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Joint overlay and underlay resource allocation with weighted fairness in OFDM‐based cognitive radio systems
Author(s) -
Xu Wenjun,
Wang Yan,
Niu Kai,
He Zhiqiang,
Lin Jiaru
Publication year - 2014
Publication title -
international journal of communication systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.344
H-Index - 49
eISSN - 1099-1131
pISSN - 1074-5351
DOI - 10.1002/dac.2776
Subject(s) - subcarrier , computer science , underlay , cognitive radio , resource allocation , interference (communication) , overlay , maximization , orthogonal frequency division multiplexing , mathematical optimization , joint (building) , constraint (computer aided design) , frequency allocation , spectral efficiency , computer network , distributed computing , telecommunications , signal to noise ratio (imaging) , wireless , mathematics , architectural engineering , channel (broadcasting) , geometry , engineering , programming language
Summary In this paper, the problem of hybrid overlay and underlay spectrum access is investigated for OFDM‐based cognitive radio (CR) systems. Both the metrics for system (e.g. capacity) and users (e.g. fairness) are integrated into the unified framework of weighted‐capacity maximization with the interference constraint in CR systems. For easing the procedure of resource allocation, two criteria, respectively, for subcarrier assignment and power allocation are theoretically derived based on the Karush–Kuhn–Tucker conditions. Under the guidance of the two criteria, max‐capacity subcarrier assignment and optimal power allocation are proposed to flexibly distribute spectrum resources to secondary users. In order to reduce the computational complexity further, a suboptimal power allocation algorithm, referred to as cap‐limited waterfilling, is also presented by decomposing the interference constraint. Simulation results show that the capacity and fairness performance of the proposed algorithms is considerably better than the conventional ones in references. The proposed suboptimal algorithm with substantially lower complexity approaches to optimal power allocation in the vicinity of only 1% performance gap. Meanwhile, joint access model is greatly beneficial to spectrum efficiency enhancement in CR systems. Copyright © 2014 John Wiley & Sons, Ltd.