Communication Standards in Wireless Sensor Networks Bachelor Thesis - PowerPoint PPT Presentation

Lehrstuhl für Netzarchitekturen und Netzdienste Institut für Informatik Technische Universität München Communication Standards in Wireless Sensor Networks Bachelor Thesis Lukas Tillmann Advisors: Alexander Klein, Corinna Schmitt

Outline  Definition of WSN  Communication Standards  Goals of this thesis  Analysis technology and methods  Evaluation  Conclusion Communication Standards in Wireless Sensor Networks 2

Outline  Definition of WSN  Communication Standards  Goals of this thesis  Analysis technology and methods  Evaluation  Conclusion Communication Standards in Wireless Sensor Networks 3

Communication Standards - Overview  There is no uniform protocol standard in Wireless Sensor Networks (WSNs)  Independent development by different interest groups trying to meet similar challenges  IEEE 802.15.4  Implementation of the Physical and Data Link Layers  Specifically designed for use in Wireless Low-Power Networks (WPANs)  Provides usage of different frequency ranges, CSMA and address ranges  Maximum Transmission Unit (MTU) of 128 bytes  ZigBee and 6LoWPAN - two IEEE 802.15.4 based Standards Communication Standards in Wireless Sensor Networks 4

Communication Standards - ZigBee  ZigBee  Holistic standards solution in WSNs  Implements all Layers up to the Application Layer  Provides mechanisms for network creation, maintenance, adressing, application interfaces, etc. Communication Standards in Wireless Sensor Networks 5

Communication Standards – 6LoWPAN  6LoWPAN (IPv6 over Low-Power Wireless Personal Area Network)  Implementation of an Adaption Layer to enable the usage of IPv6 in WSNs  Provides several mechanisms to shorten IPv6 frames Communication Standards in Wireless Sensor Networks 6

Goals of this thesis  Presentation of ZigBee and 6LoWPAN regarding  Functional principles  Network creation  Data transmission / shortening mechanisms  Integrated security mechanisms  Behavior in simulations  Questions handled in this thesis  What different approaches were taken?  How it data transmission handled?  How are the specific challenges in WSNs managed?  How do these protocol standards behave in simulations? Communication Standards in Wireless Sensor Networks 7

Used Analysis Tool  Simulating different scenarios using OPNET – ZigBee simulator  6LoWPAN not supported by OPNET simulation   Reasons for using just one simulator/protocol standard: Very few noticeable differences between two similar standards.  Problems comparing the results of two different simulators because of  Different possiblities/limitations when it comes to data input  Different ways of computing the statistics  Communication Standards in Wireless Sensor Networks 8

Analysis Methods  Used simulation topologies: Star, Chain, Grid  Used simulation variations:  Differing number of nodes active within a network  Differing traffic intensity  For each simulation run, one network model is used  Nodes are present and signed in to the PAN at all times  Differing start and stop times for application data transmission Communication Standards in Wireless Sensor Networks 9

Gathering the data  Gathering the data  Ten simulation runs with differing seed values are performed  Merging and sorting the data by using a small Java program Communication Standards in Wireless Sensor Networks 10

Star topology  All traffic is directed towards the Coordinator  Nodes gradually join in on data transmission Communication Standards in Wireless Sensor Networks 11

Star topology Interarrival Time 5 seconds Packet size 64 bytes  Overall delay respective to the number of nodes active in the network Communication Standards in Wireless Sensor Networks 12

Star topology Interarrival Time 1 second Packet size 128 bytes  Overall delay respective to the number of nodes active in the network  Increase in delay as more retransmission become necessary  Decrease in variance as retransmission become the norm Communication Standards in Wireless Sensor Networks 13

Star topology Interarrival Time 1 second Packet size 128 bytes  Percentage of packets dropped (maximum number of backoff retransmissions reached (4)) in a star topology high traffic variant Communication Standards in Wireless Sensor Networks 14

Chain topology  All traffic is directed towards the Coordinator Increasing number of hops towards the destination   Only one node sends at a time Communication Standards in Wireless Sensor Networks 15

Chain topology Interarrival Time 5 seconds Packet size 128 bytes  Gradual and steady growth of End-to-End delay as number of hops increases (avg. 6.145 ms per additional hop)  Increase in variance due to escalation from previous values Communication Standards in Wireless Sensor Networks 16

Grid topology  All traffic is directed towards the Coordinator  Nodes drift away from the center with 0.25 meters/minute  Topology structure (parent-child associations) remains intact  Start: 10 meters spacing between adjacent nodes  End: 150 meters spacing between adjacent nodes Communication Standards in Wireless Sensor Networks 17

Grid topology Interarrival Time 2 seconds Packet size 64 bytes  Packet loss ratio after maximum number of backoffs (4) is reached  Decrease as node density is eased Communication Standards in Wireless Sensor Networks 18

Grid topology Interarrival Time 2 seconds Packet size 64 bytes  Load in bits/s respective to the distance between two adjacenting nodes  Load decreases as node density decreases due to fewer required retransmission attempts Communication Standards in Wireless Sensor Networks 19

Conclusion  ZigBee  All-in-One solution  Provides interfaces in the Application Layer  Best suited for secluded systems  6LoWPAN  Built for adaption of IPv6 in WSNs  Handles the parsing between IPv6 and 6LoWPAN headers  No application support provided  Best suited for traffic that exceeds the WSN  Used protocol standard can be chosen according to the needs of a specific WSN! Communication Standards in Wireless Sensor Networks 20

Questions Thank you for your attention ! Communication Standards in Wireless Sensor Networks 21

OPNET Screenshot – Star Low Traffic „Time average“ Communication Standards in Wireless Sensor Networks 22

OPNET Screenshot – Star Low Traffic „As Is“ Communication Standards in Wireless Sensor Networks 23