• Title/Summary/Keyword: MANET

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An Dynamic Congestion Window Tuning Algorithm for TCP Performance Improvement in Wireless Ad-hoc Network (무선 Ad-hoc 네트워크에서 TCP 성능 향상을 위한 동적 혼잡윈도우 조정 알고리즘)

  • Kim, Kwan-Woong;Bae, Sung-Hwan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.8
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    • pp.1384-1390
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    • 2008
  • The TCP protocol is originally designed for wired network, however it performs very poor in wireless network due to different nature of wireless network from wired networks. In terms of TCP performance improvement in wireless Ad-hoc network, many researches show that small congestion window size of TCP connection can improve TCP performance. We propose a new TCP algorithm to improve TCP performance in wireless Ad-hoc network. The basic idea of our approach is that TCP receiver estimates the optimum window size and then sets congestion window limit of TCP sender to an optimum value by using the advertised window field in TCP ACK packet. From extensive computer simulation, the proposed algorithm shows superior performance than traditional TCP protocols in terms of packet delivery ratio and packet loss.

Efficient restriction of route search area in cluster based wireless ad hoc networks (클러스터 기반 무선 애드 혹 네트워크에서의 효율적인 경로 탐색 지역 제어)

  • Lee, Jangsu;Kim, Sungchun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2012.11a
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    • pp.792-795
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    • 2012
  • 애드 혹 네트워크(MANET: Mobile Ad hoc NETworks)는 기본적인 내부구조(infrastructure) 없이 노드들만으로 네트워크 망을 구성한다. 경로 탐색 정책으로 리액티브(reactive) 방식과 프로액티브(proactive) 방식이 있는데, 전통적으로 리액티브 방식의 성능이 더 좋은 것으로 평가된다. 그리고 두가지 방식의 장점을 취합한 하이브리드(hybrid) 방식의 클러스터 토폴로지(cluster topology) 도입에 관한 연구가 이루어지고 있다. 그 중, HCR(Hybrid Cluster Routing)이 제안되었는데, 이는 프로액티브 방식에 보다 중심을 둔 기법이다. HCR 은 리액티브 방식 경로 탐색 방법인 플라딩(flooding)의 탐색 지역을 한정된 범위로 제한할 수 있으나, 프로액티브 방식의 전체 네트워크 구성 정보 유지에 따른 막대한 오버헤드를 발생한다. 본 논문에서는 이러한 오버헤드를 줄이기 위해, 클러스터 내부 경로 탐색 기법인 MICF(Maginot path based Intra Cluster Flooding)를 제안한다. MICF 는 HCR 을 개선한 FSRS(First Search and Reverse Setting) 기반의 기법으로서, 클러스터 내부의 마지노 패스(maginot path)를 기준으로 경로 탐색 지역을 제한한다. MICF 는 게이트웨이(gateway) 간 최단 거리가 항상 클러스터 헤드(cluster head)를 중점으로 원의 내각 지역에 존재함을 바탕으로 하며, 최단 경로의 보장과 플라딩 지역 제한을 동시에 만족한다. 실험 결과, MICF 는 FSRS 기반의 기존 클러스터 내부 플라딩 방식보다 총 에너지의 7.79%만큼 더 에너지를 보존하였다. 결론적으로, MICF 역시 기존의 방식보다 에너지를 더 효율적으로 사용할 수 있으며, 마지노패스 설정과 이를 기반으로 한 제어 과정에 추가적인 오버헤드가 발생하지 않는다. 그리고 플라딩 면적이 작을수록 오버헤드가 줄어들게 됨을 알 수 있다.

Epidemic & Prediction based Routing Protocol for Delay Tolerant Network (DTN에서 에피데믹과 예측 기반 알고리즘을 이용한 라우팅 프로토콜)

  • Dho, Yoon-Hyung;Lee, Kang-Whan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.05a
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    • pp.404-407
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    • 2014
  • Delay Tolerant Network (DTN) is a networking architecture that is designed to solve network problem in unstable and stressed environments using the Store-Carry-Forward method. Different form general networks, DTN does not guarantee the end-to-end connectivity, it is hard for the exiting TCP/IP based protocols to normally work due to the characteristic such as large latency and unstable link connectivity. And the condition that send massage without the information of the destination occurs frequently. Thus, suitable routing protocols for DTN are required and being researched. In this paper, we propose a novel routing protocol for DTN utilizing epidemic and prediction based algorithm to prevent the defect of previously DTN routing protocols such as the absence of the holistic view of the network. Proposed algorithm predicted destination using the mobility information recorded in neighbor node's history and utilize epidemic based algorithm when occurred condition without destination's information. This algorithm is enhanced in terms of delivery ratio, decreases latency and overhead in sparse network such as DTN.

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Reducing Flooding Latency in Power Save Mode of IEEE 802.11-based Mobile Ad hoc Networks (IEEE 802.11 기반 이동 애드혹 망의 전력 절감 모드에서 플러딩 지연의 개선)

  • 윤현주;서명환;마중수
    • Journal of KIISE:Information Networking
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    • v.31 no.5
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    • pp.532-543
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    • 2004
  • Mobile Ad hoc NETworks (MANET) consist of mobile nodes which are usually powered by battery Approaches for minimizing power consumption have been proposed for all network layers and devices. IEEE 802.11 DCF (Distributed Coordination Function), a well-known medium access control protocol for MANETS, also defines a power save mode operation. The nodes in power save mode periodically repeat the awake state and the doze state in synchronized fashion. When all nodes are in the awake state, the exchange the announcements for the subsequent message transmission with neighbors. The nodes that send or receive the announcements stay awake for data transmission, and others go into the dole state. The previous works for enhancing the power save mode operation have focused on shortening the duration of the awake state. We observed that the longer sleeping period results in seriously long delivery latency and the consequent unnecessary power consumption as well, because the packets can move forward only one hop for a fixed interval. In this paper, we propose an improved protocol for the power save mode of IEEE 802.11 DCF, which allows the flooding packets to be forwarded several hops in a transmission period. Our approach does not reduce the duration of compulsory awake period, but maximizes its utilization. Each node propagates the announcements for next flooding to nodes of several hops away, thus the packets can travel multiple hops during one interval. Simulation results of comparison between our scheme and the standard show a reduction in flooding delay maximum 80%, and the unicasting latency with accompanying flooding flows near 50%, with slight increase of energy consumption.

A Coding Packet Group-Based ARQ Scheme for File Delivery Services in a Multi-Hop Wireless Network (다중 홉 MANET에서의 파일 전송 응용을 위한 코딩 패킷 그룹 기반 ARQ 기법)

  • Kim, Youngsil;Kang, Kyungran;Cho, Young-Jong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.7
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    • pp.612-622
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    • 2013
  • In this paper, we propose a coding packet group-based ARQ scheme (rNC) for file delivery in wireless networks. rNC assumes multiple network coding points between the source and the destination. Each network coding point gathers and codes a group of packets according to the queue polling system. A queue polling system makes a few or several packets available for coding in a queue while polling the other queues in the system. Thus, we assuem a queue polling system at each network coding point. We call this group of packets as coded packet group. Each coding point acknowledges the reception of every code packet group to its previous coding point for reliable delivery. Thus, the intermediate coding points including the source can release its buffer before the packet is delivered to the destination. To guarantee the ultimate file delivery to the destination, the destination sends acknowledgement to the sender. We evaluate our proposed scheme using ns-2 and compare the performance with CodeCast. The results show that rNC works better than CodeCast in terms of packet delivery ratio and control overhead in unreliable wireless networks.

Multiple Path Security-Aware Routing Protocol Mechanism for Ad Hoc Network (Ad Hoc 네트워크 라우팅 보안을 위한 다중경로 기반의 MP-SAR 프로토콜)

  • Han, In-Sung;Ryou, Hwang-Bin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.5B
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    • pp.260-267
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    • 2008
  • As pervious the SAR(Security Aware Routing)[10] protocol is an secure Ad Hoc network protocol that finds a secure path, it is the security routing protocol that uses the security level of nodes as the routing information. However, the SAR protocol sometimes transfers data through inefficient transmission paths because it always tries to find secure nodes for a safe transmission. Since it is a protocol based on AODV[6], it will cause transmission delay as researching of security routing path. when a node is out of the data transmission range as its battery dying or movement. Although it is possible to connection of nodes because a characteristic of the SAR protocol, the connection is not easy to reconnect when the security level of intermediate node is lower than the level requested by a source node. In this paper, we suggest the MP-SAR based on the SAR to solve the SAR protocol's problem. The MP-SAR seeks multiple secure path for maintenance of data confidentiality using the expanded secure path detection techniques based on the SAR. It can transfer data quickly and reliably by using the shortest efficient path among multiple paths. In the research result, we proved a outstanding performance of MP-SAR than the previous SAR through comparison and analysis.

A Research of LEACH Protocol improved Mobility and Connectivity on WSN using Feature of AOMDV and Vibration Sensor (AOMDV의 특성과 진동 센서를 적용한 이동성과 연결성이 개선된 WSN용 LEACH 프로토콜 연구)

  • Lee, Yang-Min;Won, Joon-We;Cha, Mi-Yang;Lee, Jae-Kee
    • The KIPS Transactions:PartC
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    • v.18C no.3
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    • pp.167-178
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    • 2011
  • As the growth of ubiquitous services, various types of ad hoc networks have emerged. In particular, wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are widely known ad hoc networks, but there are also other kinds of wireless ad hoc networks in which the characteristics of the aforementioned two network types are mixed together. This paper proposes a variant of the Low Energy Adaptive Cluster Hierarchy (LEACH) routing protocol modified to be suitable in such a combined network environment. That is, the proposed routing protocol provides node detection and route discovery/maintenance in a network with a large number of mobile sensor nodes, while preserving node mobility, network connectivity, and energy efficiency. The proposed routing protocol is implemented with a multi-hop multi-path algorithm, a topology reconfiguration technique using node movement estimation and vibration sensors, and an efficient path selection and data transmission technique for a great many moving nodes. In the experiments, the performance of the proposed protocol is demonstrated by comparing it to the conventional LEACH protocol.

A Method for Reducing Path Recovery Overhead of Clustering-based, Cognitive Radio Ad Hoc Routing Protocol (클러스터링 기반 인지 무선 애드혹 라우팅 프로토콜의 경로 복구 오버헤드 감소 기법)

  • Jang, Jin-kyung;Lim, Ji-hun;Kim, Do-Hyung;Ko, Young-Bae;Kim, Joung-Sik;Seo, Myung-hwan
    • Journal of IKEEE
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    • v.23 no.1
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    • pp.280-288
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    • 2019
  • In the CR-enabled MANET, routing paths can be easily destroyed due to node mobility and channel unavailability (due to the emergence of the PU of a channel), resulting in significant overhead to maintain/recover the routing path. In this paper, network caching is actively used for route maintenance, taking into account the properties of the CR. In the proposed scheme, even if a node detects that a path becomes unavailable, it does not generate control messages to establish an alternative path. Instead, the node stores the packets in its local cache and 1) waits for a certain amount of time for the PU to disappear; 2) waits for a little longer while overhearing messages from other flow; 3) after that, the node applies local route recovery process or delay tolerant forwarding strategy. According to the simulation study using the OPNET simulator, it is shown that the proposed scheme successfully reduces the amount of control messages for path recovery and the service latency for the time-sensitive traffic by 13.8% and 45.4%, respectively, compared to the existing scheme. Nevertheless, the delivery ratio of the time-insensitive traffic is improved 14.5% in the proposed scheme.

Efficient Content Sharing using the Selection of Minimum Forwarding Peers in an Ad Hoc Network (최소의 Forwarding Peer 선택을 통한 애드 혹 네트워크에서의 효율적 콘텐츠 분배 방법)

  • Kang, Seung-Seok
    • Journal of the Korea Society for Simulation
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    • v.18 no.4
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    • pp.165-173
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    • 2009
  • Recent portable devices are so versatile that they have multiple communication channels and play several multimedia formats. Especially, many services are under development for users who connect Internet or nearby devices via WWAN (Wireless Wide Area Network) and/or WLAN (Wireless LAN). In case of paying the telecommunication cost proportional to the amount of data downloaded, it is necessary to reduce the cost by constructing a special ad hoc network in which each participating peer downloads a specific portion of the want-to-be-shared content over the payable WWAN channel and exchanges the remaining portion with other peers using the cost-free WLAN channel. If all peers participate in forwarding packets, some transmissions are redundant which results in the unnecessary consumption of bandwidth as well as the delayed content distribution time. In order to reduce the redundant transmission, this paper proposes both the excluding method which discourages some peers not to forward redundant packets, and the minimum cover set method in which only the minimum number of peers are in charge of forwarding packets. These two methods obviate redundant packet forwarding, and result in reduction of content distribution time by up to around 29%.

A Study on the Comparative Art theory in the Arts and Crafts Movement and Post-impressionism (미술 공예 운동과 후기 인상주의 비교 예술론 연구)

  • 박연실
    • Archives of design research
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    • v.20
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    • pp.279-291
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    • 1997
  • The history of modern design begins with the arts and crafts movement(1860). The importance of the movement which decorated the outset gave birth to all the trends of thought which would occur under the circumstances within it, and is deemed that the ideas of the figures who played an active part in the movement might be ceaselessly continued through the works and ideas of their outstanding juniors or purpils as a doctrine of the philosophy of design. Therefore, it might be a prerequisite that the significance and spirit of the movement, and its developing process should be addressed in detail in the first place, but for the limited space of this paper, it was intended to desvribe only the part which can be interpreted in duplicate, linked with post-impressionism. The subject of this thesis is about a theory of art in which both ideas of the movement(1860) and the post-impressionism(1910) are comparatively reviewed. The genre, strictly speaking, is classified into the history of painting, and there is a gap fo about an half century between the issues which are comparatively discussed here. Both the movements began in a same environmental place of England, specially the movement at Milieu in England, and since there is a common point that the representative runners of each movement, William Morries(1834-1896) and Roger Fry(1866-1934), belong to a same race of Engol-Saxon, their ideas coincide with an aesthetic scholar, H. Tanie's aesthetic interpretation method and the more important is, as being elucidated in the comment and aesthetic theory for which Roger Fry gave effort and activity in his later life, that when he read intensively Ruskin's books, $\ulcorner$Modern Painters$\lrcorner$and$\ulcorner$Stones of Venice$\lrcorner$he had solidified his idea of post-impressionism while giving approval and criticism on them. After all, as in a co-painter, Windyham Lewis's reference of 'Roger Fry's Too Late Morris Movement', he, inspired by the actual activities of Morris, played activities similar to that of Morris in which exhibiting and selling some of his decorative art works signed by him and the works of post-impressionism through (1913-1920). Herein, that is wished to add a remark by this author is a point that the author of$\ulcorner$Vision and Design$\lrcorner$, Roger Fry, has not be made a subject of discussion specially in the Korean world of design. So, with this case of a thesis, it's wished that many latent awakened, design persons in korea give efforts to researching into Roger Fry so that their findings could be officially announced in the would. By the way, what is tried to describe in this paper from now on is to analyse and review the origin of post-impressionism which idea was first coined in the art world through the 1st and 2nd exhibitions of 'Manet and Post-impressionism' which were opened each at the Grafton Gallery in 1910 and 1913 by him. And also, it is intended to review it through the art journals and some references by critics of the day in which favorable criticism or severe criticism were ready to comment through the opinions and influences of the coworkers of Roger Fry, say, Clive Bell, Desmond Maccarthy, etc. and of himself as a main axis, on the art ideas of Gauguin, Gogh, Matisse, and Cezanne whose works were the typical ones participated and exhibited in those 1st and 2nd exhibitions.

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