• 방송공학회논문지
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• 제23권4호
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• pp.549-558
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• 2018

360 VR(Virtual Reality) 비디오와 같이 고품질의 비디오를 기존 케이블 망에서 IPTV 또는 OTT(Over the Top) SettopBox과 같은 저사양 미디어 서비스 기기를 통해 저지연 라이브 스트리밍 서비스를 할 수 있도록 MPEG DASH(Dynamic Adaptive Streaming over HTTP) 기반의 스트리밍 서버를 설계하고 구현하였다. 또한, 서버 응답 지연 시간을 줄이기 위해 스트리밍 영상 파일(MPD, Segment Files)을 메모리상에 캐싱 하여 서비스 할 수 있는 관리 프로세스를 설계하고 적용하였다. 그리고 실험을 통해 bitrate가 50,000kbps 이상이고, 8K@60P 급의 고품질 분할 영상 스트리밍을 지원하는 것을 확인하였다

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.350-353
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• 2014

클라우드 기반의 주식 체결 시스템에서는 대규모의 데이터가 운영되고 있다. 그러나 주식 체결 시스템에서 클라우드 기반으로 데이터 상호운용은 쉽지 않은 기술이다. 또한 시스템상의 최적의 전송속도와 데이터 적시성을 만족하기에는 어려움이 따른다. 그로 인한 저지연 최소화 문제와 처리 속도 향상을 위한 다양한 기술이 도입되고 있다. 하지만 Socket Direct Protocol, TCP/IP Offload Engine과 같은 하드웨어로는 속도 개선의 한계가 있으며, 도입 효과 또한 낮다는 것이 현실이다. 본 논문에서는 클라우드 환경의 XMDR-DAI 기반 주식 체결 시스템 제안하여 데이터 적시성을 만족하고, 최적의 전송 속도와 신뢰성을 만족하기 위해 Safe Proper Time 방식을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.35-57
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• 2021

Fog computing aims to provide the solution of bandwidth, network latency and energy consumption problems of cloud computing. Likewise, management of data generated by healthcare IoT devices is one of the significant applications of fog computing. Huge amount of data is being generated by healthcare IoT devices and such types of data is required to be managed efficiently, with low latency, without failure, and with minimum energy consumption and low cost. Failures of task or node can cause more latency, maximum energy consumption and high cost. Thus, a failure free, cost efficient, and energy aware management and scheduling scheme for data generated by healthcare IoT devices not only improves the performance of the system but also saves the precious lives of patients because of due to minimum latency and provision of fault tolerance. Therefore, to address all such challenges with regard to data management and fault tolerance, we have presented a Fault Tolerant Data management (FTDM) scheme for healthcare IoT in fog computing. In FTDM, the data generated by healthcare IoT devices is efficiently organized and managed through well-defined components and steps. A two way fault-tolerant mechanism i.e., task-based fault-tolerance and node-based fault-tolerance, is provided in FTDM through which failure of tasks and nodes are managed. The paper considers energy consumption, execution cost, network usage, latency, and execution time as performance evaluation parameters. The simulation results show significantly improvements which are performed using iFogSim. Further, the simulation results show that the proposed FTDM strategy reduces energy consumption 3.97%, execution cost 5.09%, network usage 25.88%, latency 44.15% and execution time 48.89% as compared with existing Greedy Knapsack Scheduling (GKS) strategy. Moreover, it is worthwhile to mention that sometimes the patients are required to be treated remotely due to non-availability of facilities or due to some infectious diseases such as COVID-19. Thus, in such circumstances, the proposed strategy is significantly efficient.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.43-46
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• 2006

IEEE 802.16 WirelessMAN aiming to broadband wireless access (BWA) is evolving to 4G mobile communication system through the standardization of IEEE 802.16e supporting mobility on existing fixed WirelessMAN system. It is necessary for hand-over to provide seamless data service while MS (Mobile Station) moves to another BS (Base Station). Because the performance of handover affects packet loss or delay of any communications, it must consider low latency handover mechanism in packet based network. In this paper, we describes handover scheme of IEEE 802.16e with the cell edge interference problem and shows the way to solve the problem in frequency reuse one deployment. Our scheme reduces the handover latency and packet loss probability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.473-493
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• 2019

5G vehicular communication is one of key enablers in next generation intelligent transportation system (ITS), that require ultra-reliable and low latency communication (URLLC). To meet this requirement, a new hybrid vehicular network structure which supports both centralized network structure and distributed structure is proposed in this paper. Based on the proposed network structure, a new vehicular network utility model considering the latency and reliability in vehicular networks is developed based on Euclidean norm theory. Building on the Pareto improvement theory in economics, a vehicular network uplink optimization algorithm is proposed to optimize the uplink utility of vehicles on the roads. Simulation results show that the proposed scheme can significantly improve the uplink vehicular network utility in vehicular networks to meet the URLLC requirements.

• 전자통신동향분석
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• 제36권4호
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• pp.34-47
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• 2021

To realize remote surgery from hundreds of kilometers away, a new communication environment with ultra-low latency and high-precision features is required. Thus, ultra-high precision networking technology that guarantees the maximum latency and jitter of end-to-end traffic on an Internet-scale wide area network is in development as part of 6G network research. This paper describes the current status of various networking technologies in ITU-T, ETSI, IEEE, and IETF to ensure ultra-low latency and high precision in wired networks.

• International Journal of Internet, Broadcasting and Communication
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• 제15권1호
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• pp.157-163
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• 2023

Recently, as businesses and data types become more complex and diverse, efficient data analysis using machine learning is required. However, since communication in the cloud environment is greatly affected by network latency, data analysis is not smooth if information delay occurs. In this paper, SPT (Safe Proper Time) was applied to the cluster-based machine learning data analysis agent proposed in previous studies to solve this delay problem. SPT is a method of remotely and directly accessing memory to a cluster that processes data between layers, effectively improving data transfer speed and ensuring timeliness and reliability of data transfer.

• 한국인터넷방송통신학회논문지
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• 제18권2호
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• pp.55-62
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• 2018

VANET은 급격히 부상하고 있는 서비스 영역으로 수 ms 수준의 엄격한 latency 요구사항을 가진다. 이러한 수준의 낮은 latency를 보장하기 위해 latency가 보장되면서 coordinator에 의한 scheduling 없이 join/leave가 자유로운 Autonomous TDMA(ATDMA)가 제안된 바 있다. 본 연구에서는 hidden node, 채널 페이딩, 노드 밀집도 변이 등이 존재하는 non-perfect decoding 환경에서 동작하도록 ATDMA를 확장한 ATDMA revision(ATDMA-R)을 고안하였다. 또한 시뮬레이션을 통해 ATDMA와 ATDMA-R의 성능을 비교하여 ATDMA 대비 ATMDMA-R이 다양한 실제적 환경에서 강인성을 보이는 것을 확인하였다.

• 방송공학회논문지
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• 제26권7호
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• pp.855-861
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• 2021

Neural Architecture Search (NAS) is cutting-edge technology in the machine learning community. NAS Without Training (NASWOT) recently has been proposed to tackle the high demand of computational resources in NAS by leveraging some indicators to predict the performance of architectures before training. The advantage of these indicators is that they do not require any training. Thus, NASWOT reduces the searching time and computational cost significantly. However, NASWOT only considers high-performing networks which does not guarantee a fast inference speed on hardware devices. In this paper, we propose a multi objectives reward function, which considers the network's latency and the predicted performance, and incorporate it into the Reinforcement Learning approach to search for the best networks with low latency. Unlike other methods, which use FLOPs to measure the latency that does not reflect the actual latency, we obtain the network's latency from the hardware NAS bench. We conduct extensive experiments on NAS-Bench-201 using CIFAR-10, CIFAR-100, and ImageNet-16-120 datasets, and show that the proposed method is capable of generating the best network under latency constrained without training subnetworks.

• 한국컴퓨터정보학회논문지
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• 제27권10호
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• pp.105-113
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• 2022

본 논문에서는 5G 시스템과 IEEE 시간 민감형 네트워킹(TSN)에 대해서 소개 분석하고 초저지연 네트워크를 지원하기 위하여 5G-TSN에서 시간 민감형 통신을 위한 새로운 이동성 관리 방안을 제안한다. 시간 민감형 네트워킹(TSN)은 이더넷 기반의 저지연, 높은 신뢰성, 결정형 통신을 제공할 수 있는 핵심 요소 기술로써 산업 자동화와 산업용 사물인터넷(IIoT) 분야의 유망한 미래 기술이다. TSN 지원 단말이 TSN 비서비스 영역에서 TSN 서비스 영역으로 이동했을 때, 단말은 관련 이동성 관리가 적절히 수행되지 못하기 때문에 신속하게 TSN 서비스를 받을 수 없다. TSN 서비스 영역의 이동성 상황의 경우, 제안하는 방안은 기존 5G 이동통신망에서의 방안과 비교하여 TSN 서비스 및 초저지연 통신을 즉시 제공받기 위해서 TSN 서비스 사용 가능성을 네트워크에 알리고, 초기 등록을 동작시킨다.