ETC系统中DSRC协议软件的设计与实现

发布时间：2018-04-20 12:58

本文选题：DSRC协议 + OBU　；参考：《电子科技大学》2014年硕士论文

【摘要】：欧美、日本在上个世纪九十年代已经开始研发电子收费系统。我国在21世纪初开始研究专用短程通信协议,并在2007年正式发布,它统一了RSU与OBU之间的通信规则。国内很多研究单位主要致力于三方面的开发:RSU设备、OBU设备、DSRC协议开发。本文按照国标GB\T20851,对DSRC协议进行了软件实现。目的是实现协议功能、提高交易效率、缩减通信时间。本文基于arm+linux的平台。分别对物理层、数据链路层、应用层及设备应用层进行了设计与实现。物理层主要由射频芯片BK5823实现的,这里BK5823的驱动以模块的形式加载到linux内核中。由于DSRC协议是不对称协议,即实现通信的两端软件不一致。数据链路层在RSU与OBU的实现方式不一样。RSU中通过一个状态机实现,这个状态机有3个状态,十几种事件。OBU端的状态机只有1种状态,它是一个被动设备。数据链路层的设计参考了停止等待协议。在数据链路层中,利用了hash表作为存储帧的数据结构,同时利用linux的众多机制(异步通知、内存分配、中断上下部等)保证了通信的实时性。应用层中T-KE设计最主要包括编码解码、分段并段等功能。应用层使用ASN.1抽象语言描述的,这里使用eclipse插件来作为ASN.1编译器。这样可以将ASN.1结构映射为C语言结构体。利用PER编解码库实现C语言到比特流的转换。分段、并段的功能设计思想参考了TCP\IP协议中的分片、重组的思想。I-KE层设计了两个状态机。RSU端四个状态的状态机完成了I-KE层的功能,而OBU端状态机也有三种状态。这部分完成了DSRC协议“握手”的过程。应用层实现了B-KE的接口功能。设备应用层主要是设计ICC卡和PSAM模块。这里使用握奇公司的TimeCOS卡作为ICC卡和PSAM。使用ISO7816协议对TimeCOS卡进行操作。建立了ETC的应用文件夹、实现了安全传输功能。利用访问许可、信息鉴别、密文传输三种方式实现了安全传输功能。最后对每个模块进行了测试。分别对RSU模块、OBU模块、安全传输模块等进行了测试。模块测试时,测试用例分别使用正常帧和非正常帧进行测试,得出结果与预期一致。测试结果表明,此协议软件实现性能良好,符合DSRC协议的功能。
[Abstract]:Europe and the United States, Japan in the last century in the 1990 s have begun to develop electronic charging system. In the beginning of the 21st century, China began to study the special short-range communication protocol, which was published in 2007. It unified the communication rules between RSU and OBU. Many research units in China are mainly devoted to the development of the DSRC protocol for the OBU equipment. According to GB\ T 20851, the DSRC protocol is implemented by software in this paper. The purpose is to achieve protocol function, improve transaction efficiency and reduce communication time. This paper is based on the platform of arm linux. The physical layer, data link layer, application layer and device application layer are designed and implemented. The physical layer is mainly implemented by RF chip BK5823, where the BK5823 driver is loaded into the linux kernel in the form of modules. Because the DSRC protocol is asymmetric, that is, the software of both ends of communication is inconsistent. The realization of data link layer in RSU and OBU is different. RSU is implemented by a state machine. This state machine has three states, and the state machine of more than ten kinds of events .OBU has only one state. It is a passive device. The design of the data link layer refers to the stop wait protocol. In the data link layer, the hash table is used as the data structure of the storage frame, and the real-time communication is ensured by the many mechanisms of linux (asynchronous notification, memory allocation, interrupt upper and lower parts, etc.). In the application layer, T-KE design mainly includes encoding and decoding, segmenting and segmenting and so on. The application layer is described in the ASN.1 abstract language, where eclipse plug-ins are used as ASN.1 compilers. In this way, the ASN.1 structure can be mapped to C language structure. The conversion from C language to bit stream is realized by using PER codec library. The function design idea of segment and parallel section refers to the partition in TCP\ IP protocol. The recombination thought. I-KE layer designs two state machines with four states at the end of the state machine. The state machine of the OBU end has three states, and the state machine of the OBU terminal has three states. This part completes the DSRC agreement "handshake" process. The application layer realizes the interface function of B-KE. The device application layer mainly designs ICC card and PSAM module. The TimeCOS card of the company is used here as the ICC card and the PSAM card. Use the ISO7816 protocol to operate the TimeCOS card. The application folder of ETC is established and the function of secure transmission is realized. Access permission, information authentication and ciphertext transmission are used to realize secure transmission. Finally, each module is tested. RSU module OBU module, security transmission module and so on were tested. When the module is tested, the test cases are tested with normal frame and abnormal frame respectively, and the results are consistent with the expectation. The test results show that the performance of the protocol software is good and conforms to the function of DSRC protocol.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U495

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