Byung-Jin Lee

Implementation of a dynamic high-performance Notch Filter for Power-Line Communications

Recent studies have been conducted on powerline communications as a viable alternative to the spread of the spread of the Internet and the Internet as the chief source of information act in the information age, the internet does not reach local Last Mile Solution. Powerline communication, but because it has been designed to transfer power to the high frequency signal to be sent when the close of wireless communications services impacted. The notch filters of a common way to eliminate the interference are used. In this paper, a dynamic high-performance notch filter applying WDF performance was verified through MATLAB and was implemented using a TI`s TMS320C6416T DSP board.

Propagation Characterization Based on Geographic Location Variation for 5G Small Cells

Developments in next-generation wireless transmission technology and efficient frequency-use research are based on understanding the characteristics of the exact radio channel. With regard to developments in next-generation mobile communication systems, performance verification of the development system is essential, for which it is necessary to estimate the exact wireless-space channel. This paper presents results of the analysis of radio propagation characteristics based on location variation in outdoor environments for small-cell 5th generation (5G) mobile systems. Changes due to variation in location were measured using a channel sounder in a microcell environment with a 0.5 km radius in Korea. In order to analyze the propagation characteristics, the best distribution model reflecting the characteristics of the locations was derived. A comparison between actual measurements and three-dimensional ray-tracing simulation results confirmed the validity of the measurement result.

Measurement and analysis for 3.5GHz small-cell environment with time and spatial ratio

Recently, researches regarding spectrum sharing has been underway due to the insufficiency of spectrum resources. Basically, it is necessary to solve the temporal or spatial environment in order to share the frequency. In this paper, we will introduce to our own channel sounder and we use this system to generate path loss modelling based on time and space ratio.

Enhanced Transmit-Antenna Selection Schemes for Multiuser Massive MIMO Systems

Massive multiple-input multiple-output (MIMO) systems are a core technology designed to achieve the performance objectives defined for 5G wireless communications. They achieve high spectral efficiency, reliability, and diversity gain. However, the many radio frequency chains required in base stations equipped with a high number of transmit antennas imply high hardware costs and computational complexity. Therefore, in this paper, we investigate the use of a transmit-antenna selection scheme, with which the number of required radio frequency chains in the base station can be reduced. This paper proposes two efficient transmit-antenna selection (TAS) schemes designed to consider a trade-off between performance and computational complexity in massive MIMO systems. The spectral efficiency and computational complexity of the proposed schemes are analyzed and compared with existing TAS schemes, showing that the proposed algorithms increase the TAS performance and can be used in practical systems. Additionally, the obtained results enable a better understanding of how TAS affects massive MIMO systems.

A wireless channel sounding system for 3.5GHz band small-cell environmental measurements

Recently, 3.5GHz band is determined as mobile communications frequency in IMT-2020. Basically, TD-LTE in small-cell environment and downlink supplement in hotspot area can be utilized in 3.5GHz band. According to this latest trends, channel sounder for 3.5GHz band is harmoniously implemented by universal devices such as NI equipment for baseband and transceiver and self-developed modules which are high power amplifier, RF switch, timing module and antenna. From this channel measurement system, we obtain the various measurement parameters through real wireless channel measurement in urban and suburban areas for 3.5GHz band.

Link Relay H-ARQ mode for Throughput improvement in a Satellite Communication network

Satellite communication is a communication method using a satellite as a repeater communication on the air and have a communication range is wide and is possible to transmit high-speed data, so Satellite communication has been highlighted as the next generation communication. However, because the distance between the ground and the satellite is far away, there is a disadvantage that propagation delay time is very long and packet is damaged. Therefore, this study was applied to Link Relay H-ARQ system in order to complement the damage to the packet. Furthermore, we propose the Modified Link Relay H-ARQ scheme is a new scheme to supplementation the delay time. By applying the Markov channel for implementing a channel of satellite communications, the results of analyzing the performance, when applying the Link Relay HARQ scheme, BER and PER performance was improved, when applying the Modified Link Relay H-ARQ scheme, Throughput performance was confirmed improvement.

Performance Comparison of Modulation Schemes according to the Dimming Control in MIMO-VLC System

Visible light communication is a communication method using an LED’s blinking(ON/OFF), it has a feature of light because of the limit of perception by the human’s optic nerve. LED’ dimming control used in the VLC system is important factor needed to provide energy saving and life benefits. With advances in VLC system, MIMO technology has received much attention in that it can be obtain channel capacity proportionate to the number of antenna. Therefore, in this paper, with RC method which is one of the MIMO style in VLC system, it is compared communication performance using RZ-OOK, VPPM, MPPM and OPPM. As a result of the simulation was run against this, MPPM works well in terms of Power requirement and OPPM works well in terms of Spectral efficiency and Bandwidth requirement, also it was confirmed that there is a significant impact on the communication performance of each modulation scheme according to the dimming.

Performance Comparison of MIMO-VLC Systems based on CSK-OFDM

Abstract Visible light communication is a converging communication by technologies that enable solutions using the LED Lighting. There is a need to research about it in order to improve the performance of the wireless communication by using a Color LED and improve the efficiency of data. In this paper, Assume the General indoor communication environment and LED communication systems based on CSK-OFDM applied to a MIMO communication system, We studied about transmitting method of more efficient communication. After performing the simulation based on IEEE 802.15.7 Standardization, as a result of the analysis of performance, it was confirmed the there is a significant impact on the performance of SNR and BER performance by the transmitting method based on MIMO and external noise using the LED communication system based on CSK-OFDM. Key Words : VLC, Color LED, CSK, OFDM, MIMO, External Noise * 준회원충북대학교 전파통신공학과 ** 준회원 충청지역사업평가원 *** 정회원 충북대학교 정보통신공학과 (교신저자)접수일자 : 2014년 6월 13일, 수정완료 : 2014년 7월 13일게재확정일자 : 2014년 8월 8일Received: 13 June, 2014 / Revised: 13 July, 2014 Accepted: 8 August, 2014

Performance Analysis of the Visible Light Communication System based on MIMO under Various Interference environments

We perform simulation. It is that LED panels is fixed and moving the terminal with PD in order to analyze the performance of visible-light wireless communication system based on MIMO under variety of the interference environment. And, based on the technology MIMO, we analyzed whether the interference caused by external light to give what effect changes in the quality of the communication channel. The distortion due to time delay in channel transmission must be compensated by using the equalizer. Especially, use of equalizer is need absolutely as data rate becomes high speed. Therefore, in this paper, the system VLC, were analyzed BER performance using channel equalization.