1. SEP routing protocol in WSN
Lab 2
Networks and Communication Systems Department
TA. Maram Almuhareb
SEP routing protocol in WSN

2. Introduction
A WSN is made up of multiple stations meant for detection, called sensor nodes.
The most important aspect of WSN applications is its lifetime which is primarily constrained and limited by the amount of energy consumed by the sensors, which are driven by un-rechargeable batteries also hard to replace due to deployment In hostile environments.

3. Cont.
Once the nodes begin to exhaust their energies (become dead), the tolerance of the network goes on decreasing, until such a time when it can no longer be operational.
The period of time from the beginning of network operation till the first node dies may be referred to as the stability period

4. The Problem
An endeavor to study a protocol that may increase this stability period of a WSN as one of the aims of increasing the efficiency and lifetime of the network to improve WSN’s commercial viability.
We will study the effect of a protocol named Stable Election Protocol (SEP) and try to make some small, innovative changes to improve this stability period.

5. PERFORMANCE MEASURES
We define here the measures we use to evaluate the performance of clustering protocols:
Stability Period: is the time interval from the start of network operation until the death of the first sensor node
Network lifetime: is the time interval from the start of operation (of the sensor network) until the death of the last alive node
Total Energy Consumption by the nodes in each round

6. PERFORMANCE MEASURES
Number of dead (total, advanced and normal) nodes per round: This instantaneous measure reflects the total number of nodes and that of each type that have not yet expended all of their energy.
Number of cluster heads per round: This instantaneous measure reflects the number of nodes which would send directly to the sink information aggregated from their cluster members.
Throughput: We measure the total rate of data sent over the network, the rate of data sent from cluster heads to the sink as well as the rate of data sent from the nodes to their cluster heads.

7. SEP
SEP is a WSN protocol that assumes heterogeneity in a network, making it the basis to prolong the stability period in a hierarchically clustered.
For Heterogeneous networks, it is assumed that each node has different energy

8. How SEP works
Nodes are treated differently based on their initial energy levels.
The nodes with lower energy are called normal nodes and assigned a weighted election probability Pnrm which is lower to Padv which is the weighted election probability assigned to the advanced nodes, i.e., the nodes with higher energy levels.

9. Cont.
This ensures that higher energy nodes have higher probability of being elected CH, thus ensuring that the energy within the network is consumed in a balanced manner thus prolonging the stability period.

10. Stochastic Threshold Algorithm
Cluster-heads can be chosen stochastically (randomly based) on this algorithm:
If n < T(n), then that node becomes a cluster-head
The algorithm is designed so that each node becomes a cluster-head at least once
 Each node uses a stochastic algorithm at each round to determine whether it will become a cluster head in this round. In the approach, advanced nodes have higher probabilities to become a cluster head in a particular round than the normal nodes. 

11. Flow chart

12. PROPOSED PROTOCOL
We have analyzed a heterogeneous sensor network environment. There two types of nodes :
Advanced node : have higher energy source
Normal nodes: less energy source
Where m is the percentage of advance and normal nodes having a times more energy than the normal nodes that are distributed randomly over the sensor field.

13. SEP Simulation on Matlab
The proposed approach has been implemented in MATLAB and the performance has been evaluated by simulation. In this work, we have measured the lifetime of the network in terms of rounds when the first sensor node dies.
Simulation Area in meter
xm=100; ym=100;
Number of Nodes in the field
100
Base Station Location
x and y Coordinates of the Sink (50,50)
Initial Energy of sensor in Joul
0.5
Optimal Election Probability of a node to become cluster head
0.1
maximum number of rounds
1000
The following set of results represent the simulation of both LEACH at 0.1 probability that is the percentage of total nodes which can become cluster head is 20% of the total number of nodes.
Table 1: Various parameters and their values

14. Simulation parameter

15. Simulation and Analysis of Results
The parameters taken into consideration while evaluating SEP are as follows:
Round Number vs Number of Dead Nodes (with variation of round number )
Round Number vs Average Energy of Each node (with variation of round number )
Round Number vs Throughput in Kbits (with variation of round number )

16. Simulation results Figure 1: 100 Node
Figure 1 is showing the WSN in active mode with active as well as with some dead nodes represented by yellow triangle . As it is SEP so all nodes represented by circles are normal nodes and nodes with circle and and all nodes represented by plus (+) are advance nodes and with star(*) are cluster heads. the blue lines which are representing the different clusters and each has its CH
Figure 1: 100 Node

17. Cont.
Figure 2: 1700 Rounds
Figure 3: 1800 Rounds

18. Cont.
Figure 4: 1900 Rounds
Figure 5: 2000 Rounds

19. Cont.
Figure 6: 1700 Rounds
Figure 4: 1800 Rounds

20. Cont.
Figure 8: 1900 Rounds
Figure 9: 2000 Rounds

21. Cont. Figure 10: number of dead normal nodes
Figure 11: number of dead advance nodes

22. Cont. Figure 12: number of cluster heads
Figure 13: Throughput in Kbits

23. Analyses of Results
In figures 2 – 13 show SEP behavior in the presence of heterogeneity
Our SEP protocol successfully extends the stable region by being aware of heterogeneity through assigning probabilities of cluster-head election weighted by the relative initial energy of nodes.
Due to extended stability, the throughput of SEP is also higher than that of current (heterogeneous- oblivious) clustering protocols.

24. Analyses of Results
Is also observed that the advanced nodes follow the death process of normal nodes, as the weighted probability of electing cluster heads causes the energy of each node to be consumed in proportion to the node’s initial energy
Furthermore, as shown in Figure 13, the throughput from cluster heads to the sink. The throughput of SEP is significantly larger than that of LEACH in the stable region and for most of the unstable region. This means that because SEP guarantees cluster heads in more rounds then these cluster heads will report to the sink.
SEP is more resilient than LEACH in judiciously consuming the extra energy of advanced nodes—SEP yields longer stability region for higher values of extra energy

25. Conclusion
From the above graphs it is clearly visible that in the simulations, the SEP is much better than LEACH, with regard to all important performance parameters, such as Total Energy Consumption, Total Data received by BS, Number of dead Nodes at simulation end, and the main focus as well as Stability Period.

26. References
G. Smaragdakis, I. Matta and A. Bestavros, “SEP: A Stable Election Protocol for Clustered Heterogeneous Wireless Sensor Networks”, Proceedings of the 8th International Workshop SAPNA, pp. 1-11, 2004
SEP Code hange/44282-sep--a-stable-election-protocol--in- wireless-sensor-network