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1、Design and implementation of indoor environment fire alarm system based on Wireless Sensor NetworkAuthor: Xiu Wen Fu, Wenfeng Li, Lin Yang As a new network technology, wireless sensor networks (WSN) are widely used in various emergency events because of their strong local cooperative sensing and the

2、 ability to interpret data from the environment. In this paper, we propose a fire alarm system called firealarming system indoor environment (fasie), which innovatively integrates wireless fire alarm network with hand fire extinguishing rescue support system. Unlike traditional wireless sensor netwo

3、rks that implement fire networks, the fasie is able to fire into fire, including fire alarms, providing full range of services, firerescuing and Firefighter positioning. In order to explain Fahey better, we first give a general description of fasie and introduce the architecture of the system. Then,

4、 the hardware and system performance are introduced. Key words: Wireless Sensor Networks (WSN), indoor environment, fire alarm system, handheld fire rescue support system 1 Introduction With the new manufacturing and integration technology, reduce the cost, the size of the wireless sensor, we have w

5、itnessed another revolution, is conducive to the control and observation of our life and the physical world, as the network technology to do, micro sensors connected to each individual and organization deeply embedded into the physical environment of information exchange network we can observe with

6、the environment and in a loyal, previously not real-time human-computer interaction. As one of the most influential aspects of fire protection applications, public safety activities have also achieved significant benefits in the emergence of wireless sensor networks and their further development in

7、2. In this paper, we propose a wireless fire alarm system fire alarm system for indoor environment (fasie) the main contribution is the introduction of the wireless network and handheld fire alarm fire rescue fire alarm and rescue support system to provide comprehensive technical support. The rest o

8、f this article is organized as follows. Section 51.2 describes the state-of-the-art of existing fire alarm systems. In the 51.3 section, fasie is introduced from the point of view of system composition and function. The 51.4 section describes the fasie layered architecture. The 51.5 section introduc

9、es the key hardware of fasie. The 51.6 part analyzes the performance of fasie. Finally, conclusions and future work are presented in sect. 51.7. 2 related work Because wireless sensor networks have great potential in the field of fire protection, many fire protection systems have been developed base

10、d on WSN. But in most cases, the only purpose of the network is to obtain environmental data, which are collected and displayed in a base station, stored in a database, or sent to a remote location 3,4. Here, several representative proposals differ from the traditional paradigm as follows: (1) CFFDR

11、S 5 is a forest fire that has been extensively implemented in the United States and new zealand. The main component of the system is the fire weather index (FWD), and this index is the key meteorological element through the fire, such as temperature, evaluation of relative humidity, wind speed and p

12、recipitation. The acquisition of CFFDRS information relies on wireless sensor nodes deployed in thousands of forested areas. The CFFDRS monitoring network collects various information (e.g., temperature, wind speed, and humidity). The base station of the monitoring network provides environmental inf

13、ormation directly to the remote server.(2) scier 6 is a comprehensive system for the detection, monitoring and prediction of natural disasters. Scier's target applications are urban and rural areas. The unique component in scier is the local alarm control unit, used to control the wireless senso

14、r network (WSN) and is responsible for the early detection, location and subsequent fire alarm function of the fire. Scier develops wireless sensor nodes in two different urban and rural areas: citizens, masters, public sensors, sensors. The citizens of the owners, sensors, and sensors of public own

15、ership, sensors, and installations are different, depending on their application scenarios. (3) Eidos 7 is a comprehensive system including alarm, fire alarm and rescue. The main component of the system is a network composed of thousands of sensor nodes, deployed in the field of unmanned aerial vehi

16、cles (UAV). Another key element of the system is the handheld device that firefighters carry. The network is responsible for monitoring the monitoring area and sending environmental information to remote servers. Handheld devices are integrated with lightweight browsers that have access to remote da

17、tabases or data centers. In summary, although the system has experienced significant improvement compared with the traditional cases, most of them only focus on the realization of single professional fire alarm network or fire rescue support network, resulting in inability to undertake more complex

18、tasks. To a certain extent, they do waste a lot of resources. Therefore, the fasie aims to provide more comprehensive services for fire protection activities, including fire monitoring, fire fighting, rescue and fire personnel positioning. 3 system introduction The fasie system consists of two compo

19、nent application architectures: a wireless fire alarm network and a handheld fire rescue support system. Wireless fire alarm networks are deployed by hundreds of wireless sensor nodes in buildings and other application scenarios. Since wireless sensor nodes have specialized applications in fire scen

20、arios, each node is encapsulated in fire protection package. With WSN forest monitoring, the main applications of fasie are mainly focused on indoor environmental monitoring. Therefore, the node is equipped with two power modules (battery module and fixed power module). When the fire happens, the wi

21、reless fire alarm network can detect the fire at once and send out alarm information to the base station. In fasie, the base station is a small high-performance embedded system with two communication interfaces (such as Wi-Fi and 3G), which can be deployed easily. When the base station receives the

22、alarm information, the alarm information is forwarded to the monitoring platform through the Wi-Fi, and corresponding evacuation and call service decisions are made according to the received information. A key element of the handheld fire rescue support system in FASIE is unique features that can di

23、stinguish this system from other existing support systems for fire protection. A handheld fire rescue system consists of two devices: a fire PDA and a wireless sensor node with a Bluetooth interface. Portable wireless sensor nodes can share information with PDA via Bluetooth interface. Information (

24、such as RSSI and LQI) is dynamically self organized. Through the indoor environment location algorithm, PDA can access the accurate location of fire fighters and notify the supervision platform through the 3G network. In addition to indoor location services, the handheld fire rescue system also incl

25、udes outdoor location services and health status monitoring. With the support of the GPS chip within the PDA, the PDA is able to access the exact location and can provide great help to fire equipment and crew scheduling. Because of the integration of multiple sensors for portable wireless sensor nod

26、es, wireless sensor nodes are able to sense the ambient environment and monitor the physical parameters of the firefighters. Through the 3G network, the monitoring center can monitor the firefighter's health and surrounding conditions. When the fire fighters are in danger, supervise the platform

27、 and organize rescue immediately. In addition, since the handheld firealarming system is a lightweight browser integration, firefighters can access remote databases through Web services.4 Tier Architecture In order to improve the versatility, flexibility and scalability of the system, the fasie desi

28、gn adopts a hierarchical architecture, followed by the open system interconnection reference model (OSI), and the 8 is divided into six layers. From top to bottom, they are application layer, forwarding layer, assembly layer, link management layer, equipment layer and sensing layer. 1.as the lowest

29、level of the system, the perception layer is responsible for the environment awareness and information collection. In general, the sensing layer collects environmental information and information passed to the device layer via data interfaces (such as SPI and PC). Depending on the device, the data r

30、elayed from the sensor layer is also different. For wireless sensor nodes, sensing layer mainly fuses smoke and temperature information. For handheld devices, the sensor layer also includes physical parameters such as ECG and blood pressure, in addition to the environmental parameters mentioned abov

31、e. The selection of sensor and data interface and the configuration of sampling rate are the key technologies of sensor layer. 2. the device layer is the basis of the system, and all client oriented functions must be implemented through this layer. The responsibility for the device layer is to provi

32、de hardware support for wireless communications between devices (such as Wi-Fi, ZigBee, and Bluetooth). In general, the device layer mainly includes gateway devices, and its core technology is to realize the sharing of information. There are many kinds of devices between different types and differen

33、t data interfaces. 3. link management layer plays an important role in network self organization, and is considered as the main technical bottleneck that hinders the progress of WSN research. The responsibilities of managing link layer include neighbor discovery, authentication and link estimation a

34、nd self-organization. In fasie, when a new device, such as a wireless fire alarm node, is added to the network, the link management detects the device and submits the relevant information to the forwarding layer. It is worth noting that when handheld fire fighters enter the detection area, link mana

35、gement should also be able to capture the trajectory of fire fighters. 4.the forwarding layer is responsible for data transmission and dependence layer. More specifically, if the link management layer is used to build the channel, the forwarding layer is designed to solve such problems as selecting

36、which channel and which path the data should follow. As for fasie, the role of the broadcast layer in the forwarding system is to determine that the lower hoop should establish a message queue to the target node to achieve effective cache management. 5、 the assembly layer can be considered as a link

37、 between high-level applications that connect network applications, and its functions usually include encryption, protocol conversion, and name service. Due to the high sensitivity of WSN energy consumption, the data provided from one device to another need to be re coded to shorten the length of me

38、ssages, thus ensuring the safety and energy saving of information. When the encoded message arrives at the device, the assembly layer also requires decoding the information to ensure the integrity of the information. Fasie involves several network media. Different network media require different net

39、work protocols. Therefore, the assembly layer requires protocol transformations to maintain the information flow across different types of networks. 6. Application layer as the highest level of the system, responsible for providing services to customers. Application layer performance pays close atte

40、ntion to the user experience, thus affecting the future application market. Extensible and flexible API is an important part of the application layer, which can help customers to diversify their functions according to their own requirements. One 5 device design 5.1 wireless sensor nodes Wireless sen

41、sor node fasie, we chose the ATMEL microcontroller ATmega128 8 bit processor as a controller, Chipcon as the RF chip CC2530. To ensure the accuracy of the test results, two types of sensors (such as smoke sensors and thermometers) are used to detect fire. We choose MQ-2 resistance sensor, smoke sens

42、or, select temperature acquisition, DS18B20 digital temperature sensor CC2530 is a real system on chip (SOC) IEEE 802.15.4 ZigBee RF4CE application solution. It enables powerful network nodes with very low total material cost bills. CC2530 combines the leading RF transceiver with the industry standa

43、rd for its excellent performance of the enhanced 8051 microcontroller, the system programmable flash memory, the 8KB RAM, and many other powerful features. CC2530 has different operating modes, making it ideal for systems requiring ultra-low power consumption. The short transition time between the o

44、perating modes ensures further low energy consumption by 91. MQ-2 smoke sensors, resistive sensors are used to measure flammable gases in the air. The voltage required for normal operation is 5 V and the supply voltage is MQ-2. The sensing node is supplied by the ATmega128 microcontroller board 6 V.

45、 DS18B20:DS18B20 is a high precision thermometer in air sensing temperature. Its operating temperature range is between - 55 and 125 OC and the exact range of + 0.5 oc - 10 OC to 85 oc. Power supply range 3.05.5 v. wireless sensor node for fasie, power supply depends on the ATmega128 microcontroller

46、 board and the power supply voltage is 5 V.5.2 embedded gateway Embedded gateway is based on the x20ii board as the core controller of S5PV210 samsung. The embedded gateway is equipped with a wireless ieee801.ll B / g interface and a fast Ethernet interface that enables customers to select different

47、 network interfaces relative to the actual network environment. In addition, the embedded gateway also provides 2 RS232 serial ports and 4 USB ports (Figure 51.4). 5.3 hand fire fighting rescue support system As shown in Figure 51.5, hand held fire extinguishing systems consist of two parts: high pe

48、rformance PDA and portable fire sensor nodes. The function of PDA is to receive, display and relay data from the portable fire sensor node, and the main function of the portable sensor node centralized network receiving position data in the collection of environmental information from the scene of t

49、he fire and the deployment of wireless fire alarm. Here, we chose the fasie U880 ZTE PDA hardware platform. Since U880 is a powerful mobile communication device that supports Bluetooth and GPS positioning, it is fully qualified in the FASIE shoulder PDA task. Portable fire rescue support system cons

50、ists of four modules: ATmega128 microcontroller based controller, CC2530 RF chip, Bluetooth module and sensor module. Since the design and installation of the wireless sensor node with the amtega128 controller and the CC2530 RF chip, the nodes described in the wireless sensor node are similar. 5.1.

51、In FASIE, we select the Bluetooth module, and the Bluetooth module is supported by the CSR hc-05, which supports the AT instruction set and the master-slave mode switch. In fasie, the Bluetooth module's supply voltage is provided by the ATmega 128 controller and its data transmission is dependen

52、t on the TTL serial port. 6 experimental evaluation To further illustrate the performance of fasie, in this section, we select the performance parameters of a single sensor node, such as the battery lifetime and the average delay of the whole network. In a lifetime test of a wireless sensor node, a

53、fully changed 9 V battery is placed at the sensing node, and the sampling frequency is configured to be 2 per second. Throughout the overall performance of the network, the test site is located at a 2000 km "train station" where the fasie system has been deployed and functioning properly.

54、For the installation of fire alarm nodes according to the national mandatory regulations, the monitoring area of single sensor nodes is limited to within 20 meters-. In addition, we use the CSMA MAC protocol to incorporate the presence of interference in the backup and further avoid the occurrence o

55、f packet loss. 6.1 battery life The performance of wireless sensor nodes improves in our deployment. At the start, the battery is fully charged, and when the voltage is 5 V, the voltage of the battery is less than 4.1 V, and the operation of the node becomes unstable. Therefore, here, we can conside

56、r the time of battery voltage from 5 to 4.1 V as the node lifetime. As shown in the diagram, the voltage value of the battery decreases smoothly over time, and it will take more than 2 months to reach the node failure threshold, which is far beyond what we call target 6 weeks. It is worth noting tha

57、t in the initial experiment, the node can only last for a maximum of one week. The reason for this is that we are only setting the idle mode in the controller processor idle, but not the power consumption of the RF chip. In fact, according to the parameters mentioned in L L, more than 70% of the ene

58、rgy is consumed in the data transfer phase. 6.2 Time Delay Here, we employ a new parameter to measure the time delay that occurs during data transmission. Assuming that a network node is created, a predefined packet is provided with a time stamp through the cardiac network and then sent to the base station. Once the base station receives a packet, a confirmation packet will be created and sent back immediately. When the base station node obtains the confirmation pack