Reliability Measurement Based Transmission Scheme for Wireless Sensor Network

In wireless sensor networks (WSNs), life time and energy efficiency have been considered as long-lasting technical challenges as sensor nodes usually suffer from rigorous energy constraints. Data transmission consumes substantial sensor's power, however, this precious energy is wasted to transmit erroneous or low-reliable local decisions occasionally. In this paper, we study a sample and efficient transmission scheme to improve the energy efficiency of triple-layer WSNs scenarios. A number of local sensors are employed to monitor single source event with multiple possible states. In particular, each of the local sensors calculates the probabilities (soft information) for all the possible states. All the calculated possibilities are ordered, and the the ratio of the largest one to the second largest one is expressed as λ. Then, the value of λ is compared with the pre-set transmission threshold λT. If and only if λ > λT, the corresponding sensor node will send its local decision to the fusion center (FC), otherwise, it will keep silent. The local decisions are transmitted to the FC using M-Ary phase-shift keying (MPSK) modulation through Rayleigh fading channels. At the FC, final decision is made via select combining (SC) principle. This novel reliability measurement based transmission scheme has two major advantages. 1) It improves the overall energy efficiency of WSN system significantly. 2) Better overall detection performance is achievable when reasonable value of the threshold λT is set.