The Meraka Indoor wireless mesh test bed A new multi hop routing benchmarking tool

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The Meraka Indoor wireless mesh test bedA new
multi hop routing benchmarking tool

• David Johnson
• Senior Researcher
• Wireless Africa Programme
• Meraka
• CSIR

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450 million rural people in Africa are isolated
from the rest of the world
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Connect them all by 2017
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Sound crazy?
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How do these sound?
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7 trillion wireless devices serving 7 billion
people by 2017 Wireless World Research Forum
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Affordable mobile communications for half the
world's population by 2015 Nokia
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Half the world have Internet access by 2015 AMD
50x15
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Creates cognitive dissonance
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Heres how it could be done
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Turn the first mile into an open bazaar of
community networks
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As easy to setup as a TV
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Telcos just provide backhaul
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Income stays in the communities
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Modernized without being urbanized
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Ubuntu community networks mesh networks
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• Plenty of research problems to address
• Routing protocols and routing metrics
• Gateway selection for multiple gateways
• Power efficiency
• Auto channel allocation
• Distributed services
• Multimedia over mesh
• Clustering optimization
• Smart antennas for mesh
• Business models for village entrepreneurs
• Security over mesh
• Vulnerability of first time exposure to the
  internet
• Building technical skills in developing regions
• Logistics

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Why build a test bed?
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Mathematical models good enough for rules of
thumb but no tractable solution for a real
network
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Simulation models good for early protocol
development and testing but still far from reality
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Real outdoor wireless reality but difficult to
build and manage
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Indoor test beds provide controlled environment
and expose theoretical simplifications
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Construction of the meraka wireless grid
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Construction of the meraka wireless grid
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Construction of the meraka wireless grid
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Construction of the meraka wireless grid
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Construction of the meraka wireless grid
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Challenges when building experiments
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Challenges when building experiments
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Challenges when building experiments

• Which combination of mode/rate/txpower to use
• Experiments are time consuming ... 52 hours to
  test 4 routing protocols using all combinations
  of 49 nodes in the grid with 20 second test time

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Electromagnetic modelling of the grid
Done with WIPL-D modelling software
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Electromagnetic modelling of the grid
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Results 49 node multi hop chain
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Results 49 node multi hop chain
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Results 49 node multi hop chain

• After 4 hops
• Gupta best 50
• Gupta worst 42.47
• Gupta indoor measurements 9.74
• Meraka lab 25.7

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Choosing routing protocols to benchmark
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Results hop count distribution
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Results Routing traffic overhead
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Results Routing traffic overhead
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Results throughput, packet loss, delayString
of 7 nodes
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Results throughput, packet loss, delayFull 7x7
grid
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Comparison of throughput to baseline
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Conclusions

• Proved that multi hop wireless networks possible
  on scaled test beds (up to 5 hops were achieved
  in a space of 7Mx7M)
• Complexity in the grid is high and produces a
  worst case scenario for routing algorithms.
• The AODV protocol showed the weakest performance
  but had the lowest routing overhead.
• DYMO showed good results for its low routing
  overhead with the least amount of delay for the
  full 7x7
• The RFC version of OLSR had the best overall
  performance the full 7x7 grid.
• OLSR with the ETX extension performed better in
  medium size networks of about 21 nodes.

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Future improvements to the mesh lab

• Compare results to NS2 simulations
• Add a lab sandbox
• Add a lab scheduler to make it simple for
  multiple interested parties to run experiments
• Build a measurement framework to simplify setting
  up experiments
• Test virtual mobility and install a roaming robot
• Experiment with parameters beyond the RFC values
  for routing protocols
• Add support for power measurements
• Add support for control of smart antennas

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For further information

• http//wirelessafrica.meraka.org.za