• Title/Summary/Keyword: network recovery

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Study on UxNB Network Deployment Method toward Mobile IAB

  • Keewon Kim;Jonghyun Kim;Kyungmin Park;Tae-Keun Park
    • Journal of the Korea Society of Computer and Information
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    • v.28 no.12
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    • pp.105-114
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    • 2023
  • In this paper, we propose a deployment and operation scheme of UxNB network toward mobile IAB. By operating a UxNB network based on SDN(Software Defined Network), UxNBs are deployed in areas where mobile communication services are desired. After deploying UxNB in the service area, IAB can be set up to perform mobile communication services. For this purpose, this paper first proposes a UxNB Network Controller consisting of a UAV Controller and an SDN Controller, and proposes the necessary functions. Next, we present a scenario in which a UxNB network can be deployed and operated in detail step by step. We also discuss the location of the UxNB network controller, how to deliver control commands from the UAV controller to the UxNB, how to apply IAB for UxNB networks, optimization of UxNB networks, RLF(radio link failure) recovery in UxNB networks, and future research on security in UxNB networks. It is expected that the proposed UxNB Network Controller architecture and UxNB network deployment and operation will enable seamless integration of UxNB networks into Mobile IAB.

A Study on the Development of One-way Bypass TAP Device for Strengthening the Security of Flood and Environment Surveillance Network (홍수 및 환경 감시망의 보안성 강화를 위한 단방향 Bypass TAP 장치 개발에 관한 연구)

  • Lee, Jin-Young;Kong, Heon-Tag
    • Journal of Digital Convergence
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    • v.13 no.8
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    • pp.473-481
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    • 2015
  • The flood and environment surveillance network on riverside is a network requiring a way to efficiently manage the information from all kinds of sensors, along with an optical communication device that can deliver high-quality video information at high speed. Since on-site prompt recovery is very important especially for communication problems that occurred due to cut-off or aged network, various researches have been carried out on this. However, because the security against outside hacking or outside intrusion with illegal purposes is very important for environment surveillance network, such as the national backbone network, an efficient network maintenance and repair should be enabled while satisfying security and reliability at the same time. A characteristic of requirement is that when security is improved, the efficiency of maintenance and repair drops as they are conflicting to each other. Therefore, this research proposed a system in order to satisfy the conflicting requirement and improve security, by developing a one-way Bypass TAP and an android-based smartphone app that can enable efficient network maintenance and repair.

A Study on Reliable Multicast Transmission using Recovery Cluster (복구 클러스터를 이용한 신뢰성 있는 멀티캐스트 전송에 관한 연구)

  • Gu, Myeong-Mo;Kim, Bong-Gi
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.11
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    • pp.1-6
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    • 2019
  • Multicast is an efficient method for real-time transmission in many multimedia applications. It is important to recover lost packets and to manage multicast groups according to the network status in order to improve the reliability of multicast transmissions. In this paper, we propose a method that can efficiently recover lost packets in a large multicast group. In the proposed method, we create a recovery cluster (RC) using a multicast domain (MD) for recovery of lost packets. In the conventional methods, clusters send a request message for lost packets to the senders in order to recover the packets lost from many multicast applications. This increases packet delay time and overhead because of the feedback messages and retransmitted packets. In the proposed method, we improve these problems using the RC, which consists of many MDs (which have overlay multicast senders), and many cluster heads (CHs). We divide the message into blocks, and divide each block into many segments for packet recovery using the CHs. When packet loss occurs, all CHs share the segment information and recover the lost segments at the same time. Simulation results show that the proposed method could improve the packet recovery ratio by about 50% compared to the conventional methods.

A Study on the Reconstruction of Self-Life of the Recovering Substance Addicts -Qualitative Case Study Approach- (마약중독에서 탈출한 회복자들의 자기 삶 재건에 대한 연구 -질적 사례연구접근-)

  • Kang, Sun Kyung;Moon, Jin Young;Yang, Dong Hyun
    • 재활복지
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    • v.20 no.1
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    • pp.87-111
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    • 2016
  • This study is a qualitative case study of 5 substance abusers recovered from drug addiction. It is useful socially and practically to understand about the rehabilitation and its process of recovering from drug addiction. Since this study deals with very private and sensitive issues, qualitative research approach is suitable. Data were collected through one to one in-depth interviews, and were analyzed by using analysis within/cross cases suggested by Creswell(2007). 5 individual cases were presented including substance addicts experiences and recovery process through within-cases analysis. Based on the within-cases analysis, common themes were presented through cross-cases analysis. Total 19 themes, related with recovery from substance addicts, were derived from the five individual cases, and 4 common themes were classified. These 4 common themes were first, recovery of sense of reality, second, taking self-existing pattern, third, self reconstruction in the context of social network, fourth, self-love. Based on the study results and discussions, practical implications were suggested to help persons claiming recovery from substance addicts for their recovery and rehabilitation.

Performance Evaluation of Symbol Timing Recovery Algorithm for S-DMT Cable Modern (S-DMT 케이블 모뎀을 위한 심볼 타이밍 복원 알고리즘 성능평가)

  • Cho Byung-Hak
    • Journal of Digital Contents Society
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    • v.6 no.1
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    • pp.41-48
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    • 2005
  • In this paper, we propose and evaluate symbol timing recovery algorithm for S-DMT cable modern, which supports more channels and better quality symmetric mutimedia service over HFC network. We adopt timing recovery algorithm of PN sequence insertion in time domain and evaluate the performance of it in various noise channel such as AWGN, ISI, impulse. We verified that performance of this algorithm is depends on the channel noise environment and sampling clock offset and that over 10 dB degradation of Eb/No is occurred at the timing failure probability of $10^3$ in the composite noise channel of AWGN, ISI, and impulse in comparison with impulse noise-alone channel. finally, we verified that this algorithm showed good timing failure probability in case of sampling clock optimization was performed in advance.

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Packet Lossless Fast Rerouting Scheme without Buffer Delay Problem in MPLS Networks (MPLS망에서 버퍼지연 문제가 발생하지 않는 무손실 Fast Rerouting 기법)

  • 신상헌;신해준;김영탁
    • Journal of KIISE:Information Networking
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    • v.31 no.2
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    • pp.233-241
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    • 2004
  • In this paper, we propose a packet-lossless fast rerouting scheme at a link/node fault in MPLS (Multiprotocol Label Switching) network with minimized accumulated buffer delay problem at ingress node. The proposed scheme uses a predefined, alternative LSP (Label Switched Path) In order to restore user traffic. We propose two restoration approaches. In the first approach, an alternative LSP is initially allocated with more bandwidth than the protected working LSP during the failure recovery phase. After the failure recovery, the excessively allocated bandwidth of the alternative LSP is readjusted to the bandwidth of the working LSP. In the second approach, we reduce the length of protected working LSP by using segment-based restoration. The proposed approaches have merits of (ⅰ) no buffer delay problem after failure recovery at ingress node, and (ⅱ) the smaller required buffer size at the ingress node than the previous approach.

Autologous Peripheral Blood Stem Cell Transplantation Using G-CSF Combined Conditioning in AML Patients (급성 골수성 백혈병 환자에서 G-CSF를 포함한 고용량 화학요법 후 자가 말초혈 조혈모세포이식의 효과)

  • Kim, Byung Soo;Kook, Hoon;Hwang, Tai Ju;Choi, Chul Won;Kim, Jun Suk
    • IMMUNE NETWORK
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    • v.2 no.1
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    • pp.49-52
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    • 2002
  • Background: The possibility that G-CSF recruits leukemic cells from the G0 to S phase, which may lead to a greater susceptibility to cytotoxic drugs, such as ara-C, has been presented in Harada's study. Methods: In this study, we referred to the protocol of Harada et al 1 to try G-CSF combined marrow-ablative chemotherapy and autologous PBSCT, for the treatment of AML patients in CR1 status. Between January 1997 and March 1998, six AML patients (3: children, 3: adults) in CR1 status were autografted and followed up to 3 years. Results: The major regimen related toxicity was composed of mucositis and diarrhea without death. The time of ANC recovery to 500/L and 1,000/L was 11~48 and 16~81 days, respectively. The mean time of platelet recovery to 20,000/L and 50,000/L was 21~233 and 35~370 days, respectively. The platelet recovery time to 50,000/L was markedly prolonged for more than 100 days in four patients (66.7%). Moreover, four patients (66.7%) experienced a relapse of leukemia after transplantation, with a mean interval of 147.5 days after PBSCT. Two patients were in CR status for 53 and 51 months after PBSCT, respectively. Conclusion: The G-CSF combined marrow-ablative chemotherapy and autologous PBSCT resulted in a markedly delayed platelet recovery and no advantages for decreasing the relapse rate of AML. But, further studies will be warranted.

Fault-Management Scheme for Recovery Time and Resource Efficiency in OBS Networks (OBS 망에서 복구 시간과 자원의 효율성을 고려한 장애 복구 기법)

  • 이해정;정태근;소원호;김영천
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.9B
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    • pp.793-805
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    • 2003
  • In OBS (Optical Burst Switching) networks which decouple the burst from its header, the fault of a fiber link can lead to the failure of all the light-path that traverses the fiber. Because each light-path is expected to operate at a rate of a few Gbps by using WDM (Wavelength Division Multiplexing) technology, any failure may lead to large data loss. Therefore, an efficient recovery scheme must be provided. In this paper, we analyze network utilization and BCP (Burst Control Packet) loss rate according to each link failure by applying the conventional restoration schemes in OBS networks. And through these simulation results, an ASPR scheme is proposed improve the fault management scheme in terms of recovery time and throughput. Finally, We compare the performance of our proposed scheme with that of the conventional one with respect to burst loss rate, resource utilization and throughput by OPNET simulations.

An AODV Re-route Methods for Low-Retransmission in Wireless Sensor Networks (무선센서네트워크에서 저-재전송율을 위한 AODV 경로 재설정 방법)

  • Son, Nam-Rye;Jung, Min-A;Lee, Sung-Ro
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.9A
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    • pp.844-851
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    • 2010
  • Recently, AODV routing protocol which one of the table driven method for the purpose data transmission between nodes has been broadly used in mobile wireless sensor networks. An existing AODV has a little overhead of routing packets because of keeping the routing table for activity route and re-routes to recovery the routes in route discontinuation. However that has faults in that excesses useless of the network bandwidth to recovery the route and takes a lone time to recovery the route. This paper proposes an efficient route recovery method for AODV based on wireless sensor networks in connection breaks. The proposed method. The propose method controls the number of RREQ message considering the energy's node and distance between nodes to restrict the flooding range of RREQ message while expanding the range of local repair. In test results, the proposed method are compared to existing method, the number of drops decrease 15.43% and the delay time for re-route decrease 0.20sec.

Flush Optimizations to Guarantee Less Transient Traffic in Ethernet Ring Protection

  • Lee, Kwang-Koog;Ryoo, Jeong-Dong
    • ETRI Journal
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    • v.32 no.2
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    • pp.184-194
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    • 2010
  • Ethernet ring protection (ERP) technology, which is defined in ITU-T Recommendation G.8032, has been developed to provide carrier grade recovery for Ethernet ring networks. However, the filtering database (FDB) flush method adopted in the current ERP standard has the drawback of introducing a large amount of transient traffic overshoot caused by flooded Ethernet frames right after protection switching. This traffic overshooting is especially critical when a ring provides services to a large number of clients. According to our experimental results, the traditional FDB flush requires a link capacity about sixteen times greater than the steady state traffic bandwidth. This paper introduces four flush optimization schemes to resolve this issue and investigates how the proposed schemes deal with the transient traffic overshoot on a multi-ring network under failure conditions. With a network simulator, we evaluate the performance of the proposed schemes and compare them to the conventional FDB flush scheme. Among the proposed methods, the extended FDB advertisement method shows the fastest and most stable protection switching performance.