Extending Global IP for Ad Hoc Networks

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Extending Global IP for Ad Hoc Networks

• Author Christer Åhlund and Arkady Zaslavsky

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Extending Global IP Connectivity

• Published at
• Telecommunication System (journal), 2003
• Extended work of
• Integration of ad hoc networks and IP network
  capabilities for mobile hosts, ICT,2003

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Introduction

• Hot spot areas (802.11 infrastructure) provide
  wireless network access by connecting to one
  single AP
• No way to connect to multiple AP
• Multipath propagation, fadding effects
• 802.11 infrastructures hard to configure.
• Frequency planning, network configuration
• Hard to provide good coverage

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Introduction

• Ad hoc networks
• Everyone contributes to the coverage as whole
  (shared coverage)
• Easy to setup
• Does not require a predefinied infrastructure
• Use the same frequency
• Has been viewed as standalone networks without
  connectivity to the Internet, until now...

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Introduction

• Suppose ad-hoc networks could be used just as
  another sub network, i.e use an ad-hoc network as
  a link-layer?
• Combine ad-hoc and infrastrcutures
• Increase performance
• Increase reliability
• Better support for roaming
• Rapid deployment of Internet connected wireless
  networks

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User scenario

• Emergency places
• Hard to deploy an infrastructure
• Industrial places
• Factories etc.
• Everybody has to agree on sharing its resources

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Theory

• Global connectivity
• Connecting heterogenous networks togeather in
  order to achive global reachability
• For example connecting an Ethernet network to a
  token-ring network
• The gateway between the network must be equipped
  with both access types
• Some nodes must be run both ad-hoc and
  infrastructure mode, the gateway

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Theory
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Theory

• Ad-hoc routing
• Definition How to find a path to the Internet?
• Non-Broadcast Multiple Access
• Must use the network layer to reach other nodes
• Reactive and proactive routing protocols
• Ad-hoc On-Demand Distance Vector Protocol is used
  
• Mobility
• Manage mobility between ad-hocs networks and
  other sub-networks
• Mobile IP ...

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Theory

• Scientific contribution
• A gateway connecting IP networks and ad-hoc
  networks
• An extention to MIP, allowing multiple agent
  registrations
• The best connection is selected based upon agent
  advertisement arrivial times
• Metric (SampleDela-MeanDelta)2u ......
• Assumtion the metric will increase if the
  performace decrease
• A prototype using MIPv4 and AODV

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Results

• Simulation study
• Assumption the last hops (bad coverage) is
  causing bad performance
• Study the effect of agent advertisements arrival
  times
• Results The simulation shows that the proposed
  metric is a good representive for the link
  quality
• Personal reflection
• Why not use RSSI or perhaps available battery/CPU
  load or even user requirements as parameters?

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Personal conclusion

• Interference is a big problem for 802.11
• Need to be able to associate with multiple base
  stations or other clients
• Three solutions
• Christer work
• Link layer improvement (Channel AP hopping)
• Or, imagine a network card with 3 or more 802.11
  devices. 2 devices allow multiple association.
  The 3rd is used as a base-station.