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OTICOR: Opportunistic Time Slot Assignment in Cognitive Radio Sensor Networks

Current Wireless Sensor Networks (WSNs) are deployed over unlicensed frequency bands that face an increased level of interference from various wireless systems. Cognitive Radio Sensor Networks (CRSNs) overcome this problem by allowing sensor nodes to access new spectrum bands to minimize interferences. In this paper, we focus on the MultiChannel Time Slot Assignment problem (MC-TSA) in CRSNs. Each sensor node is assigned the number of time slots it needs to transfer its own data as well as the data received from its children in the rooting tree rooted at the sink without interfering with other secondary users. Besides, sensor nodes cannot transmit on a channel occupied by a primary user. Our objective is to increase the network throughput offered to sensor nodes. We start by formulating the MC-TSA problem as an Integer Linear Program where the goal is to minimize the number of slots in the schedule. We then propose an Opportunistic centralized TIme slot assignment in Cognitive Radio sensor networks (OTICOR). We evaluate its performance in terms of number of slots and throughput.