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Robert Morris Daniel Aguayo, John Bicket, Sanjit Biswas, Douglas De Couto

MIT Roofnet Performance. Robert Morris Daniel Aguayo, John Bicket, Sanjit Biswas, Douglas De Couto http://pdos.lcs.mit.edu/roofnet. Roofnet node map. 1 kilometer. Typical rooftop view. Roofnet radio links. 1 kilometer. A Roofnet Self-Installation Kit. 50 ft. Cable ($40)

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Robert Morris Daniel Aguayo, John Bicket, Sanjit Biswas, Douglas De Couto

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  1. MIT Roofnet Performance Robert Morris Daniel Aguayo, John Bicket, Sanjit Biswas, Douglas De Couto http://pdos.lcs.mit.edu/roofnet

  2. Roofnet node map 1 kilometer

  3. Typical rooftop view

  4. Roofnet radio links 1 kilometer

  5. A Roofnet Self-Installation Kit 50 ft. Cable ($40) Low loss (3dB/100ft) Antenna ($65) 8dBi, 20 degree vertical Miscellaneous ($75) Chimney Mount, Lightning Arrestor, etc. Computer ($340) 533 MHz PC, hard disk, CDROM Software (“free”) Our networking software based on Click 802.11b card ($155) Engenius Prism 2.5, 200mW Total:$685 Takes a user about 45 minutes to install on a flat roof

  6. Roofnet Node Software sshd apache dhcpd User-space Linux Kernel Linux TCP/IP ETX NAT antenna srcrr Click 802.11 eth Living-room ethernet

  7. Roofnet link quality distribution 1 megabit/second Packet Delivery Probability 11 mbits/sec Node Pair

  8. S/N vs loss w/ cable + attenuator

  9. S/N vs loss for Roofnet links

  10. Transmit bit-rate choice 11 megabits/second 5.5 Packets/second received 2 1 Node Pair

  11. Basic Roofnet performance

  12. Multi-hop packet loss?

  13. What is a typical radio range? Delivery probability Distance (Meters)

  14. Effect of transmit power level

  15. Would a less-dense mesh work? • Roofnet is about twice as dense as it needs to be • Higher densities provide higher throughput

  16. Mesh versus access points • 5 APs are required for full connectivity • N mesh gateways give higher throughput than N APs

  17. Conclusions • Roofnet provides Internet access to 40+ users • Easy for users to install, self-configuring • Throughput > 200 kilobits/second for most users • Even 9-hop routes average 150 kilobits/second • Radio range up to 2km, density 10 nodes/km2 • Hard to beat mesh performance w/ access points • Multi-hop packet loss costs about a factor of two

  18. How reliant on the “best” nodes? Average Throughput (KB/s) Number of Best Nodes Eliminated

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