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Data Management in WSN

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Abdalkarim Awad, Reinhard German and Falko Dressler. Chair for Computer Networks and Communication Systems. Erlangen-Nuremberg University ... – PowerPoint PPT presentation

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Title: Data Management in WSN


1
Data-Centric Cooperative Storage in Wireless
Sensor Networks
Abdalkarim Awad, Reinhard German and Falko
Dressler Chair for Computer Networks and
Communication Systems Erlangen-Nuremberg
University November 2009
2
Wireless Sensor Networks (WSNs)
Limited storage capacity!
3
WSNs Algorithms
storage
4
VCP Virtual Cord Protocol
  • How to build the cord?
  • How to route using the cord?
  • How to make use of
  • the available storage capacity ?

5
VCP-Join
range 0,1
Requirements
One node must be pre-programmed as initial node,
i.e. it gets position 0
0
Proactive each joined node sends hello messages
periodically
6
VCP-Join
0
0
1
7
VCP-Join
0
1
1
0.50
0
8
VCP-Join
1
0.50
0
1
0.50
0.75
0
9
VCP-Join
1
0.50
0.75
0
1
0.75
0.50
0
0.6
10
VCP-Join
1
0.75
0.50
0
0.6
0.52
1
0.75
0.50
0
0.6
11
VCP-Routing
Routing greedy forwarding based on local
information
Hash(Data)0.781
Given a static network, routing in VCP is loop
free.
12
Cooperative Storage
  • If the nodes are supposed to store data for long
    time, the storage capacity of an individual
    sensor node can gets exhausted.
  • Use the successors on the cord to store data
  • Bloom filters can be used to restrict query
    forwarding

Ring disabled
Ring enabled
13
Bloom Filters
  • Compact data structures to represent a set of a
    data items
  • Appropriate to answer membership queries

14
Bloom Filters (contd)
0
H1(x)
Belong(y)
check the bits at positions H1(y), H2(y),
H3(y).
Insert(x)
H2(x)
set the bits at positions H1(x), H2(x), H3(x).
H3(x)
m
15
Bloom Filters (contd)
  • Appearance of false positives.
  • False positive the probability that the filter
    recognizes an element as belonging to the set
    although it does not.
  • P (1 - e-kn/m)k
  • k number of hash functions
  • nnumber of data items
  • m size of the filter

16
Performance Evaluation
Simulation using OMNET
INET Framework IEEE802.11b-complete network stack
17
Ability to store Data
Stored data items
Query success rate
18
Path length
Data insertion path length
Query path length
19
Different parameters - insertion path length
Network Size
Partial Storage
Data Distribution
20
Conclusion
  • Cooperative storage suits the characteristics of
    WSN
  • Our approach has several attractive
    characteristics
  • Self-Organizing
  • The successors and predecessors are in the
    vicinity
  • Lightweight
  • Simulation Results shows
  • Stability in the Performance, efficient usage of
    resources

21
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