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TARGET TRACKING IN WIRELESS SENSOR NETWORKS GROUP NO:11

J.DINESH 11071A0417 V.SANDEEP 11071A0453 C.NAVEEN 12075A0411PROJECT GUIDE:SHAIK KHADAR SHARIF

ABSTRACTTarget tracking deals with finding spatial coordinates of a moving object and being able to track its movements.In the tracking scheme illustrated, sensors are deployed in a triangular fashion in a hexagonal mesh such that the hexagon is divided into a number of equilateral triangles.The technique used for detection is the trilateration technique in which intersection of three circles is used to determine the object location. While the object is being tracked by three sensors, distance to it from a fourth sensor is also being calculated simultaneously. The difference is that closest three sensors detect at a frequency of one second while the fourth sensor detects the object location at twice the frequency. Using the distance information from the fourth sensor and a simple mathematical technique, location of object is predicted for every half second as well.WHY TARGET TRACKING USING WIRELESS SENSOR? Wireless communication and MEMS - the two technologies which have revolutionalized the way we live have also resulted in the development of wireless sensor networks. These comprise of relatively inexpensive sensor nodes capable of collecting, processing, storing and transferring information from one node to another. These nodes are able to autonomously form a network through which sensor readings can be propagated. Since the sensor nodes have some intelligence, data can be processed as it flows through the network. The latter is being done wirelessly using networking principles. The flexibility of installation and configuration has greatly improved resulting in a flurry of research activities commencing in the field of sensor networks owing to their ready acceptance in various industriesTRILATERATION TECHNIQUE A network of sensors in a 2D plane is considered. A triangular network is considered i.e. the sensors are placed in a triangular fashion. Typically, the network is considered as a hexagonal mesh. Each sensor is aware of its physical location and that of its neighboring sensors. All the sensors have a processor, a memory and required hardware to support sensing, information gathering and communication capabilities. Each sensor has a sensing radius, r which is equal to the length of the side of the triangle. Three sensors are used to determine the location of the object. The methodology used in this case is called the triangulation technique of detecting the spatial coordinates. The sensors in this case are assumed to have different sensing radii. The work presented aims to track the moving path of an object in the network. The sensors have an overlapping region of sensing which is known as the working area and the areas surrounding these are known as backup areas which imply that as soon as the object moves into these areas ahandover should take place.

The present technique employs the trilateration technique for estimating the location of the object with three sensors at the end of every one second.Distance between the object and the sensor is found by mathematical formulae

As soon as a movement is detected, an election process is conducted among the sensors based on their distance from the object. The sensor closest to the object is chosen as the master agent while the next two are chosen as slave agents. As soon as the election process is done, all the other sensors are prohibited from tracking the object by sending them blocking messages. Using the trilateration technique, these sensors calculate the position of the object.

Sensors usually have four modes of operation: Transmit Receive, Idle and Sleep based on the operation they are performing. Each of the nodes has a different level of power consumption. Initially, all the sensors operate in the Idle mode of operation in which they continuously detect any object within their sensing scope. The variance of signal strength with distance is measured and smoothed out using a regression quadratic polynomial. Signal strengths can vary and the measurements are not very accurate. Thus, there are always some errors between estimated distances and actual distances. The trilateration technique used basically uses the intersection of three circles to find out the exact spatial coordinates of the object.Negotiation Based ProtocolsThese protocols are called SPIN (Sensor Protocols for Information via Negotiation)protocols. As the name suggests, there is negotiation prior to transfer of date betweenthem. Meta-data are information descriptors here and used to eliminate the transmission of redundant data. In SPIN, track is kept of the energy level of the node. Prior to transmission, a node checks with it as to whether it has sufficient energy to carry out the transmission of data. The three main types of messages passed between nodes in thisfamily of protocols are:ADV: Whenever a node has some new data, it sends this message advertising toits neighbors. The message contains a meta-data as well.REQ: Whenever a node wishes to receive some data, it sends out this message.DATA: This message contains the actual data along with a meta-data header.The following protocols constitute the SPIN family of protocols:8a) SPIN-PP: This is a point-to-point communication protocol. b) SPIN-EC: This is also a 3-way handshake protocol but has energy constraints.c) SPIN-BC: This protocol is for broadcast networks. The nodes use a single sharedchannel for communication purposes. d) SPIN-RL: This is primarily an extension of the above protocol. APPLICATIONS Applications of target tracking and/or data fusion are found in diverse civilian and military fields. Civilian applications include air traffic control, navigation, fault tolerant systems and decision problems. In the military field, applications include surveillance, target identification, command and control, sensor management and weapon guidance.

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