Design And Implementation Of The Terminal RRC Layer Protocol Software In LTE

With the third-generation (3G) mobile communication technology put into a wide range of worldwide business, and the growing of 3G users, wireless broadband multimedia and data services grow faster and faster.3G wireless communications turn our life to digitization and broadband, while also facing a big test, in order to meet the bandwidth needs of the new situation,3GPP started the largest R&D projects in recent years-the long term evolution (LTE)of wireless access technology, the target is to evolve smoothly from 3G wireless communications network to the next generation 4G.Compared with the 3G, LTE has a higher peak data rates which can reach uplink 50Mb/s, downlink 100Mb/s,supports bandwidth of less than 5MHz and the highest 20MHz,reduce network delays, increases cell edge bit rate, increases system Capacity, addresses the problem of cell edge coverage, also have good compatibility with 2G and 3G. LTE has been supported by service operators and equipment suppliers all over the world.LTE aims to provide the network with compatibility, which means that radio resource management issues are more important. RRC layer is the main body of radio resource management, according to different scenarios RRC provide different software controlling processes, such as allocation of radio bearer, managing mobility of UE and ENB and the UE accession of control,to balance the system load, use the resources rationally and provide quality Services.The main contents of the system is the design and implementation of the RRC layer protocol software in LTE. The goal is to achieve the main signaling procedure of RRC software on control plane so that protocol software can be integrated with other software of wireless access network control plane, in the procedure RRC does management of the lower layers. Software design is divided into module design, data structure design and procedure design.According to the functions of RRC and interactions of different objects, the module is divided into seven parts, three of which called User's Equipment Center (UE-CENTER) module, the Mobility module (MOBILITY), the System Information module (SYSTEM-INFO) are Core module. UE-CENTER is mainly responsible for the establishment rebuilding, modification, and delete of the radio bearer, processing paging message and configuration of the security algorithms; MOBILITY is responsible for managing measurement procedure in both idle and connection mode, mobility management in idle code, such as cell selection and re-election; SYSTEM-INFO is responsible for controlling, receiving and storage of the system information.Data structure design primarily follow the principles of easy to store, use, maintain and extend. Including system information, logos and the map of other network element, and the design of the public context and primitives used between layers.Call setup,the typical procedure of communication, includes tow main processes-calling and being called including four key functional processes, the RRC connection establishment, RRC connection re-establishment, Paging and Receiving System Information.They fully reflect control function of the RRC layer.In the part of implement, design the four control message interaction procedure in detail, draw a complete message sequence Chart, define the context data structure, public message body, layer primitives, describe in detail the process of dealing with the function.In the main phase of subsystem integration, design normal and abnormal cases to test the fault tolerance and implementation of the software. The test results show that the software can achieve the requirements of the functional design, the implementation of the RRC protocol software is completed.