Design And Implementation On Dispatching Station Of Digital Trunking System

TETRA digital trunking system is famous for its dispatching functionalities. As an important part of TETRA system, the dispatching station provides an operation platform for dispatchers to efficiently command and control people. It has a significant impact in the development and application of TETRA system to design a feature-rich, reliable and user friendly dispatching station software. This paper undertakes a research on control center and dispatching station and presents a practical software design solution against the background of the development of digital trunking experimental system.With the development of Internet Protocol and multimedia technology, TETRA has been in the transition from circuit switch to packet switch and TETRA over IP becomes the mainstream solution. TETRA over IP uses IP to connect TETRA units; moreover, traffic, signalling and network management data are carried over IP links. On contrast against conventional TETRA system, the network architecture and benefits of TETRA over IP system are analyzed.This paper presents a dispatching station project based on TETRA over IP. The station is a multimedia PC and access to TETRA network via LAN or WAN. The dispatcher dispatches people in his organization with the software running on the station. In the design of its profile management, the dispatcher subscriber identity and relative profile is assigned according to the username. The concept of dispatch server is introduced and the complicated signalling and data processing of the TETRA system is progressing in it. This will simplify the software design and be capable of further development. The software communicates with the dispatch server via a set of interface functions. The sequence charts of the commanding and dispatching services, such as call control, monitoring, short messages are given referring to TETRA air interface protocol.The software is modular design and written in Delphi. The function implement of the software is described in terms of instances. The dispatching station software is validated and accord with the design target of the paper.