Low-energy adaptive clustering hierarchy: Difference between revisions

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'''Low-energy adaptive clustering hierarchy ("LEACH")'''<ref>[[Wendi Rabiner Heinzelman|Heinzelman, W.]], Chandrakasan, A., and Balakrishnan, H., "Energy-Efficient Communication Protocols for Wireless Microsensor Networks", Proceedings of the 33rd Hawaaian International Conference on Systems Science (HICSS), January 2000. [http://pdos.csail.mit.edu/decouto/papers/heinzelman00.pdf Paper]</ref> is a [[Time division multiple access|TDMA]]-based [[Media access control|MAC]] protocol which is integrated with clustering and a simple routing protocol in [[wireless sensor network]]s (WSNs). The goal of LEACH is to lower the energy consumption required to create and maintain clusters in order to improve the life time of a wireless sensor network.

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Low Energy Adaptive Clustering Hierarchy(LEACH) is a routing protocol in wireless sensor network(WSN).It is an hierachical protocol. Stochastic Cluster head selection algorithm is used in this protocol. LEACH

• Cluster based approach

• Random cluster head selection each round with rotation

• Communication done with cluster head via TDMA

communicating with non cluster nodes)

• Cluster membership adaptive

• Data aggregation is done at cluster head

• Cluster head communicate directly with sink or user

Based on the model the following can be said about

- The sources and users are stationary and events monitored

- The interest propagation is predetermined

- Data dissemination mechanism is broadcasting

==Protocol ==

Together, these features allow LEACH to achieve the desired properties. Initial simulations show that LEACH is an energy-efficient protocol that extends system lifetime.

LEACH is a hierarchical protocol in which most nodes transmit to cluster heads, and the cluster heads aggregate and compress the data and forward it to the base station (sink). Each node uses a [[stochastic]] algorithm at each round to determine whether it will become a cluster head in this round. LEACH assumes that each node has a radio powerful enough to directly reach the base station or the nearest cluster head, but that using this radio at full power all the time would waste energy.

Nodes that have been cluster heads cannot become cluster heads again for ''P'' rounds, where ''P'' is the desired percentage of cluster heads. Thereafter, each node has a 1/''P'' probability of becoming a cluster head again. At the end of each round, each node that is not a cluster head selects the closest cluster head and joins that cluster. The cluster head then creates a schedule for each node in its cluster to transmit its data.

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. Communication protocols, which can have significant impact on the overall energy dissipation of these networks. It has been found that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, because of this reason LEACH (Low Energy Adaptive Clustering Hierarchy) has been proposed which is a clustering-based protocol that utilizes randomized rotation of local cluster base stations (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show that LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional routing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.

All nodes that are not cluster heads only communicate with the cluster head in a TDMA fashion, according to the schedule created by the cluster head. They do so using the minimum energy needed to reach the cluster head, and only need to keep their radios on during their time slot.

LEACH also uses [[code division multiple access|CDMA]] so that each cluster uses a different set of CDMA codes, to minimize interference between clusters.

==Properties==

Properties of this algorithm include:

• *Cluster based approach

• *Random cluster head selection each round with rotation. Or cluster head selection based on sensor having highest energy

• *Cluster membership adaptive

• *Data aggregation is done at cluster head

• *Cluster head communicate directly with sink or user

• *Communication done with cluster head via TDMA

*Threshold value

== Shortcomings of LEACH ==

Shortcomings of LEACH include:<ref>{{Cite book|last1=Varshney|first1=Shweta|last2=Kuma|first2=Rakesh|title=2018 8th International Conference on Cloud Computing, Data Science & Engineering (Confluence) |chapter=Variants of LEACH Routing Protocol in WSN: A Comparative Analysis |date=2018|language=en-US|publisher=IEEE|pages=199–204|doi=10.1109/confluence.2018.8442643|isbn=9781538617199|s2cid=52125657 }}</ref>

* Remaining energy among the nodes isn't considered when selecting Cluster Heads

* Random and variable size cluster formations

* Random and uneven distribution of cluster heads

* Single hop communication in situations where energy use is less efficient from cluster head to base station

* Multi-clustering might not be required at some point and, at some point, number of optimum clusters could be as high as N (number of live nodes in the network)<ref>{{Cite journal |last1=Roy |first1=Nihar Ranjan |last2=Chandra |first2=Pravin |date=2018 |title=A Note on Optimum Cluster Estimation in LEACH Protocol |journal=IEEE Access |volume=6 |pages=65690–65696 |doi=10.1109/ACCESS.2018.2877704 |s2cid=53779139 |issn=2169-3536|doi-access=free |bibcode=2018IEEEA...665690R }}</ref>

== References ==

{{reflist}}

[[Category:Wireless sensor network]]

[[Category:Cluster analysis algorithms]]