MODLEACH A Variant of LEACH for WSNs Prepared

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

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. 2

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. 3

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. 4

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

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. 6

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. 7

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. 8

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. 9

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. 10

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. 11

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. 12

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. 13

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. 14

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. 15

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. 16

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. 17

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

MODLEACH with Hard 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. 19

Simulations Tool and Parameters • Simulations are conducted using MATLAB (R 2009 a) and to get precise plots, confidence interval is taken. MODLEACH: A Variant of LEACH for WSNs. 20

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. 21

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

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. 23

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. 24

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. 25

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. 26

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. 27