Wireless Home Security and Automation System Utilizing ZigBee based Multi-hop Communication Rozeha A. Rashid, Mohd Adib B. Sarijari, Mohd Rozaini Abd Rahim Faculty of Electrical Engineering University of Technology Malaysia Skudai, Johor Email: rozeha@fke.utm.my, adib_sairi@fke.utm.my, mohd_rozaini@yahoo.com Abstract Nowadays, smart home using wireless communication is replacing the wired system which was very messy and difficult to setup. However, the existing wireless smart home system only can cover up to a certain range of area that is limited by the range of wireless module being used. This paper introduces the conceptual understanding and strategy of ZigBee IEEE 802.15.4 standard to be deployed in smart home environment. ZigBee technology offers a multi-hop communication capability for data transfer. Multi-hop communication will provide unlimited range of communication for the system as long as there are intermediate nodes that will pass the data from one node to another until it reaches the destination. Prototype systems of home security and automation are built utilizing Zigbee based sensor network to present an insight for its practical implementation in smart home concept. Keywords: Zigbee IEEE 802.15.4 standard, sensor network, wireless communication, smart home I. INTRODUCTION Currently, there are various wireless technologies available, for instance Bluetooth, Infrared (IR), ZigBee, Radio Frequency (RF) and etc. Radio frequency (RF) module is a wireless device that basically works on either 413 MHz or 315 MHz frequency. Basically, the module doesn t contain any protocol and it will broadcast the signal with no security included. RF only supports star topology and the wireless range can cover up to 100 meters. Bluetooth is a wireless technology that had been introduced 10 years ago for short-range communication. Bluetooth technology is developed to be used in Personal Area Network (PAN) network for low power communication between devices such as phones, personal computers (PC), Personal Digital Assistance (PDA) and etc [1]. The range for Bluetooth wireless device can be up to 10 meters with 2.5mW (4dBm) power consumption. Bluetooth operates in unlicensed Industrial Scientific-Medical (ISM) band at 2.4 GHz with the capability of frequency hopping [1] and it only supports star topology communication. Zigbee is a protocol that had been developed based on Open System Interconnection (OSI) layer model. It builds on IEEE standard 802.15.4 which defines the physical and Medium Access Control (MAC) layers. Zigbee supports three types of communication topologies; star topology, tree topology and mesh topology. Zigbee wireless device operates with very-low power consumption which makes it the most attractive wireless device to use in Wireless Sensor Network (WSN). Zigbee has multi-hop communication capability, hence providing an unlimited range of communication. Under smart home environment, numerous sensors; i.e. motion detectors, smoke detectors, water leakage detectors and etc., and communication devices can be utilized for connection throughout the house, capable of monitoring and detecting the physical events. The input from these sensors can be used to alert the owner of any unauthorized intrusion or control home appliances such as lightings. Thus, maintaining seamless connectivity between devices and the main controller is very crucial. A lost connectivity can jeopardize the security of the home. It is also an important factor to ensure the devices being used operate in very-low power consumption so that they would last longer. Aimed at control and sensor applications, ZigBee promises robust and reliable, and self-configuring networks that provides a simple, cost-effective and battery efficient application. These allow the technology to take advantage of short-range wireless protocol, flexible mesh networking, strong security tools, well-defined application frameworks, and a complete interoperability [3]. Therefore, in this project, Zigbee wireless modules from Digi International are chosen to be used for establishing communication between all devices (sensor nodes) in the house with the main controller. Table 1 shows comparison between several wireless technologies and their respective specifications and applications.
Table 1. Comparison of specifications of existing wireless technologies II. MULTI-HOP COMMUNICATION The coverage area of wireless communication is limited by the capability of the wireless device used. The device that gives a wide coverage area will be very expensive and yet, there is still a limit to it. Moreover, the more powerful wireless device is, the more it will consume power. Moreover, it will produce a high electromagnetic radiation which can be hazardous to human health [4][12]. Multi-hop communication offers a solution for this problem. Figure 1 illustrates how the data is being sent from source to the destination through a numbers of intermediate sensor nodes. Therefore, the sensor at the source can communicate with its counterpart at the destination no matter how far the destination is as long as there is an intermediate nodes which will transfer the data from one node to another until it reaches the destination. can send data up to 30m and it has low power consumption (1mW for transmitting data). Xbee works in 2.4 GHz frequency and offers three modes of operation; AT mode, Application Programming Interface (API) mode and API with Escape (ESC) character mode. API operation is chosen to be used in this project due to several reasons. Firstly, it can transmit data to multiple destinations without having to enter the command mode. Secondly, it can identify the source address of each packet and thirdly, it will receive update on the transmission status whether it is successful or fail. The data frame for API operation is shown in figure 2. The frame is being divided into four sections; start delimiter section, length section, frame data section and checksum section. Figure 2: Xbee Zigbee Module API Data Frame The checksum is being calculated as below: Checksum = 0xFF of all bytes in API structure Xbee can support up to 16-bit of addressing number, therefore, nodes for MSHome can be up to 65535 nodes. IV. METHODLOGY The methodology of this project design can be divided into two sections; hardware and software implementations. The hardware implementation consists of the development of the main controller, sensor nodes and the smart home sensor network while the software implementation focuses on the programming of the microcontroller using MikroC C compiler from Mikroelektronika. A. Hardware Implementation Figure 1: Multi-hop Communication III. ZIGBEE IEEE802.15.4 ZigBee is a wireless technology developed by Zigbee Alliance as an open global standard to address the unique needs of low-cost, low-power, wireless sensor networks [5]. The standard takes full advantage of the IEEE 802.15.4 physical radio specification and operates in unlicensed bands worldwide at the following frequencies: 2.400 2.484 GHz, 902-928 MHz and 868.0 868.6 MHz. The Zigbee used in this project is Xbee Zigbee Module from Digi International. It Main controller is the most important part of the system in this project. Main controller will be the interface between the user and the system. Figure 3 shows the main controller of the prototype smart home hardware. PIC18f452 microcontroller is used as the brain of the main controller. It has 32 general I/O port and the clock speed can be up to 40 MHz. This microcontroller is a CMOS technology IC which enable the low power consumptions (lower than 1.6mA in the typical mode and lower than 0.2uA in the sleep mode).
the valve for watering the plant. When owners were not at home and want to water their plants, they simply send a command to the house by using an SMS. The main controller will receive the SMS and then send the command to the desired node through a number of intermediate nodes via multi-hop communication. Sensor nodes can be added in the house by simply putting them at desired locations accordingly. The main controller will detect the new node automatically. User just has to inform the main controller by keying-in the specific use of the new node. Figure 3: Main Controller The main controller is equipped with a GSM modem that is used to send and receive SMSes. Users can store up to nine phone numbers in the main controller. These phone numbers are the only numbers the main controller will communicate with, whether to send an alert signal or to receive a command. The main controller is also being equipped with an alphanumeric LCD display and keypads as user interface. The interface on the main controller allows users to change the setting as they wish. They can switch on and off the system, changing the phone numbers, adding a new node and etc. To access the main controller system, user must first keyin the password. This password can be changed as desired. B. Software Implementation The software part consists of programming PIC16LF452 microcontroller using MikroC compiler from Mikroelektronika. The scope of programming includes USART communication programming, LCD character module programming and analog to digital converter programming. All of this programming is done using C language. Figure 4: Security System V. SYSTEM IMPLEMETATION AND DISCUSSION This project offers two importance features of a smart home; home security and home automation. In home security system, the triggered sensor node (indicating an unauthorized intrusion or a fire) will send an alert signal to the main controller through the intermediate nodes using multi-hop communication. When the main controller receives the alert signal, it will then send the alert signal to the user by using SMS via the GSM Modem which is attached to the main controller. Figure 4 shows the operation of this built home security system. In home automation system, user can control their house by sending the command through SMS to the main controller at home. When the home main controller received the command, it will send the command to the destination node through the intermediate nodes using multi-hop communication. The destination node then will carry out the task as commanded by the user. Figure 5 shows the operation of the home automation system for the house. For instance, a valve controller is placed on one of the sensor node to control Figure 5: Home Automation System VI. CONCLUSION This paper describes ZigBee communication protocol and presents its potential deployment in smart home environment. Examples of prototype applications in home security and automation utilizing a ZigBee based wireless sensor network are illustrated. A comparison is made between the designed Zigbee based wireless smart home system and other existing systems in market. This system has attractive features such as
two-way remote control ability via SMS, stores up to 9 contact numbers and home automation via Wireless Personal Area Network (WPAN) with multi-hop capability. In general, sensors and communication devices used for the deployment in smart home are not required to have highspeed communication capacities; rather more consideration needs to be focused on a limited amount of delay in communication and a low energy consumption. In this perspective, ZigBee is emerging network technology as a wireless communication standard that is capable to satisfy such requirements. Moreover, its specification, which is based on IEEE 802.15.4 wireless protocols, promises robust mesh network and complete interoperability. VII. ACKNOWLEDGEMENT Financial and management support from the Ministry of Science, Technology and Innovation, Malaysia and Research Management Center University of Technology Malaysia through E-science funding vote no. 79211 is acknowledged with gratitude. REFERENCES [1] Rozeha A. Rashid, Rohaiza Yusoff. Bluetooth Performance Analysis in Personal Area Network (PAN), International RF and Microwave Conference, Palm Garden Hotel, IOI Resort, Putrajaya; Sept.12-14 th, 2006. [2] Rozeha A. Rashid, Hong Ling Zhen. Wireless Monitoring System Using ZigBee IEEE 802.15.4 Standard, Int l Wireless Telecommunication Symposium (IWTS06), Grand Bluewave Hotel, Shah Alam, 15-17 th May 2006. [3] Zucatto, Fabio L, Biscassi, Clecio A, Monsignore, Ferdinando, Fidelix, Francis, Coutinho, Samuel; Rocha, Monica L. ZigBee for building control wireless sensor networks. Microwave and Optoelectronics Conference, 2007. IMOC 2007. SBMO/IEEE MTT-S International Oct. 29 2007-Nov. 1 2007 Page(s):511 515. [4] Ali Zamanian, Cy Hardiman. Electromagnetic Radiation and Human Health: A Review of Sources and Effects. High Frequency Electronics Copyright 2005 Summit Technical Media, From July 2005. [5] Product Manual v1.xax - 802.15.4 Protocol For OEM RF Module Part Numbers: XB24-...-001, XBP24-...-001. [6] Tunheim, Svein Anders. Implementing an IEEE 802.15.4 and ZigBee Compliant RF Solution, Chipcon Paper IIC-China ESC-China 2005. [7] R. Shepherd. Bluetooth wireless technology in the home. Electronics and Communication Engineering Journal, October 2001 [8] Doshi. Wireless technology-a skyway to the future. Personal Wireless Communications, 1997 IEEE International Conference on 17-19 Dec. 1997 Page(s):275 282. [9] Hsu, Sheng-Fei, Chiang, Chi-Hui. Wireless Technology: A Challenge toward Supply Chain Management. Management of Engineering and Technology, Portland International Center for 5-9 Aug. 2ontrol007 Page(s):2361 2364. [10] Shepherd. Bluetooth wireless technology in the home. Electronics & Communication Engineering Journal Volume 13, Issue 5, Oct. 2001 Page(s):195 203. [11] Ran Peng, Sun Mao-heng, Zou You-min. ZigBee Routing Selection Strategy Based on Data Services and Energy-Balanced ZigBee Routing. Services Computing, 2006. APSCC '06. IEEE Asia-Pacific Conference on Dec. 2006 Page(s):400 404. [12] http://www.sciencedaily.com/releases/2000/10/001016073704.htm. Accessed on 1 Februarry 2008.