The Design And Realization On DMR Terminal’s Data Link Layer In Derect Mode

DMR is the standard of digital trunking communication system proposed byEuropean Telecommunications Standards Institute in2005. It is compatible with analogtrunking communication system and has the very high spectral efficiency. It is mainlyused in the production dispatching and command etc. Now it has been widelyrecognized by the global communications industry.At present, DMR research is already very mature, but there are still the followingproblems:(1) Channel coding gain is low. DMR data link layer and physical layer both arebased on DSP platform, which leads to lack of resoureces. The selection of thedecoding algorithm needs to be a compromise between resources andperformance.(2) Interface design reusability is low. The DMR radio interface design is closelyrelated to hardware platform. So it is necessary to design different communicationinterface for the specific platform.For this purpose, considering the practical application of DMR, the paper proposesthe demand and designs channel code algorithm, software architecture and interferencefor DMR data link layer of direct mode based on the DSP platform.First, the paper researches channel coding of DMR data link layer. In derect mode,the main algorithm includes: Goaly code, Reed-Solomon code and Turbo product code.Through researching decoding performance and complexity, selecting decodingalgorithm, simulating the algorithm, finally, channel coding gain is consistent withtheory and it can be use to implement.Second, the paper builds DMR data link layer software architecture. Based on DSPkernel in TI DM3730chip, the paper designs voice communication process and moduleinterference; ensure that DMR terminal has a clear a structure and high work effiency.Third, the paper verifies that DMR data link layer software architechure is rationaland roburst. Based on the ultrashort communication platform the hardware teamdeveloped, the data link layer software architecture, module interface as well aspoint-to-point communication scenario test shows that the design of the data link layerto achieve the desired objective.In this thesis, it offers a solution for DMR data link layer design in direct mode. Thefinally obtained DMR terminal has theoretical and practical value. It can keepcommunicating in other network unavailable or poor.