• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.4
• /
• pp.27-30
• /
• 2016

in this paper, to improve the narrow bandwidth problem of the microstrip antenna for WLAN and WiFi dual band array antenna was designed to satisfy the bandwidth of 3.6GHz and 5.2GHz it contained with IEEE 802. 11. The substrate of proposed microstrip array antenna is FR-4(er=4.3) and $25mm{\times}45mm{\times}0.8mm$ size and thickness t=0.035mm, and the simulation was used for CST Microwave Studio 2014. input return loss compared -10dB less than operates at and when gain 3.6GHz 2.516dB, 5.2GHz showed the results of 3.581dB. the antenna designed to be miniaturized and the be used in electronic devices such as mobile phone.

• Journal of Advanced Navigation Technology
• /
• v.26 no.1
• /
• pp.1-8
• /
• 2022

Telemetry system is a system that measures and transmits status information in the aircraft to the ground. The data received from the ground is information for monitoring the state of the aircraft, and can be checked and analyzed in real time through the test program. Data processing test system for telemetry currently in operation is built to transmit data using wired communication and perform test. As smart devices become popular due to the continuous development of information and communication technology, wireless communication networks are becoming important, and technologies for improving performance are steadily being developed. In this paper, we suggests and builds data processing ground test system for telemetry using wireless communication(Wi-Fi) that can be checked through smart devices such as tablets, in order to break away from the existing method and apply future-oriented technology. Finally, the suggested test system performance was proved by testing in various environments by linking test equipment and test program.

• Annual Conference of KIPS
• /
• 2015.10a
• /
• pp.821-823
• /
• 2015

우리나라에서 어딜 가든 WI-FI를 이용해 네트워크에 접속할 수 있는 환경이 되었다. 하지만 rogue AP로 인한 모바일 기기들의 좀비화, 개인정보 유출, BYOD환경으로 인한 회사의 자료유출까지 다양한 정보들을 보호하고 모바일 기기의 해킹가능성을 줄여야 한다. 본 논문에서는 접속 AP정보와 GPS기반 위치정보를 신뢰 테이블에 등록해 이동 중에는 신뢰테이블 외 신호는 사용자의 확인을 거쳐 rogue AP에 자동접속 되어 기기가 감염되거나, 개인정보가 유출되는 일을 방지하기 위한 방법을 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.11
• /
• pp.1554-1557
• /
• 2020

Looking at the direction of the recent amendments of 802.11 family, there are two major trends. One is to enable the wireless transceivers to support the extremely high-speed wireless transmissions, which has been the mainstream so far. Another big trend is providing a high-performance wireless application platform that meets the demands of the market. This paper summarizes the brand-new IEEE 802.11 amendments from 11ax to 11bf under development by analyzing the innovative features and use cases on them. We provide the vision and direction for the research on the revolutionary data-hungry Wi-Fi 6 and the IEEE 802.11be, alias Wi-Fi 7.

• Journal of the Korea Convergence Society
• /
• v.10 no.11
• /
• pp.9-14
• /
• 2019

In modern society drones are actively utilized in the fields of security, defense, agriculture, communication and so on. Smart technology and artificial intelligence software have been developed with convergence, and the field of use is expected to expand further. On the point of the excellent performance of drones one of the essential technologies is the wireless communication that make the ground facility receive the video streaming obtained by the drones in the air. In the research the concept of communication region is proposed to cover the both the low altitude region for Wi-Fi communication and the high altitude region for LTE communication for the sake of video transmission. Also the hybrid communication structure is designed along the proposed concept and the proposed system is implemented as a communication system in the small size which can be mounted in a small size of drone. It is confirmed that the proposed system contains the effectiveness by showing the ability to successfully transmit HD video streaming in the range of 500 meters and the transfer time between two different communication systems is measured in 200msec by the experiments.

• Journal of IKEEE
• /
• v.24 no.1
• /
• pp.90-96
• /
• 2020

As various communication services have emerged due to the development of mobile communication technology, there is a need for a wideband antenna supporting multiple communication services with one antenna. In this paper, we propose a planar slot wideband antenna that can support all the communication services of 3.1~4.99GHz, the low frequency band of 5G, in addition to the existing communication services such as WiFi, LTE 2300/2500, and WiMAX. Through the simulation, the optimized antenna design parameters were obtained, and the antenna was fabricated to implement an antenna with a frequency bandwidth of 1.96~6.01GHz (S11 <-10dB) and presented the radiation pattern and gain of the antenna. The proposed antenna is a multi-band antenna that can provide all the services of LTE, Wifi, WiMAX, and 5G low frequency bands. It can be used as a repeater antenna in radio shadow area such as buildings, dense areas, and ships.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.1
• /
• pp.41-47
• /
• 2013

This letter describes a dual-band compact monopole antenna with two branches for Wi-Fi applications. The proposed antenna is based on a planar monopole design, and composed of two branches of radiating patches for dual-band operation. The ground size of the antenna matches the ground size of a typical hand-held cellular phone for improved compatibility with mobile phone printed circuit boards. The antenna is designed using a simulator and fabricated with optimized parameters. The fabricated antenna is measured at the lower and higher operating frequencies, and the return loss coefficient, gain, and radiation patterns are determined.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.11
• /
• pp.2657-2675
• /
• 2013

A novel neighbor selection-based fingerprinting algorithm using matrix correlation (MC) for Wi-Fi localization is presented in this paper. Compared with classic fingerprinting algorithms that usually employ a single received signal strength (RSS) sample, the presented algorithm uses multiple on-line RSS samples in the form of a matrix and measures correlations between the on-line RSS matrix and RSS matrices in the radio-map. The algorithm makes efficient use of on-line RSS information and considers RSS variations of reference points (RPs) for localization, so it offers more accurate localization results than classic neighbor selection-based algorithms. Based on the MC algorithm, an error estimation method using artificial neural network is also presented to fuse available information that includes RSS samples and localization results computed by the MC algorithm and model the nonlinear relationship between the available information and localization errors. In the on-line phase, localization errors are estimated and then used to correct the localization results to reduce negative influences caused by a static radio-map and RP distribution. Experimental results demonstrate that the MC algorithm outperforms the other neighbor selection-based algorithms and the error estimation method can reduce the mean of localization errors by nearly half.

• Journal of Satellite, Information and Communications
• /
• v.11 no.1
• /
• pp.21-25
• /
• 2016

In this paper, we propose an algorithm for optimal selection of communications for smart lighting in heterogeneous networks. The smart lighting can be used for information communications and lighting simultaneously. To improve BER performance of smart lighting in heterogeneous networks, it adaptively selects a communication method among OCC, Wi-Fi, BLE based on distance between sensors and smart lightings, low power consumption for user requirements, operating time of smart lighting in Line-of-Sight(LOS)/Non-LOS channels. Thus, simulation results demonstrate effectiveness of the proposed algorithm contrary to baseline methods in LOS/NLOS channels.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.3
• /
• pp.1373-1392
• /
• 2017

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.