base station, the paper gives the solution of a new BSS. The two parts of the new BSS, AC and AP, are adopted the master-slave structure. The equipments of new BSS and transport network all use IP technique. The new BSS accords with modularization, IP and distribution development trend of base station.The paper firstly addresses the system structure, interface and layered protocol model of traditional BSS of GSM. Secondly, this paper discusses the structure and features of the new BSS, carries through research on the AP and its software architecture and points that call handling is the core traffic of AP traffic application subsystem. Third, based on the function of traffic application of AP, it divides traffic application into six modules, and then discusses the interfaces and communication signaling of each module related to call handling at detail. Fourth, this paper analyzes the message flow and adopts the method of transferring call information from master AP to slave AP to complete the establishment of call setup. Then, it explains the the reasons for the occurrence of exceptions in message flow and then discusses the handling of two typically exceptions. Fifth, this paper gives the model of finite state machine of call handling, and in the design process of finite state machine, it simplifies the finite state machine by summarizing the exceptions as four cases of exceptions. At last, the paper gives the design of key data structure of the call handling.Tests indicate that call handling can complete the whole process of call, and in the situation of exception, it can perform the correct exception handling flow and releases the channels.