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Cognitive networks are proposed in the framework of evolution of network architectures as novel paradigms to provide autonomous in-network reasoning to support end-to-end goals. While several approaches are available that propose different approaches, still the problem of reasoning represents a challenging issue. The paper aims at proposing a mathematical model, based on fuzzy cognitive maps, to support...
In this paper we address the problem of resource allocation in the context of cognitive radio networks (CRN). With the deployment of K antennas at the cognitive base station (CBS), an efficient transmit beamforming technique combined with user selection is proposed to maximize the uplink throughput and satisfy the signal-to-noise and interference ratio (SNIR) constraint, as well as to limit interference...
In future wireless networks, the users will have the capability to access to multiple networks via multi-mode terminal. There is a need to have mechanism in place to decide which radio access network is the most suitable for the user and for the services that the user requires. To address these issues, we propose an access system(AS) selection algorithm, based on a combination of multi-attribute utility...
In most existing channel decision mechanisms for cognitive radio (CR), it is assumed that instantaneous channel state information (CSI) and primary user (PU) activity information is available. However, in many CR network applications, frequent channel sensing and estimation could introduce excessive overhead and reduce system throughput. Channel sensing by secondary users (SUs) may also not be completely...
Cognitive radio(CR) is a potential technology for efficient utilization of under-utilized spectrum via spectrum sensing. CR users should move from current allocating channel to empty channel to avoid the interference to the primary user if the primary user is allocated that channel. Thus, CR system cannot support the CR user's QoS(quality of service). In this paper, we propose a dynamic frequency...
Cognitive radio is presently being researched as a means to greatly improve spectrum usage efficiency, connectivity and QoS among wireless devices and systems. In parallel, efficient and fair resource allocation strategies are being studied in order to address the requirements of future wireless technologies. In this paper, we assess a novel resource allocation scheme for OFDM systems which aims to...
In this paper, we study the sensing-throughput tradeoff problem for a multiple-channel cognitive radio (CR) network. In particular, using the sensing-throughput tradeoff metric, we investigate the design of the optimal spectrum sensing time and power allocation schemes so as to maximize the aggregate ergodic throughput of the cognitive radio network to guarantee the quality of service (QoS) of the...
This paper presents a customizable framework for employing Cognitive Radio in Intermittently Connected Wireless Networks, which aims to maximize transmission opportunities that arise when fully connected network partitions are formed. Various layer 3 routing and information dissemination protocols would benefit from increased opportunity utility. We propose to use Cognitive Radio to permit multiple...
Cognitive wireless mesh networks have great flexibility to improve the spectrum utilization by opportunistically accessing the authorized frequency bands, within which the secondary users (SUs) should not violate the quality of service (QoS) requirement of the primary users (PUs) while transmitting. In this paper, we consider inter-cluster connection among neighboring clusters under the framework...
In recent years, cognitive radio has received a great attention due to tremendous potential to improve the utilization of the radio spectrum by efficiently reusing and sharing the licensed spectrum bands, as long as the interference power inflicted on the primary users of the band remains below a predefined threshold level. It allows the secondary user in the cognitive radio network to access the...
The paper investigates on fairness of utilities between uplink and downlink traffic flows in IEEE 802.11 Wireless Local Area Networks (WLAN) with an infrastructure mode. We propose a cognitive resource allocation scheme to tackle the fairness problem. The proposed scheme is cognitive by using neural networks to on-line learn the nonlinear function between the adopted Medium Access Control (MAC) parameters...
IEEE 802.22 is the first wireless standard based on cognitive radio (CR) technology. It defines the air interface for a wireless regional area network (WRAN) that uses fallow segments of the TV broadcast bands. CR technology enables unlicensed users in WRANs to utilize licensed (incumbent) spectrum bands on a non-interference basis to incumbent users. The coexistence between incumbent users and unlicensed...
Dynamic Spectrum Access (DSA) MAC protocols allow a Cognitive Radio (CR) device to opportunistically access unused or less crowded spectrum while ensuring protection for the incumbents. Though DSA shows great potential to enhance spectrum efficiency, the associated constraints on QoS may limit its usefulness. QoS support in a DSA-based network is not trivial due to the fact that in addition to unfavorable...
We study a cognitive radio system in which the spectrum handover technique is applied by secondary users when they have to vacate a channel due to a primary user arrival. In order to limit the forced termination probability of secondary users a fractional guard channel reservation scheme is applied to give priority to spectrum handovers over new arrivals. We show that, contrary to what has been suggested,...
This paper presents a novel distributed framework to decide the spectrum assignment in a primary cellular radio access network. The distributed nature of the framework allows each cell to autonomously decide (by means of machine learning procedures) the best frequencies to use in order to maximize spectral efficiency, preserve quality-of-service, and generate spectrum gaps, so that secondary cognitive...
As advanced integrated network architecture, ldquocognitive radio technologies,rdquo which aim to improve the spectrum efficiency, have been studied. In the cognitive radio networks, each node recognizes radio conditions, and according to them, optimizes their wireless communication routes with the integration of the heterogeneous wireless systems not only by switching over them but also aggregating...
We discuss the design of a common application requirement interface (CAPRI) for cognitive wireless networks. Applications can use CAPRI to express optimization goals and policies they expect the network to follow, which can subsequently be used by cognitive engines in their optimization processes. We believe that CAPRI design fills in an important gap in the current architectural understanding of...
Cognitive radios have a great potential to improve spectrum utilization by enabling secondary (unlicensed) users to opportunistically access the spectrum without disturbing the primary (licensed) users' communication. However, to assure acceptable QoS for secondary users without interfering with primary users several challenges must be overcome under physical constraints. Because of hardware constraints,...
This paper proposes a self-organized spectrum assignment strategy in the context of next generation multicell orthogonal frequency division multiple access networks. The proposed strategy is able to dynamically find spectrum assignments per cell depending on the spatial distribution of the users over the scenario, opening new spectrum access opportunities for secondary spectrum usage. Reinforcement...
Recently, cognitive radio access in time-slotted systems has gained interest. In these systems, the beginning of the slot is used for detection. If no signal is found to be present, remainder of the slot can be used for cognitive radios (secondary users). Detection of the occupancy status of the slots is characterized by false alarm probability and detection probability. The detection probability...
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