Rab Nawaz Jadoon DCS. Assistant Professor. Department of Computer Science. COMSATS Institute of Information Technology. Mobile Communication

Transcription

1 Rab Nawaz Jadoon DCS Assistant Professor COMSATS IIT, Abbottabad Pakistan COMSATS Institute of Information Technology Mobile Communication

2 WSN Wireless sensor networks consist of large number of sensor nodes with one or more base station(s) (BS), which communicate either directly or using multihop fashion to each other or with the BS. All nodes in the network are interconnected by wireless communication links or channels. Each sensor node in the network has the capability to sense the data from its surrounding, process that data, and then communicate the data with rest of the nodes or with the BS. BS is responsible to gather information from all the deployed nodes in the sensing region and act as a gateway to outside world or actuator. 2

3 Generic Architecture of WSN Internet Sink D C B A User Sensor Field Sensor nodes Sensor node 3

4 Wide Range of Applications Structural monitoring Bio-habitat monitoring Humidity Sensing Soil Moisture Sensing Disaster management Military surveillance Temperature sensing Smoke Sensors Fire Detection Sensors Security Sensors 4

5 Predetermined deployment WSN Deployment densely deployed either inside the phenomenon or very close to it --- Deployment Known Random deployment The position of sensor nodes need not be engineered or pre-determined. This allows random deployment in inaccessible terrains or disaster relief operations. Re-deployment Additional nodes can be deployed at any time to replace malfunctioning nodes. 5

6 Sensor abilities Some important and common characteristics, Self organizing capabilities Cooperative effort Data processing (Fusion, Aggregation) 6

7 WSN vs Adhoc Sensor Network Applications require wireless ad hoc networking techniques. Although many protocols and algorithms have been proposed for traditional wireless ad hoc networks, they are not well suited for the unique features and application requirements of sensor networks. 7

8 Difference b/w WSN and Adhoc Networks The number of sensor nodes in a sensor network can be several orders of magnitude higher than the nodes in an ad hoc network. Sensor nodes are densely deployed. Sensor nodes are prone to failures. The topology of a sensor network changes very frequently. Sensor nodes mainly use broadcast communication paradigm whereas most ad hoc networks are based on point-to-point communications. 8

9 Cont Sensor nodes are limited in power, computational capacities, and memory. Sensor nodes may not have global identification (ID) because of the large amount of overhead and large number of sensors. 9

10 Power efficiency Since large number of sensor nodes are densely deployed, neighbor nodes may be very close to each other. Hence, multihop communication in sensor networks is expected to consume less power than the traditional single hop communication. Multihop communication can also effectively overcome some of the signal propagation effects experienced in longdistance wireless communication. 10

11 Limitations One of the most important constraints on sensor nodes is the low power consumption requirement. Sensor nodes carry limited, generally irreplaceable, power sources. Therefore, while traditional networks aim to achieve high quality of service (QoS) provisions, sensor network protocols must focus primarily on power conservation. many to one communication environment where all the sensor nodes in the network send their sensed data to one BS through multihop fashion; and energy limitation requires highly optimized protocol, which works efficiently as far as network lifetime is concerned. 11

12 Transmission Media In WSN, nodes are connected to each other through wireless communication links or channels. The problem associated with wireless links is fading, and it effects the operation of the sensor networks. Traditionally sensor nodes have a very low data rate i.e. of kbps. Transmission media is handled effectively through design of MAC. One approach to MAC design is to utilize TDMA (Time Division Multiple Access) based protocols that conserve more energy as compare to other contention based schemes like CSMA. Band used --- ISM 12

13 Protocol Stack 13

14 Power management plane is concerned with efficient use of power related issues. Mobility management plane is responsible for movement of the sensor nodes Task management plane is used for balancing and scheduling the sensing tasks for a certain region in the sensing field. Cont 14

15 Mobile sensor networks Mobile wireless sensor networks (MWSNs) can simply be defined as a wireless sensor network (WSN) in which the sensor nodes are mobile. 15

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