• Journal of Convergence Society for SMB
• /
• v.6 no.3
• /
• pp.37-41
• /
• 2016

In this paper, we propose a fire alarm system that utilizes Wi-Fi to alarm multiple people at once. This system, based on Arduino, uses smoke, flame and temperature sensor units to sense fire and send detection data to a server via wireless communication system. The server uses stored data to relay current fire situations gathered from nearby sensors to smartphones. It also automatically reports the fire using location data from sensors. Using this system, we were able to retrieve fire alarm from sensors via push notification of our smartphone. We also confirmed the establishment of linkage with sensors and automatic report of fire via SMS. From this result, the possibility of sending real-time notifications via the Internet toward nearby smartphones about disasters such as conflagration has been proven to be feasible.

• Journal of Internet Computing and Services
• /
• v.15 no.2
• /
• pp.19-31
• /
• 2014

In this paper, a parallel backoff delay procedure on multiple IEEE 802.15.4 channels and a channel searching method considering the frequency spectrum of WiFi traffic are studied for IEEE 802.15.4 nodes to avoid the interference from WiFi traffic. In order to search the channels being occupied by WiFi traffic, we analyzed the methods measuring the powers of adjacent channels simultaneously, checking the duration of measured power levels greater than a threshold, and finding the same periodicity of sampled RSSI data as the beacon frame by signal processing. In an wireless channel overlapped with IEEE 802.11 network, the operation of CSMA-CA algorithm for IEEE 802.15.4 nodes is explained. A method to execute a parallel backoff procedure on multiples IEEE 802.15.4 channels by an IEEE 802.15.4 device is proposed with the description of its algorithm. When we analyze the data measured by the experimental system implemented with the proposed method, it is observed that medium access delay times increase at the same time in the associated IEEE 802.15.4 channels that are adjacent each other during the generation of WiFi traffic. A channel evaluation function to decide the interference from other traffic on an IEEE 802.15.4 channel is defined. A channel searching method considering the channel evaluations on the adjacent channels together is proposed in order to search the IEEE 802.15.4 channels interfered by WiFi, and the experimental results show that it correctly finds the channels interfered by WiFi traffic.

• Journal of Practical Engineering Education
• /
• v.13 no.2
• /
• pp.321-326
• /
• 2021

Wireless communication is a core technology constituting the Internet of Things (IoT), but there is no suitable educational equipment to learn various wireless communication technologies used in the Internet of Things through practice. This paper deals with the development of advanced education and training equipment that can perform various IoT wireless communication practices. It uses an Arduino mega board as a device to control various sensors. As wireless network technologies to send and receive the sensing date wirelessly, it makes use of RFID/NFC and Bluetooth among WPAN technologies, WiFi among WLAN technologies and LoRa and 2.4GHz wireless transceiver among WWAN technologies. In addition, GPS, infrared communication, I2C communication, and SPI communication are organized so that various IoT wireless communication technologies can be learned through practice. In addition, since the educational equipment developed in this paper is equipped with two devices, it is designed to perform transmission and reception experiments for wireless network technology within the equipment.

• Journal of the Korea Convergence Society
• /
• v.11 no.6
• /
• pp.43-49
• /
• 2020

In spite of the notable advancements of millimeter wave communication technologies, the 60 GHz Wi-Fi is still not widespread yet, mainly due to the high limitation of coverage. Conventionally, it has been hardly possible to support a high data rate with fast beam adaptation while keeping atmospheric beamforming coverage. To solve these challenges in the 60 GHz communication system, holistic system designs are considered. we implemented an enhanced design LDPC decoder enabling 6.72 Gbps coded-throughput with minimal implementation loss, and our proposed phase-tracking algorithm guarantees 3.2 dB performance gain at 1 % PER in the case of 16 QAM modulation and LDPC code-rate 3/4.

• Journal of Satellite, Information and Communications
• /
• v.8 no.4
• /
• pp.64-69
• /
• 2013

Recently, users who are interested in the service at indoor spaces is increasing. An indoor positioning system can minimize a range of positioning error using a variety of wireless communication infrastructure. Also, the system improves an indoor positioning accuracy by combining a mobile communication network. However, flexible positioning technologies regardless of an environment are insufficient. Therefore, this is time for a systematic study on an indoor positioning system business model. This paper classify differences between an indoor positioning system technology and outdoor positioning system technology. And we research a construction and application of the indoor positioning system that is adapted a wireless communication system (Wi-Fi, Bluetooth, RFID, UWE, Fingerprint, etc.) in domestic and foreign. We present a successful model of indoor positioning system and the development for future systems.

• Journal of Satellite, Information and Communications
• /
• v.10 no.1
• /
• pp.12-16
• /
• 2015

In this paper, we introduce a wireless package system based on the amateur radio HR(HAM Radio) and satellite communication as a novel wireless disaster communication system and have configured a interference scenario receiving interference from adjacent base stations and D2D groups in the disaster network. In such interference scenarios, we propose a frequency re-allocation method to avoid interference and communicate with disaster networks by securing the channel capacity required between D2D terminals. As a result of computer simulation, we can find the proposed method has improved BED performance of a gain of 1.5dB and overall system throughput than conventional methods.

• Journal of information and communication convergence engineering
• /
• v.6 no.2
• /
• pp.233-237
• /
• 2008

This paper presents proposal for an application (only for Windows-based Mobile) that can synchronize the Third Generation Windows-based mobile with the prescribed server. This application can be used by mobile users to send information directly to the WAS server wirelessly. In this paper a comparison between Third Generation technology and WLAN ( both are parallel technologies first one embodied by IMT-2000 standards and the second one by ITU Standards) has been made and also a comparison between Wi-Fi and Bluetooth has been made.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.255-258
• /
• 2011

Wi-Fi is a rapidly spreading communications network with Smart phone's publication, the technology has become Ubiquitous-based core network which is connected to personal computers, laptops, and tablet PC. Wi-Fi can send currently a variety of data standard due to developed wireless LAN communications network. One of Wi-Fi standard protocols, which is IEEE 802.11n, use 2.4GHz and 5GHz band. 2.4GHz band is used for 802.11b/g protocol because wavelength is long, diffraction and receiving distance is enough to connect other device. 5GHz band has more available channels to use than 2.4GHz band, so there is no frequency interference of other wireless device such as Bluetooth, RFID. Moreover, there is low interference between channels due to small users in each bandwidth level. In the thesis, we are going to analyze 802.11a/b/g protocol which has used since the beginning of Wi-Fi protocol and 802.11n protocol which is used lately. Furthermore, we look into development and direction for standardization of the next generation wireless LANs which are 802.11ac and 802.11ad. In addition, we will consider for the security, vulnerabilities and its countermeasure in Wireless LAN.

• Convergence Security Journal
• /
• v.16 no.7
• /
• pp.121-127
• /
• 2016

Recently, the popularity of smart devices such as Wi-Fi and LTE has increased the use ratio of wireless dramatically. On the other hand, the use ratio of wired internet is decreasing. The IoT(Internet of Things) is not only for people but also for communication between people and things, and communication between things and things by connecting to a wireless without choosing a place. Along with the rapid spread of the IoT there is a growing concern about the threat of IoT security. In this paper, the proposed scheme is a efficiency group key agreement in IoT environment that guarantees secure communication among light-weight devices. The proposed scheme securely be able to communication with the group devices who share a group key, generated by own secret value and the public value. Such property is suitable to the environment which are required a local area and a group.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.21 no.6
• /
• pp.17-23
• /
• 2021

In the present study, a more compact dual-band slot antenna is newly proposed for Wi-Fi application. The proposed antenna is composed of rectangular two stepped slot with open end which can generate standing wave resonance at dual frequency bands and L-type microstrip feed line. The measured impedance bandwidths are 50 MHz(2.412 ~ 2.470 GHz) at low frequency band and 452 MHz(5.451 ~ 5.903 GHz) at high frequency band respectiviely. Furthermore its size of 14 × 21 mm² is reduced by 30% compared to the size of 20 × 21 mm² of a conventional similar compact slot antenna. It has the omni-directional radiation pattern characteristics of a typical dipole antenna on the H-Plane, so it is suitable for commercial wireless network applications such as Wi-Fi.