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A low cost gsmgprs based wireless home security system

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  • 1. A Low Cost GSM/GPRS Based WirelessHome Security SystemYanbo Zhao and Zhaohui YeAbstract — Home security system is needed for occupants’convenience and safety. In this paper, we present the designand implementation of a low cost, low power consumption,and GSM/GPRS (Global System for Mobile Communication/General Packet Radio Service) based wireless home securitysystem. The system is a wireless home network which containsa GSM/GPRS gateway and three kinds of wireless securitysensor nodes that are door security nodes, infrared securitynodes and fire alarm nodes. The nodes are easy installing.The system can response rapidly to alarm incidents and has afriendly user interface including a LCD (Liquid CrystalDisplay) and a capacitive sensor keyboard. The wirelesscommunication protocol between the gateway and the nodes isalso suitable for other home appliances. Furthermore, somemethods are taken to ensure the security of system information.Index Terms — Security, GSM/GPRS, WirelessI. INTRODUCTIONTHERE is a growing interest in intelligent home network as away to offer a comfortable, convenient and safe environmentfor occupants [1]. In order to enhance the occupants’convenience and safety, home security system is indispensablein the field of intelligent home network. The requirements of ahome security system include low cost, low powerconsumption, easy installation and rapid response to alarmincidents.According to connecting mode, home network can bedivided into two kinds: wireless network and non-wirelessnetwork [2]. The wireless technology has some remarkablebenefits comparing with non-wireless technology. For example,it makes the installation and maintenance easier and reducesthe system cost. Bluetooth [3], ZigBee [4], [5], 802.11 [6] andwireless USB [7] are the most popular technologies in the fieldof home wireless network. [3] introduces a method to form ahome network which provides flexible and dynamic servicesvia Bluetooth. However, the system mentioned in [3] is highpower consumption and high cost so that it is not convenient touse in security system. [4] and [5] present how to applyZigBee/IEEE802.15.4 to establish a home network that is cost-effective and low power consumption. However,Yanbo Zhao is with the Department of Automation, Tsinghua University,Beijing, China (Email: zhao-yb06@mails.tsinghua.edu.cn).Zhaohui Ye is with the Department of Automation, Tsinghua University,Beijing, China (Email: yezhaohui@mail.tsinghua.edu.cn).[4] and [5] don’t present the implementation. Wireless homenetwork based on the IEEE802.11 standard, also known asWiFi, provides a good solution for many home network needssuch as transferring file and media date [6], but this standard isalso high cost and high power consumption. [7] presents thedesign of a home network using a wireless USB controller thatoffers several benefits such as low cost, expandability andoutstanding performance. Wireless USB can also be used inhome security system.How to inform user in real time when alarm incidents occurhas become a crucial feature of home security system. This canbe done via internet or GSM/GPRS. GSM/GPRS is moreconvenient than internet. The main reason is that theGSM/GPRS network has wide spread coverage making thewhole system available for almost all the time. Furthermore,GSM/GPRS network has high security infrastructure whichmakes sure that the information sent or received cannot bemonitored [8]. The network examples mentioned in [3], [5], [6]and [7] send the information to remote users via internet. [8]and [9] are examples of home systems using GSM/GPRSnetwork for remote controlling. However, [8] only illustratesthat GSM is communication method between remote user andhome network server but doesn’t apply it to home securitysystem. The system in [9] only applies GSM/GPRS technologyto intrusion detecting and its communication is non-wireless.In this paper, a low cost GSM/GPRS based wireless homesecurity system is presented. The system includes two parts:wireless security sensor nodes and a GSM/GPRS gateway. Ithas the following features:(1) Low cost. All the microprocessors used in the sensornodes and the gateway are cheap 8-bit microprocessors,and all other devices are inexpensive.(2) Low power consumption. All security sensor nodes arepowered by batteries.(3) Easy installing. Because the nodes communicate with thegateway by wireless, they can be installed anywhereinside the home.(4) Rapid response. The GSM/GPRS gateway will sendSMS (Short Message Service) messages to informremote PMP (Property Management Person) and userswhen alarm incidents occur.(5) Friendly user interface. The system has a friendly userinterface including sixteen capacitive sensor keys and aLCD. Users can view the states of security sensor nodes,modify password of the gateway and change the mobilephone number for receiving the alarm messages.(6) Emergency alarm function. There is an emergency alarmkey (SOS key) in the GSM/GPRS gateway which makesusers at home to alarm in emergency situations.Manuscript received December 6, 2007 0098 3063/08/$20.00 © 2008 IEEEY. Zhao and Z. Ye: A Low Cost GSM/GPRS Based Wireless Home Security System 567
  • 2. (7) Information security method. In order to ensure thesecurity of system information, some security methodsare taken, such as a password for gateway to preventunauthorized person to access the system, and a pseudosecurity key for data encryption and decryption toensure security wireless communication.The paper is organized as follows. Section II presents thegeneral structure of the proposed system, as well as its mainfeatures and components. Section III shows the design ofGSM/GPRS gateway and Section IV shows the design ofsecurity sensor nodes. Section V discusses the communicationbetween the gateway and the security sensor nodes. In SectionVI, the preliminary experimental functions of the system areshown and, finally, in Section VII, conclusions are presented,referring perspectives for future work.II. THE HOME SECURITY SYSTEMThe general structure of the home security system is shownin Fig. 1. The system includes two parts: wireless securitysensor nodes and a GSM/GPRS gateway. There are three kindsof sensor nodes in this system: door security nodes, infraredsecurity nodes and fire alarm nodes. The GSM/GPRS moduleis the interface between the gateway and the GSM/GPRSnetwork.Security nodesGSM/GPRSgatewayUARTinterfaceThe mobilephone ofremote userSMSGSM/GPRSmoduleFig. 1. The structure of home security systemThe microprocessor used in this system is 8-bit PSoC(Programmable System on Chip) device. There are threereasons to use this device. Firstly, it makes the design easierand reduces system cost. It has configurable analog and digitalblocks, as well as programmable interconnects logic. Thisarchitecture allows users to create customized peripherals suchas filters, amplifiers, analog to digital converters,communication interfaces and so on. Secondly, this device hasa sleep timer and SMP (Switch Mode Pump) circuit, which areuseful to reduce power consumption. Thirdly, there is a specialPSoC device which reduces the design complexity ofcapacitive sensor keyboard in the system.The wireless data transfer between gateway and sensornodes is implemented with a wireless transceiver module. Themodule operates in the unlicensed worldwide 2.4GHz ISM(Industrial, Scientific and Medical) band and has manyexcellent features: (1) low power consumption, 21mAoperating current and sleep current less than 1μA; (2) DSSS(Direct Sequence Spread Spectrum) data rates up to 250kbps,GFSK (Gaussian Frequency Shift Keying) data rate of 1 Mbps;(3) Operating range is 10m plus; (4) 4 MHz SPI (SerialPeripheral Interface) microcontroller interface.III. THE GSM/GPRS GATEWAYA. Hardware of GSM/GPRS GatewayThe diagram of the hardware of GSM/GPRS gateway isshown in Fig. 2. The GSM/GPRS gateway contains six majorcomponents:(1) Microprocessors, including I and II;(2) Wireless transceiver module;(3) LCD;(4) LEDs (Light Emitting Diodes) and a buzzer;(5) Capacitive sensor keyboard;(6) GSM/GPRS module.Fig. 2. The diagram of GSM/GPRS gatewayMicroprocessor I is the central device of the gateway. Itreceives the information coming from nodes and sends outalarm messages to remote users via GSM/GPRS module.Microprocessor II deals with the keys’ signals and sends thesignals to microprocessor I through its SPI interface.In this system, the communications between the GSM/GPRSmodule and Microprocessor I are implemented in the form ofAT (Attention) commands.The implementation of GSM/GPRS gateway is shown in Fig.3.568 IEEE Transactions on Consumer Electronics, Vol. 54, No. 2, MAY 2008
  • 3. Fig. 3. The implementation of GSM/GPRS gatewayB. Software Design of GSM/GPRS gatewayThe working procedure of gateway is as follows:(1) The wireless transceiver module receives the statesinformation of security sensor nodes and sends theinformation to microprocessor II through its SPIinterface.(2) LCD displays the information of sensor nodes. Whenalarm incidents happen, LCD will display alarminformation. LEDs and the buzzer will warn the users athome. At the same time, the gateway will send alarmSMS messages to remote PMP and users through theGSM/GPRS module.(3) Sixteen capacitive sensor keys including an emergencyalarm key (SOS key) are designed to modify passwordand mobile phone number for receiving the alarmmessages. What’s more, the SOS key is used to startupemergency alarm.The function of microprocessor II is receiving keyboard’sinformation and sending it to microprocessor I through SPIinterface. Its procedure workflow is to scan keyboard in turnsand to send out signals corresponding to the keys which aretouched by fingers of user.The flowchart of main program of microprocessor I isshown in Fig. 4.(1) Initializes system.(2) Receives information of sensor nodes and keyboard.(3) If any node alarms, the program calls alarm subprogramto display alarm message on the LCD and sendscorresponding SMS messages to remote PMP and users.(4) If user at home presses the SOS key, it means he/shewants to alarm immediately. Then, the system will sendthe SOS message to remote PMP and users at once.(5) If user wants to use the menu function of gateway,he/she need to press the Menu key. Then, the programcalls menu subprogram.Fig. 4. The flowchart of main program of microprocessor IFig. 5 shows the flowchart of the menu subprogram.(1) Check up password.(2) If the password is right, the menu appears on LCD,otherwise the sub program ends at once.(3) Press 1 to 4 corresponds to the four functions of themenu: 1 for initializing password and the SOS number,2 for changing password, 3 for changing the SOSnumber and 4 for quit. These functions are discussed inSection IV in detail.Fig. 5. The flowchart of menu subprogramY. Zhao and Z. Ye: A Low Cost GSM/GPRS Based Wireless Home Security System 569
  • 4. IV. WIRELESS SECURITY SENSOR NODESA. The General Structure of the Sensor NodesThe general diagram of wireless security sensor nodes isshown in Fig. 6. Every sensor node has a wireless transceivermodule and a microprocessor. The microprocessor receivesand analyses the sensors’ signals to detect the state of node.Fig. 6. The general diagram of nodesTwo methods are taken to reduce power consumption ofnodes:(1) SMP circuit. It can be used to generate typical operatingsupply voltages off a single battery using only a fewexternal components. As long as external voltage ismore than one volt, the microprocessor would worknormally, so the node can work steadily for a long time.(2) By configuring the sleep timer, the microprocessor cango into sleep mode periodically, which reduces averagepower consumption.B. The Door Security NodeDoor security node adopts magnetic sensor. The sensordoesn’t need external power supply and has an ON/OFF signaloutput according to the distance from magnet to dry spring.The distance threshold is 16 mm. As the sensor is normally inON state, the circuit in Fig. 7 is designed to use a 1MΩresistor R1 to limit the circuit current so as to reduce powerconsumption. The implementation of a door security node isshown in Fig. 8.VCC330R21MR1Micro-processorMagneticsensorFig. 7. Circuit of door security nodeFig. 8. The implementation of a door security nodeC. The Infrared Security NodeThe infrared security node adopts a pyroelectric infraredsensor (PIR). PIR sensor responds to the infrared radiation ofhuman body whose radiation is strongest at wavelengthbetween 9.4 μm and 10.4 μm [10]. The sensor can be placed inthe entrances of rooms or other areas. When an intruder entersthese areas, the sensor will detect the infrared radiationgenerated by the intruder and output a signal whose range isabout 1mV and frequency is about 1Hz, as shown in Fig. 9.Fig. 9. Output signal of PIR sensorSince the output signal of PIR sensor is very small, signalprocessing circuit must be designed. The common method isusing a special amplifier to process the signal [11]. The circuithas a stable output and a quick response. However, it iscomplex, high power consumption and high cost.Since microprocessor contains configurable analog anddigital blocks which can be configured as filters, amplifiersand analog to digital converters, the other simpler method is touse these configured filter, amplifier and ADC (Analog toDigital Converter) to process the signal, as shown in Fig.10.The output signal of PIR sensor is wired to microprocessor570 IEEE Transactions on Consumer Electronics, Vol. 54, No. 2, MAY 2008
  • 5. after a RC (resistor-capacitor) filter. The signal processesinside the microprocessor include amplifying, further filtering,analog to digital conversion and comparing with the alarmthreshold determined by experiments. This method greatlysimplifies circuit and reduces the power consumption.The implementation of infrared security node is shown inFig. 11.6.8M6.8M 20K0.01u47uVCCFig. 10. Circuit of PIR sensor with a RC filterFig. 11. The implementation of an infrared security nodeD. The Fire Alarm NodeThere are many fire-detection techniques. The commonmethods are based on temperature sampling, relative humiditysampling, smoke analysis, in addition to ultraviolet andinfrared sampling. [12] presents a fire-alarming method basedon video process. Although the method mentioned in [12] canprovide additional information about the process of burning, itis too expensive to be used in home security system.In this system, each fire alarm node adopts a temperaturesensor and an infrared receiver. The temperature sensormonitors environment temperature and infrared receivermonitors heat and flames. If temperature or infrared ofenvironment exceed defined thresholds, the node sends outalarm signal. The implementation of a fire alarm node isshown in Fig. 12. It is simple design, low cost and suitable touse in home.Fig. 12. The implementation of a fire alarm nodeV. THE WIRELESS COMMUNICATIONWhen alarm incidents occur, the nodes will send alarminformation to the GSM/GPRS gateway immediately. If thereis no alarm incident, the gateway and sensor nodes use aquery-reply communication mode. When a node is queried, itreturns its state to the gateway. The communication packetformat between the gateway and node is given in Fig. 13. Thepacket consists of Preamble (P), Start of Packet (SOP), PacketLength (PL), Payload Data (PD) and the CRC16 bits.Payload data have two bytes. The first byte represents theidentity of security node, the second byte represents the stateof node (0x00000001: “Open” State; 0x00000010: “Close”State; 0x00000100: “Alarm” State) or query command(0x00001111) from gateway. Before the payload data istransferred, it is encrypted with a pseudo security key. Thepayload data is decrypted with the same pseudo security keyafter received. The security key is generated by GSM/GPRSgateway and is sent to each node when installing.Fig. 13. The communication packet formatVI. THE SYSTEM FUNCTIONA. Alarm FunctionThe home security system discussed above has two kindsof alarms: abnormal alarms issued from three sensor nodes andemergency alarm started by users when they touch “SOS” key.Table I presents messages on LCD and SMS messages sent touser when alarms take place.TABLE IALARM FUNCTIONS OF SYSTEMAlarm Type LCD SMSdoor security nodes’ alarm Door AlarmMESSAGE SENTDoor Alarminfrared security nodes’ alarm Stealing AlarmMESSAGE SENTStealingAlarmfire alarm Fire AlarmMEDSSAGESENTFire Alarmemergency alarm SOS!!!MESSAGE SENTHELP!!!Y. Zhao and Z. Ye: A Low Cost GSM/GPRS Based Wireless Home Security System 571
  • 6. B The Menu Function“Menu” key should be touched in order to use functions ofmenu. User is requested to enter password firstly. If the inputpassword is correct, the system menu will show on the LCD.(1) InitializationPress “1”, the system password is changed to “222333”and mobile phone number for help is changed to“00000000000”.(2) Change passwordPress “2”, the system requests user to enter newpassword. When completed, the system asks user toinput again to verify. If two inputs are same, thepassword will be changed to the new one. During theprocess, you can use “Cancel” key to delete what youhave entered.(3) Change mobile numberPress “3”, the system displays the existing mobilenumber and prompts user to enter new number. Whenfinish inputting mobile phone number, press “Set” key tocomplete the amendment.(4) QuitPress “4”, the system quits the menu.VII. CONCLUSIONThis paper presents the design and the implementation of awireless home security system. PSoC devices and wirelesstransceiver modules are adopted. The system has a friendlyuser interface and employs some methods to reduce the powerconsumption.Communication of the system is complete wireless, whichmakes the system easy to install and use. The system is lowcost, low power consumption and easily operable. In addition,the wireless transceiver modules enable the system to transferother information such as voice and picture rather than justalarm signals. As a result, the system can lightly be expandedto other applications.The system is secured with a login password. As a futurework, we are currently working to establish a more securesystem by researching a proper wireless security protocol.ACKNOWLEDGMENTThe author would like to thank Lucan Lin, Xiaolong Chenfor their contribution to the design and implementation of thesystem.REFERENCES[1] K. C. Lee, “Network-based fire-detection system via controller areanetwork for smart home automation,” IEEE Trans. ConsumerElectron., vol. 50, no. 4, pp. 1093-1100, Nov. 2004.[2] A. Z. Alkar, “An internet based wireless home automation system formultifunctional devices,” IEEE Trans. Consumer Electron., vol. 51, no.4, pp. 1169-1174, Nov. 2005.[3] Y. Tajika, T. Saito K. Termoto, N. Oosaka and M. Isshiki, “Networkedhome appliance system using bluetooth technology integratingappliance control/monitoring with internet service,” IEEE Trans.Consumer Electron., vol. 49, no. 4, pp. 1043-1048, Nov. 2003.[4] J. A. Gutierrez, M. Naeve, E. Callaway, M. Bourgeois, V. Mitter, and B.Heile, “IEEE 802.15.4: a developing standard for low-power low-costwireless personal area networks,” IEEE Network, vol. 15, no. 5, pp. 12-19, Sept-Oct. 2001.[5] Y. P. Tsou, J. W. Hsieh, C. T. Lin, and C. Y. Chen, “Buliding a remotesupervisory control network system for smart home applications,” IEEEInternational Conf. on System, Man and Cybernetics, pp. 1826-1830,Oct. 2006.[6] L. Ophir, “802.11 Over Coax – A Hybrid Coax – Wireless HomeNetwork Using 802.11 Technology,” Consumer Communications andNetworking Conference, pp. 13-18, Jan. 2004.[7] H. S. Kim, and C. G. Lee, “Wireless USB based home security systemon the OSGi service platform,” International conf. on ConsumerElectron., pp. 1-2, Jan. 2007.[8] B. Yusekkaya, A. A. Kayalar, M. B. Tosun, M. K. Ozcan, and A. Z.Alkar, “A GSM, internet and speech controlled wireless interactivehome automation system,” IEEE Trans. Consumer Electron., vol. 52,no. 3, pp. 837-843, Aug. 2006.[9] A. Alheraish, “Design and implementation of home automationsystem,” IEEE Trans. Consumer Electron., vol. 50, no. 4, pp. 1087-1092, Nov. 2004.[10] S. Lee, K. N. Ha, and K. C. Lee, “A pyroelectric infrared sensor-basedindoor location-aware system for the smart home,” IEEE Trans.Consumer Electron., vol. 52, no. 4, pp. 1311-1317, Nov. 2006.[11] B. Li, B. Jiang, and B.Q. Wang, “Application of BISS0001 on heat-released infrared switch,” Application Science and Technology, vol. 33,no. 2, pp. 31-33, Feb. 2006.[12] P. H. Huang, J. Y. Su, Z. M. Lu, J. S. Pan, “A fire-alarming methodbased on video processing,” Intelligent Conf. on Intelligent InformationHiding and Multimedia Signal Processing, pp. 359-364, Dec. 2006.Yanbo Zhao was born in Shijiazhuang, China on July 18,1984. He received the B.S degree from Harbin Institute ofTechnology, Harbin, China, in 2006. He is currentlypursuing his M.S degree at Tsinghua University, Beijing,China. His main research interests are home automationnetwork, home network security and electronictechnology applications.Zhaohui Ye was born in Hunan Province, China onDecember 14, 1968. She received her B.S, M.S., andPh.D degrees in Industry Automation Instrument, ReactorEngineering and Reactor Security, and Control Scienceand Engineering from Tsinghua University, Beijing,China, in 1992, 1994, and 2004, respectively. She hasbeen working in Automation Department at TsinghuaUniversity, Beijing, China since 1994, and now she is anassociate professor. From September, 2002 to March, 2003, she studied as aVisiting Scholar in Extension and Teaching Development Center atUniversity of California, at San Diego, USA. Her main research interests arehome automation network, electronic technology application, and analogintegrated circuit design.PHOTO572 IEEE Transactions on Consumer Electronics, Vol. 54, No. 2, MAY 2008