MODLEACH: A Variant of LEACH for WSNs

1. MODLEACH: A Variant of LEACH for WSNs Prepared by: Danish Mahmood

2. Abstract • Cluster Based Routing in Wireless Sensor Networks • We divided our work into two parts • First phase: • Modification in LEACH protocol • Efficient Cluster Head Replacement scheme • Dual Transmission power levels • Second Phase • Implement soft and hard thresholds in MODLEACH • Performance analysis with respect to network stability, throughput and cluster head formation. MODLEACH: A Variant of LEACH for WSNs.

3. Introduction: Routing in Wireless Sensor Networks • Major Limitations of Wireless Sensor Networks. • Energy • Uncontrolled environment • Role of routing protocol to cope with these limitations • Minimal usage of energy is key responsibility of routing protocol running on WSN however, environment can not be controlled fully. MODLEACH: A Variant of LEACH for WSNs.

4. Cluster Based Routing (1) • In clustering, whole network is divided into fixed or variable sized clusters containing sensor nodes in it. • Each cluster is represented by a cluster head that is responsible for communication between base station/ sink and other non cluster head nodes. • Non cluster head nodes of cluster communicates only with cluster head hence minimizing energy utilization. MODLEACH: A Variant of LEACH for WSNs.

5. Cluster Based Routing (2) BS MODLEACH: A Variant of LEACH for WSNs.

6. Cluster Based Routing (3) • Here nodes are organized into clusters that communicate with a local BS (CH) and these local Base Stations transmit the data to the global BS, where it is accessed by the end user. • Reduced distance of data transmission as the local BS (CH) is typically close to all nodes in the Cluster but BS becomes energy constrained • As soon as cluster -head node dies, all nodes from that cluster effectively die since there is no way to get their data to the base station. • In Adaptive clustering, cluster heads change as nodes move in order to keep the network fully connected MODLEACH: A Variant of LEACH for WSNs.

7. Cluster Based Routing (4) • Cluster based routing has proven itself as efficient routing strategy in WSNs. • Many routing protocols are derived using clustering mechanism that gives efficient wireless sensor network. • LEACH, being the parent routing protocol receives many enhancements. MODLEACH: A Variant of LEACH for WSNs.

8. MODLEACH • To understand the proposed modifications or enhancements in LEACH, • we initially have to understand • Functionality & • operability of LEACH protocol. MODLEACH: A Variant of LEACH for WSNs.

9. LEACH Routing Protocol • LEACH (Low-Energy Adaptive Clustering Hierarchy) is a routing protocol for wireless sensor networks in which: • The base station (sink) is fixed • Sensor nodes are homogenous • LEACH conserves energy through: • Aggregation • Adaptive Clustering MODLEACH: A Variant of LEACH for WSNs.

10. LEACH Properties • Adaptive Clustering • Distributed • Randomized Rotation • Biased to balance energy loss • Heads perform compression • aggregation • In-cluster TDMA MODLEACH: A Variant of LEACH for WSNs.

11. LEACH Functioning (1) • Cluster Head and Cluster Formation: • Leach is based on adaptive Clustering. • Every node has equal chances to be a cluster head • Sensors elect themselves to be the local cluster heads at any given time with a certain probability, and broadcast their status to other sensors each sensor node choosing the cluster-head with strongest signal (can minimize transmission power) MODLEACH: A Variant of LEACH for WSNs.

12. LEACH Functioning (2) • Randomized Rotation • The high energy cluster head position rotates among the various sensors in order to not to drain the battery of a single sensor. (currently just random) • Sensors elect themselves to be the local cluster heads at any given time with a certain probability, and broadcast their status to other sensors each sensor node choosing the cluster-head with strongest signal (can minimize transmission power) MODLEACH: A Variant of LEACH for WSNs.

13. LEACH Operation • The operation is broken up into rounds • Advertisement phase • use CSMA MAC protocol, and all cluster heads transmit with same energy • Set up phase : Cluster is organized • each node transmits to which cluster head it wants to belong to using a CSMA MAC • Steady State Phase: Data Transfers to Base Station occur MODLEACH: A Variant of LEACH for WSNs.

14. Problems and their solutions • LEACH gives adaptive clustering mechanism which very efficiently deals with energy conservations. • However, Leach doesn’t take account of residual energy of a node. • To address this, a novel technique as efficient Cluster head Replacement is proposed. • LEACH use same amplification energy for both kinds of transmissions i.e. CH to BS and CM to CH. • To address this, multi amplified power levels are introduced. MODLEACH: A Variant of LEACH for WSNs.

15. Modifications in LEACH: MODLEACH (1) • For every round, protocol will check if energy of Cluster Head has fallen a defined threshold than it will undertake CH and cluster formation process. Else same CH will continue its operations. • This is how much of energy that goes wasted in cluster head formation process can be saved. Moreover, control overhead is also limitized. MODLEACH: A Variant of LEACH for WSNs.

16. Modifications in LEACH: MODLEACH (2) • In an adaptive clustering hierarchic, there can be three kinds of communications w.r.t distances. • Inter cluster communication. • Intra cluster communication. • Cluster head to base station/ sink communication. • Using equal signal amplification energy for all of above communications is also not needed. Hence multi power levels are adjusted for all three kinds of communication to preserve energy. MODLEACH: A Variant of LEACH for WSNs.

17. MODLEACH • Basically, in MODLEACH, two modifications/ enhancements are made. • These enhancements are (as discussed earlier): • Efficient cluster head replacement technique • Dual amplification power levels MODLEACH: A Variant of LEACH for WSNs.

18. LEACH Vs MODLEACH MODLEACH: A Variant of LEACH for WSNs.

19. MODLEACH withHard and Soft Threshold. • Implementation of hard and soft threshold in MODLEACH gives much better results • Reactive nature of routing protocol not only result in lower routing over head but also better network life time. • Applying thresholds in MODLEACH make the protocol reactive in nature. MODLEACH: A Variant of LEACH for WSNs.

20. Simulations Tool and Parameters • Simulations are conducted using MATLAB (R2009a) and to get precise plots, confidence interval is taken. MODLEACH: A Variant of LEACH for WSNs.

21. Simulation Results • Simulations show that MODLEACH performs better considering metrics of throughput, network life time, and optimized cluster head formation of network w.r.t LEACH. • MODLEACH is further improved by using the concept of soft and hard threshold as introduced by TEEN. MODLEACHHT further improve efficiency however, MODLEACHST performs best amongst all. MODLEACH: A Variant of LEACH for WSNs.

22. Metrics under consideration • LEACH, MODLEACH, MODLEACHHT and MODLEACHST are simulated keeping • Network life time • Throughput • Cluster head formation and scope Under consideration MODLEACH: A Variant of LEACH for WSNs.

23. Network Life Time • MODLEACHST gives maximum network life time amongst all protocols. • Reasons are: • Concept of soft threshold • Efficient cluster head replacement technique • Dual amplification power levels for inter and CH to Bs communications. MODLEACH: A Variant of LEACH for WSNs.

24. Throughput • Maximum throughput is achieved by MODLEACHST. • Comparing MODLEACH and LEACH, MODLEACH gives better throughput • increased network life time due to dual amplification power levels and better cluster head replacement scheme. • the mode of operation. • LEACH and MODLEACH both are proactive (periodical transmissions) in nature while MODLEACHHT and MODLEACHST are reactive (event driven). • This also depicts that • proactive routing protocols have lower throughput than reactive routing protocols. MODLEACH: A Variant of LEACH for WSNs.

25. Cluster head formation and scope • Figure 6 (next slide) and Figure 7 show number of cluster heads chosen at each round. • All the techniques basically used same algorithm hence no major difference is there in cluster head formation and calculation manner • However, MODLEACH differs from LEACH in a sense that initially its number of cluster heads remain stable and then cluster head formation behavior goes similar to that of LEACH. MODLEACH: A Variant of LEACH for WSNs.

26. Cluster head formation and scope • Initially as modified in LEACH, MODLEACH executes same cluster heads for next round/s if they have energy greater than defined threshold. • This is the reason of stable number of cluster heads initially. MODLEACH: A Variant of LEACH for WSNs.

27. Conclusion • In this work, we propose MODLEACH, a new variant of LEACH • The two techniques utilized in MODLEACH can further be utilized in other clustering routing protocols for better efficiency. • MODLEACH tends to minimize network energy consumption by • efficient cluster head replacement after very first round and • dual transmitting power levels for intra cluster and cluster head to base station communication. • Further, soft and hard thresholds are implemented on MODLEACH to give a comparison on performances of these protocols considering throughput and energy utilization. • In future, we will carry our work • to calculate routing load of MODLEACH, MODLEACHST and MODLEACHHT analytically • And to apply efficient cluster head replacement mechanism along with dual transmission power levels in other clustering routing protocols of wireless sensor networks to study their impact in a broader sense. MODLEACH: A Variant of LEACH for WSNs.