Chapter 2 wireless sensor

1. supervisor Dr.shiri
prepare Ahmed
Altememe
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2.  Network architectures and protocols are important aspects in the design of
wireless sensor networks (WSNs).
 has a big impact on the energy consumption and thus the operational lifetime of
the whole network.
 It requires a suite of network protocols to implement various network control and
management functions.
 for example, synchronization, self - configuration, medium access control, routing,
data aggregation, node localization, and network security.
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4.  A sensor network typically consists of a large number of sensor nodes densely deployed in a
region of interest.
 one or more data sinks or base stations that are located close to or inside the sensing region.
 the sink(s) also serves as a gateway to outside networks for example Internet.
 It collects data from the sensor nodes sends relevant information (or The processed data) via
the Internet to the users who requested it or use the information.
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5.  To send data to the sink, each sensor node can use single - hop long – distance.
 long - distance transmission is costly in terms of energy consumption.
 the energy consumed for communication is much higher Than that for sensing and computation.
 For example, the energy consumed for Transferring one bit of data to a receiver at 100 m away
is equal to that needed To execute 3,000 instructions .[2]
 The ratio of energy consumption for communicating 1 bit over the wireless medium to that for
processing the same bit could be in the range of 1,000 –10,000 [3,4] .
 the energy consumed for Transmission dominates the total energy consumed for communication
and the Required transmission power grows exponentially with the increase of transmission
distance.
 it is desired to reduce the amount of traffic and transmission distance in order to increase energy
savings and prolong network lifetime.
 Multihop short - distance communication is highly preferred .
 a sensor node transmits its sensed data toward the sink via one or more intermediate nodes
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7.  The architecture of a multihop network can be organized into two types:
 Flat architecture.
 Hierarchical architecture.
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8.  each node plays the same role in performing a sensing task and all sensor nodes
are peers
 data gathering is usually accomplished by using data - centric routing
 it is not feasible to assign a global identifier to each node in a sensor network.
 only the sensor nodes that have the data matching the query will respond to the
sink
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10.  sensor nodes are organized into clusters.
 the cluster members send their data to the cluster heads while the cluster heads
serve as relays for transmitting the data to the sink.
 A node with lower energy can be used to perform the sensing task.
 send the sensed data to its cluster head at short distance.
 This process can not only reduce the energy consumption for communication, but
also balance traffic load
 improve scalability when the network size grows.
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11.  The major problem with clustering is how to select the cluster heads
 there are many clustering strategies.
 According to the distance between the cluster members and their cluster heads.
 According to the number of tiers in the clustering hierarchy.
A sensor network can be organized into a single - tier clustering architecture or a
multitier clustering architecture.
 To address the clustering problem, a variety of clustering algorithms have been
proposed in the literature
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13.  WSNs are application specific.
 According to different criteria.
 WSNs can be classifi ed into different categories:
Static and Mobile Network.
 Deterministic and Nondeterministic Network.
 Static - Sink and Mobile - Sink Network.
Single - Sink and Multisink Network.
 Single - Hop and Multihop Network.
Self - Reconfi gurable and Non - Self - Confi gurable Network.
 Homogeneous and Heterogeneous Network.
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15. The application layer contains a variety of application - layer protocols to generate
various sensor network applications.
 The transport layer is responsible for reliable data delivery required by the
application layer. (end-to-end data delivery between sensor nodes and the sink(s))
.
 The network layer is responsible for routing the data from the transport layer.
The data link layer is primarily responsible for data stream multiplexing, data
frame transmission and reception, medium access, and error control.
 The physical layer is responsible for signal transmission and reception over a
physical communication medium, including Frequency generation, signal
modulation, transmission and reception, Data encryption, and so on.
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16.  Network architectural design has a big impact on the energy consumption and
thus the operational lifetime of a WSN.
 sensor networks require a new suite of network protocols to perform various
network control and management functions,
 This chapter gave an introduction of fundamental concepts on network
architectures and protocol stack for sensor networks.
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17.  [1] Ian F. Akyildiz et al., “ A survey on sensor networks ” , IEEE Communications Magazine vol. 40 , no. 8 , Aug. 2002 , pp. 102 – 114 .
 [2] G. Pottie and W. Kaiser , “ Wireless integrated sensor networks (WINS) ” , Communications of the ACM vol. 43 , no. 5 , May 2000 , pp. 51 – 58 .
 [3] J. Hill , R. Szewcyk , A. Woo , D. Culler , S. Hollar ,and K. Pister , “ System architecture directions for networked sensors ” , in Proceedings of 9th
International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLoSIX) , Cambridge, MA , Nov. 2000, pp. 93 – 104 .
 [4] W. M. Merrill , K. Sohrabi , L. Girod , J. Elson , F. Newberg , and W. Kaiser , “ Open standard development platforms for distributed sensor networks
” , in Proceedings of SPIE— Unattended Ground Sensor Technologies and Applications IV (AeroSense 2002) , vol. 4743, Orlando, FL , Apr. 2002 , pp. 327 – 337 .
 [5] J. N. Al - Karaki and A. E. Kamal , “ Routing techniques in wireless sensor networks: survey ” , IEEE Wireless Communications , vol. 11 , no. 6 , Dec. 2004 ,
pp. 6 – 28
 [6] R. Rajagopalan and P. Varshney , “ Data - aggregation techniques in sensor networks:A survey ” , IEEE Communications and Surveys and Tutorials , vol. 8 ,
no. 4 , 4th Quarter 2006 , pp. 48 – 63 .
 [7] A. A. Abbasi and M. Younis , “ A survey on clustering algorithms for wireless sensor networks ” , Computer Communications , vol. 30 , nos. 14 – 15, Oct. 2007 ,
pp 2826 – 2841 .
 [8] G. Gupta and M. Younis , “ Load - balanced clustering of wireless sensor networks ” , Proceedings of 2003 IEEE International Conference on Communications
(ICC ’ 03) Anchorage, AK , May 2003, pp. 1848 – 1852 .
 [9] S. Bandyopadhyay and E. J. Coyle , “ An energy effi cient hierarchical clustering algorithm for wireless sensor networks
 [10] W. Heinzelman , A. Chandrakasan , and H. Balakrishnan , “ An application - specifi c protocol architecture for wireless microsensor networks ” , IEEE
Transactions on Wireless Communications , vol. 1 , no. 4 , Oct. 2002 , pp. 660 – 670 .
 [11] O. Younis and S. Fahmy , “ Heed: A hybrid, energy - effi cient, distributed clustering approach for ad - hoc sensor networks ” , IEEE Transactions on Mobile
Computing , vol. 3 , no. 4 , Oct. – Dec. 2004 , pp. 366 – 379 .
 [12] P. Wang , C. L i, and J. Zheng , “ Distributed minimum - cost clustering protocol for underwater sensor networks (UWSNs) ” , in Proceedings of 2007 IEEE
International Conference on Communications (ICC ’ 07 ), Glasgow, UK , June 2007 , pp. 3510 – 3515 .
 [13] S. Banerjee and S. Khuller , “ A clustering scheme for hierarchical control in multi – hop wireless networks ” , in Proceedings of IEEE INFOCOM ’ 01 ,
Anchorage, AK , Apr. 2001 , pp. 1028 – 1037 .
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