1. Pushpita Biswas (10EC65R10) Guided by Prof. R. DattaDepartment of Electronics and Electrical Communication Engineering Indian Institute of Technology Kharagpur1/18/2012 1

2. Contents Introduction Motivation Literature Survey Improved protocol technique (Work Done) Results and future work1/18/2012 2

3. Introduction Why Wireless Sensor Networks? According to MITS 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.1/18/2012 3

4. MOTIVATION Only 2.12% of the research work done in energy-optimization techniques for wirelesssensor networks is related to the network layer routing protocols. The existing protocols have certain disadvantages that can be improved upon.OBJECTIVEPropose a modification of the existing protocol or a new routing protocol that wouldextend the life time of the sensor network. 1/18/2012 4

5. These are a few types of routing protocols : Data-centric protocols Hierarchical protocols Location-based protocols Network flow and QoS-aware protocols1/18/2012 5

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. 1/18/2012 6

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

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 headsSteady 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 1/18/2012 15

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_initialAdvantages :Residual energy of nodes taken into considerationTremendous advantage when base-station is far away from sensing areaDisadvantages : Non-uniform distribution of cluster heads, thus increases the total energy dissipated in thenetworkTwo-Layer Leach (TL-LEACH) [5]The cluster heads themselves form another layer of nodes which in themselves group to formclusters.Advantages :Increase of 30% of the lifetime compared to LEACH once the first node has diesDisadvantages :Inferior performances in the initial phase of work Non-uniform distribution of cluster heads, thus increases the total energy dissipated in thenetwork 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 DoneAlgorithm to find perfect cluster and change T(n) :Step 1 : After cluster formation, farthest node in north, south, east, westdirection from CH is found.Step 2 : The corresponding distances are calculated > n, s, e, wStep 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 DoneAlgorithm 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 donot get exhausted.Step 6: Random value generated for each node n be ran(n) and If ran(n) < T(n) then noden is a cluster head 19

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/node1. 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 1/18/2012 21

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 arough terrain. (LEACH is designed on a plane)1/18/2012 22

23. References1. 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 660-6702. 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 924-9353. 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 715-7184. 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. Loscr, 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 1/18/2012 23

24. Thank you!