• 한국위성정보통신학회논문지
• /
• 제9권2호
• /
• pp.28-32
• /
• 2014

본 논문에서는 LTE 시스템을 위한 Cyclostationary 신호 검출 기법의 성능을 분석하였다. 스펙트럼 사용 효율을 높이고 주파수를 공유하는 인지무선(Cognitive radio, CR)기술에 Cyclostationary 신호검출 기법을 적용하여, Long term evolution(LTE) 환경의 주파수 대역 내에서 신호를 검출하였다. LTE 시스템은 3rd generation partnership project(3GPP)에서 최대 전송률을 높이고, 낮은 지연을 제공하기 위한 표준으로 지정되었다. 본 논문에서는 하향링크 직교 주파수 분할 다중 접속(Orthogonal frequency division multiple access, OFDMA) 신호를 기준으로 LTE 신호를 생성하였으며, 생성된 신호의 Segment 및 임계값에 따라 검출성능을 분석하였다. 모의실험에 적용된 채널은 가우시안 채널이고, 추후 LTE 시스템에 CR을 적용하기 위한 향후 연구 방향에 대하여 논의하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.2193_2194
• /
• 2009

A digital over current relay(OCR) is realized by using TMS320C32 microprocessor. Fourier Transform is used to obtain the phasor of a current signal and a 2nd low pass filter is adopted to prevent aliasing error. H/W test shows almost same results with those of the S/W test. It could be possible that confirm simularity between H/W and S/W test in this paper.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
• /
• pp.44-47
• /
• 2001

In a competitive environment of electric power industy, the level of uncertainty increase due to generation investment decisions creating new challenge to transmission system planner. The use of a locational signal and the provision of a indicative plan to control the generation investment reasonably is very important in the viewpoint of a regulator. The main target of this stuty is to emphasize on the necessity for considering simultaneously both generation and transmission expansion plan. This paper demonstrate the many case studies to make certain of the necessity for the interconnection between generation and transmission planning. In addition to, the planning in Korea power industry is considerd.

• Journal of Positioning, Navigation, and Timing
• /
• 제1권1호
• /
• pp.29-34
• /
• 2012

A software GNSS signal generator for the GPS L1/L2/L5 and Galileo E1/E5 signals is proposed in this paper. And this signal generator is designed and implemented with several components by considering the reuse and expansion of components for similar GNSS signals. The characteristics of the reusability of the components are confirmed with the carrier generation and the band-pass filter components. And the functionality of the GNSS multi-band IF signal generator is validated by using the commercial software GPS L1 receiver, and the performance of signal acquisition, tracking and accuracy of horizontal position error are analyzed for this validation. As a result, the GPS L1 signal generator operates successfully and it could be expected that other signal generators also operate well because most of components are the same as those of the GPS L1 signal generator.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권9호
• /
• pp.4390-4407
• /
• 2019

The paucity of pilot signals in Massive MIMO system is a vital issue. To accommodate substantial number of users, pilot signals are reused. This leads to interference, resulting in pilot contamination and degrades channel estimation at the Base Station (BS). Hence, mitigation of pilot contamination is exigency in Massive MIMO system. The proposed Time Shifted Pilot Signal Transmission with Pilot signal Hopping (TSPTPH), addresses the pilot contamination issue by transmitting pilot signals in non-overlapping time interval with hopping of pilot signals in each transmission slot. Hopping is carried by switching user to new a pilot signal in each transmission slot, resulting in random change of interfering users. This contributes to the change in channel coefficient, which leads to improved channel estimation at the BS and therefore enhances the efficiency of Massive MIMO system. In this system, Uplink Signal Power to Interference plus Noise Power Ratio (SINR) and data-rate are calculated for pilot signal reuse factor 1 and 3, by estimating the channel with Least Square estimation. The proposed system also reduces the uplink Signal power for data transmission of each User Equipment for normalized spectral efficiency with rising number of antennas at the BS and thus improves battery life.

• 한국군사과학기술학회지
• /
• 제15권3호
• /
• pp.343-349
• /
• 2012

To detect targets for autonomous navigation of unmanned ground vehicle, mounted sensors are required to work all-weather condition. In this point of view, the FMCW radar is quietly appropriate. In this paper, we present development results of target signal simulator for multi-beam type FMCW radar. A target signal simulator make pseudo target signals which simulates multiple moving targets. And we describe how to make hit information for each target in multi-beam type radar. The developed methods are utilized for target tracking device. Moreover it can be applied to similar target signal simulator.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 A
• /
• pp.395-397
• /
• 2001

A new automatic generation control (AGC) signal transmission format will be adopted in the new energy management system (EMS) that KEPCO is planning to install for managing and operating the power system efficiently under the deregulation environment. Therefore, it is necessary for the power plants to make the AGC processing logic fit the new AGC signal flow format. In this work, we compare the new signal transmission scheme with the conventional one in view of its effect to the signal flow in the distributed control systems (DCS) that ale equipped in power plants to handle AGC operation. Then we propose a basic logic configuration for DCS that can be used with the new signal format. In the design of the configuration, some practical issues that should be discussed for the proper operation of the plants are considered.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집
• /
• pp.442-446
• /
• 2009

As the railway transportation is getting faster and its operation speed has increased rapidly, its signal control has been complicated. For real time signal processing it is very important to prohibit any critical error from causing the system to malfunction. Today, most of the railroad's controling communications between wayside and train are made in one way. Therefore, by using a forward error correction technique, which receiver can actively correct the signal error, we can increase the performance and the stability of the railroad signaling system. In this paper, we introduce low density parity check(LDPC) that is used by next generation wireless communications and DMB technique. We verified that we can achieve low bit error rate(BER) in high signal to noise ratio(SNR) by using LDPC.

• 반도체디스플레이기술학회지
• /
• 제10권1호
• /
• pp.7-15
• /
• 2011

In this paper, we implement measurement functionality for the 3GPP (Third Generation Partnership Project) WCDMA (Wideband Code Division Multiple Access) modem. Generally speaking, the receiving algorithms in normal modems cannot be used directly to the measurement system due to the lack of the measurement accuracy. In this paper, we propose the new measurement algorithm for precise 3GPP WCDMA signal measurements. In the measurement algorithm, 4-stage parameters estimation scheme is used. To improve the measurement accuracy, we increase the number of the received signal samples by interpolation. The proposed 3GPP WCDMA signal measurement algorithm can be used for verifying and implementing SoC/FPGA modem measurement systems.

• Current Optics and Photonics
• /
• 제5권4호
• /
• pp.466-476
• /
• 2021

Frequency-multiplication technology based on microwave photonic principles can be used to generate microwave and millimeter wave signals with a wide frequency tuning range. However, the existing cascaded external modulation frequency-tupling scheme needs to ensure the phase coherence of the modulated Radio Frequency (RF) signal, while the phase modulation directly limits the frequency tuning range of the external modulation frequency multiplication. In this paper, a novel approach for generating an incoherent frequency 12-tupling signal with cascade modulation is proposed. The structure of cascaded dual-parallel Mach-Zehnder modulators can generate a frequency 12-tupling signal. The proposed structure uses no filter or phase control of the RF driving signal. Microwave photonic frequency-tupling was realized under incoherent conditions. Software simulations and experiments validated the proposed structure and proved that it can generate frequency 12-tupling microwave signals under incoherent conditions. Both the frequency range and reliability of the frequency-tupling system has been improved by the proposed structure.