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In the non-time-slotted cognitive radio networks (CRNs), the synchronization between PUs and secondary users (SUs) cannot be guaranteed, resulting in two challenging problems: the reactivation-failure of PUs and the frequently unexpected hand-offs among SUs. The reactivation-failure of PUs is the incident that the SUs cannot detect the PUs' reactivation when the SUs are occupying the channels to transmit...
Cognitive radio sensor network (CRSN) is a novel wireless sensor network, which can effectively alleviate the scarcity of spectrum resource by equipping the cognitive technology. Usually, CRSN deploys numerous sensor nodes around the monitoring area. But the energy and storage of those nodes are both limited. Compared with the centralized CRSN, we focus more on a decentralized situation without the...
In this paper we consider distributed cognitive radio networks (CRNs) with channel aggregation (CA) scheme where there are multiple wireless channels and multiple secondary users (SUs). SUs in CRNs with CA can transmit bits of data through more than one idle channels which are not used by primary users (PUs). SUs decide whether to access idle channels or not based on the access probability (AP), and...
One important issue associated with spectrum management in heterogeneous cognitive radio network is: how to appropriately allocate the spectrum to the secondary senderdestination (S-D) pair for sensing and utilization. In this work, the authors investigate the spectrum allocation problem under a more practical scenario, taking the heterogeneous characteristics of both secondary S-D and PU channels...
With the growing demand for wireless applications, there is an incalculable rise in bandwidth consumption that in turn leads to the spectrum scarcity. The conflict between spectrum underutilization and spectrum scarcity is solved by a well-known technology called Cognitive Radio (CR). The main aim of CR is to exploit unutilized spectrum of licensed users/Primary Users (PUs) and enable opportunistic...
Conventional cooperative spectrum sensing (CSS) schemes in cognitive radio networks (CRNs) require that the secondary users (SUs) report their sensing data sequentially to the fusion center, which yields long reporting delay especially in the case of large number of cooperative SUs. By exploiting the computation over multiple-access channel (CoMAC) method, this paper proposes a novel CoMAC-based CSS...
Spectrum sensing is used to detect spectrum holes and find active primary users, while randomly selecting channel for sensing leads to secondary user's lower throughput in high traffic cognitive radio networks. Spectrum prediction forecasts future channel states on the basis of historical information. A new frame structure is proposed in this paper for the imperfect spectrum prediction, improving...
Energy management is an acute challenge for battery powered devices. In this work, we consider a cognitive radio (CR) equipped with energy harvested finite capacity battery. The cognitive radio harvests energy from radio frequency (RF) source (primary channel) as well as from non-RF sources (ambient sources such as wind, solar, and vibration). Energy harvesting from the primary channel occurs only...
Cognitive radio is proposed as an efficient way to address the issue of spectrum shortage and under- utilization, in which cooperative spectrum sensing (CSS) is used to enhance the sensing performance. One of the most fundamental problems of CSS is: how to appropriately assign the secondary users (SUs) to sense the primary user (PU) channels? In this paper, We study the CSS problem under a more practical...
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...
Dynamic spectrum access in the form of cognitive radio (CR) has gained traction in wireless sensor networks (WSN) because of a) scarcity caused by the proliferation of wireless devices and service and b) it provides spectrum efficient communication for the resource constrained WSNs. However, proper means have to be devised to satisfy the requirements of both WSNs and CRs and to enjoy the benefits...
Dynamic spectrum access in the form of cognitive radio (CR) has gained traction in wireless sensor networks (WSN) because of a) scarcity caused by the proliferation of wireless devices and service and b) it provides spectrum efficient communication for the resource constrained WSNs. However, proper means have to be devised to satisfy the requirements of both WSNs and CRs and to enjoy the benefits...
In recent years, with the rapid growth in wireless communication applications, issues in energy consumption has been increasingly critical, especially in cognitive radio (CR) systems with the exclusive functionality of spectrum sensing. In this paper, we consider a self-powered cognitive radio system, in which the SU has no fixed power supplies (e.g. batteries) and is powered by an energy harvester...
This paper proposes a new adaptive spectrum handoff scheme where sensor nodes opportunistically use licensed channels as long as its transmission does not cause interference with primary receivers (PRs) in cognitive radio-based industrial wireless sensor networks (CR-IWSNs). We incorporate proactive spectrum sensing into the proposed spectrum handoff scheme to reduce the number of spectrum handoff...
In this paper, we consider a CR system operating in slotted mode, in which the SU has no fixed power supplies and extract energy only via wireless energy harvesting from ambient radio signal. It is assumed that the SU operates in a saving-sensing-transmitting (SST) fashion, which partitions a timeslot into non-overlapping fractions for the three operations. Considering the tradeoff between durations...
In a cognitive radio network, cooperative spectrum sensing can improve the accuracy of spectrum sensing and alleviate the hidden terminal problem. Cooperative spectrum sensing frame has three phases: sensing phase, cooperation phase and transmission phase. In this paper, we investigate the problem of designing the power and number of cooperative node (CN) in the cooperation phase to maximize the average...
In the current literature on cognitive radio, it is commonly assumed that fixed time durations are assigned for spectrum sensing and data transmission. It is however possible to improve the performance by finding the best tradeoff between sensing time and network throughput. In this paper, we formulate the sensing-throughput problem to dynamically assign a number of SUs for cooperatively sensing each...
As Cognitive Radio (CR) technology is recently emerged as a potential solution to overcome the problem of spectrum scarcity, Cognitive Wireless Mesh Networks (CogMesh) have great potential for enhancing the performance of wireless networks and meeting the demands of future generation wireless applications. By utilizing the available frequency bands that are unutilized by primary (licensed) users,...
With the growing number of wireless network standards operating in the unlicensed frequency band and the military moving toward commercial off the shelf technology, the next generation of wireless sensor networks must be robust against unintentional and hostile interference. One method that has gained interest to cope with the increased spectrum use and to combat the interference vulnerability in...
This paper investigates an optimal mode selection policy for cognitive radio sensor networks powered by RF energy harvesting. The RF energy harvesting enables the sensor node to operate with a potentially perpetual lifetime. We assume that the sensor node harvests RF energy received from the primary network and it cannot carry out RF energy harvesting and opportunistic spectrum access at the same...
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