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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...
An experimental evaluation of an LTE Cognitive Radio (CR) Network, implemented using highly integrated Software Defined Radio (SDR) platform is presented. Each transceiver can be configured as a primary (resp. secondary) eNodeB or a primary (resp. secondary) user in this framework. We propose simple distributed algorithms which the secondary eNodeB can employ to efficiently manage the spectral opportunities...
As the wireless networks has the capability toharvest RF signal's energy and therefore can be referred as selfsustained networks. Wireless networks can act as self-sustaining byharvesting the energy from RF signals (radio frequency). In recenttime, researchers have developed efficient circuitries &components for harvesting the RF energy for low powered wirelesselements. By its support, and based...
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...
The two major concerns of the wireless communication system are throughput of the network and underutilization of wireless channels. Opportunistic routing (OR) aims at improving the former and coping with the latter. Due to the unreliable characteristics of such channels, traditional routing achieves poor throughput. Since traditional routing arbitrarily selects high lossy links among diverse paths...
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...
Cognitive Radio (CR) [4] has a capacity to dynamically utilize the unused spectrum because of the advances in electronics and government policies. Dynamic spectrum access (DSA) [9] is the technique to utilize the free spectrum and release the current spectrum if the original user (incumbents) arises on that spectrum within channel move time. This paper analyzed the DSA characteristics in IEEE 802...
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...
Cognitive radio now-a-days has opened a new horizon for researchers to mitigate the up-growing demand for RF spectrum within our limited resources. The threshold plays very important role for sensing process in energy based detectors as it is widely used in CR network due to its fast performance and ability to perform without any prior knowledge or information. Conventional energy detectors has fixed...
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...
In this paper, we develop an energy cooperation scheme for secondary users' (SU) spectrum access in the hybrid energy supply primary system, which will improve both energy efficiency and spectral efficiency. Specifically, the cooperation is implemented into two stages. In the first stage, the secondary system is allowed to access the licensed for secondary transmission. Simultaneously, the primary...
The paper considers an underlay cognitive radio model, which includes multiple primary and secondary users. Under the interference limitations imposed for the conservation of a high quality of service (QOS) for the primary users, this work aims to enhance the throughput of the secondary users. A joint optimization of secondary to primary user assignment and the power allocation at the secondary user's...
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...
The integration of cognitive radios and wireless sensor networks enables a new paradigm of communication in which, sensor nodes can avoid heavily crowded transmission bands by tuning their transmission parameters to less crowded bands thanks to the cognitive radio capabilities. In such setting, sensor nodes act as a secondary user, opportunistically accessing vacant channels within a band originally...
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...
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