A Two-Level Cluster-Based Cognitive Radio Sensor Network: System Architecture, Hardware Design, and Distributed Protocols

In this paper, we present an integrated hardware design and software implementation for a cognitive-radio wireless sensor network (CR-WSN). The implemented CR-WSN is an event-driven cluster-based network, where the sensor nodes in the network are organized into a two-level hierarchy of clusters, each with its own cognitive-enabled cluster-head (CR-CH). According to CR-WSN, the sensed data by a sensor node is reported to the associated CR-CH. The CR-CH opportunistically transmits the collected information over one of the idle primary radio channels to the data collecting node (sink). Specifically, we first describe the hardware design and implementation of the CRWSN. Then, we propose a novel hybrid MAC design for the CR-WSN that ensures reliable and timely data delivery. The proposed protocol divides the MAC-layer operation into two domains: single-channel intra-cluster and cognitive inter-cluster domains. Experimental results are provided, which verify the effectiveness of the proposed MAC protocol and demonstrate a reliable, robust and scalable performance of the proposed system.