• Journal of Satellite, Information and Communications
• /
• v.8 no.2
• /
• pp.44-49
• /
• 2013

LED communication is a wireless communication technology to transmit information using visible light coming out from the LED(Light Emitting Diode). It is a technique that can overcome RF(Radio Frequency) communication problems that are frequency allocations, human body hazards, security vulnerabilities, and interference between electronic devices. As a technique that can be used as lighting and communications with using LED, LED communication is suitable for ubiquitous environment. This paper introduces the process of data transmission algorithm for LED communication systems algorithm using LED, PD(Photodiode), and MCU(Micro Controller Unit).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.3
• /
• pp.754-762
• /
• 2021

Seamless wireless communication network access technology enables users to guarantee service continuity. Hence, it is necessary for disaster situations in which network service may be interrupted. The Multi-path router is a technology to improve network stability and strengthen field operability, particularly in a disaster environment where network failure can occur by providing high-performance data transmission using multi-communication networks and network security by VPN-based wireless IP. In this paper, a prototype system for an MPR-based wireless communication network was proposed to improve the operation performance for disaster field investigation applications. A comparative experiment was performed on various data transmission performances with the existing single wireless communication network. In addition, another experiment was conducted by measuring the data packet transmission and receiving performance in the existing/new wireless communication system first and then assessing the UDP transmission performance in a single router environment to understand the transmission capability of the new MPR. The experimental results showed that the sending and receiving performance was improved by approximately double that of the existing single wireless communication system. The proposed prototype system is expected to allow users to share and disseminate collected on-site data more quickly and efficiently during a disaster site investigation.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.519-522
• /
• 2002

Currently, in spite of continual efforts, the information utility of the construction industry does not communicate well with other industries. This problem arose from mistaken and misguided efforts on the parts of the construction industry because it left out of consideration construction characteristics which are at the center of construction, and this information system was directly introduced and operated from outside the industry. There were also other mistakes that the existing information systems disregarded in trying to fix these problems. Therefore, this study describes a new process, which proposes to build and utilize a Bridge Management System using the mobile internet concept, to solve the problems of the existing construction information management system.

• The Journal of Society for e-Business Studies
• /
• v.15 no.2
• /
• pp.1-18
• /
• 2010

Mobile Communication Companies are trying to increase data services rather than telephone communication services that already became saturated as the competition of mobile communication market gets intensified. However, it is hard and time-consuming for customers to find desired mobile phone wireless services because of the limitation of screen and speed of the mobile phone. Therefore, the market does not grow rapidly as mobile communication companies expected. In our research, we suggest a personalized wireless service recommendation system that considers each individual context by using geographic information and wireless internet usage logs to overcome the mentioned problems. In order to design and implement the system, we conducted clustering analysis on base stations and real service usage logs of each base station, and suggested a personalized recommendation system based on collaborative filtering that uses the clustering results. Moreover, we verified the performances of our system with experiments.

• Information and Communications Magazine
• /
• v.31 no.3
• /
• pp.96-102
• /
• 2014

지난 반세기 동안 전세계 통신 기술은 기지국-셀간 1:1 대응을 기반으로 설계 되고 만들어 졌다. 이에 따라 셀 간 경계에서의 통신 품질 저하는 당연한 현상으로 받아 들여졌다. 이와 같은 전제 하에 무선 경계에서 통신 품질 향상을 목표로 다양한 스케줄링 기법, ICIC, eICIC[1] 등의 간섭 회피 기법등이 연구 되었다. 하지만 이러한 방식은 기지국간 정보 공유의 제한과 delay에 의해서 실용성이 현저히 떨어진다. 이를 극복하기 위해 모든 정보를 공유하는 가상화(cloud) 기술이 대안으로 떠오르고 있다. 현재 국내 통신 사업자인 KT는 LTE통신망에 가상화 기술을 적용하여 세계 최초로 가상화 기반 LTE 통신서비스를 제공하고 있다. 이에 본고에서는 현재 구현되어 있는 가상화 기술과 현황, 앞으로 구현될 기술에 대해서 알아본다.

• Information and Communications Magazine
• /
• v.27 no.2
• /
• pp.27-31
• /
• 2010

Tera 대역으로 일반적으로 여겨지는 300 ~ 3000GHz 대역을 이용하여 무선 근거리 개인 영역 통신 (WPAN) 에서 20~40Gbps 급의 데이터 통신을 하기 위한 국제 표준화가 현재 IEEE802.15표준화 그룹에서 진행 중이다. 본 논문에서는 표준화의 진행 상항과 더불어 테라 대역의 주파수 할당, 물리계층에서 테라 대역을 이용하여 WPAN이 가능하기 위한 요소 기술로서 빔포밍 기법에 대하여 정리한다. 주파수 할당은 비허가 주파수 대역의 가능성 여부 및 시기 등에 대하여 지난 수년간 테라 대역과 관련되어 ITU에서 발표된 문서들을 요약한다. 테라 대역에서 WPAN을 위한 물리계층의 요소 기술로서는 테라 대역의 주파수 특성인 전파의 직진성 및 거리에 따른 전력 감쇄를 극복하기 위하여 저전력 빔포밍 기술에 대하여 소개한다. 본 논문은 향후 약 5년 후에 표준화가 완성될 것으로 예상되는 시점에서 국내의 통신 관련 연구자에게 초고속 데이터 통신을 가능하기 위한 테라 대역 WPAN시스템을 준비하는데 있어서 유용한 자료로서 사용될 수 있을 것이라 여겨진다.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.5
• /
• pp.283-288
• /
• 2018

In this paper, it is required that the next generation wireless transmission system can support a large number of users without distortion of transmission signal with high data rate in various different propagation environment while using limited resources as efficiently as possible, and therefore an efficient transmission system is continuously required. Because of the large amount of data to be handled in a limited frequency band, a very complex digital modulation scheme is adopted. the linearity of the power amplifier determines the linearity of the entire communication system, and thus a linear amplifier is required. In cognitive radion systems, there is a power control issue in the relationship between primary and secondary users. This problem is solved by simulating the communication system so as to select the cognitive radio power while power control while overcoming linearity by using feed-forward PA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2004.05b
• /
• pp.190-195
• /
• 2004

In this paper, Error rate performance of Convolution coded DS-CDMA 16 QAM signal is analyzed using selective combining diversity reception techniques and maximal ratio combining diversity reception techniques under the environments of Rician fading. With the results of analysis, maximal ratio combining diversity reception techniques provides the performance improvement of about 3-8[㏈] over selective combining diversity reception techniques for the good error performance lot data communication. And it is found that a synergistic performance improvement is show to both diversity reception and Convolution coding, techniques overcoming mobile wireless data communication channel environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.4
• /
• pp.99-107
• /
• 2009

Visible Light Communication (VLC) is a promising wireless communication technology. It offers huge, worldwide available and free bandwidth without electro-magnetic interference, which makes it very attractive for RF-sensitive operating environments. We propose colored LED-based VLC system for hospital use which includes voice recognition system for operating the medical equipments. New Mr hlation Scheme based on the Light Color Space is suggested to overcome the effect of noise generated by background light. Different color space constellations for different symbol sizes are also suggested which would give better bit error rate performance. Finally, Slotted ALOHA or TDMA medium access control protocols are suggested for multi-user operations.

• Journal of Satellite, Information and Communications
• /
• v.12 no.3
• /
• pp.41-49
• /
• 2017

This paper will describe lunar lava tubes' five analyzed fields, such as geology, geomorphology, internal configuration, stability, communication and habitats requirements. This research gets through qualitative and qualitative data analysis as following results. A huge size and configuration differences between lunar lava tubes and earth one on geology and landform environments. Exo-genetics activities, such as meteorites, radiation, and sudden temperature bigger affect than Endo-genetic activities, such as effusion and earthquake of the lunar lava tubes. Landform and internal configuration of the lunar lava tubes due to the huge cave perilous landform that gravity difference have a technical limitation from internal approach and data obtain of the huge skylights and sinuous rilles. Stability of the lunar lava tubes deals with geology and landform. It was obvious geo-structural stability elements results generated on low rate of collapsed halls(skylights), low gravity, and relatively thick covers. In terms of the communication capability on the external and internal lunar lava tubes cordless communication techniques will overcome limitations of the sun-power generates supporting communication systems. Through this research it realized obvious differs between potential habitats possibility by accumulative theories by scholars and techniques of the lunar lava tubes. Especially, it is a favorable expectation throughout overcoming attempt on zero gravity, cosmo radiation, lunar dust of the exo-genetic limitations to the steep escarpment of skylights to approach and achieve techniques by the civil engineering, networking and GIS techniques as the endo-genetic environment treatment.