Research And Development Of Logic Link Control Protocol Layer For Basic Link In TETRA Digital Trunked System

TETRA digital trunked systems provide secure, reliable and efficient voice and data communications. They are being widely used in many countries around the world. So far, the TETRA digital trunked systems used in China are all made by foreign manufactures. They are too expensive and threatening our National Security. Therefore, it is very important to develop TETRA digital trunked system with our own independent intellectual property right.Logic Link Control (LLC) protocol layer is one of the most important part of TETRA digital trunked system protocol stack, and it shall handle the point-to-point logical links between the Mobile Station and the Base Station. It provides two different services called Basic Link and Advanced Link. Basic Link is used to transmit basic signalling messages in TETRA digital trunked system. Advanced Link offers a high grade of service, especially for packet data transfer. Therefore, the development of LLC protocol layer for Basic Link is the key of the development of protocol stack in TETRA digital trunked system.The thesis summarizes the technology characteristics of TETRA digital trunked system and its developing situation at home and abroad. Based on analysing TETRA digital trunked air interface protocol stack, the functions of Basic Link in LLC protocol layer, such as exchanging of controlling messages and user data with MLE, handling of logical links, scheduling of data transmission, re-transmissions, error measurement and acknowledgement of received data are researched. The developing languages, tools and method are given after analyzing and comparing several methods. Based on Telelogic Tau G2 integrated development environment, the acknowledged data transmission and unacknowledged data transmission services of Basic Link in LLC protocol layer are implemented by using UML, SDL and C languages, and the protocol conformance tests are made. The test results are in accordance with "ETS 300 392-2 TETRA V+D Part 2: Air Interface " and satisfy the design requirement completely.