Browsing by Author "Karaca, HM"
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Item Throughput Optimization of Multichannel Allocation Mechanism under Interference Constraint for Hybrid Overlay/underlay Cognitive Radio Networks with Energy HarvestingKaraca, HMBy harvesting energy from ambient radio frequency (RF) signals, significant progress has been achieved in wireless networks self-maintaining their life cycles. Motivated by this and improved spectrum reuse by combined use of overlay/underlay modes of cognitive radio networks (CRNs), this paper proposes a novel multi-channel (m-channel) allocation performance maximization algorithm for low-power mobiles. CRNs, called secondary transmitters (STs), can harvest energy from RF signals by nearby active primary transmitters (PTs). In the proposed scheme, PTs and STs are distributed as independent homogeneous Poisson point processes and contact their receivers at fixed distances. Each PT contains a guard zone to protect its intended receiver from ST interference, and provides RF energy to STs located in its harvesting zone. Prioritization of STs during opportunistic allocation of channels is critical as properties like energy level and harvesting capability improve channel distribution performance. A novel metric is proposed that prioritizes STs based on initial energy levels, harvesting capability, and number of channels through which they can transmit. For comparison, three algorithms were considered: a greedy mechanism for m-channel allocation of hybrid CRNs without harvesting, the proposed m-channel allocation schemes based on maximum independent sets (MIS), and the proposed metric of hybrid CRNs with harvesting capability. The simulations show that the proposed m-channel allocation method based on MIS outperforms the greedy algorithm. The proposed m-channel allocation using the proposed metric on hybrid CRNs with energy harvesting ability produced the best performance of the three methods, proving the superiority of the proposed algorithm.Item RETRACTED: Throughput maximization of multichannel allocation mechanism under interference constraint for hybrid overlay/underlay cognitive radio networks with energy harvesting (Retracted Article)Karaca, HMBy harvesting energy from ambient radio frequency (RF) signals, significant progress has been achieved in wireless networks self-maintaining their life cycles. Motivated by this and improved spectrum reuse by combined use of overlay/underlay modes of cognitive radio networks (CRNs), this paper proposes a novel multi-channel (m-channel) allocation performance maximization algorithm for low-power mobiles. CRNs, called secondary transmitters (STs), can harvest energy from RF signals by nearby active primary transmitters (PTs). In the proposed scheme, PTs and STs are distributed as independent homogeneous Poisson point processes and contact their receivers at fixed distances. Each PT contains a guard zone to protect its intended receiver from ST interference, and provides RF energy to STs located in its harvesting zone. Prioritization of STs during opportunistic allocation of channels is critical as properties like energy level and harvesting capability improve channel distribution performance. A novel metric is proposed that prioritizes STs based on initial energy levels, harvesting capability, and number of channels through which they can transmit. For comparison, three algorithms were considered: a greedy mechanism for m-channel allocation of hybrid CRNs without harvesting, the proposed m-channel allocation schemes based on maximum independent sets (MIS), and the proposed metric of hybrid CRNs with harvesting capability. The simulations show that the proposed m-channel allocation method based on MIS outperforms the greedy algorithm. The proposed m-channel allocation using the proposed metric on hybrid CRNs with energy harvesting ability produced the best performance of the three methods, proving the superiority of the proposed algorithm.Item Age of Information Minimization for Energy Harvesting Overlay/Underlay Cognitive Radio NetworksKaraca, HMCognitive radio networks (CRNs) having energy harvesting capability have been an encouraging technology to solve the spectrum deficiency problem in wireless networks. Nevertheless, the wireless spectrum must be correctly administered to achieve the strict needs on integrity and transmission of information with minimum delay. Influenced by this, this paper takes into account the measure of the Age of information (AoI) to serve as the newness of data in the multi-channel (m-channel) allocation problem of hybrid CRNs. Here, energy can be harvested by secondary transmitters (STs) to improve channel distribution performance. Two new mechanisms have been proposed to limit average AoI values whilst assigning channels to STs by satisfying energy and collusion constraints. A new measure is proposed to assign precedence to STs, and they are permitted to utilize channels only if the resultant AoI value fulfills presented conditions. AoI levels are computed based on cochannel interference between STs and minimized by reducing interference levels. For comparison, three algorithms were studied: a greedy mechanism for m-channel allocation of hybrid CRNs without AoI control, and the presented m-channel distribution schemes based on ranking STs according to the presented measure and limiting AoI levels based on cochannel interference. The simulations highlight that the performance of the presented m-channel allocation schemes outweighs the greedy scheme in terms of both AoI minimization and maximization of channel allocation performance which demonstrates the primacy of the proposed algorithms.