a novel virtual anchor node- based localization algorithm for wireless sensor networks pengxi liu,...
DESCRIPTION
Introduction WSNs usually are arranged at special scout region, and sense special physics information in the region. Sensor nodes are often deployed by random bestrewing. The application of WSNs is often related to the positions of nodes. So the localization of sensor nodes has become a hot topic in WSNs.TRANSCRIPT
A Novel Virtual Anchor Node-based Localization Algorithm for Wireless Sensor Networks
Pengxi Liu, Xinming Zhang, Shuang Tian, Zhiwei Zhao, Peng SunDepartment of Computer Science and TechnologyUniversity of Science and Technology of China
International Conference on Networking 2007
Outline Introduction Error analysis of typical localization
algorithms Virtual Anchor Node-based Localization
Algorithm (VANLA) Performance evaluation Conclusion
Introduction WSNs usually are arranged at special scout region, and sense special physics information in the region.
Sensor nodes are often deployed by random bestrewing. The application of WSNs is often related to the positions of nodes. So the localization of sensor nodes has become a hot topic in WSNs.
Introduction Most of the existent researches suppose
The network includes a small number of anchor nodes. The existence of various errors
The location precision will be restricted Some nodes even cannot be located.
The improvement of localization precision with lower cost less energy consumption less hardware support
Introduction The new algorithm finds out virtual anchors
to provide highly precise positions for unknowns nodes to assist in locating the rest unknowns along with primary real anchors.
Error analysis of typical localization algorithms The authors choose two concrete algorithms to
carry out error analysis. Euclidean
Range-Based
DV-hop Range-Free
Error analysis of typical localization algorithms - Euclidean
Each sensor has ability to measure their relative distance.
A
B
C
L1
D
α β
L3
L2
Error analysis of typical localization algorithms - Euclidean
The draw back of Euclidean The ranging error is the main flaw of Range-based algorithm. This error can be accumulated hop by hop.
Error analysis of typical localization algorithms – DV-hop
DV-hop Use the corrected factor ci to fixed the hop distance.
A
B
C
X
cA
Error analysis of typical localization algorithms – DV-hop
The draw back of DV-hop In practical application, the communication range of each node is not a standard circle ideally.
Error analysis of typical localization algorithms – DV-hop
A BC
n-hop n-hop
n*r n*r/2
The corrected factor is (3n*r/2*2n)=3r/4
Distance AC is n* 3r/4 =3n*r/4
The error is n*r-(3n*r/4)=n*r/4
This error can be accumulated hop by hop.
Virtual anchor node-based localization algorithm There can be only a few anchor nodes deployed in the network due to high cost and energy issue Virtual anchor node-based localization algorithm
The Selection of Virtual Anchor Node The Upgrade of Virtual Anchor Node
Virtual anchor node-based localization algorithm Assumption
The WSN is a dense network There are few anchor node in the
network The shape of the path with the
smallest hop count is asymptotic to a beeline
Virtual anchor node-based localization algorithm Scenario
AC
B
D
UE
y
Virtual anchor node-based localization algorithm The Selection of Virtual Anchor Node
A
B
C
HopA=1x
Compare Hop with “HopA=nA”
If the hop has not received or is smaller than present hop Store HopA=nA
HopA=nAHopB=nBHopC=nC
HopA=nAHopB=0HopC=nC
D
Virtual anchor node-based localization algorithm The Selection of Virtual Anchor Node
A
B
C
HopA=nAHopB=0HopC=nCHopD=nd
y
HopA=AyHopB=ByHopC=CyHopD=DyIF Ay+By=nAcandidate virtual anchor
D
Virtual anchor node-based localization algorithm
AB
If Max(hopA , hopB) – Min(hopA , hopB)= shortest pathAB, it is also an candidate anchor
y
HopA=nAHopB=nBnAB nB
nA= nAB+nBnA- nB =nAB
Virtual anchor node-based localization algorithm The Selection of Virtual Anchor
Node
A
B
C
D
Virtual anchor node-based localization algorithm The Upgrade of Virtual Anchor Node
A
B
C
D
UE
Virtual anchor node-based localization algorithm
AC
B
D
UE
Node UE can upgrade as a anchor node
Virtual anchor node-based localization algorithm Node UE can upgrade as a anchor
node
W
Y
X
ZUH
UF
UG
Virtual anchor node-based localization algorithm
AC
B
D
UE
Calculate UE’s position(Xb,Yb)
(Xa,Ya)
(Xd,Yd)
(Xc,Yc)(Xe,Ye)
Virtual anchor node-based localization algorithm
AC
B
D
UE
Calculate UE’s position
F
G
Performance evaluation Compiler: oCaml Language: caml OS: Cygwin
Performance evaluation Random deployment Field:32000m x 32000m Radius: 2200m 500nodes Ranging error 20%~50%
Performance evaluation
Performance evaluation
Performance evaluation
Performance evaluation
Performance evaluation Random deployment Field:10000m x 10000m Radius: 2100m 500nodes
Performance evaluation
Conclusion In this paper, the authors proposed
a distributed algorithm for virtual anchor nodes upgrading it can increase the density of virtual
anchor nodes at low physical cost assist some algorithms which already
exist to enhance the precision of localization in
the network with dense nodes
