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

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.906-918
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• 2012

Wireless Fidelity (WiFi) and Wireless microphone are assumed to operate on adjacent channels in TV White Spaces(TVWS). The Scenario of WiFi potentially interfering with Wireless microphone is analyzed through Minimum Coupling Loss (MCL) and Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) based on the Monte-Carlo simulation method. In the case of single WiFi interfering with Wireless microphone, the protection distance between WiFi and the Wireless microphone should be at least 25.12 m to avoid WiFi impact on Wireless microphone. When the active number of WiFi is 12, the guard band between WiFi and Wireless microphone should not be less than 4.97 MHz to guarantee that WiFi does not interfere with the Wireless microphone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.585-594
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• 2017

Wireless Docking system can provide enhanced convenience to user experience of handheld device such as smart phone by using previously deployed peripheral devises such as monitor and keyboard. In this environment, user can easily use the handheld device with variable peripheral devices at any docking system place. This system would be composed of peripherals except host computing device contrarily to previous desktop and laptop environment. For this system, Wi-Fi Alliance has been developing standard technology based on Wi-Fi Direct(Wi-Fi Peer-to-Peer Technical Specifications v1.2, 2010) technology. However, this system can make a problem which may lead to complex connectivity on handheld device due to non-compatible communication interface. To address given problem, we designed a new method of Bluetooth tunneling technology via previous Wi-Fi Direct communication, and evaluated it with experiment results.

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

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1327-1332
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• 2015

In this paper, we studied several aspects that affect the quality of VoIP using WiFi network. It's clear that the background data traffic within an AP, the end-to-end delay and the traffic loss of TCP/IP network gives serious effects on the voice quality. A kind of access control for the VoIP connection within an AP should be done for the acceptable voice quality.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.59-64
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• 2014

This paper address the scheme for WiMAX backhaul in mobile communication network. These days most ISPs has implemented Wi-Fi backhaul using T1/E1 and DSL. if WiMAX is installed as the alternative to the mobile backhaul, it can decrease the costs drastically for the installation and operations. And it will be one of the best cost-effective solutions to cover the service areas which has not the wired communication infrastructure. WiMAX can be used for Base station, Subscriber Station, and Relay. In this paper, the performance is measured for downstream and upstream using NAT and port forwarding functions by configuring WiMAX server and WiMAX SS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5479-5486
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• 2012

In this paper, we have measured PRR, RSSI and LQI of ZigBee channels under Wi-Fi environment and have assessed channel characteristic and link quality. To confirm any relationship among RSSI, LQI values and PRR under Wi-Fi interference in overlapping and non-overlapping channels of Wi-Fi and ZigBee, the experiments were performed without Wi-Fi, with Wi-Fi and file download through Wi-Fi. Under Wi-Fi interference, We perfomed experiments to ensure channel characteristics and link quality by fixing Wi-Fi and ZigBee receiver and varying the distance between ZigBee receiver and transmitter. ZigBee transmitter sends packet of 256 bits every second to ZigBee receiver. PRR was measured from ZigBee with variance of distance between fixed Wi-Fi and ZigBee. RSSI, LQI, PRR were measured from ZigBee with fixed Wi-Fi, fixed ZigBee receiver and variance of distance of ZigBee transmitter. As a result, we confirmed decrease of PRR under Wi-Fi interference but RSSI, LQI values similar regardless of overlapped or non-overlapped channel and Wi-Fi interference. Therefore, PRR should be used for interference detection in ZigBee communication under Wi-Fi environment but RSSI and LQI are not appreciate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2143-2148
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• 2016

Recently due to development of IT technology, ideas and technology that blend with environment have evolved. This technology can help people's living environment and in the future it is an essential component of the connected society. In this paper, we propose WiT(WiFI Trashcan) which takes advantage of the IT technology fusion and environmental factors at the same time to create a more pleasant environment. WiT provides a free WiFi when trash is disposed in the trash can. WiT detects whether a user disposes trash, determines the volume of the trash and provides free WiFi. To detect trash we use ultrasonic sensor and trash weight is measured by using weight sensor. Also by using Phython programming the measured sensor value is transmitted to Raspberry Pie and WiFi delivery time is determined. We used Arduino and Raspberry Pi to design and implement WiT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.74-77
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• 2015

WiSee is by utilizing the frequency of Wi-Fi(802.11n/ac), a technique for performing the operation recognized by the user's gesture. Current motion recognition scheme are using a dedicated device (leaf motion, Kinekuto) and the recognition range is 30cm ~ 3.5m. also For recognition range increases the narrow recognition rate, there is inconvenience for maintaining a limited distance. But WiSee is used by Wi-Fi it is possible to anywhere motion recognition if available location. Permeability also has advantages as compared with the conventional recognition method. In this paper I take a look at the operation process and the recent trend of WiSee.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.5
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• pp.669-674
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• 2012

This study presents the remote control of a mobile robot using iPhone based on Wi-Fi communication. The paper proposes the following set of user interfaces : acceleration mode, arrow touch mode, and jog-shuttle mode. To evaluate the proposed three interfaces, a virtual robot is controlled in a monitor to follow a referenced trajectory using iPhone. In simulation, the standard deviation and summed errors are analysed for showing good and weak points of the proposed three interfaces. The proposed interface replace an additional remote controller requiring cost with a cellular phone. Results of an experiment show that the proposed interfaces can be effectively used for remote robot control.