A new scheme for maximizing the lifetime of heterogeneous wireless   sensor networks
  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. 
Reem Aldaihani and Hosam AboElFotoh
cs.NI