Abstract
A data-dependent sensor MAC protocol and a cross-layered fusion rule that exploits MAC timing information are proposed for distributed detection in sensor networks. In this system, each sensor first makes a local decision at the beginning of each observation period and transmits the decision to the fusion over a random access channel. Based on the slotted ALOHA random access protocol, we derive a transmission control function that assigns transmission probabilities to each sensor based on the reliability of its local decisions. By doing so, the packet arrival time at the fusion center may embed soft information regarding the sensors' observations and may be exploited to reduce the error probability at the fusion center. We then extend the proposed strategies to the multi-cluster scenario where the sensors' local decisions are transmitted to the fusion center in a two-hop fashion. More specifically, the sensors first send their local decisions to their respective cluster-heads, where a local fusion is performed, and the resulting decision is then forwarded to the fusion center. We show, through numerical simulations, that the proposed schemes outperform those without cross-layered transmission and fusion strategies.