• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1528-1533
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• 2020

Recently, indoor location recognition technology using Wi-Fi fingerprints has been applied and operated in various industrial fields and public services. Along with the interest in machine learning technology, location recognition technology based on machine learning using wireless signal data around a terminal is rapidly developing. At this time, in the process of collecting radio signal data required for machine learning, the accuracy of location recognition is lowered due to distorted or unsuitable data for learning. In addition, when location recognition is performed based on data collected at a specific location, a problem occurs in location recognition at surrounding locations that are not included in the learning. In this paper, we propose a learning data preprocessing technique to obtain an improved position recognition result through the preprocessing of the collected learning data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1074-1081
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• 2021

It has recently been noticed that the headway of unlicensed wireless technology is necessary as user's demands of wireless tech increase and the development of high-speed data service by using low-power short-range wireless network is needed. Hence, it is inevitable to study sharing and coexistence for broadband spectrum of diverse unlicensed application with wide bandwidth. In this paper, an interference examination between unlicensed WiFi (Wireless Fidelity) in the 6GHz and OB (Outside Broadcasting) system which is an incumbent service in the same frequency band was conducted and it suggests separation distance for the coexistence. Thus, MCL (Minimum Coupling Loss) and MC (Monte Carlo) methods were used to set up interference scenarios for the interference analysis and compute the separation distance between two systems according to the same frequency band and frequency separation.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.135-141
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• 2013

Subway in Korea, most of a metropolitan public transport use only worth ten million people a day floating population of wireless communication can be considered HOT SOPT. These three operators' 2G/3G/4G / Wi-Fi / T-DMB frequency and the number of services to co-exist, and the subway train passengers and subway party for operation and management of the communication network is also the co-subway passenger safety and for this service for the effects of mutual interference of whether the verification was necessary. This research and testing different frequency / communication interference between services and testing to determine whether, through the subway authorities and mobile operators in each frequency-specific interaction check and there is no interference to the safety and quality of subway passengers communication services that can be verified as the data was found. The verification methods in the metro area, not just from one region to determine whether the interference with a common verification methods can be applied.

• Journal of Advanced Technology Convergence
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• v.2 no.1
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• pp.1-7
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• 2023

Recently, there have been increasing interests in researches to apply wireless communication technologies for smart farm. This paper introduces the problems in the smart farm for the outdoor culture and technical considerations to solve the problems. As candidate technologies, this paper selects LoRa, Sigfox, NB-IoT, and Wi-Fi and then determines that LoRa is a suitable technology based on the CAPEX, coverage, transmission rate, battery, and the price. To provide technical analysis, this paper introduces technologies related to the physical and medium access control (MAC) layers as well as the security. Specifically, this paper includes the modulation technology in the physical layer, Class (Class A, B, and C) based protocol operations in MAC layer, and security architecture based on the LoRa version.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.25-30
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• 2024

Smart City, a key application area of the AIoT (Artificial Intelligence of Things), provides various services in safety, security, and healthcare sectors through location tracking and location-based services. an IPS (Indoor Positioning System) is required to implement location-based services, and wireless communication technologies such as WiFi, UWB (Ultra-wideband), and BLE (Bluetooth Low Energy) are being applied. BLE, which enables data transmission and reception with low power consumption, can be applied to various IoT devices such as sensors and beacons at a low cost, making it one of the most suitable wireless communication technologies for indoor positioning. BLE utilizes the RSSI (Received Signal Strength Indicator) to estimate the distance, but due to the influence of multipath fading, which causes variations in signal strength, it results in an error of several meters. In this paper, we conducted research on a path loss model that can be applied to BLE IPS for proximity services, and confirmed that optimizing the free space propagation loss coefficient can reduce the distance error between the Tx and Rx devices.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.329-336
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• 2016

In the outdoor advertising and industrial sites, are trying to implement the LED electric bulletin board system that is based on image processing in order to express a variety of intention in real time. Recently, in various field, rather than simple text representation, the importance of intuitive communication using images is increasing. Thus, instead of outputting the simple input information for communication, a system that can output a real-time information being sought. Therefore, the system is directed to overcoming by converting the problem of mapping an image on a variety of conventional LED display that can not be output images, the possible image output formats. Using an LED of low power, it has developed to output the efficient messages and images within a limited resources. This paper provides a system capable of managing the LED display on the wireless network. Atmega2560, Wi-Fi module, using the server and Android applications client, rather than printing a text only, it is a system to reduce the load generated image output character output in to the conversion process as can be managed by the server.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.281-286
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• 2018

In recent days, when the development in smartphones has made it common to operate objects by using them, this study aimed to present a guideline for the UI/UX designs for applications which are necessary for operating various objects through the wireless communication technology. To suggest the application guideline, existing object control application case studies were analyzed, and based on this investigation the object control application UI/UX design guidelines were proposed. This study classified the types of wireless connections used by smartphones (LTE, Wi-Fi, Bluetooth, NCF, RFID) and analyzed the necessary design factors for operating objects by each type. Based on such analysis, this study presented the design sequence, factors, and methods for the UI/UX guidelines of applications. First, the method of connection was selected; second, the control device was selected. This new direction for designing smartphone applications for operating objects will likely help systemize the design process and enable the user to operate the object more intuitively. In future research, case studies will be designed applying the guidelines suggested from this study.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.397-406
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• 2014

Radio frequency (RF) jamming is a denial of service attack targeted at wireless networks. In resource-hungry scenarios with constant traffic demand, jamming can create connectivity problems and seriously affect communication. Therefore, the vulnerabilities of wireless networks must be studied. In this study, we investigate a particular type of RF jamming that exploits the semantics of physical (PHY) and medium access control (MAC) layer protocols. This can be extended to any wireless communication network whose protocol characteristics and operating frequencies are known to the attacker. We propose two efficient jamming techniques: A low-data-rate random jamming and a shot-noise based protocol-aware RF jamming. Both techniques use shot-noise pulses to disrupt ongoing transmission ensuring they are energy efficient, and they significantly reduce the detection probability of the jammer. Further, we derived the tight upper bound on the duration and the number of shot-noise pulses for Wi-Fi, GSM, and WiMax networks. The proposed model takes consider the channel access mechanism employed at the MAC layer, data transmission rate, PHY/MAC layer modulation and channel coding schemes. Moreover, we analyze the effect of different packet sizes on the proposed jamming methodologies. The proposed jamming attack models have been experimentally evaluated for 802.11b networks on an actual testbed environment by transmitting data packets of varying sizes. The achieved results clearly demonstrate a considerable increase in the overall jamming efficiency of the proposed protocol-aware jammer in terms of packet delivery ratio, energy expenditure and detection probabilities over contemporary jamming methods provided in the literature.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.449-452
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• 2010

현재 출시되고 있는 휴대 단말기는 기존의 이동통신망뿐만 아니라 와이파이(WiFi), 와이브로(WiBro) 망등 다양한 무선망을 지원하고 있다. 이러한 단말기를 통해 기존의 이동통신망 기반 서비스뿐만 아니라 무선 IP 네트워크 기반의 다양한 서비스들이 제공되고 있으며, 산업 현장에서 실시간 그룹 통신을 지원하기 위해 사용되는 무전기 및 TRS 등의 시스템을 대체할 수 있는 그룹 통신 기술의 대체 가능성에 대한 기대도 증가하고 있다. 그러나, 무전기 및 TRS의 그룹 통신 기능을 지원하고, 동시에 휴대폰의 개별 통신 기능도 지원할 수 있게 되기 위해서는 PTT 발언권 송신 지연 최소화, 개별 통신과 그룹 통신 서비스 통합 등 다양한 요소들에 대한 고려가 필요하다. 본 논문에서는 무선 IP망인 와이브로망 기반의 개별 통신과 그룹 통신을 동시에 지원하는 단말 시스템 설계 및 구현 방법에 대해 제안하고자 한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.103-107
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• 2019

As the number of foreign tourists increases worldwide, it provides tourism services with various information and convenience. Most foreign tourists have difficulty using existing methods that require internet connection because internet communication is restrictive. In this paper, we propose a mobile device based digital signage via WPAN that can support multi-lingual for foreign tourists. the proposed method shows a menu by combining a template of mobile client with fundamental contents from digital signage through WPAN. To evaluate the performance of the proposed method, it is compared with a conventional webpage method. The results of the evaluation confirm that the latency decreases compared to the conventional webpage method due to the improved loading time.