Design And Implementation Of Idle State Of RRC In NB-IoT Terminal System

As a role that leads LTE to the The 5th Generation mobile communication(5G)communication massive Machine Type of Communication(m-MTC)scenario,Narrowband Internet of Things(NB-IoT)technology has drawn extensive attention from academia and industry,and the industry chain has been gradually maturing.In the meantime,the NB-IoT user terminal camps on the cell,receives the network message and responds,and quickly accesses the network,which is an important process for improving the performance of the NB-IoT user terminal.As the control center of the entire protocol stack,the RRC layer plays an important role in the development of the terminal protocol stack,and the functional characteristics of the terminal in the idle state are prerequisites for the terminal communication to be realized.Therefore,the RRC idle state of the NB-IoT terminal system was taken as the main research content,so as to ensure that the designed and implemented Radio Resource Contral(RRC)idle state of the terminal system meets the requirements of international standards.Chongqing's major industry theme project “Development and application of NB-IoT terminal of SOC” werer relied on to carry out related functions of RRC layer idle mode of NB-IoT terminal system.Research,design,implementation and testing work was done.Specific research work and innovations are as follows.1.Based on the research of NB-IoT network architecture and RRC idle state,the overall design scheme of RRC idle state of NB-IoT terminal system is proposed.Based on the function of 3GPP protocol RRC idle state and the characteristics of NB-IoT system,the Functional process design of RRC idle state is proposed.Since NB-IoT uses the ASN.1 coding scheme independent of LTE,the design of the NB-IoT terminal system ASN.1 decoding module is proposed for the RRC idle state function.At the same time,in order to increase the efficiency and stability of the NB-IoT terminal system operation,a timer design scheme is proposed.2.According to the overall design scheme,the implementation of inter-layer primitives and state machine laid the functional realization of RRC idle state.According to the design of the timer,the timer is implemented by using multi-threading and C language function library,and the implemented timer can be generally used for development of each layer of the protocol stack.According to the design of the decoding module of the NB-IoT terminal system ASN.1,the ASN.1 decoding module is implemented by bit operation and big endian mode.According to the flow design of each function of the RRC idle state and the above implementation,various functions of the RRC idle state are implemented.3.Based on the process design,the code implemented was validated and the outputs were analyzed.By designing test cases,and test execution,it is verified that the designed and implemented RRC idle state of the NB-IoT terminal system is reasonable and feasible.Additionally,by executing 64 test cases,the 100% test case pass rate indicates that the correct decoding of the implemented ASN.1 decoding module,the stability of the timer operation and the designed RRC idle state of the NB-IoT terminal system meets the protocol requirements and satisfies the protocol conformance.