  Heterogeneous wireless sensor network consists of wireless sensor nodes with
different abilities, such as different computing power and different initial
energy. We present in this paper a new scheme for maximizing heterogeneous WSN
lifetime. The proposed scheme employs two types of sensor nodes that are named
(consistent with IEEE 802.15.4 standard) Full Function Device (FFD) and Reduced
Function Device (RFD). The FFDs are the expensive sensor nodes with high power
and computational capabilities compared to the RFDs which are cheap sensors
with a limited power supply. The scheme divides the network into smaller
sub-networks (regions) that are built from sectors and tracks. The objective of
this research is to balance and reduce the communication load on RFDs, reduce
the delay, and increase the connectivity and lifetime, by using a limited
number of FFDs. We investigate the performance of our scheme via numerical
simulation and compare it to other related schemes that are presented for
homogeneous WSNs with chain topology, such as Pegasis, Epegasis and Chiron. In
addition to extending the lifetime, our scheme also results in reducing the
data transmission delay compared to the related schemes. Furthermore, the
scheme increases the network security and reduces the RFDs power consumption by
preventing the direct communication with the base station (BS). The FFD is the
communication bridge between RFDs and BS. The FFD communicate with the BS using
the one-hop approach or multi-hop approach through other FFDs.
