Topic
Cognitive network
About: Cognitive network is a research topic. Over the lifetime, 4213 publications have been published within this topic receiving 107093 citations.
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06 Oct 2014
TL;DR: The SP structure and its cooperation with other CM modules are described, consisting of three logical modules: Clustering (CL), Clusters Graph Coloring (CGC) and Supervisor (SP) with Sensing Client (SC).
Abstract: Apart from efficient use of assigned spectral resources as a primary user, Cognitive Radio (CR) has the ability to act as a secondary user, utilizing available radio resources, which are not used by primary users for a certain period of time. This paper refers to mobile CR network management, based on multi-stage machine method. The article shows the idea of the Cognitive Manager (CM), consisting of three logical modules: Clustering (CL), Clusters Graph Coloring (CGC) and Supervisor (SP) with Sensing Client (SC). SP is responsible for management of all other cognitive manager blocks. This paper describes the SP structure and its cooperation with other CM modules. Prepared simulation scenarios take into account the propagation phenomena and presence of other users and jammers, that can use the same frequency channels as CR network. The events like lack of communication between nodes, bad links quality and presence of jamming, cause the appropriate reaction of SP. In such cases, SP performs analysis of current situation, and if necessary, it changes actual used frequency (color) using backup channels list, which is permanently updated. The presented idea has been implemented in the CORASMA (Cognitive Radio for dynamic Spectrum Management) simulator.
15 citations
TL;DR: Some theoretical and practical issues and research directions in the field of wireless communications and networking that are common to most if not all application areas are presented.
Abstract: Scientific and technological innovations of the last few decades in the field of wireless telecommunications and networking have enabled a wide area of applications and services in healthcare, transportation, environmental protection, infotainment, industrial automation, homeland security, smart urban environments and other disparate fields. At the same time the complexity and criticality of these systems creates many technical challenges in their design, development and operation. This paper reviews a number of important application fields of wireless communications and networking and discusses recent results, key challenges and unsolved issues in each one of them. It goes on to present some theoretical and practical issues and research directions in the field of wireless communications and networking that are common to most if not all application areas. These include theoretical link and network capacity limits, cognitive radio and cognitive networking, programming and in-field reprogramming of wireless devices, and complex system design inspired by biology and physics.
15 citations
TL;DR: The concept secure and reliable communication probability (SRCP) is introduced as a performance metric to evaluate the considered system, as well as the efficiency of the four power allocation policies.
Abstract: This paper investigates the problem of secure and reliable communications for cognitive radio networks. More specifically, we consider a single input multiple output cognitive model where the secondary user (SU) faces an eavesdropping attack while being subject to the normal interference constraint imposed by the primary user (PU). Thus, the SU must have a suitable power allocation policy which does not only satisfy the constraints of the PU but also the security constraints such that it obtains a reasonable performance for the SU, without exposing information to the eavesdropper. We derive four power allocation policies for different scenarios corresponding to whether or not the channel state information of the PU and the eavesdropper are available at the SU. Further, we introduce the concept secure and reliable communication probability (SRCP) as a performance metric to evaluate the considered system, as well as the efficiency of the four power allocation policies. Finally, we present numerical examples to illustrate the power allocation polices, and the impact of these policies on the SRCP of the SU.
15 citations
TL;DR: The authors attempt to achieve the maximum transmission capacity of the secondary users under the primary and secondary outage constraints, which depend on the secondary density in the cognitive network, in a hybrid cognitive network model with overlay and underlay models.
Abstract: The concept of cognitive radio is to exploit efficiently the spectrum resources by allowing the coexistence of the primary and secondary users in the same bandwidth without interfering the performance of primary users. Three coexisting models (overlay, underlay and interleave) were presented in recent literature. In this study, the authors propose a hybrid cognitive network model with overlay and underlay models, whereby a primary link leases its fractions of transmission time to the secondary users for their cooperation (i.e. these nodes form as a virtual multiple input multiple output (VMIMO) group) under the outage constraints of the primary and secondary systems. A new cooperative protocol between primary and secondary users is presented. The authors attempt to achieve the maximum transmission capacity of the secondary users under the primary and secondary outage constraints, which depend on the secondary density in the cognitive network. This study gives the upper bound density of the secondary transmitters that are modelled as a homogeneous marked Poisson point process. The maximum density is achieved by computing an optimal set of system parameters such as power control factor of the secondary user and the dirty paper coding (DPC) parameter. Simulation results illustrate that the maximum secondary density obtained using VMIMO is superior to that obtained by direct primary transmission.
15 citations
26 Apr 2009
TL;DR: The optimal access policy is proposed as an optimal tradeoff point between transmission collision and overlooked opportunity in each channel and the optimal cooperative spectrum sensing strategy is studied to solve the following questions: to what extent each cognitive user should cooperate with others and which part of spectrum it should choose to sense.
Abstract: In cognitive radio systems, as the sensing ability of single cognitive user is limited, the opportunistic spectrum access has to allow different cognitive users to cooperatively search for and exploit instantaneous spectrum availability. In this paper, we address the design of opportunistic spectrum access for cognitive radio system employing cooperative spectrum sensing. The opportunistic spectrum access strategy contains two parts: an access policy to maximize the transmission throughput in each channel, and a cooperative spectrum sensing strategy to maximize the overall transmission throughput of the cognitive network. We first propose the optimal access policy as an optimal tradeoff point between transmission collision and overlooked opportunity in each channel. Then the optimal cooperative spectrum sensing strategy is studied to solve the following questions: to what extent each cognitive user should cooperate with others and which part of spectrum it should choose to sense. Simulation results are given to demonstrate the promising performance.
15 citations