ZigBee-GSM BasedAutomatic Meter Reading SystemaAryo H. Primicanta, bMohd Yunus Nayan, and aMohammad AwanaElectrical & Electronic Engineering DepartmentbFundamental and Applied Science DepartmentUniversiti Teknologi PETRONASBandar Seri Iskandar, Perak, MalaysiaEmail : email@example.com, firstname.lastname@example.org, email@example.comAbstract—Tenaga Nasional Berhad (TNB) as the power utilitycompany have to deliver good services to their customers.Metering method is one of the problems that TNB have toovercome. Automatic Meter Reading (AMR) technology hasproved effective in reading meter readings with TNB’s largecustomers (LPC, Large Power Customers). Global System forMobile communication-based (GSM) AMR technology is used.Here GSM module is attached to each LPC’s meter, and datareading can be done automatically without visiting thecustomer’s sites. The same way can be done with theirdomestic customers (OPC, Ordinary Power Customers), butthe cost would be quite high since the numbers of OPC quitebig. In this paper we described the AMR technology with leastcost. The system is a combination of ZigBee and GSMtechnology. In this propose system, ZigBee module will beattached to the meter by using interface board and the datacollector will be connected to the central computer by usingGSM. The system is suitable with Malaysian environmentwhich was already implemented GSM-based AMR in LPC.With this system TNB can save cost in doing meter reading andprovide better services to their customers.I. INTRODUCTIONIn 2008, Malaysian Energy Commission has introduceda standard for electricity supply in order to enhance theservices in utility industries. Tenaga Nasional Berhad (TNB)as a utility company which deal with electricity has tofollows this standard. Table 1 shows the number and typesof complaints received by Energy Commission forelectricity supply services. The complaints on electricitybilling, metering, disconnection and reconnection of supplyrecorded the highest percentage of total complaints onelectricity supply services of TNB in 2008 .TNB have two methods to take the metering data fromtheir customers. For Large Power Customers (LPC), theyused GSM-based Automatic Meter Reading (AMR). But fortheir Ordinary Power Customer (OPC), they send a meterreader officer to read the meter on monthly basis. When themeter is inaccessible due to several factors (weather, pets,customers not at the site, etc), the meter reader will do theestimate reading. This estimate reading is a normaloccurrence nowadays. TNB reported that for year 2008,numbers of customers with estimated readings are 839,478customers and all of them are given notice about thismethod. This numbers is increasing compared to year 2007(559,834), 2006 (447,339), 2005 (353,369), and 2004(355,318). With the increase numbers of TNB’s customers,the numbers of estimated readings will increase. Thisproblem has to be solved in order to improve the quality ofservice.TABLE ITNB ELECTRICITY SUPPLY SERVICESIssues No. ofComplaintsreceivedPercentageElectricity supply interruptions 21 14.58Application and connection ofelectricity supply13 9.03Tariff and charges 2 1.39Electricity billing, metering,disconnection and reconnection ofsupply49 34.03Safety of installations 22 15.28Rentice of transmission line or damageto TNB installations by third parties25 17.36Public lighting, other matter on supplyand customer services12 8.33TOTAL 144Automatic Meter Reading (AMR) technology can beimplemented to solve this metering problem. The idea ofAMR technology is to do the meter reading automaticallyand accurate. with high precission. There are two types ofAMR system: wire-based and wireless. Examples of wire-based AMR system are Power Line Carrier (PLC) andTelephone Line Network, where both of these systems usethe existing electric power line and telephone line networkto transfer data from each meter to a server in the utilitycompany. However, the stability and reliability of meterreading data are low because the carrier wave signal(power/telephone line) is very easily disturbed by noise .Other problems with wire-based AMR system aretransmission distance, transmission cost, maintenance andsecurity of data transmission. Advancement of the wirelesstechnology gives rise to the research and development ofusing the technology in AMR system. Malaysia is usingGSM-based AMR and it is still on a basis with largeindustry and none of these wireless AMR systems had beenimplemented for residential areas meter reading.In this research, an Automatic Meter Reading systemwhich is the combination of ZigBee and GSM technologybased on embedded system is developed. In this system,distributed structure is employed which consists of digitalmeters, microcontroller, data collector, ZigBee module andGSM module. The customers (represented with powermeter) are divided to a small cluster. Each cluster will have
a collector for collecting data from each meter. The collectorcollect meter reading stored in microcontroller attached toeach meter using ZigBee communication. The data collectoris used as the ZigBee gateway in the system. Fortransmission to the collection points or utility companyserver, GSM is used.II. GSM AND ZIGBEE TECHNOLOGYGSM stands for Global System for Mobilecommunication. In 1980’s, cellular telephone system wasalready used in Europe. Each country use different protocoland frequency for this cellular technology. Each of thistechnology is interoperable and analogue. Since thetechnology was growing rapidly, in 1982 Group SpecialMobile was formed among Europe countries. This groupstandardized cellular communication protocol which weknow as the Global System for Mobile communicationnowadays.Most GSM networks in the world operate in 900 MHzor 1800 MHz bands. However, some countries are usingdifferent frequencies since the allocated frequency hadalready been used. GSM use Time Division Multiple Access(TDMA) and Frequency Division Multiple Access (FDMA)for multiple access method and use Gaussian MinimumShift Keying (GMSK) for its modulation method. GSMarchitecture consists of a lot numbers of network elementswhich will form a Public Land Mobile Network (PLMN).Generally the network elements can be divided into:a. Mobile Station (MS)MS is device at customer’s side. Handset and SubscriberIdentity Module (SIM) card include in this networkelement. International Mobile Subscriber Identity (IMSI)and Mobile Subscriber Integrated Services DigitalNetwork (MSISDN) information are stored in this SIMcard.b. Base Station Sub-system (BSS), consist of :− Base Transceiver Station (BTS), connect directlywith Mobile Station (MS)− Base Station Controller (BSC), control the BTSc. Network Sub-system (NS), consist of :− Mobile Switching Center (MSC) for cellular-to-cellular or cellular-to-PSTN interconnection− Home Location Register (HLR), store informationabout subscriber permanently− Visitor Location Register (VLR), store subscriber’sinformation− Authentication Center (AuC)− Equipment Identity Registration (EIR), store allsubscribers informationd. Operation and Support System (OSS)OSS is network component which function as acontroller such as fault management, configurationmanagement, performance management, and inventorymanagement. All these network components is managedby telecommunication operator like Digi, Celcom andMaxis in MalaysiaThe frequency used for GSM is regulated by localauthorities. Deploying a new GSM network also need a lotof cost. That’s why the frequency band can’t be used freely.ZigBee is a standard-based network protocol supportedsolely by the ZigBee Alliance that uses the transportservices of the IEEE 802.15.4 network specification .ZigBee Alliance is a group of companies which maintainand publish ZigBee standards. Nine companies in ZigBeeAlliance are called promoters. They are Chipcon, BMGroup, Ember, Freescale, Honeywell, Mitsubishi, Motorola,Philips, and Samsung . ZigBee is intended for wirelessapplication that requires low data rate, low powerconsumption, low cost, and secure networking. ZigBeelayered on top of IEEE 802.15.4 standard which defines thephysical (PHY) layer and Medium Access Control (MAC)layer. ZigBee Alliance itself defines the application andsecurity layer specifications. The stack can be drawn infigure 1.Figure 1. ZigBee/IEEE 802.15.4 stackThe IEEE 802.15.4/ZigBee standard defines dual PHYlayer, which are 2.4 GHz and 868/915 MHz. Table IIsummarize specification for these two PHY layers.TABLE IIIEEE 802.15.4 PHY LAYERIn 2.4 GHz PHY layer, the Offset Quadrature Phase-Shift Keying (O-QPSK) modulation technique is used whilein 868/915MHz PHY layer Binary Phase-Shift Keying(BPSK) is used as modulation technique. Both O-QPSK andBPSK minimize power consumption and reduce complexity. Since there is another application which uses samefrequency band, ZigBee use Direct Sequence SpreadSpectrum (DSSS) and CSMA-CA (Carrier Sense MultipleAccess-Collision Avoidance) channel access. In addition,ZigBee can be used in multiple topology, such as star ormesh or cluster tree depending on application.The PHY is responsible for the following tasks :− Data transmission and reception.− Clear Channel Assessment (CCA) for CSMA-CA.− Activation and deactivation of the radio transceiver.− Energy detect within the current channel.
− Channel frequency selection.− Link Quality Indicator (LQI) for received packets.The MAC is used to interfacing between ZigBeeNetwork (NWK) and PHY layer and also responsible for thefollowing tasks :− Providing a reliable link between two peer MAC entities− Handling the CSMA-CA mechanism for channel access− Personal Area Network (PAN) association anddisassociation− Beacon generation and synchronization− Device securityThe IEEE 802.15.4 defines two types of device:a. Full Function Device (FFD).FFD is able to do all the nodes function. It needs to bealways active and listening on the network, thus it needsinexhaustible power source. The device can function inany topology and also being the network coordinator. Itcan talk to any other devices.b. Reduced Function Device (RFD).RFD has limited function. RFD cannot be networkcoordinator and can be talk only to a networkcoordinator. The use is limited to the star topology. Thepower source is easily exhaustible so RFD usually sleepsmost of the time.ZigBee takes the concept of FFD and RFD and createsthree ZigBee protocol devices which are:a. ZigBee Coordinator (ZC)Start the network. Able to store information about thenetwork and forms the network tree and might used asbridge to other networks. This ZC is a type of FFD.b. ZigBee End Node (ZED)Physically interfaces to a sensor or executes controlfunction. It can be RFD or FFD type, depends on theapplicationc. ZigBee Router (ZR)This device is optionally deployed, act as intermediaterouter.Another popular wireless technology is Bluetooth.Bluetooth use 2.4 GHz frequency. Bluetooth used for shortrange data transfer, similar like ZigBee. Koay et al  try touse Bluetooth for metering purpose. The significancedifference between ZigBee and Bluetooth is in spreadingsystem. Bluetooth use Frequency Hopping Spread System(FHSS) with master slave protocol, while ZigBee is usingDirect Sequence Spread System (DSSS) with a star or peer-to-peer protocol. ZigBee and Bluetooth are two solutions fortwo different applications . For sensor networkapplication, ZigBee is the best suited technology.III. DETAILED DESIGN OF THE SYSTEMThe system will use ZigBee and GSM system forcommunication protocol. The ZigBee is used since theapplication does not need high speed data rate, but need tobe low powered and low cost. For frequency, 2.4 GHz bandwill be used. Each ZigBee node will be connected to thecollector node and from collector node the data will be sentto the central computer by using GSM. Since TNB isalready using GSM for AMR for their Large PowerConsumer (LPC) customers, there is no need to build andtest another new technology infrastructure. The system isshown in Figure 2.FIigure 2. ZigBee-GSM based AMRBased on the data from Malaysian Intelligent Metering(MiM), one of TNB’s vendors which supply power meter,TNB is no longer buying new analogue meter and preparedto use solid state meter as meter instrument for theircustomers. The prototype system will use solid state meteras reference. The solid state meter reads current and voltageand processed digitally to calculate the power consumption.This research uses a Metronix single phase 2 wire kWhmeter loaned by MiM. It will produce 1000 pulses for 1 kWpower used. These pulses will be used for data input to themeter-to-ZigBee board interface (shown in Figure 3). Thesepulses will be captured by board interface and processed bymicrocontroller. If there is no command to sent data out, thedata will be kept inside microcontroller. PIC 18F4520 is beused since it can support UART communication as shown inFigure 4. Thus it will be easier to send the data out toZigBee module. Rx pin and Tx pin from microcontrollerwill be connected to Din and Dout pin at ZigBee module.Thus anytime there is a command to send the data out, theusage data will be easily sent to the ZigBee module andtransmitted to the collector node.Each meter will be connected to the collector pointwhich in turn will be connected to the central computer byusing GSM. Thus collector coverage range need to be aswidest as possible, thus mesh topology is chosen (figure 2).The node can communicate with another node, so if there isa node that is placed outside collector coverage area, datastill can be sent through nearest node around it, no need tocommunicate directly with collector point. At the centraloffice, a computer will take all the data and process the datato be a bill.
Figure 3. Meter-to-ZigBee Interface BoardFigure 4. PIC18F4520 pin configuration IV. ZIGBEE COMMUNICATION IN DETAILTo collect data from meter to collector, ZigBee is used.Meter is connected to ZigBee End Device. This end devicemust be able to communicate with the collector in order tosend data. The collector also has to know which end nodethat send the data so the data can be read accurately. Each ofZigBee modules has a unique 64-bit permanent address, sothe addressing won’t be much difficult.ZigBee mesh routing allows data packets to “hops” tomultiple nodes in a network to route data from a source to adestination. A process called route discovery is use toestablishing the routes. ZigBee route discovery is based onAd-hoc On-demand Distance Vector (AODV) routingprotocol.ZigBee module’s serial engine is slower than themicrocontroller. Figure 5 below shows internal data flowdiagram of a ZigBee module. There is a Serial ReceiveBuffer to buffer received data from UART and a SerialTransmit Buffer to buffer data before transmitting to UART.Sometimes, data received by the module is corrupted. Thiscould happen because next data from UART is coming butthe buffered data haven’t finished yet transferred. Toovercome this problem, the flow control is needed.Figure 5. ZigBee Module Internal Data Flow Diagrams There are several parameters that need to be set beforethe ZigBee module can be used. For this research,parameters for modules are:- ID-PAN ID is set 0 for the collector to chooserandom PAN ID and for end node also set 0 forjoining any PAN ID.- SC-Scan Channels is set 0x1FFE to scan allchannels- ZS-ZigBee Stack Profile is set 2 to choose ZigBeePRO Stack.- NJ-Node Join Time is set to 0xFF for always allowjoining.- DH-Destination Address High and DL-DestinationAddress Low is set 0x000000000000FFFF forcollector for broadcast the data to the entire node inrange. In the end node DH and DL is set0x0000000000000000 to send data directly tocollector.- BH-Broadcast Radius is set 0 for maximum radius.- PL-Power Level is set 4 for +3dBm output power.- PM-Power Mode is set 1 (boost mode) to improvessensitivity by 1dB and increases output power by2dB- BD-Baud Rate is set to 9600.After the parameter has been set, loopback test wasdone to test the performance of the module. Data was sent100 times from collector to end node. From end node, thedata was sent back to the collector. From the test, the datacan be sent and received successfully either by using unicastcommunication or multicast. Figure 6 show the result.Figure 6. Loopback test result for Unicast (left) andMulticast (right)V. CONCLUSION AND FUTURE WORKFrom the preliminary study in current metering problemin Malaysia and the AMR technology, the study has showthat GSM and ZigBee can be used for solving the meteringMETERPOWERINPOWEROUTPULSEOUTMICOM[PIC18F4520]ZigBeemodule[802.15.4]DATAOUT
problem in Malaysia. The loopback test shows that themodule can work well in sending and receiving datasimultaneously. An embedded system is researched byauthors. After the system is built, it will be tested to see theperformance.ACKNOWLEDGMENTWe would like to express our appreciation to UniversitiTeknologi PETRONAS (UTP) for providing the financialsupport and Malaysian Intelligence Meter Sdn Bhd (MIM) inlending us the meters and providing technical support for usto embark on this project.REFERENCES Malaysia. Malaysian Energy Commission, ElectricitySupply Industri in Malaysia, Performance andStatistical Information 2008, Suruhanjaya Tenaga,2008. L. Cao, W. Jiang, Z. Zhang, “Networked WirelessMeter Reading System Based on ZigBeeTechnology”, IEEE Chinese Control and DecisionConference 2008, pp. 3455-3460. “Sistem Telepon Selular Digital GSM,” June, 1995.[Online]. Available: http://www.elektroindonesia.com/elektro/no5b.html. [Accessed Dec. 2009] Fred Eady, “Hands-On ZigBee, Implementing 802.15.4with Microcontrollers”, Elsevier. 2007 “ZigBee, a technical overview of wireless technology. “Available:http://ZigBee.hasse.nl. [Accessed Dec. 2009] Wi-Fi, Bluetooth, ZigBee and WiMax. H Labiod, HAfifi, C De Santis. Springer. 2007 B.S Koay, S.S Cheah, Y.H.Sng, P.H.J.Chong, P.Shum,Y.C Tong, X.Y.Wang, Y.X.Zuo, and H.W.Kuek,“Design and Implementation of Bluetooth EnergyMeter”, ICIS-PCM, December 2003, pp. 1474-1477. Patrick Kenney, “ZigBee Technology: Wireless ControlThat Simply Works”, IEEE Communication DesignConference October 2002. Microchip. PIC18F2420/2520/4420/4520 Datasheet.2008Xbee/Xbee PRO OEM RF Modules. Digi International.2008