New devices in the field of wireless sensor networks. Areas of use. Basic operating principles

Maxim Sergievsky

Newest technologies wireless communication and progress in the field of microcircuit production have allowed, over the past few years, to move to the practical development and implementation of a new class of distributed communication systems - sensor networks.

Wireless sensor networks consist of miniature computing and communication devices - motes ( from English motes - specks of dust), or sensors. A mote is a board usually no larger than one cubic inch in size. The board houses a processor, flash and RAM memory, digital-to-analog and analog-to-digital converters, a radio frequency transceiver, a power supply and sensors. Sensors can be very diverse; they are connected via digital and analog connectors. The most commonly used sensors are temperature, pressure, humidity, illumination, vibration, less often - magnetoelectric, chemical (for example, measuring the content of CO, CO2), sound and some others. The set of sensors used depends on the functions performed by wireless sensor networks. The moto is powered by a small battery. Motes are used only for collecting, primary processing and transmission of sensory data. Appearance mots produced by various manufacturers are shown in Fig. 1.

The main functional processing of data collected by motes is carried out on a node, or gateway, which is a fairly powerful computer. But in order to process the data, it must first be received. For this purpose, the unit must be equipped with an antenna. But in any case, only motes that are close enough to it are accessible to the node; in other words, the node does not receive information directly from each mote. The problem of obtaining sensory information collected by motes is solved as follows. Motes can exchange information with each other using radio transceivers. This is, firstly, sensory information read from sensors, and secondly, information about the state of devices and the results of the data transfer process. Information is transferred from one mote to another along the chain, and as a result, the motes closest to the gateway dump all the accumulated information to it. If some of the motes fail, the operation of the sensor network after reconfiguration should continue. But in this case, naturally, the number of sources of information decreases.

To perform functions, a specialized operating system is installed on each mote. Currently, most wireless sensor networks use TinyOS, an OS developed at Berkeley University. TinyOS refers to software with open source; it is available at: www.tinyos.net. TinyOS is an event-driven, real-time operating system designed to work in resource-constrained environments. This OS allows motes to automatically establish connections with neighbors and form a sensor network of a given topology. The latest release, TinyOS 2.0, appeared in 2006.

The most important factor in the operation of wireless sensor networks is the limited capacity of batteries installed on motes. Please note that it is often impossible to replace batteries. In this regard, it is necessary to perform only the simplest primary processing on motes, aimed at reducing the volume of transmitted information, and, most importantly, minimizing the number of cycles of data reception and transmission. To solve this problem, special communication protocols have been developed, the most famous of which are the protocols of the ZigBee alliance. This alliance (website www.zigbee.org) was created in 2002 specifically to coordinate work in the field of wireless sensor networks. It includes the largest developers of hardware and software: Philips, Ember, Samsung, IBM, Motorola, Freescale Semiconductor, Texas Instruments, NEC, LG, OKI and many others (more than 200 members in total). Intel Corporation is not a member of the alliance, although it supports its activities.

In principle, to develop the standard, including the protocol stack for wireless sensor networks, ZigBee used the previously developed IEEE 802.15.4 standard, which describes the physical layer and media access layer for wireless data networks on short distances(up to 75 m) with low power consumption, but with a high degree of reliability. Some characteristics of radio data transmission for the IEEE 802.15.4 standard are given in Table. 1.

Table 1. Radio data transmission characteristics for IEEE 802.15.4

On this moment ZigBee has developed the only standard in this area, which is supported by the availability of fully compatible hardware and software products. ZigBee protocols allow devices to sleep b O most of the time, which significantly extends battery life.

Obviously, it is not so easy to develop data exchange schemes between hundreds and even thousands of motes. Along with other things, it is necessary to take into account the fact that sensor networks operate in unlicensed frequency ranges, therefore, in some cases, interference may occur from extraneous sources of radio signals. It is also advisable to avoid repeated transmission of the same data, and in addition, take into account that due to insufficient energy consumption and external influences the motors will fail permanently or for some time. In all such cases, communication schemes must be modified. Because one of the most important features of TinyOS is the automatic selection of network design and data paths, wireless sensor networks are essentially self-configuring.

Most often, a mote must be able to determine its own location, at least in relation to the other mote to which it will transmit data. That is, all motes are identified first, and then a routing scheme is formed. In general, all motes - devices of the ZigBee standard - are divided into three classes according to the level of complexity. The highest of them - the coordinator - manages the operation of the network, stores data about its topology and serves as a gateway for transmitting data collected by the entire wireless sensor network for further processing. Sensor networks typically use a single coordinator. The average complexity moto is a router, that is, it can receive and transmit data, as well as determine transmission directions. Finally, the simplest mote can only transmit data to the nearest router. Thus, it turns out that the ZigBee standard supports a network with a cluster architecture (Fig. 2). The cluster is formed by a router and the simplest motes from which it requests sensory data. Cluster routers relay data to each other, and ultimately the data is transferred to the coordinator. The coordinator usually has a connection to the IP network, where the data is sent for final processing.

Developments related to the creation of wireless sensor networks are also underway in Russia. Thus, the High-Tech Systems company offers its hardware and software platform MeshLogic for building wireless sensor networks (website www.meshlogic.ru). The main difference between this platform and ZigBee is its focus on building peer-to-peer mesh networks (Fig. 3). In such networks functionality each motor are the same. The possibility of self-organization and self-healing of mesh topology networks allows, in the event of a failure of some motors, to spontaneously form a new network structure. True, in any case a central functional unit, which receives and processes all data, or a gateway for transmitting data to the node for processing. Spontaneously created networks are often referred to by the Latin term Ad Hoc, which means “for a specific occasion.”

In MeshLogic networks, each mote can perform packet relaying, that is, its functions resemble a ZigBee router. MeshLogic networks are completely self-organizing: there is no coordinator node. Can be used as RF transceivers in MeshLogic various devices, in particular Cypress WirelessUSB, which, like ZigBee standard devices, operate in the frequency range 2.4... 2.4835 GHz. It should be noted that only the lower layers of the protocol stack exist for the MeshLogic platform. It is believed that upper levels, in particular network and application ones, will be created for specific applications. The configurations and main parameters of two MeshLogic motes and one ZigBee standard mote are shown in Table. 2.

Table 2. Main characteristics of motors from various manufacturers

Note that there are no integrated touch sensors on these boards.

Let us indicate what primarily distinguishes wireless sensor networks from conventional computing (wired and wireless) networks:

• complete absence of any cables - electrical, communication, etc.;
• the possibility of compact placement or even integration of motors into environmental objects;
• reliability of both individual elements and, more importantly, the entire system as a whole; in some cases, the network can function when only 10-20% of the sensors (motes) are working;
• no need for personnel for installation and maintenance.

Sensor networks can be used in many application areas. Wireless sensor networks are a new promising technology and all related projects are mostly in the development stage. We indicate the main areas of application of this technology:

• defense systems and security;
• environmental control;
• monitoring of industrial equipment;
• security systems;
• monitoring the condition of agricultural land;
• energy management;
• control of ventilation, air conditioning and lighting systems;
• fire alarm;
• inventory control;
• tracking of cargo transportation;
• monitoring the physiological state of a person;
• personnel control.

From a fairly large number of examples of the use of wireless sensor networks, we will highlight two. Perhaps the most famous is the deployment of the network on board an oil tanker by BP. There, using a network built on Intel equipment, the condition of the vessel was monitored in order to organize its preventive maintenance. BP assessed whether the sensor network could operate on board a ship in conditions of extreme temperatures, high vibration and significant levels of radio frequency interference found in some areas of the ship. The experiment was successful; the network was automatically reconfigured and restored several times.

An example of another completed pilot project is the deployment of a sensor network at the US Air Force base in Florida. The system demonstrated good capabilities for recognizing various metal objects, including moving ones. The use of a sensor network made it possible to detect the intrusion of people and vehicles into the controlled area and track their movements. To solve these problems, motors equipped with magnetoelectric and temperature sensors were used. Currently, the scope of the project is expanding, and a wireless sensor network is being installed on a site measuring 10,000x500 m. Relevant applications software is being developed by several American universities.

Almost all areas of life in the 21st century depend on information and communication technologies (ICT). Data is exchanged not only by people, but also by all kinds of intelligent systems, Cell phones, wearable devices, ATMs, sensors. At least 5 billion devices are already connected to the Internet of Things. Operation of any large complexes - industrial, energy, agricultural enterprises, shopping centers, museums, offices, residential buildings - involves constant monitoring of the situation on their territory. Sensitive sensors monitor the health of equipment in real time, organize the interaction of devices with each other, and warn about the need to replace them or about emergency situations. With rapidly growing volumes of data, simple and convenient way exchanging them between devices and information processing centers.

Print version:

Wireless sensor networks (WSNs, Wireless Sensor Networks), consisting of wireless sensors and control devices and capable of self-organization using intelligent algorithms, demonstrate large-scale prospects for use in monitoring human health, the state of the environment, the functioning of production and transport systems, and accounting for various resources. etc. This issue of the newsletter presents technological trends in the field of WSN related to providing permanent job wireless sensors and their application in two areas of the modern economy - advanced manufacturing and smart energy (smart grid).

Self-charging touch devices

For the development of wireless sensor networks, it is important to solve the problem of their power supply. A promising trend is the creation of durable autonomous devices with minimal energy consumption - converted from external sources.

Wireless sensor devices can, for example, be powered by radio energy sent to them from some kind of transmitter (similar to radio frequency identification (RFID) devices or contactless smart cards). This energy is used by the device both to recharge the sensor and to generate a response signal with information about the current state of the controlled object.

Another method is passive conversion of energy from the external environment (energy harvesting): solar (outside the room in fairly clear weather), thermal, mechanical vibration energy (from nearby devices - assembly machines, conveyors, etc.), vibration energy of the sensor itself (in the case of wearable devices), background radio emissions from surrounding electrical appliances (including Wi-Fi).

Implementation of advanced manufacturing based on wireless sensor networks

Irrational use of resources and production capacity, generation of large amounts of environmentally polluting waste, lack of constant monitoring of the condition of facilities at enterprises - these and other problems of modern industry stimulate the transition to an advanced manufacturing model. It is characterized by the use of new materials and environmentally friendly technologies (green technologies), as well as the widespread use of ICT and intelligent systems, in particular robotics and wireless sensor networks.

Industrial wireless sensor networks (IWSS, Industrial Wireless Sensor Networks) are the most important factor in the implementation of advanced manufacturing. To manage and monitor the state of objects at the enterprise (equipment, conveyors, assembly devices, reactors), a set of interconnected wireless sensors and information systems, which process data from sensors and interact with controlled objects using control devices. Such an automated system responds to any changes in indicators at the enterprise, notifies personnel about accidents and problem situations, analyzes the efficiency of equipment use, assesses the level of environmental pollution and the volume of waste produced.

Smart grids

The global problem of irrational use of electricity is especially relevant for Russia. High costs for generating electricity increase the cost of production, which places a double burden on the end consumer. To improve the efficiency and reliability of power systems, many countries are moving to the concept of smart grids.

Such a network controls in real time all generating sources, transmission and distribution networks and facilities that consume electricity connected to it. To manage a smart energy grid, wireless sensor networks are used that monitor the volume of energy production and energy consumption in its different sections. With the help of information systems, the optimal distribution of energy in the network is calculated, forecasts are made for different seasons and periods of the day, energy production and its delivery are synchronized, and the safety of power lines is monitored. To improve the efficiency of the power grid, its non-critical elements are turned off during periods of reduced activity.

Monitoring of global technological trends is carried out by the Institute of Statistical Research and Economics of Knowledge High school Economics () within the framework of the Fundamental Research Program of the National Research University Higher School of Economics.

The following sources were used in preparing the trendletter: Forecast of scientific and technological development of the Russian Federation until 2030(prognoz2030.hse.ru), scientific journal materials "Foresight"(foresight-journal.hse.ru), data Web of Science, Orbit, idc.com, marketsandmarkets.com, wintergreenresearch.com, greentechmedia.com, greenpatrol.ru, etc.

The advantages of wireless sensor network technologies can be effectively used to solve various applied problems related to distributed collection, analysis and transmission of information.

Building automation

In some building automation applications, the use of traditional wired data transmission systems is not practical for economic reasons.

For example, you need to implement a new or expand an existing system in an existing building. In this case, the use of wireless solutions is the most acceptable option, because no additional installation work is required to disrupt the interior decoration of the premises, virtually no inconvenience is caused to employees or residents of the building, etc. As a result, the cost of implementing the system is significantly reduced.

Another example would be open-plan office buildings where it is not possible to specify the exact sensor locations during the design and construction phase. At the same time, the layout of offices can change many times during the operation of the building, therefore, the time and money spent on reconfiguring the system should be minimal, which can be achieved by using wireless solutions.

In addition, the following examples of systems based on wireless sensor networks can be given:

• monitoring temperature, air flow, occupancy and control of heating, ventilation and air conditioning equipment to maintain the microclimate;
• lighting control;
• energy management;
• collection of readings from residential meters for gas, water, electricity, etc.;
• monitoring the condition of load-bearing structures of buildings and structures.

Industrial automation

Until now, the widespread use of wireless communications in the field of industrial automation has been hampered by the low reliability of radio channels compared to wired connections in harsh industrial environments, but wireless sensor networks are radically changing the current situation, because by their nature, resistant to various kinds of disturbances (for example, physical damage to the node, the appearance of interference, changes in obstacles, etc.). Moreover, in some conditions, a wireless sensor network can provide even greater reliability than a wired communication system.

Solutions based on wireless sensor networks fully meet industry requirements:

• fault tolerance;
• scalability;
• adaptability to operating conditions;
• energy efficiency;
• taking into account the specifics of the applied task;
• economic profitability.

Wireless sensor network technologies can find application in the following industrial automation tasks:

• remote control and diagnostics of industrial equipment;
• equipment maintenance current state(prediction of safety margin);
• monitoring of production processes;
• telemetry for research and testing.

Other applications

The unique features and differences of wireless sensor networks from traditional wired and wireless data transmission systems make their use effective in a wide variety of areas. For example:

• security and defense:
  • control over the movement of people and equipment;
  • means of operational communications and reconnaissance;
  • perimeter control and remote surveillance;
  • assistance in rescue operations;
  • monitoring of property and valuables;
  • security and fire alarm system;
• environmental monitoring:
  • pollution monitoring;
  • Agriculture;
• healthcare:
  • monitoring the physiological state of patients;
  • location control and notification of medical personnel.

Architecture of a typical wireless sensor network

Wireless sensor network is a distributed, self-organizing network of many sensors (sensors) and actuators interconnected via a radio channel. Moreover, the coverage area of ​​such a network can range from several meters to several kilometers due to the ability to relay messages from one element to another.

One of the first prototypes of a sensor network can be considered the SOSUS system, designed to detect and identify submarines. Wireless sensor network technologies began to actively develop relatively recently - in the mid-90s. However, only at the beginning of the 21st century the development of microelectronics made it possible to produce sufficiently cheap materials for such devices. element base. Modern wireless networks are mainly based on the ZigBee standard. A considerable number of industries and market segments (manufacturing, different kinds transport, life support, security), ready for the implementation of sensor networks, and this number is continuously increasing. The trend is driven by increasing complexity technological processes, the development of production, the expanding needs of individuals in the segments of security, resource control and use of inventory. With the development of semiconductor technologies, new practical tasks and theoretical problems arise related to the applications of sensor networks in industry, housing and communal services, and households. The use of inexpensive wireless sensor-based parameter monitoring devices opens up new areas for the use of telemetry and control systems, such as:

• Timely identification of possible failures of actuators by monitoring parameters such as vibration, temperature, pressure, etc.;
• Real-time access control to remote systems of the monitoring object;
  • ensuring the protection of museum valuables
  • maintaining records of exhibits
  • automatic audit of exhibits
• Automation of inspection and maintenance of industrial assets;
• Commercial asset management;
• Application as components in energy- and resource-saving technologies;
• Monitoring environmental environmental parameters

It should be noted that despite the long history of sensor networks, the concept of building a sensor network has not finally taken shape and has not been expressed in specific software and hardware (platform) solutions. The implementation of sensor networks at the current stage largely depends on the specific requirements of the industrial task. The architecture, software and hardware implementation is at the stage of intensive technology formation, which draws the attention of developers in order to find a technological niche for future manufacturers.

Technologies

Wireless sensor networks (WSNs) consist of miniature computing devices - motes, equipped with sensors (temperature, pressure, light, vibration level, location sensors, etc.) and signal transceivers operating in a given radio range. Flexible architecture and reduced installation costs distinguish wireless networks of smart sensors from other wireless and wired data transfer interfaces, especially when it comes to a large number of interconnected devices; a sensor network allows you to connect up to 65,000 devices. The constant reduction in the cost of wireless solutions and the increase in their operational parameters make it possible to gradually reorient from wired solutions in systems for collecting telemetric data, remote diagnostics, and information exchange. "Sensor network" is a well-established term today. Sensor Networks), denoting a distributed, self-organizing, resistant to failure of individual elements network of maintenance-free devices that do not require special installation. Each sensor network node can contain various sensors for monitoring the external environment, a microcomputer and a radio transceiver. This allows the device to carry out measurements, independently carry out initial data processing and maintain communication with an external information system.

802.15.4/ZigBee relayed short-range radio technology known as Sensor Networks. WSN - Wireless Sensor Network), is one of the modern trends in the development of self-organizing fault-tolerant distributed systems for monitoring and managing resources and processes. Today, wireless sensor network technology is the only wireless technology that can be used to solve monitoring and control tasks that are critical to the operating time of sensors. Sensors integrated into a wireless sensor network form a geographically distributed self-organizing system for collecting, processing and transmitting information. The main area of ​​application is control and monitoring of measured parameters of physical environments and objects.

The accepted IEEE 802.15.4 standard describes wireless channel access control and the physical layer for low-speed wireless personal area networks, that is, the two lower layers according to network model OSI. The “classical” sensor network architecture is based on a typical node, which includes an example of a typical RC2200AT-SPPIO node:

• radio path;
• processor module;
• battery;
• various sensors.

A typical node can be represented by three types of devices:

• Network Coordinator (FFD - Fully Function Device);
  • carries out global coordination, organization and installation of network parameters;
  • the most complex of the three types of devices, requiring the largest amount of memory and power supply;

• Device with full set functions (FFD - Fully Function Device);
  • 802.15.4 support;
  • additional memory and power consumption allows you to serve as a network coordinator;
  • support for all types of topologies (“point-to-point”, “star”, “tree”, “mesh network”);
  • ability to act as a network coordinator;
  • the ability to access other devices on the network;
• (RFD - Reduced Function Device);
  • supports limited 802.15.4 features;
  • support for point-to-point and star topologies;
  • does not serve as a coordinator;
  • contacts the network coordinator and router;

Notes

1. 1 2 3 Ragozin D.V.. Modeling of synchronized sensor networks. Programming problems. 2008. No. 2-3. Special issue – 721-729 p.
2. Baranova E. IEEE 802.15.4 and its software add-on ZigBee. // Telemultimedia, May 8, 2008.
3. Levis P., Madden S., Polastre J. and dr. “TinyOS: An operating system for wireless sensor networks” // W. Weber, J.M. Rabaey, E. Aarts (Eds.) // In Ambient Intelligence. – New York, NY: Springer-Verlag, 2005. – 374 p.
4. Algoritmic Considerations of Wireless Sensor Networks. // Miroslaw Kutulowski, Jacek Cichon, Przemislaw Kubiak, Eds. – Poland, Wrozlaw: Springer, 2007.
5. Intelligent systems based on sensor networks. - www.ipmce.ru/img/release/is_sensor.pdf // Institute of Precision Mechanics and computer technology them. S.A. Lebedev RAS, 2009.
6. Fully completed ZigBee modules from RadioCrafts. - kit-e.ru/articles/wireless/2006_3_138.php // Components and technologies.
7. ZigBee/802.15.4 protocol stack on the Freescale Semiconductor platform - www.freescale.com/files/abstract/global/RUSSIA_STKARCH_OV.ppt, 2004

Review of modern wireless technologies

Sensor architecture

A touch sensor consists of hardware and software, like any other telecommunications node. In general, the sensor consists of the following

subsystems: perception, data processing, monitoring, communication and power supply (Figure 1.1).

Figure 1.1 – General architecture of the sensor.

The perception subsystem consists, as a rule, of an analog device that takes certain statistics and an analog-to-digital converter. The data processing subsystem contains a central processor and memory that allow storing not only the data generated by the sensor, but also service information that is necessary for the correct and full functioning of the communication subsystem. The monitoring subsystem allows the sensor to collect environmental data such as humidity, temperature, pressure, magnetic field, air chemical analysis, etc. The sensor can also be supplemented with a gyroscope and accelerometer, which makes it possible to build a positioning system.

Progress in the field of wireless communications and miniaturization of microcircuits are opening new horizons in information and computer technologies. In addition to multi-hop networks, there are more complex routing protocols where the next node is selected based on an analysis of its characteristics, for example, energy level, reliability, and the like. The situation becomes more complicated when the nodes of a wireless sensor network move - the network topology becomes dynamic.

To implement a sensor as a small telecommunications device (no more than one cubic centimeter), many technical aspects must be taken into account. The CPU frequency must be at least 20 MHz, volume random access memory at least 4 KB, transfer speed at least 20 Kbps. Optimizing the hardware will reduce the size of the sensor, but will entail an increase in its price. Operating system(OS) must be optimized taking into account the architecture of the central processor used. Limited resources and small memory size encourage placing the OS in ROM. Currently, Tiny OS is a widely used open source operating system, which allows flexible control of sensors. different manufacturers. In the field of networking, the limited power supply in sensors imposes significant limitations on

the use of radio technologies that can be used in sensor networks. It should also be noted that the limited performance of the central processor does not allow the use of standard IP network routing protocols

– the high complexity of calculating the optimal path algorithm will overload the central processor. To date, a large number of special routing protocols for sensor networks have been developed.

The development of data transmission technology in sensor networks is one of the most important tasks when building a sensor network, since its specific architectural and system characteristics impose a whole host of strict restrictions, among which the following should be emphasized:

Limited energy reserves, which means the range is limited;

Limited processor performance;

Simultaneous operation of a large number of nodes in a limited space;

Equivalence of nodes, client-server architecture is not applicable due to its characteristic delays;

Operating in an unlicensed frequency spectrum;

Low cost.

Currently, the development of sensor networks is based on the IEEE 802.15.4 Zigbee standard, which I mentioned above. Additionally, I note that the Zigbee alliance assumes that radio access of the ZigBee standard will be used in applications such as monitoring, production automation, sensors, security, control, Appliances and much more. Thus, sensor network applications can be divided into several main categories:

Security, emergencies and military operations;

Medicine and health;

Weather, Environment and Agriculture;

Factories, factories, houses, buildings;

Transport systems and cars.

I will consider cases of specific applications of sensor networks in the above categories. At a minimum, sensor networks can be used in the following scenarios.

Application of sensor networks

Wireless sensor networks have the unique characteristics of easy deployment, self-organization, and fault tolerance. Emerging as a new paradigm for information collection, wireless sensor networks have been used for broad applications related to health, environmental control, energy, food safety and manufacturing.

Over the past few years, there have been many indications that sensor networks will become a reality. Several sensor node prototypes have been created, including Motes at Berkeley, uAMPS at MIT, and GNOMES at Rice. The elementary functions of sensor networks are positioning, sensing, tracking and detection. Besides military applications, there have also been civil applications based on elementary functions, which can be divided into habitat control, environmental surveillance, healthcare and other commercial

applications. Additionally, Sibley recently created a mobile sensor called the Robomote, which is equipped with wheels and can move around the field.

In one of the first attempts to use sensor networks for civilian applications, Berkeley and Intel Research Laboratory used the Mote sensor network to monitor storm readings on the Great Duck Islands, Maine in the summer of 2002. Two-thirds of the sensors were installed off the coast of Maine, collecting the necessary (useful) information in real time on the world wide web (Internet). The system worked for more than 4 months and provided data

For 2 months after the scientists left the island due to bad weather conditions (winter). This habitat monitoring application represents an important class of sensor network applications. Most importantly, network sensors are capable of collecting information in dangerous environments that are inhospitable to people. During the monitoring studies, design criteria were considered, including design creation, creation of a sensor system with the possibility of remote access and data management. Numerous attempts have been made to achieve the requirements, leading to the development of a set of prototype sensor network systems. The sensor system used by Berkeley and Intel Research Laboratory, although primitive, was effective in collecting interesting environmental data and providing scientists with important information.

Sensor networks have found applications in the fields of observation and prediction (guessing). A living example of such an application is the Automated Local Evaluation in Real-Time (ALERT) system developed by the National Weather Service with wireless network sensors. Equipped with meteorological/hydrological touch devices,Sensors in a given environment typically measure several properties of ,local weather such as water level, temperature, wind. Data is transmitted via line-of-sight radio communication through sensors at the base station. The Flood Forecast Model was adapted to process the data and issue automatic warnings. The system provides important information rainfall and water levels in real time to assess the possibility of potential flooding anywhere in the country. The present (current) ALERT system is installed throughout the West Coast of the United States and is used for flood warnings in California and Arizona.

Lately, Sensor systems are heavily used in the healthcare industry, used by patients and doctors for glucose tracking and monitoring, cancer detectors, and even artificial organs. Scientists suggest the possibility of implanting biomedical sensors into the human body for various purposes. These sensors transmit information to external computer system via wireless interface. Several biomedical sensors are integrated into an application system to determine the diagnosis and treatment of disease. Biomedical sensors herald a more advanced level of medical care.

The main difference between wireless sensor networks and traditional computer and telephone networks is the absence of a permanent infrastructure that belongs to a specific operator or provider. Each user terminal in a sensor network has the ability to function not only as an end device, but also as a transit node, as shown in Figure 1.2.

Figure 1.2 – Example of connecting network sensors