• Title/Summary/Keyword: Check path algorithm

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An Adaptive FEC Algorithm for Mobile Wireless Networks (이동 무선 네트워크의 전송 성능 향상을 위한 적응적 FEC 알고리즘)

  • Ahn, Jong-Suk;John Heidmann
    • The KIPS Transactions:PartC
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    • v.9C no.4
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    • pp.563-572
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    • 2002
  • Wireless mobile networks tend to drop a large portion of packets due to propagation errors rather than congestion. To Improve reliability over noisy wireless channels, wireless networks can employ forward error correction (FEC) techniques. Static FEC algorithms, however, can degrade the performance by poorly matching their overhead to the degree of the underlying channel error, especially when the channel path loss rate fluctuates widely. This paper investigates the benefits of an adaptable FEC mechanism for wireless networks with severe packet loss by analytical analysis or measurements over a real wireless network called sensor network. We show that our adaptive FEC named FECA (FEC-level Adaptation) technique improves the performance by dynamically tuning FEC strength to the current amount of wireless channel loss. We quantify these benefits through a hybrid simulation integrating packet-level simulation with bit-level details and validate that FECA keeps selecting the appropriate FEC-level for a constantly changing wireless channel.

Automatic Node Configuration Protocol for Small Sized Mobile Ad-Hoc Networks (소규모 이동 애드혹 네트워크에서의 자동 노드 설정 프로토콜)

  • Lee Hyewon K.;Mun Youngsong
    • Journal of KIISE:Information Networking
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    • v.32 no.1
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    • pp.100-109
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    • 2005
  • A Mobile Ad-Hoc Network (MANET) supports a multi-hop wireless network without any prepared base station (BS). The MANET is capable of building a mobile network automatically without any help from DHCP servers for address allocation or routers to forward or route messages. Many routing protocols have been proposed for the MANET, but these specify the most optimized or shortest path from a source to a destination, and they assume that nodes are pre-configured before communication. To make up for this, address allocation algorithms, such as MANETConf [1] and prophet address allocation algorithm [2], have been proposed. Especially, MANETConf proposes address allocation algorithm with duplication address check. In this paper, we present a dynamic node configuration protocol based on 2-tierd hierarchical network architecture for mobile ad-hoc network, modified from [1]. Especially, it reduces the number of broadcast message exchange between nodes when a new node somes into a network, which lessens network overhead, remarkably. This protocol is based on two-tired structure, and it ensures address allocation with simple duplication address defection mechanism.

Interference Analysis of Wireless Systems with Arbitrary Antenna Patterns and Geographic Information in the VHF/UHF Bands (VHF/UHF 대역에서 지리정보와 임의 안테나 패턴을 갖는 무선시스템의 간섭분석 연구)

  • Suh, Kyoung-Whoan
    • Journal of Broadcast Engineering
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    • v.18 no.3
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    • pp.445-454
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    • 2013
  • By using the radio propagation prediction of Rec. ITU-R P.1546, geographic information system, and S-I plane, we presented the methodology of interference analysis based on the minimum coupling loss, and also suggested the local coordinate system for calculating azimuth and elevation angles between the victim receiver and the interferer for an arbitrary antenna pattern. To check the presented algorithm, the map with the land-sea mixed area was taken for the given area of $80{\times}60[km^2]$ as real geography information. Field strength, path profile, and protection ratio with maximum allowable interference level have been illustrated for radar and fixed wireless system for the assumed frequency. In addition interference power of the victim receiver was calculated asa function of azimuth and elevation angles of the interferer. The developed methodology of interference analysis in the VHF and UHF bands can be actually applied to assess interoperability as well as compatibility in the civil or military applications.

The automatic generation of MPTCP session keys using ECDH (MPTCP에서 ECDH를 이용한 세션 키 자동생성에 관한 연구)

  • Sun, Seol-hee;Kim, Eun-gi
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.10
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    • pp.1912-1918
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    • 2016
  • MPTCP(Multipath Transmission Control Protocol) is able to compose many TCP paths when two hosts connect and the data is able to be transported through these paths simultaneously. When a new path is added, the authentication between both hosts is necessary to check the validity of host. So, MPTCP exchanges a key when initiating an connection and makes a token by using this key for authentication. However the original MPTCP is vulnerable to MITM(Man In The Middle) attacks because the key is transported in clear text. Therefore, we applied a ECDH(Elliptic Curve Diffie-Hellman) key exchange algorithm to original MPTCP and replaced the original key to the ECDH public key. And, by generating the secret key after the public key exchanges, only two hosts is able to make the token using the secret key to add new subflow. Also, we designed and implemented a method supporting encryption and decryption of data using a shared secret key to apply confidentiality to original MPTCP.

Improving A Stealth Game Level Design Tool (스텔스 게임 레벨 디자인 툴의 개선)

  • Na, Hyeon-Suk;Jeong, Sanghyeok;Jeong, Juhong
    • Journal of Korea Game Society
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    • v.15 no.4
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    • pp.29-38
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    • 2015
  • In the stealth game design, level designers are to develop many interesting game environments with a variety of difficulties. J. Tremblay and his co-authors developed a Unity-based level design tool to help and automate this process. Given a map, if the designer inputs several game factors such as guard paths and velocities, their vision, and the player's initial and goal positions, then the tool visualizes simulation results including (clustered) possible paths a player could take to avoid detection. Thus with the help of this tool, the designer can ensure in realtime if the current game factors result in the intended difficulties and players paths, and if necessary adjust the factors. In this note, we present our improvement on this tool in two aspects. First, we integrate a function that if the designer inputs some vertices in the map, then the tool systematically generates and suggests interesting guard paths containing these vertices of various difficulties, which enhances its convenience and usefulness as a tool. Second, we replace the collision-detection function and the RRT-based (player) path generation function, by our new collision-check function and a Delaunay roadmap-based path generation function, which remarkably improves the simulation process in time-efficiency.