WIRELESS SENSOR NETWORKS PRESENTED BY VIVEK KRISHNA KANNAN SIDDARTH RAM MOHAN ARUN OUTLINE • Wireless sensor networks • The Internet of Things and the role of WSN • TinyOS • Programming with Tinyos WIRELESS SENSOR NETWORKS • Comprises of spatially connected autonomous sensors • Typically used to measure temperature, pressure etc • Usually bi-directional allowing for control of sensor activity WIRELESS SENSOR NETWORKS MOTES/NODES • Sensors + supporting elements = Mote/Node • So, apart from the sensor, each mote typically consists of : • Radio transceiver with an internal antenna • A microcontroller • An interfacing element between the microcontroller and sensor • An energy source ( Battery or an energy harvesting element) GATEWAY • GATEWAY acts as a bridge between the WSN and other networks. This enables data to be stored and processed by devices with more resources, for example, in a remotely located server. RADIO TECHNOLOGIES AVAILABLE • Long range: 3G / GPRS • Medium range: ZigBee / 802.15.4 / WiFi • Short range: RFID / NFC / Bluetooth 4.0 ROUTING PROTOCOLS : CHALLENGES • No global IP addressing • This is due to the relatively large number of sensor nodes • Consequently overhead of ID maintenance is high • Thus IP based protocols don’t work ROUTING PROTOCOLS • The search for an ideal universal routing protocol for WSN’s is an ongoing process • A Technique is to have protocols based on the network structure • Common protocols for WSN: flat based and location based network structures ROUTING PROTOCOL : FLAT BASED NETWORK STRUCTURE • Here all the nodes are treated equally and have the same functionality • SPIN (Sensor Protocol for Information Negotiation) routing protocol can be used • Sends meta data to neighboring nodes instead of actual data • Thus the gateway can request for the desired data • Avoids redundant data transmission, saves energy and thus extends network lifetime ROUTING PROTOCOL : LOCATION BASED NETWORK STRUCTURE • Sensor nodes are addressed based on their location • Location is acquired either by GPS or by relative position wrt other nodes • Geographical Adaptive Fidelity (GAF) routing protocol can be used • Network is divided into zones • Only one node is awake in each zone • Conserves energy, thus increasing network lifetime REQUIREMENTS FOR A WSN DEPLOYMENT • QOS • Fault tolerance • Lifetime • Scalability • Density of nodes • Programmability SENSOR DEPLOYMENT OPTIONS • Random deployment: May be dropped from an aircraft. • Regular deployment: Well-planned sensors at fixed locations. • Mobile sensor nodes: Sensor nodes may move around. 1926: Nikola Tesla in an interview with Colliers magazine: "When wireless is perfectly applied the whole earth will be converted into a huge brain, which in fact it is, all things being particles of a real and rhythmic whole.........and the instruments through which we shall be able to do this will be amazingly simple compared with our present telephone. A man will be able to carry one in his vest pocket." THE INTERNET OF THINGS What is it? The Internet of Things (IoT) is the network of physical objects or "things" embedded with sensors and actuators that are connected to the internet. HISTORY • 1999: The term was first used by Kevin Ashton who cofounded the Auto-ID Center at the Massachusetts Institute of Technology (MIT). • 2008: A group of companies launched the IPSO Alliance which now boasts over 50 member companies, including Bosch, Cisco, Ericsson, Intel, SAP, Sun, Google and Fujitsu. • 2008-2009: The Internet of Things was "Born“. • 2011: IPV6 public launch - The new protocol allows for 2128 addresses. TRAFFIC MONITORING SENSORS CONNECTED TO THE INTERNET VOLCANO MONITORING PROJECT SENSING MODULE USED HOW I0T WORKS HOW WIRELESS SENSOR NETWORKS FEATURE IN THE INTERNET OF THINGS CHALLENGES IN WIRELESS SENSOR NETWORKS • Limited processing power • Limited program memory • Power consumption • Flexibility • Concurrency WHAT IS TINYOS? It is a free and open-source operating system designed for low- power wireless devices, such wireless sensor networks. Main goals: energy conservation optimal usage of limited resources HISTORY • TinyOS began as part of a project for the DARPA NEST (Network Embedded Systems Technology) program. • Born out of a collaboration between UCB, Intel and Crossbow technology. • Initial release was in 2000. • Currently maintained by the international working group, the TinyOS Alliance. • Last version was released on August 2012. WHAT TINYOS PROVIDES • Supports a wide range of sensor mote hardware platforms. • Compact (less than 400 bytes of program memory). • Supports concurrency using a split-phase execution model. • Handles power consumption and radio networking. • Intended to be incorporated into ‘smartdust’. SMART DUST • Revolutionary implementation of WSNs capitalising on advances in the IC fabrication processes. • Smart dust aims to populate the very air around us with motes, hence the name. SMART DUST • Implemented using MEMS (Micro Electro Mechanical Systems) technology. • MEMS allows us to encapsulate a battery, a nominal amount of RAM and a wireless transmitter onto dust sized particles. SMART DUST APPLICATIONS • Important to remember that smart dust is WSN’s at the micrometer range. • Thus applications which use WSN’s with conventional sized motes are suited to be replaced with Smart Dust. • Health care, forest fire detection, water quality monitoring, etc., • After all reduction in size has never been a problem. SMART DUST APPLICATIONS • Because of its uniquely smaller motes, smart dust can enter into hitherto unexplored applications. • Battlefield surveillance, with almost 0% chance of detection. • Virtual keyboards by affixing smart dust onto finger tips. • Fault detection in mechanical machinery. TINYOS AND SMART DUST • TinyOS runs code in very short snippets to perform a singular function as opposed to running long strings to perform more complex actions. • This makes it very good for the purpose of a Smart Dust mote’s capabilities of gathering and passing along data in high-frequency bursts but not powering an object like the base station that collects that data. NESC • Network embedded systems C • Sub dialect of C language, written specifically for TinyOS • Optimized for the limitations of sensor networks • Based on components "wired" together by interfaces to run applications on TinyOS PROGRAMMING MODEL Components: They offer three types of elements: • Command: Request for a component to do something • Event: Signals the completion of a command • Tasks: Functions that can be scheduled PROGRAMMING MODEL Interfaces can be provided or used by components PROGRAMMING MODEL Competitors: • Contiki • Nano-RK • LiteOS • Mantis Who uses TinyOS? R&D labs, startup companies, and commercial users such as Motorola, Intel, Arch Rock, Crossbow, and the People Power Company. TinyOS averages 35,000 downloads a year. For more information, visit www.tinyos.net .