The Design And Implementation For DMR Direct Mode In Intercom

DMR (Digital Mobile Radio) is the latest narrow-band digital trunkingcommunication system which is published by ETSI(European TelecommunicationsStandards Institute) in2006. Compared with the previous TETRA and iDEN digitaltrunking systems, DMR is simpler, shorter switching time, higher error correctioncapability and better confidentiality so that it is widely used in communicationdispatching in public affairs security, public transportation and other emergencycircumstances.This thesis mainly focuses on DMR protocol implementation and direct-mode callestablishment based on trunking intercom. OMAP-L138released by TI(TexasInstrument) is the main processor for trunking intercom platform. It is a dual-coreprocessor with low power consumption which combines the advantages of both ARMand DSP with powerful and convenient software development kit.This thesis firstly introduces current development of digital trunking system, basicadvantages of DMR and background of the thesis. Then it analyses some criticaltechnology of DMR protocol in direct mode including the basic protocol architecture,burst and channel structures, voice timing, channel access standards, some PDU andsignaling definition. And it introduces the structure of OMAP-L138and itsestablishment of the embedded software developing environment for intercom platform.What is more, it analyses the implementation of each DMR protocol layer includingsome API functions for information exchange between PL an DLL, DLL and CCLmessage communication, PDU formation and analysis, high state transition, channelaccess and so on. Finally, this thesis introduces the simulation about DMR direct modeon the intercom baseband board and finishes the voice call by using the intercom.