Design And Implementation Of RLC Layer Protocol Software Under TD-LTE Broadband Wireless Trunking

With the rapid development of information technology, people has a more profound understanding of trunking communication system(TCS), the role of TCS is also more and more attentioned. TCS plays an important role in the emergency command, coordinate production and other related fields, which can explain why governments are increasingly backing up it, thus making researment on TCS in the school and related social research institutes more and more popluar. The existing narrowband trunking communication system(NTCS) is relatively backward in the data transmission capacity and broadband multimedia services; it is difficult to meet the needs of high-speed data services and multimedia services, which makes TCS develop towards the direction of broadband. Broadband trunking communication system(BTCS) can be based on different broadband wireless communication technology. Compared with other technologies, TD-LTE has greatly improved data transmission rates and spectral efficiency. So it has more obvious advantages for BTCS based on TD-LTE technology.BTCS has a high demand on the air interface data rates and reliability, and air interface data transfer is mainly managed by the radio link control functions which achieved through RLC layer in the TD-LTE air interface protocols. Through analyzing and researching on RLC protocol, this paper completed the RLC layer protocol software design and implementation, including AM, UM, TM three data transmission modes, and interface to interacting with other layers, and carried on integration testing with other layers on the board AMC719.In chapter 1, the application, research backround and research significance of BTCS are first introduced, then,the main work of the author and the structure of the thesis are described in detail.In chapter 2, the related basic technologies of BTCS are introduced. First, the overall architecture, control plane and user plane protocol stack of BTCS based on TD-LTE are analyzed. Then, RLC protocol and protocol development tool fsmdevkit are detailed descripted.In chapter 3, the RLC protocol software is designed, which is devided into four areas: state machine design, interface design, module design and process design. The purpose of the state machine design is to divide RLC layer state, to define the type of event and to give the state transition condition, and it is the basis for the entire RLC layer functions. Interfaces designed to work with other layers of the protocol stack, including interactive way and interactive message format between layers in the protocol stack. RLC are devided into different modules,through the interaction between the modules to complete the function of RLC. According to RLC protocol, RLC common management module and RLC entity control module are designed. The common manage module mainly completes the control plane signaling function, and entity control module, including AM, UM and TM sub-modules, selectes sub-module to complete data transmission based on data service; and process design is to organize different modules together to achieve different modes of data transfer in accordance with the protocol.In chapter 4, the RLC protocol software is implemented, including the realization of the overall process, primitive processing implementation, data transfer process implementation and impotant functions implementation. The overall process implementation reflects data interactive between each module, while the primitive processing implementation is to achieve the appropriate handler based on primitive functions. RLC layer data transmission is the most important process and is the most complex in the implementation. So the implementation of important functions in the AM data transfer mode is introduced, including segmentation and concatenation, resegment, reassemble and retransmission which are simplified in realization.In chapter 5, The testing of RLC protocol software consist of two phases: in the first phase, RLC module is individually tested on the PC virtual machine, to verify RLC each performance function and the correctness of the overall process; in the second phase, RLC module is tested with other layers software on the board AMC719, to verify whether data interaction between each layer software, RLC software functions and stability meet requirements.Finally, this dissertation is summarized in Chapter 6. Possible work direction in the future is also discussed.