Virtual Adaptive Modulation Trunk Link in Mobile Sink assisted Wireless Sensor Networks

The introduction of Mobile Sink (MS) in Wireless Sensor Networks (WSNs) makes energy consumption in network balanced thus prolongs the lifetime of the network. In Mobile sink assisted WSNs (MWSNs), MS travels in a controlled way, with a limited time for data transmission, but the data transmission for traditional Binary Phase Shift Keying (BPSK) coding scheme in Sensor Nodes (SNs) used a longer time and lower reliability. In this paper, a novel modulation scheme in SNs based on Virtual Adaptive Modulation Trunk Link (VAMTL) is proposed to decrease the retransmission times and reduce the data transmission time in MWSNs. SNs with different modulation modes work together in a cluster, some nodes with a proper modulation scheme are selected as transmission nodes, which form a Virtual Trunk Link (VTL) to collect and forward the sensing data. Simulation results demonstrate that the introduction of VAMTL to MWSNs can reduce the transmission time. Besides, a new parameter called Network Quality Index (NQI) is proposed to measure the channel conditions and residual energy of the network. Both the shorter transmission time and lower energy consumption in a NQI message is used to prolong the lifetime of the network.