深圳宏电基于GPRS的无线DDN系统组网及特点ENGLISH.doc

基于GPRS的无线DDN系统组网及特点M2M over GPRS build and featureWang Zhong Bi王中碧(Shenzhen Hongdian Technologies Co., Ltd. Shenzhen, China)（深圳市宏电技术开发有限公司，广东，深圳518040）Summary: At recent years, 2.5 Generation mobile network (GPRS, CDMA 1x and EDGE) has been used by many countries, they provide a wide coverage and reliable mobile data channel for business and industrial applications. This article will tell to reader how to build a network over cellular network and feature.摘要：目前，基于GPRS无线数据传输业务广泛在移动办公、工业控制、远程遥测等多方面应用，网络运营商中国移动GPRS和联通CDMA各有其特点。文章详细描述了利用GPRS网络组建无线DDN网络的方法及特点。Keys: General Packet Radio Service, Code Division Multiple Access, Wireless DDN、DTU, Router关键词：General Packet Radio Service、Code Division Multiple Access、无线DDN、DTU1 Preface前言Along with society progress, the requirement of variational remote communication is increasing. Before the GPRS network showed up, the remote communication of signals are go through the telephone dial-up, wireless broadcast, lease link methods, but all these methods are deficient. The telephone dial-up method which dialup period is too long and line builds is difficult. The wireless broadcast method need solves the packages error rate, resist disturb problems, and that restrict is frequency of wireless committee and communication distance. The lease line method is impossible for big area, and the cost is really expensive.The GPRS based wireless digital data network adopt advanced mature GPRS communication module, based on stabilization reliable GPRS network, this solution will reduce communication cost to lowest.随着社会的发展，各种设备远程通信的需求越来越多，在GPRS网络建设以前，设备的远程通讯通常采用电话拨号、无线电台、专线等方式，但这些方式均有很多不足之处。采用电话线传输数据，拨号过程长，而且线路建设有一定困难；采用无线电台，解决误码率、抗干扰是一个令人头疼的问题，而且受无委会频率管制的影响，在频率使用、传输距离上受一定限制；采用专线电路，不可能对所有大面积分散的数据采集子站进行专线铺设，更不能承担高昂的运行费用。基于GPRS网络的无线DDN系统，采用先进成熟的GPRS DTU模块为远程传输模块，依托稳定、可靠的GPRS网络，在保证数据传输的及时、准确的前提下，将系统运行费用也降低到了最低。2 GPRS Introduction GPRS网络介绍GPRS is General Packet Radio Service built on the basis of GSM network to provide packet data service. It works at the same frequency band, the same modulation and the same TDMA frame structure with GSM. GPRS can be implemented at existing GSM BSS by plug-in packet data card and associated updated software. Therefore, the system coverage is as same as GSM network. GPRS users can transmit and receive data from end to end by packet model. Packet data service is highly efficient and low cost for customers, for it does not occupy the circuit switched network resources. In this way, GPRS is a great communication channel for interrupting and bursting data transmission. Maximum GPRS bandwidth can reach 171.2Kb/s and the actual application is 40100Kb/s. Provided TCP/IP protocol connections on this channel, GPRS network can be applied on Internet connection and data transmission, etc. GPRS is a kind of mobile packet data service that provides high speed wireless IP connection between mobile users and data network. It is developed with packet switch technology; each user can occupy multiple radio channels, at the same time, one single radio channel can be shared by multiple users. Thus, radio resources are effectively utilized and the maximum GPRS bandwidth can reach 171.2Kb/s. Remaining online all the time, users pay merely for the data transmitted and received because of this technology.GPRS 是通用分组无线业务(General Packet Radio Service)的英文简称，是在现有GSM 系统上发展出来的一种新的承载业务，目的是为GSM 用户提供分组形式的数据业务。GPRS 采用与GSM 同样的无线调制标准、同样的频带、同样的突发结构、同样的跳频规则以及同样的TDMA 帧结构，这种新的分组数据信道与当前的电路交换的话音业务信道极其相似。因此，现有的基站子系统(BSS)从一开始就可提供全面的GPRS 覆盖。GPRS 允许用户在端到端分组转移模式下发送和接收数据，而不需要利用电路交换模式的网络资源。从而提供了一种高效、低成本的无线分组数据业务。特别适用于间断的、突发性的和频繁的、少量的数据传输，也适用于偶尔的大数据量传输。GPRS 理论带宽可达171.2Kb/s，实际应用带宽大约在40-60Kb/s，在此信道上提供TCP/IP 连接，可以用于INTERNET 连接、数据传输等应用。GPRS是一种新的移动数据通信业务，在移动用户和数据网络之间提供一种连接，给移动用户提供高速无线IP。GPRS 采用分组交换技术，每个用户可同时占用多个无线信道，同一无线信道又可以由多个用户共享，资源被有效的利用，数据传输速率高达160Kbps。使用GPRS技术实现数据分组发送和接收，用户永远在线且按流量计费，迅速降低了服务成本。3 无线DDN系统网络设计 Wireless DDN system design3.1 网络拓扑Network Structure figure无线DDN系统网络拓扑图3.2 系统组网结构Network StructureThe Wireless M2M system includes Supervision station and Data center. The Supervision Station use GPRS DTU, and it provides RS-232、RS-485 and Ethernet interfaces. Data Center connects the Internet by ADSL or lease line. The connection mode detail as below:无线DDN系统分为监测点和数据中心两部分，监测点采用GPRS DTU，可提供RS-232、RS485、以及以太网接口，数据中采用宽带ADSL或专线方式接入Internet，具体接入方式如下：a) 监测点接入方式：The Supervise Station connect mode:The Supervision station connects the GPRS DTU module via RS-232、RS-485 or Ethernet interfaces, and then co figurate the parameter of DTU, each DTU inserts the mobile SIM card can use.监测点通过RS-232、RS-485或以太网接口与GPRS DTU传输模块连接，然后设置DTU相关参数，每一个GPRS DTU传输模块装入一个移动的数据SIM卡即可。b) 数据中心接入方式：The Data center connect mode:The Data center connection includes two parts:数据中心接入主要分两大类：1) 采用Internet接入 connection over InternetThe Data Center connects Internet by ADSL, this mode has some advantage that wide bandwidth、inexpensive cost, but there is some disadvantage that less secure、more delay then lease line.数据中心采用宽带ADSL接入方式，此种方式优点是带宽大、费用经济。缺点是安全性较差、延时比专线接入稍大。The Data Center connects Internet by share LAN, this mode resembles ADSL, however, pay an attention to the Network Address translation (NAT).采用局域网共享上网方式，此种方式基本同ADSL接入类似，但注意接入时需做端口映射。The Data Center connects internet by dial-up, bandwidth. So it adopts for a few points or small data transfer system.采用电话线拨号上网方式。此种方式接入带宽较窄。所以只适合于点数较少，且数据量小的组网方式。The Network Structure figure as below:网络拓朴图如下：2) 移动公司接入Mobile company connectionThe Data Center uses the channel mobile carrier provides. Actually this mode has some modes below:数据中心采用无线网络运营商（指中国移动）提供信道接入，此种方式实际中有以下几种连接方式：The Data Center uses lease line from mobile carrier, this mode advantage is wide bandwidth (about 2 Mbps), and less time delay, more secure, but it will spend expensive cost. Especially adapt for more secure user, for example: bank, POS and so on.采用移动公司机房专线接入方式，此种方式带宽大（一般为2M），对延时、安全性都非常好，但租用此专线价格较贵。特别适合银行、POS机组网等需安全系数较高的用户，对子站非常多的情况下也推荐采用此种方式。The Data Center uses GPRS wireless connection, this mode needs GPRS MODEM in the Data Center. The Data Center via it to dialup. This mode advantage is flexible to use, inexpensive cost. The defect is less bandwidth、more delay. This mode often use for test time. If use to engineering, so notice SIM card need apply APN.采用GPRS无线接入方式，此种方式在数据中心接一台GPRS MODEM，通过数据中心的PC机拨号上网。优点是组网讯速，费用经济。缺点是带宽窄（GPRS上行10Kbps,下行40Kbps），延时大。这种方式在测试时用的比较多。如果准备在实际工程中使用需注意SIM卡需申请APN。The following is Network Structure figure:网络拓朴图如下：3.3 传输方式 Transmit modeAll equipments is equal duplex transmit. Each DTU can send data to Data Center and receive data form Data Center.所有设备均为“双向传输”方式，即每个DTU既能把数据发送到数据中心，也能接处到数据中心发送的指令。3.4 全网速率 Network rateNowadays, GPRS network support CS-2 code, each RLC layer rate is 13.4kbps, and use to 4+1 channel mode. So down rate is 48kbps, update rate is 13.4kbps.If GPRS network upgrade, it will support CS-4 code, binding 8 channels, each channel RLC layer rate will be 21.4kbps, and top rate should be 171,2kbps.基于目前中国移动GPRS网络现状，目前网络支持cs-2编码，RLC层每信道速率13.4kbps。采用4+1信道方式。因此设计下行速率为48kbps，上行为13.4kbps。待GPRS网络升级后，网络将支持cs-4编码，可以捆绑8个信道，每信道RLC层速率将达21.4kbps，最高速率可达171.2kbps。3.5 网络管理及监控 Network supervisionThe Data Center can supervise all DTU over GPRS, include online state, work state and DTU parameter information, and also long-distance configure parameter, even reset DTU.在数据中心可通过软件对所有DTU进行监测，包括在线情况，工作状态以及DTU系统参数信息，也可远程配置DTU参数，甚至可以远程重启DTU。DTU provides many work modes:DTU有多种工作模式，可根据需要进行设置，具体模式如下： 永远在线模式 always onlinen 描述：保持DTU与数据中心永久连接n Description: keeps the connection from DTU to data centern Process: power on DTU, it will auto-dial and attach to the mobile network, then connections to data center and keeps heartbeat in accordance with the initial setting. Meanwhile, it detects the channel status, if it is failed due to some reasons, DTU will reconnection automatically.n Applications: for real-time data transmission applications, such as SCADA system and utilities.n 工作过程：DTU开机时自动连接GPRS网络，根据数据业务中心(DSC)的IP地址自动连接数据中心，并保持和维护链路的连接， DTU监测链路情况运行，单网络发生异常，DTU自动重新建立链路。 定时传输模式 Timing Transmissionn Description: transmit and receive the data period.n Process: according to the initial time interval setting, DTU will dial and connection the data center period, then transmit the data. After finish the data transmission it hung off the line automatically.n Applications: hydrology, weather station, environment protection and power tele-metering data collections.n 描述：由DTU定时向中心发送数据。n 工作过程：根据事先设置的发送数据间隔向数据业务中心(DSC)发送数据和接收数据，数据收发完毕，自动断线。 中心呼叫模式 Center Retrieven Description: data center requests the data transmission, DTU will establishes the channel and send back the traffic data after receiving the command.n Process: data center send a circuit calling ring to DTU, and then DTU will identify if it is a legal number, and establish the traffic channel, send back the traffic data.n Applications: alert system, oilfield, hydrology, weather station, environment protection and power tele-metering data collections. n 描述：由数据中心发起数据传输请求，DTU应答并发送/接收数据。n 工作过程：当中心需要收集或发送DTU端的数据时，数据中心发出呼叫指令，DTU立即连接GPRS网络并登录数据业务中心(DSC)，安装中心的指令传输数据。 数据触发模式User Data Triggeringn Description: if the user data change of status, DTU will send back the traffic data.n Process: DTU detect the COS by the serial port interface handshake signal, if there is a COS, DTU will start the channel connection and send back the traffic data.n Applications: oilfield, hydrology, weather station, environment protection data collections.n 描述：当有用户数据传输时，由DTU发起连接。n 工作过程：当有用户数据传输时， DTU连接GPRS网络并登录数据业务中心(DSC)，传输数据。 节电模式：Save Powern Only the CPU work in sleep mode, and shut off all radio parts.n 无数据传输时关闭无线传输部分，系统进入休眠状态。4 无线DDN系统特点Wireless DDN system features1) 透明数据传输Transparent data transmissionGPRS DTU provides transparent data transmission channel (RS232 or RS485 interface) for machine to machine connection.GPRS DTU直接提供RS232或RS485接口，使用简单、方便，为用户的数据设备提供透明传输通道。2) 无需后台计算机支持Non host supportNormally, GPRS Modem can be connection to a PC, and then dial an access number manually; it utilizes PC resources to process the data transmission and protocol conversion. GPRS DTU is a terminal built-in processor, protocol stack and application software; it is working automatically without host PC.普通GPRS Modem通常需要附着在PC机上虚拟拨号上网，利用PC机的资源进行数据收发和协议转换，GPRS DTU内置自动网络连接和协议处理模块，无需后台计算机支持。3) 点对点、点对多点、对等、实时数据传输Point to point, and point to multi-point data transmissionGPRS DTU can be configured as point to point, point to multipoint and center to multipoint network.GPRS DTU可以实现点点、点多点、中心多点的对等数据传输，传输时延一般小于1秒。4) 永远在线Always onlineGPRS DTU automatically attach to GPRS network when it is powered on, and then set up a channel to center server.GPRS DTU一开机就能自动附着到GPRS网络上，并与您的数据中心建立通信链路，随时收发用户数据设备的数据。5) 按流量计费Toll on trafficGPRS DTU can works always online, and only be charged when data transmitted.GPRS DTU一直在线，按照接收和发送数据包的数量来收取费用，没有数据流量的传递时不收费用。6) 高速传输High speedMaximum GPRS network bandwidth can be 160Kbps. It depends the operators policy. For example, only 2040Kbps bandwidth is provided at China mobile network.GPRS网络的传输速度最快将达到160Kbps，速率的高低取决于移动运营商的网络设置，根据中国移动的网络情况，目前可提供2040Kbps的稳定数据传输。7) 组网简单、迅速、灵活Simple and flexible to useWireless DDN system can be accessed via Internet. It is an easy way to build your private mobile data network at anywhere in the world.无线DDN系统可以通过Internet网络随时随地的构建覆盖全中国的虚拟移动数据