• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.5
• /
• pp.3455-3461
• /
• 2015

LTE and Wi-Fi networks provide wireless communication services to passengers in subway where the number of network access fluctuates according to passenger movement. While the number of network access increase, LTE can provide stable communication service but Wi-Fi suffers temporal access delay to network. This paper analyzes the increase in access delay of Wi-Fi network according to increasing user in subway section by making mathematical modeling of Wi-Fi network and simulation study. The access delay characteristics of Wi-Fi network is measured along an subway line and the results are compared to the theoretical study. These results can be applied to the connection method to build an efficient network structure between LTE and Wi-Fi interworking network and the future introduction of LTE-R.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.9
• /
• pp.4341-4348
• /
• 2012

This paper presents a web-based real-time monitoring system for a photobioreactor using an WiFi wireless network. An WiFi interface can support high speed data transfer, up to 11Mbps and it can be compatible with commercial wireless LAN environment. Thus, the proposed cell culture based on WiFi network can be easily applied to the reconfigurable system and real-time monitoring system. In this paper, we integrate the commercial WiFi module to the various bio-sensors and sensor control board to configure the wireless network. After we evaluate application S/W for monitoring the environment within incubator, we verify the proposed sensor networks for a cell culture system and its monitoring system. This result can be applicable for various bio-applications that require the network configuration and real-time monitoring system.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.10 no.4
• /
• pp.109-116
• /
• 2014

In recent, ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart phone, notebook computer, printer and portable multimedia devices. Accordingly, studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi device using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band causes serious network performance deterioration of wireless sensor networks. This paper examined a method of identifying channel status to avoid interference among wireless communication devices using IEEE 802.11b (Wi-Fi) and other ISM bands during communication among IEEE 802.15.4 based wireless sensor network nodes in ISM band. To identify channels occupied by Wi-Fi traffic, various studies are being conducted that use the RSSI (Received Signal Strength Indicator) value of interference signal obtained through ED (Energy Detection) feature that is one of IEEE 802.15.4 transmitter characteristics. This paper examines an algorithm that identifies the possibility of using more accurate channel by mixing utilization of interference signal and RSSI mean value of interference signal by wireless sensor network nodes. In addition, it verifies such algorithm by using OPNET Network verification simulator.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.2
• /
• pp.127-134
• /
• 2017

In this paper, we try to solve the frequency shortage due to the increase of LTE terminals and the traffic jam caused by the inefficient WiFi connection method. The proposed LTE-WIFI Vertical Handover method uses a pre-authentication method of the AP through LTE and a method of controlling the access AP of the terminal using the RADIUS server. Through the simulation, the proposed method shows that the access speed of the AP is improved by about 95% compared to the conventional connection method, and the connection speed is improved by about 18% compared to the conventional method. Providing seamless AP through pre-authentication system and improving wireless network speed through AP access distribution can solve LTE frequency shortage problem and improve wireless network usage satisfaction.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.6
• /
• pp.1143-1150
• /
• 2017

In this paper, we proposed a method to display a hazard warning of hacking in the UX(: User Experience) concept level for non experts in the open Wi-Fi access area. According to the dangers of the AP raised by capture, we developed an application that provides a warning pop-up on the danger of hacking before using for APs that are distinguished by color and selected.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2012.07a
• /
• pp.63-64
• /
• 2012

본 논문에서는 소형 무인 비행체 (Unmanned Aerial Vehicle, UAV)를 스마트폰을 이용하여 제어하기 위한 방법을 제안하고. UAV에 Wi-Fi 통신 모듈 설계 및 개발 과정을 설명한다. 스마트폰과 UAV는 Wi-Fi를 통해 통신하며, 이것의 instruction set은 MCU에서 C언어로 다운로드 된 로직으로 수행하게 된다. 데이터의 송수신은 Serial 포트를 이용하여 흐름을 제어하며 확인할 수 있다. 또한 관련 모듈들을 통합하기 위해 PCB(Printed Circuit Board)과정을 진행, 소형화하여 개발하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.5
• /
• pp.1735-1754
• /
• 2022

The reliability and performance of WiFi need optimization because of the rising number of WiFi users day by day. A highlighted point is saving power while transmitting and receiving packets using WiFi devices. Wake-on-Wlan (WoW) is also implemented to improve energy consumption, but it also needs betterment. This paper will introduce universal ideas to transmit and receive packets using low-power technology like Bluetooth or BLE (Bluetooth low energy). While looking for power-saving ways in this research, WiFi connection and maintenance also take care using lesser power-consuming technology. Identifying different use-cases where low power technology can help save energy and maintain 802.11 connection is part of the research. In addition, the proposed method discuss energy saving with unicast and broadcast/multicast data. Calculation of power-saving and comparison with standalone WiFi usage clearly shows the effectiveness of the proposed method.

• Journal of Advanced Navigation Technology
• /
• v.22 no.6
• /
• pp.636-641
• /
• 2018

In recent years, the Internet of things has grown rapidly and is being used in many fields. The function of an Internet device isto collect information in various environments and to provide useful information to users. Due to recent developments in technology, the kinds of Internet devices are increasing and the prices are getting cheaper. In addition, many open source platforms that are easy to use have been developed and are providing convenience to users. In this paper, wireless data transmission and cloud server system based on ESP-12E NodeMCU module was designed and sensor information collected from Internet devices was transmitted to cloud server through WiFi wireless communication. The collected sensor data was saved by creating channel and field in the cloud server and the data of each field was visualized as a graph.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.3
• /
• pp.13-19
• /
• 2014

Improvement of performances of potable communication devices such as laptops, tablets, and smart-phones enables people to do group meetings in any place. However, even though group members in a meeting locate close, data or information to be shared in the group are exchanged through the cellular networks. This increases unnecessary traffic loads in the wireless/backbone networks and as consequence it increase delays in communications. To resolve the problem, an android-based application is developed in this paper. The application utilizes Wi-Fi Direct so that all members in the meeting can direct exchange materials for the meeting without using cellular networks.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.6
• /
• pp.195-200
• /
• 2009

In this paper, we verified the reliability through local examination by introducing a wired network that is operated at the local waterworks to wireless LAN based Wi-Fi network. The adopted wireless network compared to the existing wired network through saving cost and reducing breakdown points have been proven to be effective qualitatively and quantitatively. This study proved that wireless networks could be introduced for the advancement of operations management of existing metropolitan water supply and the local waterworks that are operating currently.