  Wireless sensor network consists of large number of inexpensive tiny sensors
which are connected with low power wireless communications. Most of the routing
and data dissemination protocols of WSN assume a homogeneous network
architecture, in which all sensors have the same capabilities in terms of
battery power, communication, sensing, storage, and processing. However the
continued advances in miniaturization of processors and low-power
communications have enabled the development of a wide variety of nodes. When
more than one type of node is integrated into a WSN, it is called
heterogeneous. Multihop short distance communication is an important scheme to
reduce the energy consumption in a sensor network because nodes are densely
deployed in a WSN. In this paper M-EECDA (Multihop Energy Efficient Clustering
& Data Aggregation Protocol for Heterogeneous WSN) is proposed and analyzed.
The protocol combines the idea of multihop communications and clustering for
achieving the best performance in terms of network life and energy consumption.
M-EECDA introduces a sleep state and three tier architecture for some cluster
heads to save energy of the network. M-EECDA consists of three types of sensor
nodes: normal, advance and super. To become cluster head in a round normal
nodes use residual energy based scheme. Advance and super nodes further act as
relay node to reduce the transmission load of a normal node cluster head when
they are not cluster heads in a round.
