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The ever increasing demand for communication bandwidth and inefficient usage of the existing spectrum has led to spectrum scarcity. In this light, spectrum should be managed as a scare resource. For radio communication systems, efficient utilization of spectrum is the key requirement. The inefficient usage of the existing spectrum can be improved through opportunistic access to the licensed bands...
In a dynamic access network, multiple secondary users access and share channels that are not used by the primary users. Uncoordinated and random channel access by the secondary users access leads to decreased secondary network throughput as users in the close proximity interfere with each other. In order to better utilize the channels, we propose a scheduling technique that assigns unique time slots...
In this paper, we consider an opportunistic beamforming scheduling scheme of secondary users (SUs) which can share the spectrum with a primary user (PU) in an underlay cognitive radio network. In the scheduling process, the cognitive base station (CBS) having multi-antennas, generates orthogonal beams which insure the minimum interference to the PU. Then, each SU feeds back its maximum signal to interference...
In this paper we consider the problem of increasing the throughput of cognitive radio in a cognitive radio network by forming coalitions among cognitive radio users. Recently there have been numerous studies exploring the benefits of the cooperation in a cognitive radio network. The cooperation tends to increase the spectrum sensing performance which in turn results in increased transmission opportunities...
In recent years, as a demand for communication services over the VANET (Vehicle Ad-hoc Network) is increasing drastically, radio frequencies to be assigned to the new communication services are becoming insufficient. In response to this problem, we consider to apply the cognitive radio technology in general, and the cognitive use of TV white space based on the white space database (WSDB) in particular,...
In this paper we propose a spectrum aggregation-based cooperative routing protocol, termed as SACRP, for CRAHNs. The primary objective of SACRP is to improve throughput and reduce end-to-end delay for CRAHNs. In this regard, we design the Media access control (MAC) and Physical (PHY) layer, and propose different spectrum aggregation algorithms for cognitive radio (CR) users. We propose two different...
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...
In this paper, the throughput performance of a hybrid Multiple-Input-Multiple-Output (MIMO) interweave/underlay Cognitive Radio (CR) system is examined on an analytical basis. Specifically, hybrid CR systems that switch between an interweave and an underlay transmission strategy, based upon spectrum sensing measurements, are investigated. For the first time the performance of such a hybrid CR system...
In this paper, we investigate the optimal spectrum leasing and sharing for dynamic spectrum access (DSA) network which actively shares its spectrum resource with a group of secondary users (SUs) for reaping revenue. The DSA aims at maximizing its total charge to the SUs based on their achieved throughput, while taking into account the additional power consumption of the primary user (PU) to overcome...
This paper presents an energy aware cluster based architecture where trust aware model is used to improve energy efficiency and spectrum handoff framework is used to reduce handoff rate and thereby improve throughput. The main objectives are trustworthy node selection, cluster head detection, transmission power reduction and increasing successful data transmission by performing handoff. A set of cognitive...
With the broadening followers of wireless communication technology current technology for radio or wireless network is required to be enhanced in terms of managing the present provided resources. There is a committing encouraging technology that can enhance the usage of wireless spectrum. The basic approach for this is to combine hardware as well as software framework to built a architecture that...
Cognitive radio is one way to overcome the limitations of the frequency spectrum. Cognitive radio users can utilize the frequency spectrum that is not being used (white space) by detect the frequency spectrum. Spectrum sensing is done periodically to ensure there is no interference, in that sense spectrum sensing activity in cognitive radio will increase energy consumption. Therefore, energy efficiency...
Machine learning based link optimization of wireless communications often relies on past experience, accurate estimation of channel conditions, and theoretical performance models. Typically, theoretical models poorly match given situations, past experiences are limited, and spectrum sensing of noise and channel conditions pose many hurdles. Hence, traditional cognitive radio engines based on genetic...
In the current scenario Cognitive Radio (CR) is the best available solution to overcome spectrum shortage problem. Cognitive Radio Ad Hoc Networks (CRAHNs) is the use of CR technology in the wireless ad-hoc network scenario. The field of CRAHNs is still in this nascent stage therefore not much work has been done related to security issues associated with these types of networks. In order to provide...
Cognitive radio networks (CRNs) have become a popular research topic in recent years. Most existing CRN routing schemes focus on building a route that optimizes a single aspect of a network's performance, such as minimizing interference for primary users, or reducing the propagation delay or hop count. They do not consider the overall transmission performance for secondary users. In this work, our...
Unlike the static spectrum policy, spectrum sharing uses dynamic spectrum access techniques in order to utilize the spectrum efficiently. The main objective of this work is to maximize the sum throughput for the allowed secondary links that can coexist peacefully with primary links in a cognitive radio network. A binary particle swarm optimization (BPSO) is applied to solve this cognitive radio optimization...
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...
The cognitive radios (CR) utilize the spectrum resource without interfering the primary users (PU). Spectrum sensing, by which CR users detects the radio environment, is a critical technique in cognitive radios. Various collaborative spectrum sensing schemes are proposed to either improve sensing sensitivity or to reduce the sensing duration. However, most of the previous studies have not investigated...
Asynchronous iterative water filling (AIWF), which is based on Shannon Theory, distributes resources fairly among users. Unlike Game Theory that requires users to exchange packets, AIWF does not require users to exchange packets for achieving Nash equilibrium. Conventionally, AIWF computes optimal transmit power for multiple users in Gaussian Wireless Channel. In this paper, AIWF was implemented upon...
Spectrum access by an unlicensed secondary user (SU) in a cognitive radio network (CRN) is challenging due to the dynamic nature of spectrum availability and possibility of collisions with the primary user (PU). SU uses a scheme where SU's packets are interleaved with periodic sensing to detect PU's return. To utilize spectrum efficiently, this paper proposes an opportunistic spectrum approach with...
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