This protocol ensures that every sensor node in the network has the same probability
to be selected as a clusterhead, thus evenly distributing energy load to all nodes.
Therefore it can increase the network life time compared with conventional routing
protocols.
Fig. 2. Cluster formation for 60 nodes network with 5% nodes as clusterheads, which creates
three clusters in the network. Nodes within one cluster only communicate with their clusterhead.
In LEACH, nodes have the capability to adjust their transmission power such that
they can use low transmission power to communicate with their neighbors, and use
high transmission power to send packets directly to the sink. If all nodes send packets
to the sink directly, nodes will die out very soon, especially for those nodes that
are far away from the sink. If nodes use the minimum transmission energy (MTE)
routing protocol [4] to forward packets to their closest neighbor, nodes closer to the
sink will handle more traffic than nodes farther away from the sink, and therefore will
336 Kai-Wei Fan, Sha Liu, and Prasun Sinha
deplete their energy quicker. LEACH eliminates these problems by selecting some
nodes, which are the clusterheads, to send packets to the sink directly, and let other
nodes only send packets to the clusterheads. However, if the clusterheads are fixed,
they will consume more energy than other nodes and die quickly because they have
to participate in all communications.
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