【作者】 侯远政；

【导师】 严小卫； 张师超；

【作者基本信息】 广西师范大学 ， 计算机软件与理论， 2002， 硕士

【摘要】 市场广阔的移动通信是近20年来世界科技与经济发展的重大成就之一。当前国际移动通信正由第二代数字通信系统向以宽带无线接入技术为特征的第三代移动通信系统(3G)演进。在GSM占据无线通信网络绝对比重的我国，开发支持通用分组无线数据业务(GPRS)的移动终端(2.5G)，不仅能让GSM网络的巨额投资继续发挥其效益，而且还可以使当前的GSM网络平滑地向3G演进。GPRS采用了有别于GSM的更灵活地资源分配方式，非常适合以不对称为特征的数据业务传输。移动终端协议软件对于开发具有自主知识产权的国产手机具有重要的意义。 论文着重研究了GSM协议中的无线资源管理部分。无线资源管理层是协议栈的核心，它是区别其他无线通信协议的具体体现，它决定了物理逻辑器件的设计。无线资源管理的目标是提供使移动台和基础设施协调工作所需的功能，使得无论电信业务要求什么，无论用户怎样运动，都能在不可靠的无线接口上提供可靠的传输。论文在全面分析无线资源管理的基础上，给出了系统状态机的精确描述。 GSM作为一种接入网，其网络结构不仅包括无线空中接口部分，而且还有相当多的地面电路。这中间包括管理资源分配的基站子系统(BSS)，与外部网络互连的移动交换中心(MSC)，还包括用于用户位置管理、系统安全性管理的数据库。 GSM系统综合运用了频分多址(FDMA)技术，加上时分多址(TDMA)技术，并辅以跳频技术。GSM定义了许多与业务相关的逻辑信道，以及逻辑信道到物理信道的映射。GSM系统是全数字的，语音和不同速率的数据先数字化，最终调制成一串的突发脉冲发送出去。其过程依次是语音编码、信道编码、交织、形成突发脉冲、加密、无线信号的调制。 依据电路交换、分组交换这两种不同的传输机制，论文给出了实现B类MS的协议结构，并给出了各协议模块的简单的说明。B类MS可以接入GPRS和其他GSM服务，同时监控GPRS和GSM服务的控制信道，但在某一时刻只能运行一种服务。 无线资源管理的研究是论文的核心。时间提前技术为了补偿无线传输路径的延时而使MS提前发射信号，使得上行信号在各自的时隙内到达BTS。包括不连续收发技术在内的系统功率控制，使得手持式MS的功耗问题得到一定的缓解。跳频技术的应用增强了无线信道的抗干扰能力。空闲模式下的MS包括蜂房选择、重选择过程，以及相关的PLMN选择、位置注册。PLMN选择、位置注册是从运营者的角度影响MS，而蜂房选择、重选择过程是基于无线方面的考虑。依据无线路径准则C1、C2，蜂房接入优先级，以及接入控制机制，MS在空闲模式下存在两种状态：正常驻扎蜂房、任意驻扎蜂房，它影响着MS的业务范围。初始化接入过程描述了MS从空闲模式到专用模式的转换，接入过程是典型的“时隙Aloha”协议的应用。专用模式下的鉴权过程用于网络检查MS提供的识别是否真实，并给MS一个安全的密钥。加密规程是为了防止无线信道上被窃听。专用模式下的MS不仅对服务蜂房的无线链路实时地进行检测，还要试图同步临近蜂房，并检测其无线接收电平。当无线链路失败后，MS可能在临近蜂房呼叫重建立，或切换到其它的蜂房内。呼叫重建立过程是由MS发起的，而切换规程是由网络命令MS转移到合适的蜂房。 论文对当前流行的协议描述语言SDL以及功能强大的电信开发工具Tau作了简单的介绍。 协议的实现是该论文的归宿。在分析移动终端软件模块结构图的基础上，论文给出了基于电路交换的协议栈的结构，并给出了其设计思想。协议栈中无线资源管理的实现可分为两大块：空闲模式、专用模式，并用SDL图描述了各自状态下不同规程的行为。 最后，在展望无线宽带接入总趋势的基础上，论文对GPRS的网络结构，协议结构作简单的介绍，并给出了GPRS系统的设计思想。更多还原

【Abstract】 Mobile communication with wide market is one of the successes of the world scientific and economic developments in the last 20 years. Currently mobile communication is evolving from the second generation characterized by its digitalization to the third generation characterized by wireless access of wide band. In China,where the GSM holds the most proportion of the wireless network,the research and development of mobile station (MS) with the general packet radio service (GPRS,called 2.5G) not only let the vast amount of investment on GSM network continue to be profitable for a longer period,but also make the GSM network smoothly transfer to 3G. GPRS,by making better use of radio resource than GSM,is very suitable for dala service with the character of asymmetry. Protocol software of MS is very significant for the development of mobile telephone with our own property right.Our research is focused on the radio resource (RR) in the GSM protocol. As the kernel of the GSM protocol,RR is the part that distinguishes GSM from other wireless protocols. It influences the design of logical circuit. RR aims at making MS harmonically cooperate with its network,in order to provide reliable transmission on the uncertainty radio path no matter whatever telegraphic service to be asked and how (he users’ movements are. After thoroughly analyzing the principle of RR,we give the precise description of the system state machine.As a way of accessing to the backbone network,the network architecture of GSM includes both aerial interface of radio path (called Um) and many circuits on the land. For example,it has a base station system (BSS),which is responsible for the distribution of radio resource,a mobile switching center (MSC),responsible for connection to external network,and a database for managing users’ positions and secure strategies.High technology is applied to GSM,such as FDMA,TDM A,and frequency hopping. Many logical channels related to different services and the mapping of logical channels to physical channels are defined. GSM system is wholly digital,where voice and data at all speeds are digitized first and modulated to a serial of burst at last before transmission. The steps are as follow:PRE-LTP encoding,channel encoding,interweaving,burst forming,encrypting,and modulating.We build up the protocol architecture of MS of calss B according to two different transport mechanisms,i.e. circuit switch and packet switch. We also briefly illuminate each module of the protocol. MS of class B can be connected with GPRS and other GSM services and monitor their control channels at the same time. But only one service can be provide at the same time.The research of RR is the kernel of this paper. Timing Advance (TA) makes MS transmit signal ahead of schedule,to offset the delay of radio transmission line and thus transmit uplink signals of every MS to the BTS in their own timeslot. Power controls,including discontinuous receiving and transmission (DRX DTX). provide longer handset working without frequent alternation of battery. Frequency Hopping enhances its ability of channel anti-jamming. MS in idle mode carrys through the procedures of cell selection and reselection,and other pertinent procedures,such as PLMN selection,and register position. PLMN selection and position registration influence MS from network service provider,while cell selection and reselection from radio path. MS in idle mode has two states,i.e. one normally camped on cell and another camped on any cell,according to criteria Cl,C2,cell PRI,and access mechanism. These two states influence MS’s service scope from network. Procedure of initialization assignment describes the transformation of MS from idle mode to dedicated mode,which is a typical example of timeslot aloha protocol. Authority procedure in dedicate mode checks the MS’s validity,and if it is valid,a safe cipher key for the use of channel encrypting is given. Encryption procedure prevents the radio channel from being wiretapped. MS in dedicated mode not only detects the quality of radio path of更多还原