Load Balanced Routing with Constant Stretch for Wireless Sensor Network with Holes

Nguyen Phi Le, Nguyen Duc Trong and Nguyen Khanh Van

Ha Noi University of science and technology

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Agenda Background Related works Problem statement and goals Proposed scheme

Strategy to choose the forbidding area Hole bypassing routing protocol

Performance evaluation Conclusion and future work

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Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Background Geographic routing

Uses location information of the nodes Each node knows the location of the neighbors and the destination

Achieves near optimal path with network without holes

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Background Geographic routing with holes

Hole diffusion problem

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Background Geographic routing with holes

Hole diffusion problem Routing path enlargement problem

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Background Common approach

Constructing a forbidding area around the hole Nodes know the hole in advance

Routing the packet along optimal path outside the forbidding area

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Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Related works Target the hole diffusion problem

Virtual hexagon [H.Choo, ICOIN’11] Virtual Circle [F.Yu, JCN 2009]

Virtual ellipse [Y.Tian, ICC’08]

The forbidding area is very simple

The dissemination cost is small

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Related works Hole diffusion problem has not been solved thoroughly

Static forbidding area Traffic is concentrated around the forbidding area

Routing path is enlarged in some cases

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Target the routing path enlargement problem

HOLE

Related works

GOAL [Transaction on parallel and distributed computing, 2011]

Constant stretch

Data congestion on the boundary of the convex hull

BUT

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Visibility graph [G.Tan, infocom 2009]

S

D

Hole

Convex hull

Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Problem statement Hole diffusion problem has not been solved thoroughly

Static forbidding area Traffic is concentrated around the forbidding area

None of the existing schemes solves both of the two problems

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Goal Finding the optimal forbidding area

Constant stretch Load balancing Small dissemination cost

Propose a hole bypassing routing scheme which Has a constant stretch Solves the problem of hole diffusion thoroughly

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Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Theoretical model Considering networks with only one hole Modeling the geographic S-D routing path as the

Euclidean line between S and D

Real geographic routing path Euclidean routing path

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Theoretical model Euclidean stretch of the forbidding

area to the hole

Hole

Forbidding area

Euclidean routing path bypassing the forbidding area

iA

jA

lH

kH

S

D

Shortest Euclidean routing path bypassing the hole

𝐸𝑢𝑐𝑙𝑖𝑑𝑒𝑎𝑛 h𝑠𝑡𝑟𝑒𝑡𝑐 = max∀ (𝑆 ,𝐷)

|𝑆 𝐴𝑖… 𝐴 𝑗||𝑆𝐻 𝑙 …𝐻𝑘|

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Strategy to choose the forbidding area Constant stretch Load balancing Small dissemination cost

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Strategy to choose the forbidding area The shortest Euclidean path bypassing a polygon

broken line through the vertices of the convex hull

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Convex hull of polygon P: a convex polygon which covers P and its vertices are the vertices of P

Strategy to choose the forbidding area The shortest Euclidean path bypassing a polygon

broken line through the vertices of the convex hull

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The Euclidean stretch of the convex hull to the hole is 1

Is the convex hull the best forbidding area ???

Strategy to choose the forbidding area The shortest Euclidean path bypassing a polygon

broken line through the vertices of the convex hull

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The number of the vertices of the convex hull maybe very large

The dissemination cost is large too

Strategy to choose the forbidding area The forbidding area should be a convex polygon

Hole

Forbidding area

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Hole bypassing routing path

Strategy to choose the forbidding area If P is a n-gon with equal angles such that P covers the

hole and each edge of P contains at least one vertex of the hole, then Euclidean stretch of P to the hole is upper bounded by

We choose the octagon with the equal angles as the forbidding area

The Euclidean stretch does not exceed

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Strategy to choose the forbidding area Constant stretch Load balance Small dissemination cost

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Hole

Forbidding area

Traffic concentration around the boundary of the

forbidding area

Strategy to choose the forbidding area The Euclidean stretch depends on

Perimeter of the forbidding area Distance between the source and the destination

The larger the distance, the smaller the Euclidean stretch

The Euclidean stretch does not depends on The position of the forbidding area

Dynamic forbidding area The size and the position are packet specific

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Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Proposed protocol detail Initial network setup Hole bypassing protocol

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Proposed protocol detail

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Initial network setup Identifying hole boundary Determining core polygon Disseminating information of core polygon to a restricted area

Hole bypassing protocol

1. Identifying hole boundary 2. Determining core polygon 3. Disseminating core polygon 4. Hole bypassing protocol

Initial network setup Core polygon construction

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3

1. Construct a rectangle circumscribing the hole2. Construct another rectangle circumscribing the hole with edge directions of angle of to the first

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Initial network setup Core polygon construction

3. The intersections of the two rectangles form the core polygon

Core polygon information dissemination

Initial network setup

Region 1

Region 2

Dissemination area is restricted by predefined threshold δ

pC: perimeter of the core polygon; l(N): distance from N to the core polygon ; β(N): view limit from N to the core polygon

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Proposed protocol detail

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Initial network setup Identifying hole boundary Determining core polygon Disseminating information of core polygon to a restricted area

Hole bypassing protocol

1. Identifying hole boundary 2. Determining core polygon 3. Disseminating core polygon 4. Hole bypassing protocol

The packet is initiated in region 2

Hole bypassing protocol

Region 1

Region 2

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The packet is initiated in region 1 (or arrived at a node in region 1)

Hole bypassing protocol

Region 1

Region 2

I

Determines the forbidding area (A-polygon): Image of the core polygon through a homothetic transformation

The center is chosen randomly The scale factor > 1 is computed based on source-destination distance

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The packet is initiated in region 1 (or arrived at a node in region 1)

Hole bypassing protocol

Random selection of I ↓

Forbidding area is different per packet

Scale factor is computed based on the source-destination distance ↓ Constant stretch of routing path

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Region 1

Region 2

I

The packet is initiated in region 1 (or arrived at a node in region 1)

Hole bypassing protocol

Region 1

Region 2

I

Determines shortest Euclidean path which bypasses the A-polygon Virtual anchors: vertices of A-polygon

Routes the packet to the virtual anchors

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Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Performance evaluation Theoretical analysis

Proves the constant Euclidean stretch of the proposed protocol Simulation

Compares performance with existing protocols

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Theoretical analysis Constant stretch

Euclidean stretch does not exceed to (~1.09+δ）( predefined parameter)

jA

lH

kH

S

D

iA

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Simulation Benchmarks

Virtual Circle [F.Yu, transaction on communication and network 2009]

Virtual hexagon [H.Choo, ICOIN’11] Convex hull [Transaction on parallel and distributed computing,

2011] Evaluation metrics

Stretch in hop-count The ratio between the hop-count of the routing path using routing protocol

and the optimal routing path. Energy consumption of individual sensor nodes Energy overhead

The extra energy caused by the initial network setup phase in our protocol.

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Simulation Simulation scenario

Simulator :NS2 Network area: 1000m x 1000m Sensor nodes: 1500 Number of the hole: 1 Number of the vertices of the hole: 52 Simulation time: 500s Number of source-destination pair: 100 pairs Packet transmission frequency: 1packet/1s

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(Victor Shnayder et al., Simulating the power consumption of large scalesensor network applications, SenSys’04 )

Simulation Simulation result

Stretch Smaller than “virtual hexagon”, “virtual circle” Greater than “Goal” but the difference is not much Less than 1.2 (with δ=1) Does not increase when decreasing the distance between source-

destination

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18 23 28 33 38 43 480.9

1.4

1.9 Circle hexagon

Goal Proposal (δ=1)

Distance between source and destination (number of hop-counts)

Hop

-cou

nt s

tret

ch

Simulation Simulation result

Energy consumption of individual sensor nodes “Goal” is the worst The proposed scheme is the most balanced compared to the existing protocols

Proposed scheme(

Virtual circle Virtual hexagon

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GOAL

Simulation Simulation result

Energy overhead Decreases with the increasing of the stretch Just accounts for only 0.095% of the entire energy even in the worst

case

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0 1 2 3 4 50.4

0.45

0.5

0.55

0.6

δ

Ave

rage

con

sum

ed e

nerg

y (J

)

Agenda Background Related works Problem statement and goals Strategy to choose the forbidding area Our proposed routing scheme Performance evaluation Conclusion and future work

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Conclusion and future work Conclusion

We proposed a routing protocol to bypass the hole Solves the problem of hole diffusion Ensures a constant stretch

Euclidean stretch , theoretically Proposed scheme outperforms existing protocols by simulation

Hop-count stretch <1.2 (with =1)

Future work Consider the network with multiple holes Compare performance of our protocol with non-geographic

routing protocols

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Thank you for your attention !

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