• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.213-219
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• 2004

In this paper, a LNA(Low Noise Amplifier) has been developed, which is operating at L-band i.e., 1452∼1492 MHz for satellite DAB(Digital Audio Brcadcasting) receiver. The LNA is designed to improve input and output reflection coefficient and VSWR(Voltage Standing Wave Ratio) by balanced amplifier. The LNA consists of low noise amplification stage and gain amplification stage, which make a using of GaAs FET ATF-10136 and VNA-25 respectively, and is fabricated by hybrid method. To supply most suitable voltage and current, active bias circuit is designed Active biasing offers the advantage that variations in $V_P$ and $I_{DSS}$ will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets $V_{gs}$ for the desired drain voltage and drain current. The LNA is fabricated on FR-4 substrate with RF circuit and bias circuit, and integrated in aluminum housing. As a reults, the characteristics of the LNA implemented more than 32 dB in gain. 0.2 dB in gain flatness. lower than 0.95 dB in noise figure, 1.28 and 1.43 each input and output VSWR, and -13 dBm in $P_{1dB}$.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.194-201
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• 2014

This paper is able to be solved by improving degradation in multi-path environment by adjust beam pattern angle through modifying pulse phase of each antennas by using TRM (Transmitter Receiver Module). Beam Scanning Array Antenna, which is transmitter/receiver that improves degradation in multi-path environment without any signal distortion, is designed and manufactured. Beam Scanning Array Antenna should be able to send/receive signal at the antenna's longitudinal part without distortion and should not influences other systems. Also, it should include target detecting ability by beam steering.Dispersion characteristic of Beam Scanning Antenna, which is designed, is analysed by using fidelity, and steering and radar resolution performance is verified by using $1cm{\times}1cm$ sized target. To manufacture Beam Scanning Array Antenna, control board and GUI, which is able to control Vivaldi Antenna for IR-UWB, Tri-Band Wilkinson power divider, and TRM (Transmitter Receiver Module), is designed. Throughout this research, developed Beam Scanning UWB Array Antenna system is adoptable for radar application field. and time domain analysis techniques by using network analyser made the antenna characteristics analysis for setting up antenna more accurate. In addition, it makes beam width checking without difficulties.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.572-588
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• 2013

In this paper, 4K-UHDTV or 8K-UHDTV and UHD-3DTV that the next generation broadcasting implementation and the possibility of direct receiving environment construction is analyzed on the terrestrial broadcasting. Particularly, we investigated the possibility by analyzing the previous and related works with regard to UHDTV transmission by DVB-T2 that is one of the best commercialized transmission mode. In order that the UHDTV broadcasting succeeds once again after completion of digital terrestrial switch over at the end of 2012, the ultra high resolution image transfer is important. However, the direct, the indoor and ubiquitous receiving environment is important in not only TV but also the personal type multimedia terminal in the sense of UHDTV service penetration. Therefore, in this paper, by using SFN and high error-correcting mode in DVB-T2 standard, the efficient frequency utilization and effective reception environment construction is illustrated. Particularly, SFN network constitution by 2 mutually different frequencies including the VHF bandwidth and UHF band, and etc. is shown. And the method that builds the free wireless receive environment by using SFN low power radio repeater and for home use gap filler is proposed. And the effect and frequency amount required are presented, when UHDTV broadcasting use 10MHz bandwidth.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.136-150
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• 2010

Due to the effect of indoor coverage problem, the QoS of the indoor users will be degraded dramatically, with the number of indoor users. The femto cell is a popular solution for such problems. Since the price of the femto base station is usually cheap enough, one can sets up huge number of base stations in a small indoor area to reduce the size of communication cell. In this way, the QoS of the indoor users can be improved significantly. Moreover, the data rate can also be increased. However, how to decide an ideal transmitting power according to the surrounding radio environment is not a trivial problem, that still has not been addressed well. If the transmit power of femto base station is too large, the interference to the macro users will be increased. Conversely, if the transmit power of femto base station is too small; the coverage of femto base station will be reduced. To address this problem, we propose a power configuration method in femto base station using Genetic Algorithm by investigating a new fitness function. Furthermore, we adopt the weighted sum approach to improve the user performance in different modes. The simulation results show that the proposed power configuration method can not only improves the downlink SINR, but also enhance the channel capacity for both the Macro cell systems and Femto cell systems compared with some conventional methods.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.15-23
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• 2016

To support the telematics and infotainment services, vehicle-to-everything (V2X) communication requires a robust and reliable network. To do this, the 3rd Generation Partnership Project (3GPP) has recently developed V2X communication. For reliable communication, accurate channel estimation should be done. However, because vehicle speed is very fast, radio channel is rapidly changed with time. Therefore, it is difficult to accurately estimate the channel. In this paper, we propose the new linear minimum mean square error (LMMSE) channel interpolation scheme based on the Long Term Evolution (LTE) sidelink system in vehicle-to-vehicle (V2V) environments. In our proposed reduced decision error (RDE) channel estimation scheme, LMMSE channel estimation is applied in the pilot symbol, and then in the data symbol, smoothing and LMMSE channel interpolation scheme is applied. After that, time and frequency domain averaging are applied to obtain the whole channel frequency response. In addition, the LMMSE equalizer of the receiver side can reduce the error propagation due to the decision error. Therefore, it is possible to detect the reliable data. Analysis and simulation results demonstrate that the proposed scheme outperforms currently conventional schemes in normalized mean square error (NMSE) and bit error rate (BER).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.809-819
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• 2004

In this paper, in order to exclude the expansion of M/W relay frequency or its new frequency assignment possibly, we analyzed a possibility of substituting M/W system by B-WLL or optical fiber network regarding service quality and economical points. To define the target of service quality, pre-condition and analysis method for the selected media have been derived to compare each other. E1 transmission with BER 10$^{-1}$ was chosen as a reference capacity, and service distance was calculated f3r the selected media as a function of availability. Also from the economical point we considered 3 systems such as optical fiber, M/W, and B-WLL based upon basic system structure, and analyzed them for various line configurations of fiber optic and B-WLL according to service period, system capacity, transmission distance, and data rate. It was confirmed that B-WLL can provide quality of service with 99.999 % availability within 1.6 km cell radius, and for optical fiber substitution, the leased fiber conduit on an electric pole is more economical than M/W system irrespective of service period, but in case of directly digging for underground conduit, it turned out ineffective regardless of cabling duct types.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.778-784
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• 2017

In this paper, we propose wired and wireless distributed control systems designed to improve the freight logistics efficiency and verify wired distributed control systems. The verification condition required that 50 cargo vehicles be connected and operated to travel 21 km from Busan Sinhang station to Jinlye Station at an average speed of about 100km/h. The verification results show that the traction output and braking output of the control and controlled cars are dispersed by the wired distributed control system. The application is expected to more than double the efficiency of the logistics compared to the existing freight transportation system. However, in the case of the wired distributed control system, cable installation and maintenance are difficult, and it is impossible to change the combination of freight vehicles. Through the verification of the wired distributed control system, the applicability of distributed control systems to freight vehicles in Korea was confirmed and the system was further developed to produce a wireless distributed control system. In order to apply the wireless distributed control system, a propagation environment analysis for the ISM band was performed in the testbed and, as a result, it was confirmed that Wifi technology using the ISM band could be utilized. In order to use the WDP (Wireless Distributed Power) devices newly installed in the target vehicles, the transmission / reception control signals associated with the propulsion / braking / total control devices are defined. In the case of wireless distributed control systems, the convenience of their application and operation is guaranteed, but reliability and emergency safety measures should because of the dependence of the control of the vehicle on radio signals.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.73-88
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• 2015

Due to the cases of recent global warming and unusual weather etc., large-scale natural disasters such as typhoons, floods, snow damage occur frequently across the continents such as Southeast Asia and North America, South America etc. and risks of earthquakes and tsunami are also increasing gradually in Korea which has been regarded as a safe zone and disaster types are also being diversified such as typhoons, floods, heat waves, heavy snow and damage scale is also enlarged. In addition, due to geographical characteristics or lack of infrastructure, disasters tended to occur intensively around a specific region or city in the past but disasters occur throughout the country in recent years so preparation for disaster prevention has emerged as an urgent challenge issue. Therefore, considering that the plan of obtaining the effective feedback function of disaster Information is very important in the proactive and software aspects for disaster reduction, this paper analyzed this three aspects of contents, procedural and contextual aspects and proposed the plan. First, in the content aspect, building disaster prevention information communication Infrastructure, building urban and regional disaster prevention system, obtaining concurrency and sharing of information and second, in the procedural aspect, active utilization of ICT(Information and Communication Technology) of the prevention stage, disaster prevention information collection and analysis reinforcement of the preparation stage, improvement of decision-making structure and field command system of the response stage, recovery system related information promotion of the recovery stage were proposed as alternatives and finally, in the contextual aspect, if disaster prevention information is effectively managed through maintenance of disaster prevention information related systems, obtaining domainality by disaster prevention work, improvement of the ability to judge the situation, obtaining comprehensive and feedback function etc, it is considered to significantly contribute to reducing natural disasters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1048-1057
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• 2004

WCDMA system is 3rd generation wireless mobile system specified by 3GPP. In WCDMA downlink, two power control schemes are operated. One is inner loop power control operated m every slot Another is outer loop power control based on one frame time. Base staion (BS) can estimate proper transmission power by these two power control schemes. However, because each MS's transmission power makes a severe effect on BS's performance, BS cannot give excessive transmission power to the speclfic user 3GPP defined Power Control Dynamic Range (PCDR) to guarantee proper BS's performance. In this paper, we propose Adaptive PCDR algorithm. By APCDR algorithm, Radio Network Controller (RNC) can estimate each MS's current state using received signal to interference ratio (SIR) APCDR algorithm changes MS's maximum code channel power based on frame. By proposed scheme, each MS can reduce wireless channel effect and endure outages in cell edge. Therefore, each MS can obtain better QoS. Simulation result indicate that APCDR algorithm show more attractive output than fixed PCDR algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4C
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• pp.333-341
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• 2002

This article is written to make a foundation for effective radio network engineering by enabling the accurate traffic assumption between Base Station (BTS : Base Station Transceiver Subsystem) md Repeater through the scientific and systematic analysis of mobile traffic dealt within CDMA Base Station. Among these, Repeater, having direct physical connection with BTS, simply does the remote relay function but the volume of the traffic flowed into the repeater is not accountable. The total BTS traffic is the sum of traffic dealt by the BTS and multiple Repeaters. In this article, we tried traffic analysis of this kind by adopting RTD (Round Trip Delay) which is specially designed to measure distribution of the distance between the Base Station and the Mobile station by differentiating the traffic dealt by BTS from traffic dealt by Repeaters. The fact that the connection between mobile station and BTS via Repeater (which is located remotely) yields far more delay than the direct connection between mobile station and BTS is the clue of this article. Based on this fact, Time Delay equipment was put at the receiving side of the Repeater to add certain amount of delay to the traffic to BTS and the result showed that the 99.78% of the traffic can be identified.