• 방송공학회논문지
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• 제28권1호
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• pp.149-152
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• 2023

본 논문에서는 소프트웨어 정의 라디오 (SDR: Software-defined Radio)를 활용하여 실시간 동영상 송수신기를 구현하기 위한 접근 방법을 제시한다. 이를 통해 최근 주목받고 있는 개방형 무선 접속망(O-RAN: Open Radio Access Network)을 연구하고 이를 SDR 장치와 개방형 소프트웨어를 통해 구현하고자 하는 연구자들의 접근 문턱을 낮추고 새로운 시각과 통찰력을 제공할 수 있을 것으로 기대한다.

• 방송공학회논문지
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• 제19권1호
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• pp.14-23
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• 2014

본 논문은 최근 이동통신 네트워크에서 폭발적으로 증가하고 있는 비디오 트래픽이 야기한 문제와 요구사항의 해결책으로써, SDN(Software Defined Network)을 기반으로 하는 다중 무선 접속 기술(Multiple Radio Access Technology)의 제어 기법을 제안하고 그 성능을 자체 구축한 테스트베드를 통하여 평가한다. 이를 위하여, 먼저 사업자 입장에서 3rd-party의 비디오 트래픽을 사업자망으로부터 우회(off-loading)시키는 방안의 필요성과, 사용자에게 저비용으로 고속의 대용량 비디오 콘텐츠 서비스를 제공하는 방안에 대하여 논의한다. 또한 성능평가를 위한 테스트베드는 OpenStack 클라우드 및 SDN 기반으로 구축 하였다. 이를 통해, OpenFlow와 Open Switch를 이용하여 2개의 2.4GHz 무선 랜 링크와 3개의 5GHz 무선 랜 링크가 동시에 하나의 서비스를 지원하도록 함으로서 820 Mbps 급의 초고속 클라우드 비디오 서비스를 위한 전송 속도를 실현하였다.

• 정보보호학회논문지
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• 제17권2호
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• pp.61-72
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• 2007

With the increasing growth of Internet and wireless IP networks, Multimedia systems need to be envisaged as information resources where users can access anywhere and anytime. However, efficient services in these multimedia systems are open and challenging research problem due to user mobility, limited resources in wireless devices and expensive radio bandwidth. To implement multimedia services over heterogeneous network, the IP header compression scheme can be used for saving bandwidth. In this paper, we present an efficient solution for header compression, which is modified form of ECRTP. It shows an architectural framework adopting modified ECRTP when IP tunneling network using GRE over IPSec is implemented. We have conducted simulations in order to analyze the effects of different header compression techniques while delivering real-time services to the wireless access network through secured IP Network. The impacts on performance have been investigated through a series of experiments.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2019년도 추계학술발표대회
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• pp.211-212
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• 2019

Slicing Radio Access Network (RAN) can help in effectively utilizing the network bandwidth and to better manage the increasing traffic over interent. RAN slicing system discussed in this paper is based on an open-source slicing mechanism in which we write a JSON configuration file for slicing policy and send it to the FlexRAN controller. FlexRAN controlls the core networks (CNs) through OAI-RAN on the evolved packet core (EPC) component of this system. Each CN is responsible for handling a saperate RAN slice. The type of internet traffic is identified by the FlexRAN crontroller and is sent to the respective CN through OAI-RAN. CN handles the traffic according to the allocated bandwidth and in this way the internet traffic is sliced inside the EPC component.

• 전자통신동향분석
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• 제37권3호
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• pp.1-10
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• 2022

Traditional centralized radio access network architecture used for 4G is based on Option 8, a functional split between PHY and RF. This option is commonly used with a fronthaul interface based on common public radio interface (CPRI) specifications; however, the increased data rates in 5G make this option impractical because of the fronthaul interface's high bandwidth requirement. Since CPRI specifications have many vendor-specific options, achieving multi-vendor interoperability becomes challenging. Open RAN (O-RAN) Alliance is developing novel open fronthaul interface specifications based on the functional split Option 7-2x, one of the intra-PHY split options, to relax the bandwidth requirement of the fronthaul interface and achieve multi-vendor interoperability. This article provides a brief overview of the various functional split options for 5G fronthaul that have been reported so far and existing fronthaul technologies. Further, the technological trends in the 5G open fronthaul interface is discussed, focusing on the O-RAN Alliance specifications under standardization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.3711-3730
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• 2014

Cognitive radio networks (CRNs) have emerged as a promising solution to enhance spectrum utilization by using unused or less used spectrum in radio environments. The basic idea of CRNs is to allow secondary users (SUs) access to licensed spectrum, under the condition that the interference perceived by the primary users (PUs) is minimal. In CRNs, the channel availability is uncertainty due to the existence of PUs, resulting in intermittent communication. Transmission control protocol (TCP) performance may significantly degrade in such conditions. To address the challenges, some transport protocols have been proposed for reliable transmission in CRNs. In this paper we survey the state-of-the-art transport protocols for CRNs. We firstly highlight the unique aspects of CRNs, and describe the challenges of transport protocols in terms of PU behavior, spectrum sensing, spectrum changing and TCP mechanism itself over CRNs. Then, we provide a summary and comparison of existing transport protocols for CRNs. Finally, we discuss several open issues and research challenges. To the best of our knowledge, our work is the first survey on transport protocols for CRNs.

• ETRI Journal
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• 제42권6호
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• pp.976-986
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• 2020

Internet of Things (IoT) is considered the future network to support wireless communications. To realize an IoT network, sufficient spectrum should be allocated for the rapidly increasing IoT devices. Through cognitive radio, unlicensed IoT devices exploit cooperative spectrum sensing (CSS) to opportunistically access a licensed spectrum without causing harmful interference to licensed primary users (PUs), thereby effectively improving the spectrum utilization. However, an open access cognitive IoT allows abnormal IoT devices to undermine the CSS process. Herein, we first establish a hard-combining attack model according to the malicious behavior of falsifying sensing data. Subsequently, we propose a weighted sequential hypothesis test (WSHT) to increase the PU detection accuracy and decrease the sampling number, which comprises the data transmission status-trust evaluation mechanism, sensing data availability, and sequential hypothesis test. Finally, simulation results show that when various attacks are encountered, the requirements of the WSHT are less than those of the conventional WSHT for a better detection performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.3751-3774
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• 2014

With the rapid development of wireless communication, the confliction between the scarce frequency resources and the low spectral efficiency caused by the stationary spectrum sharing strategies seriously restricts the evolution of the future mobile communication. For this purpose, cognitive radio (CR) emerges as one of the most promising inventions which can overcome the spectrum shortage. As the key technology and main objective of CR, spectrum sharing can make full use of the limited spectrum, alleviate the scarcity of frequency resources and improve the system utilities, playing thereby an important role in improving the system performance of cognitive radio networks (CRNs). In this survey, the spectrum sharing in CRNs is discussed in terms of the sharing process, mainstream sharing technologies and spectrum sharing models. In particular, comparisons of different spectrum sharing strategies are concluded, as well as that of different spectrum sensing schemes in sharing procedure. Moreover, some application examples of the spectrum sharing in CRNs, such as smart grid, public safety, cellular network and medical body area networks are also introduced. In addition, our previous related works are presented and the open research issues in the field of spectrum sharing are stated as well.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2668-2717
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• 2021

Demands for high-speed wireless data services grow rapidly. It is a big challenge to increasing the network capacity operating on licensed spectrum resources. Unlicensed spectrum cellular networks have been proposed as a solution in response to severe spectrum shortage. Licensed Assisted Access (LAA) was standardized by 3GPP, aiming to deliver data services through unlicensed 5 GHz spectrum. Furthermore, the 3GPP proposed 5G New Radio-Unlicensed (NR-U) study item. On the other hand, artificial intelligence (AI) has attracted enormous attention to implement 5G and beyond systems, which is known as Intelligent Radio (IR). To tackle the challenges of unlicensed spectrum networks in 4G/5G/B5G systems, a lot of works have been done, focusing on using Machine Learning (ML) to support resource allocation in LTE-LAA/NR-U and Wi-Fi coexistence environments. Generally speaking, ML techniques are used in IR based on statistical models established for solving specific optimization problems. In this paper, we aim to conduct a comprehensive survey on the recent research efforts related to unlicensed cellular networks and IR technologies, which work jointly to implement 5G and beyond wireless networks. Furthermore, we introduce a positioning assisted LTE-LAA system based on the difference in received signal strength (DRSS) to allocate resources among UEs. We will also discuss some open issues and challenges for future research on the IR applications in unlicensed cellular networks.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2024년도 춘계학술발표대회
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• pp.381-382
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• 2024

Open RAN(Radio Access Network)을 선도적으로 연구하고 있는 O-RAN Alliance에서는 Open RAN의 E2 인터페이스에서 발생 가능한 보안 위협 중 하나로 MitM(Man-in-the-Middle) 공격을 명시하였다. 그러나 이에 대응하기 위한 보안 요구사항으로는 3계층 보안 프로토콜인 IPsec 사용을 명시하고 있으며, 2계층 공격인 ARP(Address Resolution Protocol) 스푸핑에 대한 요구사항은 명시하고 있지 않다. 따라서 본 논문에서는 MitM 공격 중 하나인 ARP 스푸핑으로부터 E2 인터페이스를 보호하기 위해, Near-RT RIC의 ARP 테이블에서 E2 인터페이스로 연결되는 장비에 대한 MAC 주소를 정적으로 설정할 수 있는 xApp을 제안한다.