Non-Orthogonal Transmission and Noncoherent Fusion of Censored Decisions

In this paper, we propose a novel signaling scheme and corresponding noncoherent fusion rules for wireless sensor networks. In the proposed scheme, sensors transmit censored decisions to the fusion center using signature vectors. To improve bandwidth efficiency the signature vector length can be chosen smaller than the number of sensors in the network resulting in non-orthogonal sensor channels. We derive the optimum noncoherent likelihood-ratio (LR) based fusion rule as well as a low-complexity energy-based fusion rule for the considered signaling scheme and Rayleigh fading. Furthermore, the performance of the energy-based fusion rule is analyzed. Numerical and simulation results show that with the proposed scheme significant improvements in bandwidth efficiency are possible at the expense of a small loss in power efficiency.