• 전자통신동향분석
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• 제33권2호
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• pp.30-38
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• 2018

Wi-Fi is a technology that has become an essential part of our lives, and not simply a convenience. Wi-Fi is mainly used indoors and is evolving in terms of an increase in the transmission speed and expanded coverage. 802.11ac Wi-Fi, operating at 5 GHz, and 802.11ad Wi-Fi, operating at 60 GHz, were standardized in the same year, 2012, as a gigabit-transmission speed Wi-Fi technology. In this article, we examine the current status of the Wi-Fi market trends and present the possibility of the development of 60 GHz Wi-Fi and future market prospects.

• 한국정보통신학회논문지
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• 제20권11호
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• pp.2143-2148
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• 2016

최근 IT기술의 발전에 힘입어 사람이 생활하는 환경에 IT기술들이 스며들고, 환경적 요소와 융합하는 아이디어와 기술들이 나날이 발전하고 있다. 이러한 기술들은 사람들의 생활환경에 도움을 주는 역할을 하고 있으며, 앞으로의 초연결사회의 필수 구성 요소이다. 본 논문에서는 IT기술을 환경적 요소와 융합하여 활용하는 동시에 더욱 쾌적한 환경을 만들 수 있는 WiT(WiFi Trashcan)를 제안한다. WiT는 쓰레기통에 쓰레기를 넣으면 WiFi를 무료로 제공해주는 쓰레기통이다. WiFi와 Trash-can을 합성한 WiT(WiFi Trashcan)는 사람이 쓰레기를 넣었을 때, 투입 여부 및 부피를 감지하여 쓰레기를 버린 사용자에게 WiFi를 무료로 제공해주는 시스템이다. 쓰레기를 감지하기 위해 초음파 센서를 사용하고, 쓰레기의 무게를 측정하기 위해 무게 센서를 사용한다. 그리고 파이썬 프로그래밍을 통해 측정된 센서 값을 라즈베리파이에 전송하여, WiFi 제공시간을 결정한다. WiT는 아두이노와 라즈베리파이를 활용하여 설계 및 구현되었다.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3455-3461
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• 2015

지하철에서는 주로 LTE와 Wi-Fi를 통하여 급증하는 무선데이터서비스를 제공하고 있다. 승객의 이동에 따라 이용객 수가 급변하는 특성을 가지고 있으며, LTE는 사용자가 증가해도 안정적인 서비스 제공이 가능한 반면에 Wi-Fi는 이용객이 증가하면 접속시간이 증가하는 등 성능이 크게 저하되는 현상이 발생한다. 본 논문에서는 Wi-Fi 전송망에 대한 수학적 모델링 및 시뮬레이션을 통하여 이용객 증가에 따른 접속지연 증가 특성을 분석하였으며, 영업운영 중인 지하철 10개 역 구간에서 Wi-Fi 망에의 접속지연 및 손실률을 측정하여 비교하였다. 측정 및 분석 결과는 지하철에서의 LTE와 Wi-Fi 간 데이터 오프로딩 구성에 필요한 접속방법 및 향후 LTE-R 도입시 효율적인 망 구성에 적용할 수 있다.

• 융합신호처리학회논문지
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• 제22권1호
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• pp.38-44
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• 2021

Wi-Fi provides some low-power connection solutions that other Bluetooth cannot provide, and at the same time brings many benefits. First, there is a potentially higher data rate: it can reach 230mbps. Wi-Fi coverage is also wider than competitors, and its operating frequency is also 5GHz, which is much less congested than 2.4GHz. Finally, it also supports IP networks, which is important if you want to send data to the cloud without complexity. The 802.11ac standard of the previous generation still accounts for most shipments (80.9%) and revenue (76.2%). However, there is a limit to accepting IoT devices that will continue to increase significantly in the future. To solve this problem, the new Wi-Fi 6 standard is expected to be the solution (IEEE 802.11ax) which is quickly becoming the main driving force of the wireless local area network (WLAN) market. According to IDC market research analysts, in the first quarter of 2020, independent access points (APs) supported by Wi-Fi 6 accounted for 11.8% of shipments, but 21.8% of revenue. In this paper, we have compared and analyzed the IoT connectivity, QoS, and security requirements of devices using Wi-Fi 6 network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권9호
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• pp.3250-3265
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• 2014

Integrated WiMAX and WiFi networks is of great potential for the future due to the wider coverage of WiMAX and the high data transport capacity of WiFi. However, seamless and secure handover (HO) is one of the most challenging issues in this field. In this paper, we present a novel vertical HO authentication scheme with privacy preserving for WiMAX-WiFi heterogeneous networks. Our scheme uses ticket-based and pseudonym-based cryptographic methods to secure HO process and to achieve high efficiency. The formal verification by the AVISPA tool shows that the proposed scheme is secure against various malicious attacks and the simulation result indicates that it outperforms the existing schemes in terms of communication and computation cost.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권5호
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• pp.2103-2123
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• 2018

Ships built today are larger in scale and feature more complex structures. The ever-evolving systems used on board a ship require vast amounts of data processing. In the future, with the advent of smart ships, unmanned ships and other next-generation ships, the volumes of data to be processed will continue to increase. Yet, to date, ship data has been processed using wired networks. Placed at fixed locations, the nodes on wired networks often fail to process data from mobile devices. Despite many attempts made to use Wi-Fi on ships just as on land to create wireless networks, Wi-Fi has hardly been available due to the complex metal structures of ships. Therefore, Wi-Fi on ships has been patchy as the ship-wide total Wi-Fi coverage has not properly implemented. A new ship-wide wireless network environment is part of the technology conducive to the shipbuilding industry. The wireless network environment should not only serve the purpose of communication but also be able to manage and control multiple features in real-time: fault diagnostics, tracking, accident prevention and safety management. To better understand the characteristics of wireless frequencies for ships, this paper tests the widely used TETRA, UHF and Wi-Fi and sheds light on the features, advantages and disadvantages of each technology in ship settings. The proposed deployment of a Super Wi-Fi network leveraging the legacy UHF system of TMS generates a ship-wide wireless network environment. The experimental findings corroborate the feasibility of the proposed ship-wide Super Wi-Fi network environment.

• Journal of Positioning, Navigation, and Timing
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• 제12권1호
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• pp.37-42
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• 2023

Wi-Fi Received Signal Strength Indicator (RSSI) is considered one of the most important sensor data types for indoor localization. However, collecting a RSSI fingerprint, which consists of pairs of a RSSI measurement set and a corresponding location, is costly and time-consuming. In this paper, we propose a Wi-Fi RSSI learning technique without true location data to overcome the limitations of static database construction. Instead of the true reference positions, inertial measurement unit (IMU) data are used to generate pseudo locations, which enable a trainer to move during data collection. This improves the efficiency of data collection dramatically. From an experiment it is seen that the proposed algorithm successfully learns the unsupervised Wi-Fi RSSI positioning model, resulting in 2 m accuracy when the cumulative distribution function (CDF) is 0.8.

• 전자공학회논문지
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• 제52권7호
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• pp.15-21
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• 2015

WiFi 기술의 비약적인 발전과 스마트폰, 스마트패드, 스마트워치 등과 같은 다양한 모바일 단말의 출현으로 인해, 사용자들의 WiFi망 데이터 사용률은 크게 증가 하고 있다. 이에 따라 사용자들이 여행 중에도 방문지에서 단순한 신원인증을 통해 자신의 홈 WiFi 망을 이용하는 것처럼 방문지의 WiFi를 이용하고자 하는 수요가 크게 증가하고 있다. 본 논문에서는 이러한 무선 네트워크 접속환경의 글로벌 확장을 지원하는 eduroam의 국내 현황을 살펴보고 향후에 국내 eduroam 서비스의 발전 전망을 제시한다. 또한, 본 논문은 국내 대학간 WiFi 공동 활용 서비스 발전 현황을 설명하고, 국내 대학의 eduroam 서비스 가입 활성화에 필요한 방안들을 제시한다.

• 한국융합학회논문지
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• 제11권6호
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• pp.43-49
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• 2020

밀리미터파 통신 기술의 주목할 만한 발전에도 불구하고, 60GHz Wi-Fi는 여전히 광범위한 적용 범위의 제한으로 인해 아직 널리 보급되지 않았다. 종래에는 높은 주파수에서 발생하는 신호 감쇄를 극복하기 위해 빔포밍 기술 도입이 필수적이지만 모든 방향으로의 빔 형성 범위를 유지하면서 빠른 빔 적응을 달성하기에는 어려움이 있었다. 또한 이와 동시에 멀티-기가비트의 높은 데이터 속도를 지원하는 것은 거의 불가능했다. 본 연구 에서는 60GHz 밀리미터파 통신 시스템에서 발생하는 이러한 문제를 해결하기 위한 전체적인 시스템 설계하고 구현하였다. 구현 손실을 최소화하면서 6.72 Gbps 코딩 처리량을 가능하게 하는 향상된 설계 LDPC 디코더를 소개하며, 향상된 위상 추적 알고리즘은 16 QAM 변조 및 LDPC 코드 속도 3/4의 경우 1 % 패킷 에러율에서 3.2 dB 성능 이득을 보장하여 높은 주파수의 빔포밍을 수행하는 도중에도 높은 데이터 전송율을 달성할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권12호
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• pp.2272-2293
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• 2011

Communication technology of future networks is predicted to provide a large variety of services including WiFi service in vehicular network. In this paper, we assume that vehicles are embedded with WiMAX antenna and in-vehicle terminals receive WiMAX traffic through WiFi interface. This assumption will impose severe performance degradation due to interference among mobile BSSs when WiFi access points (APs) are densely located. Existing interference avoidance techniques cannot properly resolve the above problems and do not cope with dynamically moving vehicular scenario since they focus only on the fixed network topology. In this paper, we propose a mobility-aware interference avoidance scheme for WiFi services. The proposed scheme computes the interference duration by exploiting mobility vector and location information of neighboring APs. If the interference duration is not negligible, our scheme searches for another channel in order to avoid interference. However, if the interference duration is negligible, our scheme continues to use the channel to reduce switching overhead. To measure the effectiveness of the proposed scheme against other existing techniques, we evaluated performance by using OPNET simulator. Through the simulation, we obtained about 60% reduction in the maximum interference frequency and about 67% improvement in throughput. Furthermore, our scheme provides fair channel usage.