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Link-level Measurements from an 802.11b Mesh Network

Link-level Measurements from an 802.11b Mesh Network. Dainel Aguyo, John Bicket,Sanjit Biswas, Glenn Judd, Robert Morris M.I.T , CMU. Abstract. Roofnet を使用して、実際に MANET を構築 ロスの解析を行なう. Roofnet. Roofnet. Distribution of Delivery Probabilities.

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Link-level Measurements from an 802.11b Mesh Network

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  1. Link-level Measurements from an 802.11b Mesh Network Dainel Aguyo, John Bicket,Sanjit Biswas, Glenn Judd, Robert Morris M.I.T , CMU

  2. Abstract • Roofnet を使用して、実際にMANETを構築 • ロスの解析を行なう

  3. Roofnet

  4. Roofnet

  5. Distribution of Delivery Probabilities • Links with intermediate loss rates are common, with no sharp transition between high and low packet loss rates.

  6. Spatial Distribution of Loss Rate • Inter-node distance is not strongly correlated with whether nodes can communicates.

  7. Time Variation of Loss Rate • Most links have non-bursty loss patterns.

  8. Effect of Signal-to-Noise Ratio • Links with very high signal strengths are likely to have low loss rates, but in general signal strength has little predictive value.

  9. Effect of Transmit Bit-rate • A link islikely to have a significant loss rate at its optimum 802.11b bit-rate.

  10. Effect of Multi-path • Mutil-path fading greatly affects outdoor links and helps explain intermediate loss rates

  11. Comparison of Routing Metrics for Static Multi-Hop Wireless Networks Richard Draves, Jitendra Padhy, Brian Zill Microsoft Research

  12. Abstract • DSR like のMANETプロトコルを実装して、Path Metric の違いによる、性能評価を行なう。 • Metric – ETX, Per-hop RTT, per-hop packet pair, minimum-hop

  13. Link Quality Metrics • Hop Count: shortest-path routing • RTT: round-trip time latency • PktPair: packet-pair latency • ETX: expected transmission count

  14. Ad Hoc Routing Architecture • DSR + support link quality metric（Link-Quality Source Routing) • Supports IPv4, IPv6 etc unmodified • Supports multiple link technologies IPv4 IPv6 IPX Mesh Connectivity Layer (with LQSR) Ethernet 802.11 802.16

  15. Impact of Long Lived TCP Flows • Route Flapping のため、RTT・PktPairは性能が良くない

  16. Impact of Path Length • EXTは shortest hop より、hop数の多い経路を使用している

  17. Impact of Path Length(Cont.)

  18. Multiple Simultaneous TCP Transfer • pktpair は ホップ数が増えるほど低下

  19. Web-like TCP Transfers • Hop 数が長いと、ETXのほうがHOPに比べ性能がよい

  20. A Mobile Scenario • ETX ではノードの移動による経路品質の変化に対し、適応できない

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