| Large-scale network test and business case shows that the emergent task which lies in front of the TD-SCDMA industry chain is to improve the current construction on the network equipment. Being the necessary part of radio access network, the base station's performance has a direct impact on network coverage and system capacity; as a logical connection between the base station and RNC, Iub interface is applied to transfer the signaling and data. Therefore, the designing of Iub protocol software is the focus that affects the Node B's R&D and network performance and also the study and discussion point of this paper.TD-SCDMA, with technical features embodied in the physical layer, followed the same standards with WCDMA in the core network. The Radio Access Network is composed of RNC (Radio Network Controller) and Node B, while RNC is responsible for radio resource management and Node B is used to transfer the signaling and data with RNC through the Iub interface. This paper, based on the survey of TD-SCDMA network infrastructure and the analysis of network development status, expatiates the significance of Node B's R&D in improving the construction on the network equipment and the worth of designing Iub software.The outline of TD-SCDMA air interface protocol stack is introduced in the second section of this paper and the logical structure and protocol level of Node B is proposed in sequence. Then in accordance with the Release 5 Iub protocol issued by 3GPP and the communicational technique standard promulgated by MII (Ministry of Information Industry) of PRC in the year 2006, the function of Iub interface which contains the NBAP signaling protocol and frame protocol is summarized for the designing requirement of Iub protocol software.According to the feature of Iub interface, the schemes of Iub protocol software designing and FAP module implementation is proposed based on the PowerPC Linux embedded operating system. FAP module is used to parse the NBAP signaling and manage the internal resources, then handle and transfer the up-link and down-link FP datagram with signaling parameters. The detailed design of FAP module includes classified missions, operation flows, data structures and implementations of Iub interface's pivotal technologies.Catapult DCT2000?, the core product of Catapult which is the world's leading company of communicational test instruments, is widely applied in communication systems test. In this paper, based on the parameters of 64 kbps packet service and the process of radio resource control for dedicated channel, the scheme for testing Iub software in Node B is proposed while Catapult DCT2000? is treated as external test equipment. The test result shows that FAP, one of the modules of the Iub protocol software, implements the function of Iub interface between Node B and RNC in the radio access network, and is qualified for the demand of project design. Finally, PowerPC Linux operating system concerned in this paper can be used on other hardware platforms. In Iub protocol software designing, the multi-task mechanism, pattern of signaling interaction, process of data operation and scheme of software testing can be used for reference in the development of multi-task software, which runs on the embedded real-time operating system. |
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