• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.1
• /
• pp.127-134
• /
• 2022

A modified folded monopole slot antenna for 3G WCDMA (1.91 ~ 2.17 GHz), 4G LTE (2.17 ~ 2.67 GHz), 3.5 GHz 5G (3.42 ~ 3.7 GHz) and Wi-Fi dual band (2.4 ~ 2.484 GHz / 5.15 ~ 5.825 GHz) was proposed for the first time. The proposed antenna is designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 35 × 60 mm². The measured impedance bandwidth of the proposed antenna is 2910 MHz(1.84 ~ 4.75 GHz) and 930 MHz(5.11 ~ 6.04 GHz), antenna gain in each frequency band is from 1.811 to 3.450 dBi. In particular, it was possible to obtain a commercially suitable omni-directional radiation pattern in all frequency bands of interest.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.186-188
• /
• 2014

In recent years, domestic as well as LTE wireless network of Wi-Fi and most used. In addition, mobile-intensive services that used mainly in our society makes it easier, SNS, application (APP), and file downloads. As such, the amount of data requested, while living at the time of mobile users will want to be safe from the earliest. And the wireless network communications mortality (3G, 4G (LTE), LTE-A) and Wi-Fi (802.11 n-2.4 G H z z H a c-5, 802.11 G), and users are mainly used in the death 4G (LTE), communication Wi-Fi, 802.11 n-2.4 GHz are used most frequently. As above, use the wireless network in order to safely and quickly developed the technology of the Li-Fi. Li-Fi light (visible light) technology to communicate with, and Wi-Fi (802.11 n-2.4 G z H) 100 times faster, LTE-A 66 times faster. However, the current Li-Fi to commercialise the big issue exists. In this paper, there are a lot of existing problems in the commercialization of Li-Fi being used in Wi-Fi, and a comparative analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.7
• /
• pp.2668-2717
• /
• 2021

Demands for high-speed wireless data services grow rapidly. It is a big challenge to increasing the network capacity operating on licensed spectrum resources. Unlicensed spectrum cellular networks have been proposed as a solution in response to severe spectrum shortage. Licensed Assisted Access (LAA) was standardized by 3GPP, aiming to deliver data services through unlicensed 5 GHz spectrum. Furthermore, the 3GPP proposed 5G New Radio-Unlicensed (NR-U) study item. On the other hand, artificial intelligence (AI) has attracted enormous attention to implement 5G and beyond systems, which is known as Intelligent Radio (IR). To tackle the challenges of unlicensed spectrum networks in 4G/5G/B5G systems, a lot of works have been done, focusing on using Machine Learning (ML) to support resource allocation in LTE-LAA/NR-U and Wi-Fi coexistence environments. Generally speaking, ML techniques are used in IR based on statistical models established for solving specific optimization problems. In this paper, we aim to conduct a comprehensive survey on the recent research efforts related to unlicensed cellular networks and IR technologies, which work jointly to implement 5G and beyond wireless networks. Furthermore, we introduce a positioning assisted LTE-LAA system based on the difference in received signal strength (DRSS) to allocate resources among UEs. We will also discuss some open issues and challenges for future research on the IR applications in unlicensed cellular networks.

• Journal of Advanced Navigation Technology
• /
• v.25 no.6
• /
• pp.536-542
• /
• 2021

In this paper, we proposed a triple band printed monopole antenna with a bent branch strips for WiFi / 5G. An antenna structure in which bent strips for generating multiple resonance are attached in the form of branches was newly proposed based on a typical monopole strip vertically erected as a triple band antenna structure. The proposed antenna is designed on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 28×40 mm². The measured impedance bandwidth is 430 MHz (2.22~2.65 GHz) in the 2.4 GHz WLAN, 450 MHz (3.38~3.83 GHz) in the 3.5 GHz and 2390 MHz (4.95~7.34 GHz), In particular, it has been observed that antenna has a stable omnidirectional radiation patterns as well as gain of 1.537 dBi, 1.878 dBi and 2.337 dBi in the entire frequency band of interest.

• 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.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2010.11a
• /
• pp.1070-1073
• /
• 2010

모바일 기기의 통신에 있어 가장 중요한 요소는 이동성 지원이다. 이에 따라 3G 와 같은 이동통신을 지원하는 기술이 출현하게 되었고 이를 통해 이동 중에도 데이터 통신이 가능하게 되었다. 하지만 이동통신은 많은 에너지 소비와 높은 통신 비용문제 등으로 대용량 전송에 적합하지 않은 문제점이 있다. 이에 반해 Wi-Fi 와 같은 Wireless 네트워크는 이동성을 지원하지 않는 대신 허가 받지 않은 주파수 대역을 이용하여(예: Wi-Fi 의 2.4GHz, 5GHz) 높은 대역폭을 제공할 뿐만 아니라 전력을 적게 사용하는 장점이 있다. 본 논문에서는 3G 와 Wi-Fi 을 동시 다중 연결을 통해 서로의 장점을 극대화하고 단점을 보안한 기법을 제시하고 시뮬레이션을 통해 이를 검증 한다.

• Journal of Information Technology and Architecture
• /
• v.9 no.4
• /
• pp.433-442
• /
• 2012

This paper focuses on developing a smartphone-based mobile office system for a logistics company in Korea using HTML5. Mobile office is smart working environment of working out of a company office using mobile devices such as smartphones and portable computers which are connected to the company servers via WiFi or 3G/4G. Recently many companies are introducing mobile office information systems with the smartphone wave, but they are having difficulties in maintaining and updating their systems due to the transformative mobile application platform. Therefore, we need a platform-independent implementation tools for the mobile office application and HTML5 is one of the solution tools. In this paper, we develop mobile and web applications applicable to all kinds of mobile devices such as iOS, android and windows mobile etc using HTML5. The proposed mobile office system consists of groupware, marketing management, reporting module and transportation management system.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.6
• /
• pp.223-229
• /
• 2023

This papart proposes single pole double throw (SPDT) switch with six-stage radial stub resonators in the 3.6~4.0 GHz band. The switch was simulated using ADS (Advanced Design Software), a design tool for the wireless communication circuits, and evaluated on a pcb substrate. The measurement results of the radial SPDT switch showed an average 90 dB isolation, and 1.5 dB insertion loss. This isolation characteristic was 20 dB superior to higher than those laboratory or commercial products reported thus far. The proposed SPDT switch is applicable to multi-band RF front-end systems, such as WiMAX, LTE/5G, Wi-Fi, and HyperLAN.

• Journal of Digital Convergence
• /
• v.10 no.3
• /
• pp.265-271
• /
• 2012

This paper proposes a communication distance performance evaluation method for mobility of service robots equipped with a Wi-Fi module. Service robots have function of mobile communication system according to classified services and utilize a (preferred) communication method, wireless lan(IEEE802.11 a/b/gin) communication method of ISM band(2.4GHz and 5.8GHz). For evaluating degradation performance of wireless data for the service robot's mobility. We measured and presented reference vectors obtained by utilizing a distance attenuation correlation method in the real world environment. To evaluate performance of the proposed method, path loss of reference vectors was assigned to the Azimuth 301W and then transmission rate and the transmit throughput of the test sample were measured by the Chariot. The proposed measurement method is necessary for securing wireless LAN communication distance for mobility of mobile smart device and service robots. In addition, if the proposed measurement method os adopted, It would be expected that mobile smart device vendors would utilize the method as an effective wireless LAN mobility communication distance performance evaluation method.