Browsing by Author "Lai, Wei-Sheng"

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A Distributed Cluster-Based Self-Organizing Approach to Resource Allocation in Femtocell Networks
(2012)
Lai, Wei-Sheng
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Lee, Ta-Sung
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電機工程學系
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Department of Electrical and Computer Engineering
Femtocell networks are an advantageous low-cost technology for providing indoor coverage and high-capacity solutions. Femtocell networks reuse the spectrum resources in co-channel environments due to its high geometric density. In this paper, a distributed algorithm is proposed, which uses a cluster-based self-organizing approach to managing the spectrum and power resources among femtocells. The aim of the proposed algorithm is to achieve an optimized throughput of the networks in a decentralized manner. The algorithm involves three phases: sensing phase, sniffer phase, and power control phase, and is performed in each femtocell. Simulation results indicate that the proposed algorithm improves the uplink throughput of the femtocell networks and effectively avoids interference with the conventional macro-cellular networks.
Game Theoretic Distributed Dynamic Resource Allocation with Interference Avoidance in Cognitive Femtocell Networks
(2013)
Lai, Wei-Sheng
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Chiang, Muh-En
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Lee, Shen-Chung
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Lee, Ta-Sung
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電機工程學系
This paper investigates new decentralized dynamic resource allocation scheme which exploits game theoretic regret-matching procedure to enhance the spectrum efficiency for cognitive femtocell networks. In order to ensure spectrum usage, we develop a new resource allocation scheme with joint overlay and underlay strategy to increase frequency reuse factor among cognitive femtocell networks. The proposed scheme can avoid interference to macrocell and the other femtocell user equipments; furthermore, the number of iterations required is less than the original regret-matching scheme, and it has been proved that at least one of correlated equilibrium exists in proposed algorithm. Computer simulations are presented to verify the proposed scheme which is effective for resource allocation. The proposed scheme is comparable to the performance of exhaustive search scheme and outperforms the original regret-matching scheme.
Joint Power and Admission Control for Spectral and Energy Efficiency Maximization in Heterogeneous OFDMA Networks
(2016-05)
Lai, Wei-Sheng
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Chang, Tsung-Hui
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Lee, Ta-Sung
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電機學院
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College of Electrical and Computer Engineering
This paper studies the joint power and admission control (JPAC) problem for orthogonal frequency division multiplexing access (OFDMA) based heterogeneous networks. We consider a small-cell network coexisting with a macro-cell network. Small cells are not only subject to constraints imposed by interference with the macro-cell network but also by the minimum achievable rates of secondary user equipment (SUE). The goal is to admit as many SUE as possible to satisfy the minimum rate requirements while maximizing a certain network utility associated with the admitted SUE. To this end, we formulate two JPAC problems aimed at maximizing the network spectral efficiency (SE) and network energy efficiency (EE), respectively, where the latter has not been considered before. In light of the NP-hardness of the admission control and SE maximization problems, prior works have often treated the two problems separately without considering OFDMA constraints. In this paper, we propose a novel joint optimization framework that is capable of considering power control, admission control, and resource block assignment simultaneously. Via advanced convex approximation techniques and sequential SUE deflation procedures, we develop efficient algorithms that jointly maximize the SE/EE and the number of admitted SUE. Simulation results show that the proposed algorithms yield substantially higher SE/EE and admit more SUE than existing methods.