  Energy conservation of sensor nodes for increasing the network life is the
most crucial design goal while developing efficient routing protocol for
wireless sensor networks. Recent technological advances help in the development
of wide variety of sensor nodes. Heterogeneity takes the advantage of different
types of sensor nodes and improves the energy efficiency and network life.
Generally sensors are deployed randomly and densely in a sensing region so
short distance multihop communication reduces the long distance transmission in
the sensor network. In this research paper MEEP (multihop energy efficient
protocol for heterogeneous sensor network) is proposed. The proposed protocol
combines the idea of clustering and multihop communication. Heterogeneity is
created in the network by using some nodes of high energy. Low energy nodes use
a residual energy based scheme to become a cluster head. High energy nodes act
as the relay nodes for low energy cluster head when they are not performing the
duty of a cluster head to save their energy further. Protocol also suggests a
sleep state for nodes in the cluster formation process for saving energy and
increasing the life of sensor network. Simulation result shows that the
proposed scheme is better than other two level heterogeneous sensor network
protocol like SEP in energy efficiency and network life.
