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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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🏛️國立陽明交通大學機構典藏

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A Geometric Approach for Optimal Power Control and Relay Selection in NOMA Wireless Relay Networks
(2020-04-01)
Gau, Rung-Hung
;
Chiu, Hsiao-Ting
;
Liao, Chien-Hsun
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, we propose a geometric approach for optimal power control and relay selection in NOMA wireless relay networks. First, for each pair of relays, to derive an optimal vector of transmission power that maximizes the network throughput, we formulate a non-convex optimization problem. To obtain a closed-form solution for the non-convex optimization problem, we adopt ellipses and hyperbolas for classification of transmission power vectors. In addition, the proposed geometric approach could be used to select an optimal pair of relays and an optimal vector of transmission power in polynomial time. Furthermore, we observe that allocating all transmission power of the BS to send data to the stronger relay is not necessarily optimal in a NOMA wireless relay network. Simulation results show that the proposed geometric approach could significantly increase the end-to-end sum rate and reduce the power consumption of wireless communications for NOMA wireless relay networks with low computational complexity.
Energy-Efficient Activation and Uplink Transmission for Cellular IoT
(2020-02-01)
Liu, Chun-Hung
;
Shen, Yu-Han
;
Lee, Chia-Han
;
電機工程學系
;
電信工程研究所
Consider a large-scale cellular network in which base stations (BSs) serve massive Internet of Things (IoT) devices. Since IoT devices are powered by a capacity-limited battery, how to prolong their working lifetime is a paramount problem for the success of cellular IoT systems. This article proposes how to use BSs to manage the active and dormant operating modes of the IoT devices via downlink signaling in an energy-efficient fashion and how the IoT devices perform energy-efficient uplink power control to improve their uplink coverage. We first investigate the fundamental statistical properties of an activation signaling process induced by BSs that would like to activate the devices in their cells, which helps to derive the neat expressions of the true, false, and total activation probabilities that reveal joint downlink power control and BS coordination is an effective means to significantly improve the activation performance. We then propose an energy-efficient uplink power control for IoT devices which is shown to save power and ameliorate the uplink coverage probability at the same time. We also propose an energy-efficient downlink power control and BS coordination scheme, which is shown to remarkably improve the activation and uplink coverage performances at the same time.
Reinforcement Learning-Based Downlink Interference Control for Ultra-Dense Small Cells
(2020-01-01)
Xiao, Liang
;
Zhang, Hailu
;
Xiao, Yilin
;
Wan, Xiaoyue
;
Liu, Sicong
The dense deployment of small cells in 5G cellular networks raises the issue of controlling downlink inter-cell interference under time-varying channel states. In this paper, we propose a reinforcement learning based power control scheme to suppress downlink inter-cell interference and save energy for ultra-dense small cells. This scheme enables base stations to schedule the downlink transmit power without knowing the interference distribution and the channel states of the neighboring small cells. A deep reinforcement learning based interference control algorithm is designed to further accelerate learning for ultra-dense small cells with a large number of active users. Analytical convergence performance bounds including throughput, energy consumption, inter-cell interference, and the utility of base stations are provided and the computational complexity of our proposed scheme is discussed. Simulation results show that this scheme optimizes the downlink interference control performance after sufficient power control instances and significantly increases the network throughput with less energy consumption compared with a benchmark scheme.
System Capacity and Convergence Rate Evaluation for Downlink Power Control in 5G MDMA Cellular Systems
(2018-01-01)
Hsiao, Wei-Han
;
Su, Jing-Jing
;
Tang, Zhi-Wen
;
Yin, Jia-Le
;
Huang, Chia-Chi
Several downlink power control (PC) algorithms are investigated in this paper for the fifth generation MDMA based cellular system. Among them, the closed-loop PC schemes are studied, which are useful to reduce the co-channel interference and increase the system capacity. Two kinds of iterative methods are commonly discussed. One is the SIR based approach, and the other is the eigenvalue based approach. Some representative PC algorithms are evaluated in terms of different performance metrics. In addition, an enhanced PC method is proposed which combines the advantages of the previous methods. It is shown by computer simulations that the proposed method achieves both desirable capacity performance and convergence rate in a 5G multipath division multiple access cellular system. Thus, the proposed method is a feasible downlink power control solution for 5G cellular systems.
Optimal Power Control and Beamforming for Full-Duplex Small Cell Wireless Networks
(2017-01-01)
Gau, Rung-Hung
;
Xiao, Zh-Hong
;
Yuan, Tseng-Lung
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, we propose an optimization framework for selecting an optimal downlink beamforming vector and an optimal uplink transmission power level in full-duplex small cell wireless networks. We study the case in which the full-duplex base station is equipped with multiple antennas and each half-duplex UE is equipped with a single antenna. To benefit from recent progresses in all-digital self-interference cancellation, we formulate an optimization problem to achieve optimal beamforming and power control. Since the studied optimization problem is not convex, we first choose the optimal direction for the beamforming vector. Next, we adopt difference of concave programming to obtain the optimal magnitude of the beamforming vector and the optimal uplink transmission power level. Simulation results show that the proposed approach could significantly improve the performance of small cell wireless networks, especially when the residual self-interference is small.
Optimal Power Control for NOMA Wireless Networks With Relays
(2018-02-01)
Gau, Rung-Hung
;
Chiu, Hsiao-Ting
;
Liao, Chien-Hsun
;
Wu, Chi-Lun
;
電信工程研究所
In this letter, we propose a novel approach for dynamically selecting an optimal relay mode and optimal transmission power levels in non-orthogonal multiple access wireless networks with relays. To maximize the network throughput, the proposed approach alternates between the one-relay mode and the two-relay mode based on channel state information. For the two-relay mode, we derive novel closed-form results on optimal power control. Unlike in a conventional one-hop network, it is not always optimal to allocate all power to the relay with the largest channel gain in the studied two-hop network. Based on the closed-form results, one could determine the optimal power levels quickly. Simulation results show that the proposed approach could significantly increase the network throughput.
User Assignment and Discrete Power Control for Scalable NOMA Multicast in Cellular Networks
(2016)
Gau, Rung-Hung
;
Chiu, Hsiao-Ting
;
電機工程學系
;
Department of Electrical and Computer Engineering
In this paper, we propose using non-orthogonal multiple access to increase the throughput of wireless multicast. To achieve optimal user assignment and discrete power control, we formulate a combinatorial optimization problem. In particular, we concentrate on the general case in which an user cluster consists of an arbitrary number of users. To enhance scalability, we propose novel and efficient algorithms for finding out an optimal pair of user assignment and transmission power vector for NOMA multicast. Simulation results show that the proposed approach could significantly improve the multicast throughput.
Triggering and Relay Node Selection for Self-User Relaying
(2015-11-01)
Chou, Chie Ming
;
Huang, Ching-Yao
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Self-user relaying technology is designed to support multiple self-owned devices especially when wearable devices are becoming more popular. In this letter, with a consideration of power control and discontinuous reception mechanism, a power model and energy metric are derived to analyze self-user relaying performance. Results show that under a typical traffic model, self-user relaying can improve energy performance when the relay node itself has the maximum traffic volume. Additionally, a simple battery budget threshold based relay node selection is suggested for limited battery budget of nodes.
以鏈結層模型解法建立一個高效能無線網狀網路---參數分析、演算法設計、及雛型系統實作
(2008)
林亭佑
;
Lin Ting-Yu
;
國立交通大學電信工程學系(所)
由於單點跳躍無線區域網路的固有覆蓋範圍限制及高部署費用(來自於有線主幹下的每一個有效的存取點的硬體需求)，在過去十年的期間，大家開始注意無線多點跳躍協力(wireless cooperative multi-hop)的無線隨意網路(ad hoc networking)，並且認為是一個可行的架構。定義上，一個無線隨意網路可視作使用非固定的寬頻網路架構(no fixed infrastructure)或中央控管機制(centralized)的一群無線主機來合力建立通訊。而近興起的無線網狀網路(wireless mesh network)則被視為無線隨意網路在應用層面所提出的無線網際網路最後一哩(last-mile)可行的解決方案，無線網狀網路的確打開了新的研究方向及可觀的數量在研究協定設計上，不過許多有關效能的問題仍尚待解決。過度的封包遺失(packet loss)、不可預測的通道行為(unpredictable)導致無法找出一個穩定且高流量的路徑(high-throughput paths)、內部資料流量(intra-flow)和資料間的互相干擾(inter-flow interference)導致網路流量的下降，都屬於尚未被完全解決的問題。在這原規劃三年執行期間的計畫中，我們已獲得國科會一年期的補助，並且有一些初步研究成果，也因此打算繼續提出後兩年的補助申請，目標是針對鏈結層潛藏的效能問題做一系列的深入分析，並且提出可能問題解法之協定及效能改進的演算法，朝著優化無線鏈結的定義/特性以及本身上層協定設定最佳化的方向來提昇系統效能。我們希望可以(i)瞭解無線鏈結如何影響實體層(PHY)/媒體存取層(MAC)屬性和影響範圍以及其他環境因素的影響，(ii)實現一個嚴謹的分析和理論來描述無線鏈結的行為，和(iii)明確定義實體層/媒體存取層相關效能控制因素，使得網路容量能夠最佳化。具體來說，我們規劃為期3年的計畫其相關研究設計要點的步驟如下：
以鏈結層模型解法建立一個高效能無線網狀網路---參數分析、演算法設計、及雛型系統實作
(2009)
林亭佑
;
Lin Ting-Yu
;
國立交通大學電信工程學系(所)
由於單點跳躍無線區域網路的固有覆蓋範圍限制及高部署費用(來自於有線主幹下的每一個有效的存取點的硬體需求)，在過去十年的期間，大家開始注意無線多點跳躍協力(wireless cooperative multi-hop)的無線隨意網路(ad hoc networking)，並且認為是一個可行的架構。定義上，一個無線隨意網路可視作使用非固定的寬頻網路架構(no fixed infrastructure)或中央控管機制(centralized)的一群無線主機來合力建立通訊。而近興起的無線網狀網路(wireless mesh network)則被視為無線隨意網路在應用層面所提出的無線網際網路最後一哩(last-mile)可行的解決方案，無線網狀網路的確打開了新的研究方向及可觀的數量在研究協定設計上，不過許多有關效能的問題仍尚待解決。過度的封包遺失(packet loss)、不可預測的通道行為(unpredictable)導致無法找出一個穩定且高流量的路徑(high-throughput paths)、內部資料流量(intra-flow)和資料間的互相干擾(inter-flow interference)導致網路流量的下降，都屬於尚未被完全解決的問題。在這原規劃三年執行期間的計畫中，我們已獲得國科會一年期的補助，並且有一些初步研究成果，也因此打算繼續提出後兩年的補助申請，目標是針對鏈結層潛藏的效能問題做一系列的深入分析，並且提出可能問題解法之協定及效能改進的演算法，朝著優化無線鏈結的定義/特性以及本身上層協定設定最佳化的方向來提昇系統效能。我們希望可以(i)瞭解無線鏈結如何影響實體層(PHY)/媒體存取層(MAC)屬性和影響範圍以及其他環境因素的影響，(ii)實現一個嚴謹的分析和理論來描述無線鏈結的行為，和(iii)明確定義實體層/媒體存取層相關效能控制因素，使得網路容量能夠最佳化。具體來說，我們規劃為期3年的計畫其相關研究設計要點的步驟如下：

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