| The Long Term Evolution-Advanced Pro(LTE-A Pro)system is proposed to protect infrastructure investment of the 4th generation mobile communication system and create more business opportunity.At the same time,in order to smoothly evolve to the 5th generation mobile communication(5G)system,new technologies such as Narrow Band Internet of Things(NB-IoT)and authorized access assistant are introduced in LTE-A Pro system,which help to facilitate backward compatibility with some of the requirements of 5G systems.Based on the application scenarios of LTE-A and NB-IoT in the Release 13 protocol,and relied on the research projects ?Key Technologies for LTE-A Multi-Base Station Load and Capacity Testing? and Chongqing Science and Technology Commission Key R&D Project ?Development and Application of 5G Terminal Analog Devices?,a testing terminal device for simulating multi users to test the maximum capacity and performance of the network was proposed.In the environment of multi-users,one device to deal with multi-users,in other word,to deal with different communication scenario,an efficient design and implication of Medium Access Control(MAC)layer is far-reaching for the data transmission and the development of LTE-A Pro and next generation communication system.Moreover,the research and application of emerging things is beneficial for maturing.A detailed design and implication of MAC of terminal protocol stack was presented and applied in practical.The main research contents as follows: random access process,multiplexing and demultiplexing of MAC protocol data unit process,and Hybrid Automatic Repeat Request(HARQ)process.In the design part,at the first place,according to the interface between layers and the communication scenarios of LTE-A Pro and NB-IoT,a primitive mechanism was designed to lay the foundation for inter-layer communication.Secondly,based on the research and advantages of state machines,relative states and trigger events were designed,which can efficiently handle the late messages.Finally,random access process,channel multiplexing process,and communication process of the HARQ process were designed,and the data retransmission mechanism was designed between physical layer and MAC to mitigate the unnecessary delay when data transmit to the physical layer.Based on the project requirement and goal,the multi-core digital signal processing(DSP)was selected and used as the development platform,and the overall distribution of the protocol stack in the project was designed.In the implication,integrated into the design of MAC layer,the relevant process of the MAC layer was implemented by using the C language on the multi-core DSP development platform.In addition,the correlative course of MAC was interpreted by function of C in detail.Whether the proposed scheme correspond with the consistency of protocols needs to be verified through multiple rounds of testing.Therefore,based on the development platform,a single-layer testing was performed through the interacting interface between layers by communication primitives.By designing a variety of test cases,and repeating 50 times for each test case,the correctness of the design process and code was verified as well as the consistency of the protocol.The results of testing show that the implemented code is applied to the project requirement and satisfied with the consistency of protocols. |
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