• 한국멀티미디어학회논문지
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• 제23권9호
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• pp.1164-1170
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• 2020

In this paper, we consider the wireless-powered backscatter communication which consists of a power beacon, a source, a relay, and a destination. For the proposed wireless-powered backscatter communication, the source transmits its signals to both the relay and the destination via a backscattering channel and the relay which has a rechargeable battery performs an energy harvesting as well as an information forwarding based on the time switching relay (TSR) protocol. Based on the decode-and-forward (DF) relay transmission, we investigate performances of the proposed system in terms of outage probability and transmission rate in which the exact performance analysis of outage probability is given. Finally, some numerical examples are given to verify our provided analytical results for different system conditions.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.111-115
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• 2012

In this paper, a solar energy powered bicycle linked to a wireless sensor network (WSN) which monitors the transfer of solar energy to an electrical energy storage unit and an analysis of its effectiveness is proposed. In order to achieve this goal, a solar-powered bicycle with an attached ZigBee and a far-end wireless network supervisory system is setup. Experimental results prove that our prototype, solar energy powered bicycle, can achieve enough solar energy for charging a two lead-acid battery pack. As a result, the user, through use of a wireless network in the parking period can be kept aware of the data on the amount of immediate solar radiation, the degree of illumination, the ambient temperature, and electrical energy storage capacity information of the bicycle through an internet interface.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.565-581
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• 2019

This paper investigates the wireless powered two way relay network (WPTWRN), where two single-antenna users and one single-antenna relay firstly harvest energy from signals emitted by a multi-antenna power beacon (PB) and then two users exchange information with the help of the relay by using their harvested energies. In order to improve the energy transfer efficiency, energy beamforming at the PB is deployed. For such a network, to explore the performance limit of the presented WPTWRN, an optimization problem is formulated to obtain the achievable rate region bounds by jointly optimizing the time allocation and energy beamforming design. As the optimization problem is non-convex, it is first transformed to be a convex problem by using variable substitutions and semidefinite relaxation (SDR) and then solve it efficiently. It is proved that the proposed method achieves the global optimum. Simulation results show that the achievable rate region of the presented WPTWRN architecture outperforms that of wireless powered one way relay network architecture. Results also show that the relay location has significant impact on achievable rate region of the WPTWRN.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1889-1910
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• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.

• Smart Structures and Systems
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• 제15권6호
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• pp.1625-1642
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• 2015

We propose an electrically self-reliant structural health monitoring (SHM) system that is able to wirelessly transmit sensing data using electrical power generated by vibration without the need for additional external power sources. The provision of reliable electricity to wireless SHM systems is a highly important issue that has often been ignored, and to expand the applicability of various wireless SHM innovations, it will be necessary to develop comprehensive wireless SHM devices including stable electricity sources. In light of this need, we propose a new, highly efficient vibration-powered generator based on a tuned-mass-damper (TMD) mechanism that is quite suitable for vibration-based SHM. The charging time of the TMD generator is shorter than that of conventional generators based on the impedance matching method, and the proposed TMD generator can harvest 16 times the amount of energy that a conventional generator can. The charging time of an SHM wireless transmitter is quantitatively formulated. We conduct wireless monitoring experiments to validate a wireless SHM system composed of a self-reliant SHM and a vibration-powered TMD generator.

• 한국정보통신학회논문지
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• 제26권1호
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• pp.176-179
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• 2022

In this paper, we consider a sectorized wireless powered sensor network (WPSN), wherein sensor nodes are clustered based on sectors and transmit data to the cluster head (CH) using energy harvested from a hybrid access point. We construct a system model for this sectorized WPSN and find optimal coordinates of CH that maximize the achievable transmission rate of sensing data. To obtain the optimal CH with low overhead, we perform an asymptotic geometric analysis (GA). Simulation results show that the proposed GA-based CH selection method is close to the optimal performance exhibited by exhaustive search with a low feedback overhead.

• 한국컴퓨터정보학회논문지
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• 제22권5호
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• pp.81-88
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• 2017

Solar-powered wireless sensor nodes can use extra energy to obtain additional data to increase the precision. However, if the amount of data sensed is increased indiscriminately, the overhead of relay nodes may increase, and their energy may be exhausted. In this paper, we introduce a sensing and compression rate selection scheme to increase the amount of data obtained while preventing energy exhaustion. In this scheme, the neighbor nodes of the sink node determine the limit of data to be transmitted according to the allocated energy and their descendant nodes, and the other nodes select a compression algorithm appropriate to the allocated energy and the limitation of data to be transmitted. A simulation result verifies that the proposed scheme gathers more data with a lower number of blackout nodes than other schemes. We also found that it adapts better to changes in node density and the amount of energy harvested.

• 한국정보통신학회논문지
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• 제26권11호
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• pp.1679-1685
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• 2022

본 논문에서는 무선전력 통신 네트워크에서 소스에서 목적지 노드까지 종단간 데이터 전송률을 최대화하기 위한 최적의 멀티홉 전송 방식을 제안한다. 에너지 하베스팅을 하면서 멀티홉 전송을 위한 프레임 구조를 제시하고, 노드간 서로 다른 에너지 수확량과 링크 품질을 고려하여 종단간 전송률을 최대화하는 각 노드의 전송 시간을 수학적 분석을 통하여 도출한다. 아울러, 고려하는 무선전력기반 멀티홉 전송의 시스템 모델링을 통하여 최적화 문제를 도출하고, 이 최적화 문제가 convex 함을 보임으로써 전역 최적해가 존재함을 증명한다. 이를 통하여 최적화 문제를 계산 가능한 형태로 변형하여 손쉽게 최적해를 찾는다. 제안한 최적 멀티홉 전송 방식은 모든 링크의 전송률이 같아지도록 노드별 전송 시간을 최적으로 할당함으로써 종단간 전송률을 최대화한다.

• 한국통신학회논문지
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• 제40권10호
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• pp.1900-1911
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• 2015

본 논문에서는 무선 센서 네트워크 환경에서 전력의 제약이 있는 센서들의 장거리통신을 가능케 하는 backscatter 통신에 대해 소개하고, 이를 접목해 무선전력 통신네트워크(wireless-powered communication networks, WPCN)의 doubly near-far 문제를 해결하는 방안을 논의한다. Backscatter에 기반한 WPCN에서 유저들은 하이브리드 엑세스 지점으로부터 전송되는 신호와 반송파 송신기로부터 전송되는 반송파 신호로부터 에너지를 수집한 후, 주파수 편이 변조를 이용한 반송파 신호의 반사를 통해 정보를 전송하게 된다. 위의 통신환경에서 energy-free 조건과 신호대 잡음비 outage 영역을 정의한다. 또한 본 논문에서는 에너지 수집과 정보 전송을 위한 최적의 시간 할당 방법을 제안하고, 이를 통해 시스템 전체의 정보전송 효율을 최대화할 수 있는 backscatter 기반의 수집 후 전송 프로토콜을 설계한다. 실험결과를 통해 제안한 backscatter 기법이 종래의 WPCN에 비해 광범위한 서비스 영역과 축소된 신호대 잡음비 outage 영역을 갖는 것을 보였고, 정보전송 효율을 최대화할 수 있음을 보였다.

• Smart Structures and Systems
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• 제10권3호
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• pp.299-312
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• 2012

The authors' research efforts recently led to the development of a customized wireless control unit which receives the real-time feedbacks from the sensors, and elaborates the consequent control signal to drive the actuator(s). The controller is wireless in performing the data transmission task, i.e., it receives the signals from the sensors without the need of installing any analogue cable connection between them, but it is powered by wire. The actuator also needs to be powered by wire. In this framework, the design of a power management unit is of interest only for the wireless sensor stations, and it should be adaptable to different kind of sensor requirements in terms of voltage and power consumption. In the present paper, the power management efficiency is optimized by taking into consideration three different kinds of accelerometers, a load cell, and a non-contact laser displacement sensor. The required voltages are assumed to be provided by a power harvesting solution where the energy is stored into a capacitor.