Implementation And Research On Radio Link Control Protocol In TD-SCDMA

Nowdays, TD-SCDMA system has been deployed massively across China, but CPU processing power faces great challenges as the evolution of products standard. The latest Tile many-core CPU chip provided by Tilera with its high performance, low power and flexibility can provide onesite integrated solutions, which causes power consumption and cost of contemporary base station multi systems reduce greatly. The Tile processors are programmed in ANSI standard C and C++, which achieves the performance of an ASIC in a software-programmable solution.In protocol stacks of TD-SCDMA system, Radio Link Control sublayer stands on top of Media Access Control sublayer to provide reliable data transmissions over the radio link. Radio Link Control provides a flexible and adaptive approach in order to operate in different radio environments and for various applications. The Radio Link Control consists of three entity types: Transparent Mode(TM), Unacknowledged Mode(UM) and Acknowledged Mode(AM).The Radio Link Control protocol is implemented on Tilera many-core system. Radio Link Control platform which is designed for many-core processor Tilera based Linux operating system, combines the features of Tilera many-core processors. Triple tuple and ring buffer data structures in VxWorks are ported to the platform. The introduction of triple tuple reduces the frequency of copies of data, and significantly improves network efficiency. The use of ring buffer, enables implementation of interprocessor communication via ring buffer. The platform provides foundation of Radio Link Control protocol, which implements three entity modules: Transparent Mode module, Unacknowledged Mode module and Acknowledged Mode module. The Transparent Mode module and Unacknowledged Mode module can be configured into transmitting entity or receiving entity, while Acknowledged Mode module is a transmitting and receiving combined entity. The design ideas of three entity modes are discussed in detail, and a more detailed flow chart and block diagram have been shown.Software testing is an essential part of software development process, which is of importance for guaranteeing software quality and reliability. Based on software architecture design, many test cases have been designed so far, and depict the testing procedure in detail. Branch coverage and path coverage belonging to while-box testing methods are performed respectively, and based on which the unit testing, integration testing, system testing are completed. Finally, based on test cases and running results, the protocol performance is analyzed.