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.

'''Low Energy Adaptive Clustering Hierarchy ("LEACH")''' is a [[routing protocol]] in [[wireless sensor network]]s (WSNs).

==Protocol ==

The goal of LEACH is to provide data aggregation for sensor networks while providing energy efficient communication that does not predictably deplete some nodes more than others.

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 [[algorithmstochastic]] 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.

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. Each node uses a stochastic [[algorithm]] at each round to determine whether it will become a cluster head in this round.

NodesAll nodes that haveare beennot cluster heads cannotonly becomecommunicate cluster heads again for ''P'' rounds, where ''P'' iswith the desiredcluster percentagehead ofin cluster heads.a TDMA Thereafterfashion, eachaccording nodeto hasthe aschedule 1/''P''created probabilityby of becoming athe cluster head. in eachThey round.do so Atusing the endminimum ofenergy eachneeded round,to each node that is not a cluster head selectsreach the closest cluster head, and joinsonly thatneed cluster.to keep Thetheir clusterradios headon then creates a schedule for each node in its cluster toduring transmittheir itstime dataslot.

LEACH also uses [[Codecode Divisiondivision Multiplemultiple Accessaccess|CDMA]] so that each cluster uses a different set of CDMA codes, to minimize interference between clusters.

All nodes that are not cluster heads only communicate with the cluster head in a [[Time Division Multiple Access|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

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

*Communication done with cluster head via TDMA

*Cluster membership adaptive

*Data aggregation at cluster head

*Cluster head communicate directly with sink or user

*Communication done with cluster head via TDMA

*TDMA within clusters

*Threshold value

*CDMA across clusters

== 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>

== External LinksReferences ==

{{reflist}}

[[Category:Wireless sensor network]]

* [http://nms.csail.mit.edu/projects/leach/ A brief description of LEACH and SPIN]

[[Category:Cluster analysis algorithms]]

* [http://wind.lcs.mit.edu/papers/leach-hicss.ps The original LEACH paper] (postscript) presented at the [[Hawaii International Conference on System Sciences]], 2000.