a distributed algorithm for the dead-end problem in wsns
TRANSCRIPT
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Project Guide :- Ms. Diya Thomas
Panel Members :- Project Members :-
Mr. Febin P Jacob Maria Lucy Thomas
Ms. Amitha Mathew Ponnu Jose
Priyanka Jacob
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Introduction
Literature Survey
System Specification
Assumption and Dependencies
Flow charts and Pseudo code
Conclusion
Future Enhancements
Bibliography
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Efficient routing in WSNs is an important field that
needs to be addressed.
This project aims to provide solution to Dead-End
problem of Location-Based Routing in Wireless
Sensor Networks.
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A message falls into a local minimum using greedy
forwarding in WSNs.
PROPOSED ALGORITHM :-
Can generate loop-free short paths with higher
delivery ratio and lower energy consumption.
Can handle large-scale networks
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Greedy Forwarding
Next hop is the neighbor that gets the packet
closest to destination.
destinationsource
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Dead-End Problem in Greedy Forwarding
Base Station
SourceSource
Successful Routing using GF
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Reactive routing protocol
Builds routes between nodes only as desired by source nodes.
A broadcast route discovery mechanism
RREQ (Route Request packet) broadcasting to find a route RREP (Route Reply packet) is used to set up forward path
Dynamic establishment of route table entries
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Destination sequence number
For updating the latest information for a route Ensures that only most efficient route is used
Routing loops avoided using (source-addr, broadcast-id) pair in RREQ packet
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Basic message set in
AODV includes:
Hello - For link status
RREQ - Route Request
RREP - Route Reply
RERR - Route Error
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Route Request (RREQ) broadcast flood
Source
Destination
RREQ
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Route Reply (RREP) Propagation
Destination
Source
RREP
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Route Reply (RREP) Propagation
Destination
Source
Packet Forwarding path
1• High route discovery latency.
2• No reuse of routing information.
3• Overhead on the bandwidth.
4 • Vulnerable to misuse.
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Sensors can figure out who its closest neighbors are (usingbeacons).
2 forwarding methods:-
- Greedy forwarding
- Perimeter forwarding
To calculate a path, GPSR uses a greedy forwardingalgorithm.
Perimeter forwarding will route around the perimeter of theregion.
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Greedy Forwarding Perimeter Forwarding
greedy fails
have left local minimagreedy works greedy fails
GREEDY FORWARDING FAILURE
Perimeter Forwarding
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Apply the right-hand rule to traverse the edges of a void:-
- Pick the next anticlockwise edge.
1• Generates longer paths with loops.
2• Risk of losing data packets is high.
3• Increases computational complexity.
4• Increases traffic burden.
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Hardware Interfaces:
Processor : Pentium P3 or higher
Ram : 2 GB recommended
HDD : 4 GB
Software Interfaces:
Platform : Ubuntu
Interface : NS-2
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Base Station
A
B C
D E
I
concave node
K
J
L
H
G
F
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A
B C
DE
F
Shadow Area
Bright Area Base Station
IK
J
L
H
G
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5
12
7
16
2018
8
15
16
2019
23
A
B C
DE
F
Euclidean distance to the BS
19+∆
∆ set as the average Euclidean
distance between neighboring
sensor nodes
Base Station
22
IK
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L
H
G
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5
12
7
16
2018
8
15
16
2019
23
A
B C
DE
F
22+∆
22
25
Base Station
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5
12
7
16
20
8
15
16
2019
23
A
B C
DE
F
23+∆
22
25 26
Base Station
IK
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5
12
7
16
20
8
15
16
2019
23
A
B C
DE
F
26+∆
2625
2229
Base Station
IK
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G
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Sensor nodes are stationary and are arranged in a 2D
sensing field.
They exchange packets through Greedy Forwarding.
Euclidean distance is considered as the cost factor.
Node A’s cost is lesser than its neighbors' cost for the
Phase 2 to initiate.
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THE SHADOW SPREAD FUNCTION RUNNING AT NODE X
Shadow_Spread(node x)
status(x) = bright;
while active do
if receive beacon(status, location) from a neighbour y then
Refresh the neighbour set N(x) by updating status and location information of y;
if DecideShadow(x) then
status(x) = shadow;
else
status(x) = bright;
end if
if beacon timeout occurs then
Copy the status and location information of node x to Beacon(status, location) and broadcast
end if
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AUXILLIARY FUNCTION DECIDE - SHADOW
Bool DecideShadow(node x)
shadow = true
for each node z€N(x) do
if((status(z)==bright)&&(distance(z)<distance(x)) then
return false;
end if
return shadow;
Check
whether
each N(x) is
shadow
Set status as bright
Copy status and location information of
node x to Beacon(status, location) and
broadcast
Stop
Start
Set status as shadowyes
no
Node x receives beacon
messages from neighbors
N(x)
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THE COST SPREAD FUNCTION RUNNING
AT EACH SHADOW NODECost-Spread(node x)
cost(x) = distance(x);
while active do
if receive beacon(cost) from a neighbor y then
Refresh the neighbor set N(x) by updating the
cost of y;
if (cost(x)<= minimum cost of neighbor set N(x)) then
cost(x) = maximum cost of neighbours + ∆;
end if
end if
if beacon timeout occurs then
copy cost of node x to beacon (cost) and send out;
end if
Shadow
nodes check
whether its’
N(x) has a
larger cost
Establish path to a neighbor with the lowest
cost and hence deliver packet to BS
Stop
Start
Increment the cost until each shadow
node has a N(x) with lesser cost
yes
no
Calculate the Euclidean
distance of each node to the
base station
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A
B C F
Base Station
IK
J
L
H
G
D E
Case 1 :
Bright node as source
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A
B C F
Base Station
IK
J
L
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D ECase 2 :
Shadow node as source
• Current methods for Dead-end problem are insufficient.
• PAGER does not require a node to memorize paths.
• It constructs loop-free paths with lengths close to shortest
path.
• Packet delivery ratio is high.
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• To consider other parameters as the cost factor.
• Algorithm can be extended to multiple base stations.
• Mobility constraint could be overcome!
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[1] Le Zou, Mi Lu, and Zixiang Xiong, “A Distributed
Algorithm for the Dead-end Problem,” IEEE Trans. On
vehicular technology, vol. 54, no.4, July 2005.
[2] L.Akyildiz, et al., “A Survey on Sensor Networks,”
IEEE Communications Magazine, Aug 2002, pp. 102-114.
[3] I. Stojmenovic, “Position-Based Routing in Ad Hoc
Networks,’’ IEEE Communications Magazine, July 2002,
pp. 128-134.
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[4] Karp B., Kung H.T, “Greedy Perimeter Stateless Routing
for Wireless Networks,” Proceedings of 6th Annual
ACM/IEEE International Conference of Mobile Computing
and Networking; Boston, MA, USA. August, 2000, pp. 243–
254.
[5] C. Intanagonwiwat, R. Govindan, D.Estrin, J.Heidemann,
and F. Silva, “Directed diffusion for wireless sensor
networking,” IEEE/ACM Trans. Netw., vol. 11, no. 1, pp. 2–
16, Feb, 2003.
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