• Journal of Communications and Networks
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• v.18 no.2
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• pp.201-209
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• 2016

In wireless sensor networks (WSNs) duty cycling has been an imperative choice to reduce idle listening but it introduces sleep delay. Thus, the conventional WSN medium access control protocols are bound by the energy-latency tradeoff. To break through the tradeoff, we propose a radio wave sensor called radio frequency (RF) wakeup sensor that is dedicated to sense the presence of a RF signal. The distinctive feature of our design is that the RF wakeup sensor can provide the same sensitivity but with two orders of magnitude less energy than the underlying RF module. With RF wakeup sensor a sensor node no longer requires duty cycling. Instead, it can maintain a sleep state until its RF wakeup sensor detects a communication signal. According to our analysis, the response time of the RF wakeup sensor is much shorter than the minimum transmission time of a typical communication module. Therefore, we apply duty cycling to the RF wakeup sensor to further reduce the energy consumption without performance degradation. We evaluate the circuital characteristics of our RF wakeup sensor design by using Advanced Design System 2009 simulator. The results show that RF wakeup sensor allows a sensor node to completely turn off their communication module by performing the around-the-clock carrier sensing while it consumes only 0.07% energy of an idle communication module.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.107-114
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• 2023

In this paper, the results of experiments conducted in indoor wired and outdoor wireless environments to reduce the interference impact of 5G mobile communication on fixed satellite services using RF Interference Reduction Module (IRM) are presented. Test results for interference signals with a 100MHz bandwidth in a wired environment demonstrate that RF IRM can reduce interference by more than 20dB in a 100MHz bandwidth. The performance of RF IRM was also tested in the S-band wireless environments. In the S-band wireless environments with interference signals having a 20MHz bandwidth, RF IRM exhibits interference reduction performance of 12-15dB, for signals with a 50MHz bandwidth, it shows 10-12dB interference reduction, and for signals with a 100MHz bandwidth, it demonstrates 5-10dB interference reduction. This paper shows that RF IRM can be used not only within transceivers but also in wireless environments to mitigate interference.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.49-59
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• 2001

Wireless communication systems will be one of the biggest drivers of semiconductor products over the next decade. Global Positioning System (GPS) and Blue-tooth, HomeRF, and Wireless-LNA system are just a few of RF-module candidate awaiting integration into next generation mobile phone. Motivated by the growing needs for lowcost and multi-band/multi-function single chip wireless transceivers, CMOS technology has been recognized as a most promising candidate for the implementation of the future wireless communication systems. This paper presents recent developments in RF CMOS technology so far, much of them have been developed in ETRI, and from them forecasts technology trends in the near future.

• The Magazine of the IEIE
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• v.29 no.9
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• pp.1020-1020
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• 2002

Wireless communication systems will be one of the biggest drivers of semiconductor products over the next decade. Global Positioning System (GPS) and Blue-tooth, HomeRF, and Wireless-LNA system are just a few of RF-module candidate awaiting integration into next generation mobile phone. Motivated by the growing needs for low-cost and multi-band/multi-function single chip wireless transceivers, CMOS technology has been recognized as a most promising candidate for the implementation of the future wireless communication systems. This paper presents recent developments in RF CMOS technology, which is classified into device technology and circuit technology and from them forecasts technology trends in the near future.

• The Magazine of the IEIE
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• v.29 no.9
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• pp.18-30
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• 2002

Wireless communication systems will be one of the biggest drivers of semiconductor products over the next decade. Global Positioning System (GPS) and Blue-tooth, HomeRF, and Wireless-LNA system are just a few of RF-module candidate awaiting integration into next generation mobile phone. Motivated by the generation mobile phone. Motivated by the growing needs for low-cost and multi-band/multi-function single chip wireless transceivers, CMOS technology has been recognized as a most promising candidate for the implementation of the future wireless communication systems. This paper presents recent developments in RF CMOS technology, which is classified into device technology and circuit technology and from them forecasts technology and from them forecasts technology trends in the near future.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3104-3110
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• 2011

This paper describes how to ensure safety of train by guaranteeing stable and continuous communication in RF-CBTC. CBTC System uses the wireless communication between onboard and wayside so that safety of wireless communication is the most important. Losing the position of train causes vital problem of train service. By losing the position of train, the other trains are blocked in the block and the train move by emergency mode so headway and safety cannot guaranteed. Therefore, safety is ensured by redundancy of wireless equipment. One of the ways to make redundancy is redundancy of equipment. However, the redundancy of equipment spends a lot of money to avoid interference in limited place like underground. Continuous communication is guaranteed by means of redundancy of wireless communication coverage to solve the problems even though one of the equipment is broken.

• Current Optics and Photonics
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• v.1 no.4
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• pp.325-335
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• 2017

Hybrid radio frequency/free space optical (RF/FSO) wireless mesh networks have attracted increasing attention for they can overcome the limitations of RF and FSO communications and significantly increase the throughput of wireless mesh networks (WMNs). In this article, a resource assignment optimization scheme is proposed for hybrid RF/FSO wireless mesh networks. The optimization framework is proposed for the objective of maximizing throughput of overall hybrid networks through joint transmission slot assignment, FSO links allocation and power control with the consideration of the fading nature of RF and FSO links. The scheme is formulated as an instance of mixed integer linear program (MILP) and the optimal solutions are provided using CPLEX and Gurobi optimizers. How to choose the appropriate optimizer is discussed by comparing their performance. Numerous simulations are done to demonstrate that the performance of our optimization scheme is much better than the current case of having the same topology.

• Journal of information and communication convergence engineering
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• v.18 no.4
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• pp.254-259
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• 2020

Phased-array antennas comprise a demanding antenna design methodology for commercial wireless communication systems or military radar systems. In addition to these two important applications, the phased-array antennas can be used in beamforming for wireless charging. In this study, a four-way analog beamforming front-end module (FEM) for a hybrid beamforming system is developed for 2.4 GHz operation. In a hybrid beamforming scheme, an analog beamforming FEM in which the phase and amplitude of RF signal can be adjusted between the RF chain and phased-array antenna is required. With the beamforming and beam steering capability of the phased-array antennas, wireless RF power can be transmitted with high directivity to a designated receiver for wireless charging. The four-way analog beamforming FEM has a 32 dB gain dynamic range and a phase shifting range greater than 360°. The maximum output RF power of the four-way analog beamforming FEM is 40 dBm (=10 W) when combined the four individual RF paths are combined.

• ETRI Journal
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• v.25 no.3
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• pp.203-209
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• 2003

This paper reports on our investigation of DC and RF characteristics of p-channel metal oxide semiconductor field effect transistors (pMOSFETs) with a compressively strained $Si_{0.8}Ge_{0.2}$ channel. Because of enhanced hole mobility in the $Si_{0.8}Ge_{0.2}$ buried layer, the $Si_{0.8}Ge_{0.2}$ pMOSFET showed improved DC and RF characteristics. We demonstrate that the 1/f noise in the $Si_{0.8}Ge_{0.2}$ pMOSFET was much lower than that in the all-Si counterpart, regardless of gate-oxide degradation by electrical stress. These results suggest that the $Si_{0.8}Ge_{0.2}$ pMOSFET is suitable for RF applications that require high speed and low 1/f noise.

• Journal of the Speleological Society of Korea
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• no.81
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• pp.43-46
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• 2007

In this paper, we implement a wireless robot in which the RF communication the dangerous place where human cannot approach. In the proposed network image control system, the noise occurred in wireless communication is reduced by implementing the noise eliminating circuit and the driving time of a wireless robot is increased by adopting the recharge battery. By constructing the wireless communication, controled in the remote site with a wireless robot.