基于ASN.1 BER规约的编解码算法及系统设计

基于ASN.1 BER规约的编解码算法及系统设计

摘  要ASN.1（抽象语法标记一）语言在各种领域有着广泛的应用。它是一种用来描述结构化信息的标记语言，主要用于为在不同计算机系统、应用程序以及网络之间传递和交换的信息定义协议标准。ASN.1提供了丰富的数据类型，灵活的扩展机制和高效的编解码规则，适合描述复杂的协议。目前，很多网络协议的消息格式都是用ASN.1语法描述的。本文研究对象LTE协议栈层3中的RRC消息数据结构也使用ASN.1描述。本文主要是对LTE系统中ASN.1编解码模块的设计与部分实现的研究。首先，简要介绍了ASN.1的基本概念、语法原则以及BER、PER编解码规则；然后，分析了ASN.1的应用流程和LTE协议栈需求，针对LTE协议栈设计了ASN.1编解码模块；最后，以BCCH_BCH_Message为例，对ASN.1编解码模块进行了部分实现。其实现首先将LTE协议中RRC消息的ASN.1描述按照一定规则转换成C语言的数据结构；然后根据转换好的C语言数据结构按照编码规则为每一个数据结构实现编解码函数。【关键词】LTE系统  RRC消息  ASN.1  编解码模块

ABSTRACTASN.1 (Abstract Syntax Notation 1) has been widely applied in various fields. It is a markup language used to describe structured information, mostly used to define protocol standards for different computer systems, application program, and the information transmited and exchanged among network. ASN.1 provides rich data types, flexible extension mechanism and efficient encoding and decoding rules, and it is suitable for complex protocols. At present, message formats of many network protocol are all described by ASN.1 syntax. The studying object of this paper--RRC message data structures of LTE protocol stack layer three are also described by ASN.1 syntax.This article mainly researches the designing and partial implementation of ASN.1 encoding and decoding module in LTE system. Firstly of all, it introduces the basic concepts of ASN.1, grammar principles and BER, PER encoding and decoding rules; and then, analyzes the application processes of ASN.1 and the requirements of LTE protocol stack, and for LTE protocol stack designs the ASN.1 encoding and decoding module; and finally, take BCCH_BCH_Message as an example, partly implements the ASN.1 encoding and decoding modules. The realization first changes the ASN.1 of RRC messages in LTE protocol into C language data structures according to certain rules; then based on the converted C language data structure for each data structure achieveing encoding and decoding functions in accordance with the encoding rules.【Key words】LTE system  RRC message  ASN.1  encoding and decoding module

目  录

前  言 1第一章  绪论 2第一节  引言 2第二节  ASN.1语言及其特点 3第三节  ASN.1在LTE协议栈中的应用 4第四节  本文研究目标和主要工作 5第五节  本文组织结构 5第二章  ASN.1抽象语法与编码规则 6第一节  ASN.1背景知识 6一、ASN.1简介 6二、ASN.1 BER/DER/CER/PER编码规则简介 7第二节  ASN.1抽象语法 8一、ASN.1数据类型 8二、ASN.1类型定义、值定义和模块定义 9三、常见子类型约束 12第三节  ASN.1 BER编码规则 13第四节  ASN.1 PER编码规则 15第五节  小结 17第三章  ASN.1编解码模块分析与设计 18第一节  ASN.1编解码模块分析 18一、ASN.1应用过程 18二、ASN.1编解码模块 18第二节  ASN.1编解码模块设计 18一、数据转换设计 18二、编解码函数设计 21第三节  小结 25第四章  ASN.1编解码模块的部分实现 26第一节  数据结构转换的实现 26第二节  编解码函数的实现 27结    论 34致    谢 35参考文献 36附    录 37一、英文原文 37二、英文翻译 45