2006 6th Intermational Coference on ITS Teleconunuiiications Proceedings

OPS Real Time Vehicle Alr Monitoring Sytem

Base on GPRS/CSD usin the Emibedded SstemXing Jianping' Zhang Jun' Cheng Hebin Li Changqing Shi Xiaohui

1) Elec. & Info. School of Beijing University of Aeronautics and AstronaulicsBeijing, 100083 Clhina

2) Institute of Modern Comm. &Tech, Shandong UniversityJinan, 250100 China

Abstract- It proposed a method of combining the two types ofdata service CSD and GPRS based on GSM applied to GPSvehicle real-time monitoring and alarming system. Based on thismethod, Basic constitution and netw ork structure of the system isgiven out, and then it implements the CSD and GPRS hardwareinterface and software flow based on the GR47 wirelesscommunication module. Arm Embedded System was used as thecentral processing unit (CPU) and uLinux was used as theappropriate operation system (OS) to the circuit design.Compared with the conventional single mode of GPRS, thismethod makes up the disadvantage of the high time delay and theincertitude of the time delay in data transmission. In this case, thereal-time data transfer of the system gets guarantee, and the dailymaintenance expense of the system is reduced. GIS is applied totrack and alarm the hardware clients on the electronic map. Thetest indicates that this method is appropriately used in theinstantaneous information real-time transmission, and has highpracticability and validity.

I. INTRODUCTION

More and more information technologies have entered thetransportation departineint and formed ITS field (IntelligentTransport System). There is no doubt that the vehicle real-timemonitoring system, which knows the vehicles locationls andvarious status is one of the most sigificant parts of ITS, whichusually combines with many techniques such as the mobilepositioning, wireless communicaon, geographical infrmationand computer network to realize the close combinationl andharmony and unity of the information of individual, vehicleamd road. The vehicle moniton sstem is often composed Ofinormation monitonng cenrte, vehicle mobile terminal, anddata communicationl network. The key problems of this systemare: (a) To precisely know the vehicles position. It is solvedusually by using GPS. (b) The real-time informationtransmission. Adopting wireless communication system cansolve it.At present, the communication system of the vehicle real-

time monitoring system consists of general commninuicalion,clustering communication, GSM SMS network, GPRS networkand so oni. The former two systems are also called prtivatesystems. The first one often using big section, with smallercoverage, is only suitable for real-lime systems with smallusers in ceMin area. As for the clustening communication, ittakes time to build up channel when it's in the TDMA (TimeDivision Multiple Access) mode. It will have ino insurance

about its real time property. GSM/SMS has more applicationnow with the advantage of large covering range, and can nseextensively in the whole nalion. However, its time delay is abottleneck. Especially when the loads of the short messagecentre are too heavy and block seriously, the real-lime propertyof the vehicle monitonrng system will lose insurance.Furthermore, the real-time SMS cost is not cheaper. The GPRSnetwork overcomes the drawbacks of the tiree commnnuicationmethods discussed above. Because it has such characteristicsas. higher transmission rate and lower cost. Therefore, GPRS ismore suitable as a powerful platform for the commuicationservice of vehicle real-time monitoring system.

It proposed a method of combining the two types of dataservice CSD and GPRS based on GSM applied to GPS vehiclereal-time alarm monitoring system. Based on it, the terniinaland center softiware are given out.

II. BASIC PRINCIPLE OF SYSTEM

A. Combination of SD and GPRSDaa rvicesNow GSM proposed two kinds of mobile data services:

Circuit Switched Data Service (CSD) and General PacketRadio Service (GPRS). CSD data service is one based oncircuit switch with 9.6kbps. CSD builds upon circuit switching,and monopolizes a whole channel at communication process,so it has lower cominu:iucation eflicienmy. Furthermore, thecost is relalively higher. BuLt CSD mode has characteristics ofreliable data trasnmission low time delay; transmi'ssion timedelay is changeless for given persisting routing. GPRS is a newmobile packet data service constructed on the base of GSMwith transmission rate up to 115kbps. Data transmits andreceives in packets due to GPRS uses packet tecluique, itmeans users keep online and calculate cost, so reduces the costrapidly. Therefore, GPRS is particularly suitable forinterrupted, burst or frequent data transmission. But the largestdrawback of packet-switching is vanrious time delays anddelays are not invairiable owing to various reasons in packet-switching.B. Basic Constitution o~fSteThe GPS real-time vehicle momntoring system is composed

mainly by information monitonrng centre cmd vehicle mobileterminals as presented in the Fig. 1. Monitoring cenitre receivesthe informAtion about its locations, and status of vehicle sentby the vehicle termiinal, after conversion and process of

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corresponding data, the vexhicle's real-time location isdisplayed on the digital map. What's more, the track of thevehicle can also be displayed according to the need and thedetected warning infornation can be warned of. Becanse ofthe database's snpport to the map display software, it canrecord and register the vehicles data. In case one cani iiqniryabout and replay the track. Except the function of receiving thedata from the vehicle termnunal, the centre also cani senddispatch commands down and modifx parameters remotely.Whicle terminals designed by us, are the basic unit of the

GPS vehicle monitoring system, are composed of GPS receiver,GPRS module, central controller, LCD display screen inChinese, power modnle and so on, as presented in Fig. 1.

GMT SMM CGSM

tPSmodule

__ GShMwxeess

Communication contr-ol server

Master controlcenter

Figure 1. the Component of systemGPS Receiver is mairny used to receive information such as

satellite signal, SNIR longitnde and latitude, speed, directionand so on, and then sends to central controller duough senalinterface. Generally GPS protocol is formatted in NEMAO 183.GSM Commumication Modem is mainly used to connect

with GSM network. As the aialysis above, the method ofcombination of CSD and GPRS two services is used to solvedata transmission problein. CSD method for data tranIsmissionis nsed when detecting warning in time, real-time controllinogwith high real-time need, and GPRS method for datatransmission when location transmission, image transmissionwith low real-time need and large nantity data. In this case,the real-time of data transfer gets guarantee and the dailymaintenance expense of the system is rednced.Main Controller designed by embedded ARM7, is nsed to

harmonize the work among every module, calcnlate, registerand dispatch information, process the information in softwarelayer. Connecting witdi GPS receiver and GPRS wirelessniodule, on one hand, it reads and gets the positioninginformation, then packs it together with status and otherinformation in the corresponding format, and transmits thepacket to monitoring centre by making nse of GPRS; on theother hand it receives the information sent from the centre anddisplay it on the screen.

III. GSM HARDWARE INTERF ACES REALIZATION

The core of date communication abont this system lies inwireless commuiication coitrol terminals that nse GSMmodnles to transfer long-distance date expediently and reliably.Cnrrently, the GSM modiles nsed extensively on the marketmainly are standard GSM modnles, which can provide todevelop txvo times. Such as the GR47/48 series of ERICSSON,the MC35 series of Siemens, the A2D series of Flacom, the

WISMO series of Wave from French compiay. Herexwechoose to use die GR47/48 series modnles, which beeninvented lately by ERICSSON can snpport the CSD and GPRStwo kinds of operation modes. The GR47/48 series ofERICSSON and the GSM 2/2+ are muntually permitted. Theyare dual-band (GSM900/ GSM1800) and cani provide thestandard UART serial interfaces as well as GSM07.05 andGSM07.07 according to the standard of ETSI. The modnle is acombination of the radio frequency circuit and basebaid, and itsnpport instructions of AT commands defined by GSM 07.05and GSM 07.07. Therefore, the MCU can connect with GSMmodnles very expediently throngh serial interfaces, anddirectly use of AT commands can implement the data businessof CSD and GPRS simply. The pins of GR47/48 series ca-ndivide into 5 tpes: pover, the data inpnt' ontp the SIM card,audio frequency interfaces and controls, the GSM modnles.

IV. SOFTWARE REALIZATION

The GSM wireless communication modnle can solve theproblems of long-distance wireless comm-inication very easy,so the work is with the software to drive the GSM inodule.Generally speaking, to carry ont the CSD and GPRS databusinesses by building up and tearing down commnnicationlink with the help of the GSM modnle. SONY- ERICSSONmodnle is a standard GSM modnle, wIhich supports instructionsof AT commands defined by GSM 07.05 and GSM07.07criterions. As long as MCU released AT commands to GSMmodnle throngh serial interface directly, it can drive the GSMmodnle easily, and carry out GPRS and CSD based on GSM toreceive and dispatch varions information.A. TSte Realization ofte CSDAlari Data

Adopting the method of CSD to tranismit data need to buildnp point to point comnnication linik by the way of dialing-up, and still need to tear down the link After date transmission.BY using GSM wireless communication module .adoptingCSD method to transmit date need a date nmnber beenbounded with SIM card nnmber, and this date nunmber can beapplied form China-Mobile Company by utilizing SIM cardniumber. When dialing, you can call that date nimber toachieve communication link,Under the CSD method,, wireless module has two states:Command State and Online State' Among them, command

state is divided into on-line command state and off-linecommand state. In addition to occnpy brief time when dialing,xvireless comimnunication module is always a kind of stateplaced in among them. After staffing wireless modnle, it isplaced in the off-line command state first, and receivescommands by the method of AT command, and then it alwaysconverts among these three kinds of states. The conversion ofmodnle states shows in Fig. 2.

(a ) Off-line Command State - Onlinie State: UseATDn command to call the opposite nnmber,, responded byATA command, if connection established, the communicationmodule will switch to online state. (b) Online StateOnline Command State. Tranismit changing code sequence

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;+++"? to wireless module, in the case of one second dela) bothbefore and after transmission, the wireless modulle will switchfrom online state to online command state, preparing forreceiving AT command. (c) Online Command State -

Online State: transmit ATO command to wireless module inthe online commaind state will switch it back to online state.(d) Online Command State -- Off-line Command State:

if transniit ATH command to wireless module will make it ringoft therefore switch from online command state to off-linecommand state. ( e) Onlline State - Off-line CommandState: if remote wireless module ring off or connectioninterrupt result in loss of catner wave signal, wireless modulewill switch from online state to ofline command state.

Establi sh conjunctionOff-line order state

ATH On-line state

ATO0On-line order stateL

lChange the code sequence...

FigLre 2. the. Conversion of Module StatesBefore dial-up, several AT commands are used to set

wireless module: (a) Carrier Mode Selecting Command:command format is AT+CBST= <speed>, <name>, <ce>,usually set to AT+CBST 7,0,1. '7' denotes speed at9600bps, '0' denotes module doesn't support data compress,'1' denotes adopting default value of transparent transmission.(b) Special Mode Selecting Command: command format isAT+FCLASS=<> , 'O' denotes data, '1' denotes a kindof fax, therefore selecting parameter is zero here.

B. areReaiion ofGPRS GPSDa CommunicationProcessing GPRS data services by wireless commuiica=tion

module is much more complex than CSD service. GPRS is akind of data switching based on packet switching, diffrentfrom data calling. First IP module in SCM system of clientterminals makes data to be sent into TCP/IP protocol switching,packed in IP data packets, and then transmit from ERICSSONGR47 module to GSM base station in GPRS data packets. Dataswitching is transmitted from base station to SGSN node, notto phonetic networks through MSC. Switching data packedaccording to SGSN is transmitted to destination SGSN thoughGPRS IP Backbone, and then transmitted to GPRS terminalsthrough base station. The new GSN deals with the GPRSsystem to connect onto Internet. In GSN, the SGSN is theprimary componleit of cellular networks that employ GPRS.The SGSN routes incoming and outgoing IP packets addressedto or from any GPRS subscriber physically that are locatedwithin die geographical area serviced by that SGSN. GPRSdestination transmitted auLtomatically to controller embeddedARM system of client tenninals by serial mode, at lastresoled in TCP/IP protocol stack of embedded system, so anintegrated data transmission was completed. GPRS uses themethod to transmit data packets like the Network AddressesTranslator (NAT) stnmcture in the Internet.

So a TCP/IP protocol stack mtust be embedded inmicrocontroller to switch data format. TCP/IP protocol is astandard protocol series designed for Wide Area Network.However, GPRS service is only used for simple datatransmission here, thans to resource of processor is limited,and not all functions of TCP/IP protocol need to be realized. Soit is recommended to select TCP/IP protocol stack uIP withopen source code, compiled absolutely in C Language, andvery easy to transplant it to ARM7 embedded system.

In the embedded systems, there are several useful operationsystems for used, such as VxWORKs. Palm OS, Windows CE.and Linux. Among diem, Linux becomes the best choice to theproposed systeim design wiith die advantages as. (a) free initialcode, (b) easy and flexible to develop as a module platform, (c)knowledgeable to promote kernel reliability, (d) powerfulInternet capability as UNIX system, (e) suitable to transplantwith other system.

In the proposed client system, ARMVI Linux is used to designthe core system. ARM Linux is to transplant ARM processoras its core and formulate uCLinux to beconie operation core.uCLinux (micro-control-Linux) is specially designed toconstruct an embedded Linux operation system using microcontrollers without memory management units (MMNW).Theadopted uLCLinux is an extension of Linux kernel 2.4-operationsystem, with some simplification but inaintain the appreciatedstability of the Lintux operation system.The important characteristics of uCLinux miigt he focused

on its memory requrements that uC Kernel plus developingtool needs only less than 900KB. The developing supportsfrom Internet are vast and easy to access.To match with the client system hardWare design based on

ARM Linux, the developing host system should install LinuxPC operation system to develop software. The developingprocedures are: Stepl: Develop your programs, Step2: Write amake file, Step3. Build the binary code, Step4' Download theexecutable file, Steps. Execute die program.As CSD, before velhicle transmission in GPRS mode, GPRS

module must be set appropriately firstly, the main settings are.(a) To set communication baud rate, by using AT+IPRcommand, set baud rate to n b/s (b) To set PDP contextparameter, by using AT+CGDCONT-1 , Ppp",,, 0, O thecommand set GPRS to connect to gateway. (c) To set mobileterminal pattern, use AT+CGCLASS= "C" to set mobileterminal pattern to B pattern, which is only applicable to GPRS.(d) To activate GPRS function, use AT+CGACT I command.Connect GPRS function firstly if there is no connection. (e) Toconnect GPRS: AT+CGATT 1; make sure terniinal in V.25tercommand state. (f) Turn into data state: AT+CGDATA=1;make sure GPRS PDP pattern set up commucation withnetwork.ARM7 Embedded system can connect to network for

transmission after initialization of ERICSSON by proper ATcommands and GPRS commands. First to monitoring whetherdiere are GPRS data, if there are, identify the data received,unpack it, process and save it for TCP data. If vehicles have

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data to transmit, then pack the data according to TCP protocolbefore transmission. Software workflow is presented as Fig. 3.

Initialization

|i aitialieation ofCPRS module

S dataappeard

Datatransmiten

Pack and transmitaccordigtolCP

Dtinguis51TCP packet

unpack and save dataaccording to TCP

Fiure 3. Flow chart of sofiware workThe tests demonstrate the software realizations of these two

services are both feasible. After optimization, software codesare abonLt 20K. What is more, the whole software is compiledwith standard C Language, so it very easy to be transplanted tovarious processors, with qnite wide practicability.C. Sewer SysemI mentation and VeificatonAt the same time communicAtion and digital map software

are exploited. In the proposed alarm monitonrng system, theserver is designed using a series of computers installed withMicrosoft Windows 2000 Server and Microsoft SQL Server2000. To process GIS data mapping and tracking, Visual Basicsoftware is prograiuned with MapX database under executionof Winsock program. The server system will receive all clientdata from Internet and display thcin otuto GIS electromic maps.To maintaiin the alarm monitoring data, a database is

established for permanent storage and further analysis. Theservers should establish the Internet connection throngh thefollowing steps - as shown in Fig. 4.

Start ) Iha,iFa,.

GPS vehicle real-time monitoring system based on abovetechniques is tested and sunimanzed in JiNai form April toMay in the year 2004. Vehicles show results in Fig. 5. (a)Positioning accuracy of GPS: no more than 10 meters. (b) Thealarn time of CSD: no more than 2 seconds. (c) The originalpositioning time of GPS: no more than 5 seconds. (d) The dataerror rate of GPRS is almost zero.

._...... :' .......

o1 st SZWWEffi4

UJ FIt ----t''-i

t le0 mB pX n , d takes

V. CONCLUSION-

the full advantage of network resonrces in existence. SingleGPRS mode cannot meet the needs of high reliability, higyhreal-lime capability. The combination of CSD and GPRS moderight offsets this need, and realizes reliable and secnrable datatransmission. It has Real-time capability and low cost of datatransmission. This system has mawy advanitages snch as largecapability, wide areas range, low operation costs, effect'ixe,strong expandability, widely nsed in vehicle trafficadrministration and system of control command, goodapplicalion prospect.

REFERENCES

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Li'u Xu and Zhang Qishan, "A Vehicle Monitoring System Based onGPRS," Remote Survey and Remote Control, 2003. 1, pp. 42-49.Wang Haipeng and Hou ChLnping. "CGoPRS Terminal Realization Basedon 8051 Embedded System," Electronic Technology Application, 2004.5..Hulang Chenan and Zhang Yao, "GPRS Wireless Earthlink ofMicrocontroller," 2003.12. pp. 19-22.Lu Manhuai, "Design of Wireless Commnunication Controller with GPRSData Transmission Service," 2004.8.ETSI OSM 09.16 v6.0.0, "Technical Specification," 1998.04.ETSI TS09.61 v6.0.0, "Technical Specification," 1998.03.Huang Yuhong and Sun Shaoling, "General Packet Radio Service(GPRS)," Telecom Science, 2002.5, pp.7-10.Zou Huaming and Hou Jianjurln, "Research for CSD and GPRSApplication in Wireless Remote Monitoring System," ICEMI2005,Beijing 2005.8 A0G.

Y

Figre 4. Flow chart ofthe server system

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