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1 ETIS - Equipes Traitement de l-Information et Systèmes 2 CEM Lab - ENIS - Département de Génie Électrique de Sfax ENIS 3 POLARIS - Performance analysis and optimization of LARge Infrastructures and Systems Inria Grenoble - Rhône-Alpes, LIG - Laboratoire d-Informatique de Grenoble

Abstract : In this paper, we study the centralized spectrum access and power management for several opportunistic users, secondary users SUs, without hurting the primary users PUs. The radio resource manager-s objective is to minimize the overall power consumption of the opportunistic system over several orthogonal frequency bands under constraints on the minimum quality of service QoS and maximum peak and average interference to the PUs. Given the opposing nature of these constraints, we first study the problem of feasibility, and we provide sufficient conditions and necessary conditions for the existence of a solution. The main challenge lies in the non-convexity of this problem because of the discrete spectrum scheduling: one band can be allocated to at most one SU to avoid interference impairments. To overcome this issue, we use a Lagrangian relaxation technique, and we prove that the discrete solutions of the relaxed problem are the solutions to the initial problem. We propose a projected sub-gradient algorithm to compute the solution, when it exists. Assuming that the channels are drawn randomly from a continuous distribution, this algorithm converges to the optimal solution. We also study a specific symmetric system for which we provide the analytical solution. Our numerical results compare the energy-efficiency of the proposed algorithm with other spectrum allocation solutions and show the optimality of our approach.

Keywords : Power allocation Lagrangian relaxation Spectrum scheduling Cognitive radio systems Projected sub-gradient algorithm

Author: Raouia Masmoudi - E Veronica Belmega - Inbar Fijalkow -

Source: https://hal.archives-ouvertes.fr/


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