Decentralized detection using noncoherent modulation: Is MAC that good?

In this paper we study the decentralized detection problem in wireless sensor networks when the sensors´ observations have to be communicated to a fusion center through a fading channel subject to an energy constraint. We analyze the noncoherent case based on a simple on/off scheme combined with optimal sensor ldquocensoringrdquo. Interestingly we find that neither the PAC (parallel-access channel) nor the MAC (multiple-access channel) based transmission scheme is always optimal. Our results show that in large sensor networks, for reliable observations at the sensors an optimal limited number of sensors should be queried using PAC, while for weak sensors´ observations the MAC scheme is preferrable.