Hierarchal Protocols for routing in wireless sensor networks...an improvement on it

1. Pushpita Biswas (10EC65R10)
Guided by – Prof. R. Datta
Department of Electronics and Electrical Communication
Engineering
Indian Institute of Technology Kharagpur
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2. Contents
 Introduction
 Motivation
 Literature Survey
 Improved protocol technique (Work Done)
 Results and future work
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3. Introduction
 Why Wireless Sensor Networks?
According to MIT’S Technology review, this technology is one of the ten new technologies
which will change the world and manner of work.
 A sensor network is composed of a large number of sensor nodes that are
randomly, densely deployed either inside the phenomenon or very close to it. This also means
that sensor network protocols and algorithms must possess self-organizing capabilities.
 The battery is an important component of the sensor so focus is on innovative energy-
optimized solutions at all levels of the system hierarchy, from the physical layer and
communication protocols up to the application layer and efficient DSP design for microsensor
nodes.
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4. MOTIVATION
 Only 2.12% of the research work done in energy-optimization techniques for wireless
sensor networks is related to the network layer routing protocols.
 The existing protocols have certain disadvantages that can be improved upon.
OBJECTIVE
Propose a modification of the existing protocol or a new routing protocol that would
extend the life time of the sensor network.
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5. These are a few types of routing protocols :
 Data-centric protocols
 Hierarchical protocols
 Location-based protocols
 Network flow and QoS-aware protocols
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6. Literature Survey – contd..
Why hierarchical protocols are preferred?
 Scalability is one of the major design attributes of sensor networks.
 Single gateway or one-hop architecture is not scalable for a large set of sensors covering a wider
area.
 Hierarchical routing efficiently involve proper energy consumption, data aggregation and fusion.
Why LEACH (Low-energy Adaptive clustering Hierarchy) is the most basic important hierarchical
protocol?
 LEACH [1] has been an inspiration for many hierarchical routing protocols. Provides a factor of 7
reduction in energy dissipation compared to direct communication
 Energy consumption should be uniform so cluster formation must be dynamic as in LEACH.
 PEGASIS [2] outperforms LEACH by 100 to 300% in terms
of lifetime but introduces excessive delay for distant
node on chain and the single leader becomes a bottle neck.
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7. Literature Survey - Overview of Leach Protocol
Cluster head selection
 Stages in LEACH Protocol
Advertisement phase
Cluster Set-up
Cluster formation
LEACH Schedule creation
Data communication to CH
Steady-state
Data fusion
 Timeline of Leach Protocol
Data communication to BS
Setup Steady-state
Round 7

8. Cluster head selection
Base
Station
8

9. Literature Survey - Overview of Leach Protocol
Cluster head selection
 Algorithm : ran(n) is a randomly generated value for each
node n :
 If ran(n) < T(n), then that node becomes a cluster-head
 Analytical and mathematical proof yield that .01<p<0.06 is
the optimal value for desired probability of cluster heads
9

10. Advertisement phase
Base
Station
ADV
10

11. Cluster formation Base
Station
11

12. Schedule creation Base
Station
12

13. Data Transmission Base
Station
13

14. Literature Survey - Overview of Leach Protocol
Cluster heads get selected in a distributed manner.
Cluster head
selection
Self-elected cluster-head for the broadcasts an advertisement
Advertisement message(ADV) using CSMA MAC protocol.
Cluster Set-up phase
phase
Cluster Non-cluster-head nodes send a Join(REQ) message to the
formation corresponding cluster-head using CSMA MAC.
Schedule The cluster head creates a TDMA schedule telling each node
creation when it can transmit.
Data Data send by node is only during their allocated transmission
transmission to time to the cluster head.
cluster heads
Steady state Cluster head aggregates the data received from nodes in the
phase Data fusion cluster.
Communication within clusters is via direct-sequence spread
Multiple clusters spectrum (DSSS), but from the cluster head nodes to the BS
to base station using a fixed spreading code and CSMA. 14

15. Literature Survey – contd..
Problems in Traditional LEACH
• Cluster Head selection is
random, that does not take into
account energy consumption
• CHs can be located at the edges of
the given area
• Setup time increases compared to
direct communication
• Does not support movement of
nodes
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16. Literature Survey – contd..
Modified-Leach [3]
The threshold function is changed to T(n)= p * En_residual
1-p[r mod(1/p)] En_initial
Advantages :
Residual energy of nodes taken into consideration
Tremendous advantage when base-station is far away from sensing area
Disadvantages :
 Non-uniform distribution of cluster heads, thus increases the total energy dissipated in the
network
Two-Layer Leach (TL-LEACH) [5]
The cluster heads themselves form another layer of nodes which in themselves group to form
clusters.
Advantages :
Increase of 30% of the lifetime compared to LEACH once the first node has dies
Disadvantages :
Inferior performances in the initial phase of work
 Non-uniform distribution of cluster heads, thus increases the total energy dissipated in the
network 16

17. Two Picture Page Layout
Work Done Till Now
 Change in cluster head selection is introduced
 Each node is having a special added threshold value Th(n)
 Residual energy is also considered
 If a perfect cluster is found, a similar type of cluster can be formed in future
rounds.
 Repetition of perfect clusters should be limited to a fixed number of times.
 Adding of extra threshold value signifies higher probability of the node
becoming a Cluster Head in future rounds
17

18. Work Done
Algorithm to find perfect cluster and change T(n) :
Step 1 : After cluster formation, farthest node in north, south, east, west
direction from CH is found.
Step 2 : The corresponding distances are calculated –> n, s, e, w
Step 3 : The calculated values must have very less difference
(for a M*M network diff < M ) else continue with steady state
̄( ∏ * p* N)
Step 4 : Change individual added threshold Th(n) for all nodes in this cluster
Th(n) = exp(-2 * dist) /avg dist -> distance of node from CH
avg -> n + s + e + w
4
18

19. Work Done
Algorithm to find perfect cluster and change Th(n) :
Step 5: If r mod (1/p) = 0 clear all Th(n) ,so that nodes at the center of d perfect cluster do
not get exhausted.
Step 6: Random value generated for each node n be ran(n) and If ran(n) < T(n) then node
n is a cluster head
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20. Simulation Conditions
Base • All nodes in network are homogenous and energy-constrained
Station
• 100 nodes randomly placed and Each packet is of 2000 bits
(25,150)
• After data aggregation 5% compaction is done to the packet size
that is transmitted to base station.
• First order Radio Model is followed for all energy
(100,100) reduction.
Eelec = 50 nJ/bit for transmitter or receiver circuitry
€amp = 100 pJ/bit/m2 transmitter amplifier
Transmitting:-
ETx(k,d) = ETx-elec(k) + ETx-amp(k,d)
ETx(k,d) = Eelec*k + €amp*k*d2
Receiving:-
ERx(k,d) = ERx-elec(k)
ERx(k,d) = Eelec*k
(0,0)
• Optimal probability is found to be 0.05 and therefore
used 20

21. Simulation results Routing protocols 0.25 0.50 1.00
J/node J/node J/node
1. 50 different random Direct 155 107 217
allocations of the 100 sensor communication
nodes in the 100*100 m area
Leach 312 883 1548
is simulated.
2. All readings correspond to the Modification 462 975 1998
round in which first node dies.
Comparison Chart
2500
2000
1500 Direct
LEACH
1000
Modification done
500
0
0.25J/node 0.50 J/node 1.00 J/node
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22. Future Work
 Formulation of the mathematical base to find a perfect cluster.
 Design of a better protocol having negative JOIN(REQ) packet send to
undesired Cluster heads to demolish them.
 Implementation of LEACH protocol on Heterogeneous types of nodes.
 Design of a routing protocol for specific application of
wireless sensor networks.
Specifically for bridges having a super structure and a sub structure on a
rough terrain. (LEACH is designed on a plane)
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23. References
1. Heinzelman.W.B., Chandrakasan.A.P., Balakrishnan.H “An application-specific protocol architecture
for wireless microsensor networks” IEEE transactions on Wireless Communication, Vol. 1, Issue.
4, 2002, pp 660-670
2. Lindsey. S, Raghavendra.C, Sivalingam.K.M “Data gathering algorithms in sensor networks using
energy metrics” IEEE transactions on Parallel and Distributed Systems, Vol.
13, Issue.9, 2003, pp 924-935
3. Yuhua Liu, Yongfeng Zhao, Jingju Gao, “A New Clustering mechanism based on LEACH Protocol”, 2009
International Joint Conference on Artificial Intelligence, 2009. JCAI '09. pp 715-718
4. S. Bandyopadhyay, E.J. Coyle, “An Energy-Efficient Hierarchical Clustering Algorithm for Wireless
Sensor Networks” , Twenty-Second Annual Joint Conference of the IEEE Computer and
Communications Societies, in IEEE INFOCOM:1713- 1723 vol.3, 2003.
5. V. Loscrì, G. Morabito, S. Marano, “A two levels hierarchy for low energy adaptive
clustering hierarchy (TL-LEACH)”, Vehicular Technology Conference, 2005, Vol. 3, pp 1809-1813
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24. Thank you!