Resource management for QoS support in cognitive radio networks

Cognitive radio technology is a key enabler to reuse a finite, scarce, and expensive resource: the radio spectrum. Guaranteeing required levels of QoS to cognitive users and ensuring necessary protection to incumbent users are the two main challenges in opportunistic spectrum access. This article identifies the main requirements and challenges for QoS support in cognitive radio networks. A framework for a twofold cognitive manager is presented; one part managing spectrum availability on longer timescales and the other handling resource management on shorter timescales. This article gives particular focus to the functionalities of the latter cognitive manager related to resource management. Finally, we present a few key scenarios and describe how QoS can be managed with the proposed approach without disturbing the communications of incumbent users

A serious gaming approach to managing interference in ad hoc femtocell wireless networks

The aim of this paper is to optimize femtocell performance by managing interference between femtocell devices and between a femtocell and a macrocell. It achieves this using a three-phase approach that involves deployment of femtocells and control of resulting connections through consideration and management of path loss, transmission power, signal strength and coverage area. Simulation experiments of the proposed three-phase approach at a local college that experiences a poor service from the macrocell predict significant improvements in femtocell performance in terms of managing both types of interference: co-tier and cross-tier, number of users who experience good service, coverage, and mitigating outage probability. The overall and individual complexity of each phase has also been considered. Our approach has been compared with some existing techniques chosen from the literature that has been reviewed and its predicted performance is significantly improved in comparison to these

[Vue perspective des batiments du Louvre et des Tuileries, prise du côté de la place Saint-Germain-l'Auxerrois] : [dessin] / [Jean-Arnould Leveil]

Référence bibliographique : Destailleur Paris, t. 5, 770Appartient à l’ensemble documentaire : DesDestai

[Façade du Luxembourg sur la rue de Vaugirard] : [dessin] / [Jean-Arnould Leveil]

Référence bibliographique : Destailleur Paris, t. 5, 871Appartient à l’ensemble documentaire : DesDestai

Cognitive resource management for QoS support in mobile opportunistic communications

Optimizing the Quality of Service (QoS) support, providing seamless mobility and ensuring the protection of incumbent users are some of the challenges that arise when the radio spectrum is accessed in an opportunistic way. The functional concept of Cognitive Resource Manager (CRM) is presented providing cognition of the environment to optimize the allocation and exploitation of radio resources, to improve the access to these resources and to ensure mobility control in the opportunistic system. Requirements for the functional architecture of the CRM are identified and addressed by defining building blocks to manage cognitive access and mobility control as well as resource allocation and usage. These functional entities are described together with their interfaces inside the CRM and with other opportunistic system entities like the Spectrum Manager. Particular decision-making cases for resource control and usage are presented by means of message sequence flows taking the overall cognitive and opportunistic context into account. Finally selected algorithms for distributed power control that implement parts of the functionalities of the CRM while considering specific QoS constraints and protection of incumbent users are discussed. Results of simulations conducted for these algorithms in a dedicated scenario illustrate the performance achieved by this concept

Low-Complexity Viterbi Metrics applied to Bit-Interleaved COFDM

In this paper, we address the problem of deriving bit-wise metrics for the Viterbi decoding of a bitinterleaved coded modulation. We put an emphasis on Gray-mapped high order QAM constellations, and illustrate the performance in the context of the IEEE 802.11a/g wireless OFDM system. Several bit metric formulas are compared, enabling a performance versus complexity trade-off. It is shown that near-optimum performance can be obtained with reasonable complexity, while a further complexity reduction can be achieved by recursively computing bit metrics for a given QAM symbol, at the expense of about 1dB PER performance loss

Palais de justice de Paris : projet d'isolement et d'agrandissement / Huyot architecte ; Leveil del. ; Hibon sc.

Échelle(s) : [1:1 020 ca], 100 mètres [= 9,8 cm

Resource management of centrally controlled cognitive radio networks

The realization of cognitive radio networks is a key solution to meet the raising expectations for high data rates and quality of service in mobile communications. This implies the design of a two-fold cognitive manager for resource management (CM-RM), to manage an opportunistic use of the whitespaces as introduced in this paper, and for Spectrum Management (CM-SM). The proposed CM-RM has been designed to be applicable to all kinds of control topologies (centralised/distributed). This paper presents the study of CM-RM functionalities for several scenarios based on a centralized management of the resources. The scenarios that have been selected are: cognitive ad hoc networks, cognitive femtocells, and cellular extension in TV white spaces. Each of them is introduced, specific mechanisms implemented in the CM-RM are proposed, and performance results are presented for validation purpose