الفهرس 
CHAPTER 1:INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Wireless Sensor Networks (WSNs) have a lot of various and important
applications. In most applications, sensor nodes have limited and non-rechargeable energy resources, such as applications with sensor nodes deployed in remote and inaccessible areas. Designing WSNs faces a lot of challenges; the most important one
is the energy conservation. Clustering is one way used to reduce energy consumption in WSNs.
In this thesis, Multi level Hierarchical Clustering (MLHC-m) algorithm is introduced, which is a new routing protocol that reduces the energy consumption in homogeneous
and heterogeneous WSNs. MLHC-m employs clustering of WSNs more than one time
every round. After the first clustering takes place, the heads of the clusters form a higher level of clustering with each other. This process is repeated form m times until reach the level m of clustering. The heads of the last level of clusters can communicate directly with the Base Station. As the number of nodes in the network increases we should use higher clustering levels .
In the first part of this thesis, MLHC-2 is introduced, which applies only two levels of clustering. The cluster heads of the first level is chosen based on the residual energy of sensor nodes. The second level cluster heads are chosen based on the residual
energy and the distance to the base station .
In the second part, MLHC-3, which applies three levels of clustering and MLHC-4, which applies four levels of clustering are introduced. The cluster heads of the higher levels are chosen in such away to conserve energy.
Simulations show that MLHC reduces energy dissipation and prolongs the life time of the overall network compared with other existing protocols. Also MLHC increases the
stability region (time from the starting of the network until the death of first node).
Keywords Wireless sensor networks, hierarchal clustering, stability period, network life time,
LEACH protocol.