• Title/Summary/Keyword: Hop Count

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A Probabilistic Routing Mechanism Considering the Encounter Frequency in the Battlefield Environment (전장 환경에서 접촉 횟수 정보를 고려한 확률적 라우팅 기법)

  • Lee, Jongmok;Kang, Kyungran;Cho, Young-Jong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.16 no.3
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    • pp.332-339
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    • 2013
  • The network nodes in a tactical network moves continuously and due to the physical and electronic obstacles, the connections are not always available. Due to the frequent disconnections, it is hard to discover the path among the nodes in a DTN. According to PROPHET(Probabilistic Routing Protocol using History of Encounters and Transitivity), one of the most well-known DTN routing protocols, a DTN node determines whom to forward a packet according to the packet delivery probability. From the viewpoint of a node, the packet delivery probability of another node is degraded while the nodes are disconnected whereas it is improved when they encounter. In this paper, we enhance the algorithm estimating the packet probability by considering the encounter count as an additional parameter. Our algorithm prefers the node that encounters the destination more frequently in selecting the next hop toward the destination. We evaluated the performance of our algorithm by simulating military operations using a DTN-dedicated simulator. Through the simulations, we show that our proposed algorithm achieve higher packet delivery ratio with similar overhead compared with PROPHET.

Efficient Spanning Tree Topology Aggregation Method in Private Networks Interface (사설망인터페이스에서 효율적 스패닝 트리 토폴로지 요약기법)

  • Kim, Nam-Hee;Kim, Byun-Gon;Lee, Jong-Chan
    • The Journal of the Korea Contents Association
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    • v.8 no.7
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    • pp.35-42
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    • 2008
  • The proposed scheme in this paper can search multi-links efficiently using the depth priority method based on hop count instead of searching the all links. To do this, we proposed a modified line segment scheme using two line segment method. The scheme represents two points which consist of delay-bandwidth pair to reduce topology information and provide a flexibility to the multiple-links aggregation. And we apply it to current spanning tree topology aggregation. To evaluate performance of the proposed scheme, we compare/analyze the current method with the proposed scheme with respect to call success rate, access time and crankback rate. Simulation result analysis showed the proposed spanning tree topology aggregation scheme presents the better performance than existing scheme.

A Model Interconnecting ISP Networks (ISP 네트워크간 상호접속 모델)

  • Choi, Eun-Jeong;Tcha, Dong-Wan
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2005.10a
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    • pp.388-393
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    • 2005
  • Private peering, public peering and transit are three common types of interconnection agreements between providers in the Internet. An important decision that an Internet service provider (ISP) has to make is which private peering/transit ISPs and Internet exchanges (IXs) to connect with to transfer traffic at a minimal cost. In this paper, we deal with the problem to find the minimum cost set of private peering/transit ISPs and IXs for a single ISP. There are given a set of destinations with traffic demands, and a set of potential private peering/transit ISPs and IXs with routing information (routes per destination, the average AS-hop count to each destination, etc.), cost functions and capacities. Our study first considers all the three interconnection types commonly used in real world practices. We show that the problem is NP-hard, and propose a heuristic algorithm for it. We then evaluate the quality of the heuristic solutions for a set of test instances via comparison with the optimal ones obtained by solving a mixed integer programming formulation of the problem. Computational results show that the proposed algorithm provides near-optimal solutions in a fast time.

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Performance Analysis of Forwarding Schemes Based on Similarities for Opportunistic Networks (기회적 네트워크에서의 유사도 기반의 포워딩 기법의 성능 분석)

  • Kim, Sun-Kyum;Lee, Tae-Seok;Kim, Wan-Jong
    • KIISE Transactions on Computing Practices
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    • v.24 no.3
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    • pp.145-150
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    • 2018
  • Forwarding in opportunistic networks shows low performance because there may be no connecting paths between the source and the destination nodes due to the intermittent connectivity. Currently, social network analysis has been researched. Specifically, similarity is one of methods of social networks analysis. In this paper, we propose forwarding schemes based on representative similarities, and evaluate how much the forwarding performance increases. As a result, since the forwarding schemes are based on similarities, these schemes only forward messages to nodes with higher similarity as relay nodes, toward the destination node. These schemes have low network traffic and hop count while having stable transmission delay.

The IEEE 802.11 MAC Protocol to solve Unfairness Problem in Multihop Wireless Ad Hoc Networks (다중 무선 에드혹 네트워크에서 불공정 문제를 해결하기 위한 802.11 MAC 프로토콜)

  • Nam, Jae-Hyun
    • Journal of the Korea Society of Computer and Information
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    • v.12 no.6
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    • pp.229-234
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    • 2007
  • In the IEEE 802.11 Wireless Local Area Networks (WLANs), network nodes experiencing collisions on the shared channel need to backoff for a random period of time. which is uniformly selected from the Contention Window (CW) This contention window is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. The BEB scheme suffers from a unfairness problem and low throughput under high traffic load. In this paper, I propose a new backoff algorithm for use with the IEEE 802.11 Distributed Coordination Function.

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Improvement of Colored Thread Algorithm for Loop Prevention (루프 방지를 위한 칼라 스레드 알고리즘의 개선)

  • 김한경
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.12C
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    • pp.167-173
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    • 2001
  • Colored thread algorithm suggested by Ohba is understood to be effective to prevent from establishing path in loop. 3 kinds of thread state, such as null, colored, transparent, defined in colored thread algorithm which makes difficult and complex to design actions of the thread events, is reconfigured and improved to a 4 states to make the finite state machines simple. The original colored thread algorithm fonds loops by receiving thread of a same color that was generated by the initiator itself and confirms the loops by hop count of unknown thread traversed again along the looped path. This method is modified as to use the same color instead of generating new colored thread for the looped path, leading to save the traversing time. And also redefined the events to make easy coupling with existing protocols.

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The Improved Full Mesh Topology Aggregation Scheme in PNNI (PNNI에서 향상된 Full Mesh Topology Aggregation 기법)

  • Kim Nam-Hee
    • Journal of Korea Multimedia Society
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    • v.7 no.11
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    • pp.1556-1563
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    • 2004
  • In this paper, we propose an efficient full mesh topology aggregation method in PNNI networks. The proposed scheme can search multi-links efficiently using the depth priority method based on hop count instead of searching the all links. To do this, we propose a modified line segment algorithm using two line segment method that represents two points which consist of delay-bandwidth pair to reduce topology information and provide a flexibility to the multiple-links aggregation. And we apply it to current full mesh topology aggregation. To evaluate performance of the proposed scheme, we compare/analyze the current method with the proposed scheme with respect to call success rate, access time and crank back rate. The result is that the proposed scheme is better than the current scheme in performance.

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A Study of an Efficient ZigBee Address Assignment Scheme for Home Area Networks of Smart Grid

  • Choi, Dongmin;Chung, Ilyong
    • Journal of Korea Multimedia Society
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    • v.16 no.5
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    • pp.566-576
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    • 2013
  • In Home Area Network (HAN) of the smart grid, Power Line Communication (PLC) technology and ZigBee communication technology can be used in the communication among the Advanced Metering Infrastructure (AMI) devices. However, according to performance evaluation results of the PLC technology, we find that using the PLC technology is unsuitable for the remote meter reading service. It is worth noting that some parts of the PLC are converted to the ZigBee communication technology in Jeju, Korea. Compared with PLC, ZigBee has no restriction of the place, where the equipments can be freely set up, due to the advantage of radio communication. However, number of usable devices will impact the network performance which is depended on the address assignment. In addition, due to the restriction of transmission range among devices, it is difficult to apply the ZigBee address assignment method to the practical circumstance. In this paper, we examine the previous ZigBee address assignment schemes and the corresponding routing algorithms, and propose a novel address assignment scheme compared with the existing methods, the performance of the proposed one is improved. In particular, evaluation results show that the proposed scheme reduces the average number of hop count, the transfer time and the processing time.

The IEEE 802.11 MAC Protocol to solve Unfairness Problem in Multihop Wireless Ad Hoc Networks (다중 무선 에드혹 네트워크에서 불공정 문제를 해결하기 위한 802.11 MAC 프로토콜)

  • Nam, Jae-Hyun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.91-94
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    • 2007
  • In the IEEE 802.11 Wireless Local Area Networks (WLANs), network nodes experiencing collisions on the shared channel need to backoff for a random period of time, which is uniformly selected from the Contention Window (CW). This contention window is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. The BEB scheme suffers from a fairness problem and low throughput under high traffic load. In this paper, I propose a new backoff algorithm for use with the IEEE 802.11 Distributed Coordination Function.

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Development of Directed Diffusion Algorithm with Enhanced Performance (향상된 성능을 갖는 Directed Diffusion 알고리즘의 개발)

  • Kim Sung-Ho;Kim Si-Hwan
    • Journal of the Korean Institute of Intelligent Systems
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    • v.15 no.7
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    • pp.858-863
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    • 2005
  • Sensor network is subject to novel problems and constraints because it is composed of thousands of tiny devices with very limited resources. The large number of motes in a sensor network means that there will be some failing nodes owing to the lack of battery in sensor nodes. Therefore, it is imperative to save the energy as much as possible. In this work, we propose energy efficient routing algorithm which is based on directed diffusion scheme. In the proposed scheme, some overloads required for reinforcing the gradient path can be effectively eliminated. Furthermore, in order to verify the usefulness of the proposed algorithm, several simulations are executed.