Frequency-hopping/M-ary frequency-shift keying wireless sensor networks with soft-sensing

In this contribution, a parallel triple-layer wireless sensor network (WSN) is introduced to monitor a source event (SE) with M states. For the sake of facilitating low-complexity noncoherent fusion rules, in the considered WSN, frequency-hopping (FH) and M-ary frequency-shift keying (MFSK) modulation are used to transmit signals from local sensor nodes (LSNs) to fusion center (FC). Hence, the WSN is referred to as the FH/MFSK WSN. We propose a soft-sensing and signal transmission scheme for improving the reliability of the FH/MFSK WSN. Two low-complexity noncoherent fusion rules are investigated, which are the conventional equal-gain combining (EGC) fusion rule and the proposed erasure-supported EGC (ES-EGC) fusion rule. The detection performance of the FH/MFSK WSN employing the EGC or ES-EGC fusion rule is investigated, when assuming that channels from LSNs to FC experience independent Rayleigh fading. Our studies and performance results show that using soft-sensing is able to enhance the detection performance of the FH/MFSK WSN. The ES-EGC fusion rule is robust to the errors made by LSNs and is able to achieve an enhanced performance over the EGC fusion rule, especially, when the sensing of LSNs is not very reliable.