SelfOrganization in Mobile AdHoc Networks: the Approach of Terminodes

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Self-Organization in Mobile Ad-Hoc Networks the
Approach of Terminodes

• Ljubica Blazevic
• Swiss Federal Institute of Technology
• IEEE Communications Magazine, June 2001
• Presented by Se-Hoon Kim

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Contents

• Introduction
• Packet Forwarding
• Mobility Management the Virtual Home Region
• GPS-free positioning
• Incentive to cooperation
• Security
• Conclusion

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Introduction

• Self-organized networks
• Distinguish themselves from traditional mobile
  networks by emphasizing their self-organization
  characteristics.
• Are non-authority based networks
• Are potentially very large and not regularly
  distributed
• Are highly co-operative

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Terminal Node Terminode

• All network functions (packet forwarding, flow
  control,..) and terminal functions (storage,
  ciphering,..) are embedded in the terminode
• Terminodes correspond to totally self-organized
  mobile ad-hoc networks
• All terminodes are potentially mobile
• A communication is relayed by intermediate
  terminodes
• The network is self-organized no human
  intervention

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Packet Forwarding
EUI End-system Unique Identifier LDA
Location-Dependent Address
Design factors Scalability and Incentive for
Cooperation (based on Nuglets) Terminode Local
Routing-Does not use location information
Terminode Remote Routing-Geographical based
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Terminode Local Routing (TLR)

• Used in close range
• Usually several hops away
• Does not use location information
• TLR uses proactive approach
• Use TLR bit is set within the packet header

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Terminode Remote Routing (TRR)

• Geographical based
• Anchored Geodesic Packet Forwarding (AGPF)
• Anchor a point described by geographical
  coordinates
• TRR is constantly modified by Path Maintenance
• Friend Assisted Path Discovery (FAPD)
• Friend there exists a good path to node

• Cost of each path
• Packet loss, delay

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Friend Assisted Path Discovery
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Mobility Management the Virtual Home Region

• Virtual home region (VHR)
• Has a fixed center (calculated by hash function
  H) and variable radius to accommodate number of
  nodes
• H(EUIA) CVHR, A?EUIi
• Nodes advertise their locations to their VHR
• Timer based or distance based
• When B wants to know As location, it queries As
  VHR
• Main functions of this architecture
• Maintaining the location information
• Distributing the location information inside the
  network

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LDA Storage
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LDA Request
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LDA Response
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Packet Forwarding
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GPS-Free Positioning

• If GPS is available Each node is aware of its
  own Location-Dependent Address (LDA) via GPS
  (Global Positioning System)

• If GPS is not available Computation of relative
  positions based on Time of Arrival (TOA)
• Self-positioning algorithm (SPA)

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Self-positioning algorithm (SPA)

• A terminode
• measures distance to its neighbors and sends this
  information to all its neighbors
• builds its Local Coordinate System (LCS) and
  computes the positions of its neighbors in LCS
• computes the density factor of its n-hop
  neighborhood
• A terminode with the highest density factor forms
  a Location Reference Group (the terminodes in its
  n-hop neighborhood) and computes the center and
  the direction of the Network Coordinate System
  (NCS)
• All terminodes compute their position in the
  Network Coordinate System

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GPS-Free Positioning
Distance are typically estimated by time of
arrival measurement
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Local Coordinate System
Every Node Choose two nodes with known
distance between them defines a coordinate
system
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Convergence to a Single Coordinate System
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Incentive to cooperation

• Assumptions
• 1. Each node is its own authority domain ?
  selfish nodes
• 2. Each node contains a trusted, tamper-resistant
  security module
• Use virtual currency - NUGLETS
• Encourage end-users to let their terminode act as
  a relay (keep them turned on)
• Discourage end-users from overloading the
  network in particular, limit the number of long
  distance communications and useless data
• 2 models, based on a virtual currency the nuglet
• Packet Purse Model (payment by the sender)
• Packet Trade Model (payment by the receiver)

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Packet Purse Model (PPM)

• Problems to be solved include
• - Nuglet forgery should be prevented
• - Nuglet robbery should be prevented
• - Each packet should indeed be forwarded
• The packet purse should be bundled to its packet
• Advantages
• - stimulate terminodes for cooperation
• - deter users from sending useless data
  and overloading the network

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Packet Trade Model (PTM)
Advantages - The sender does not need to know the
amount of nuggets that is necessary to send a
packet - Intermediaries are interested in
forwarding the packet after having bought it -
Charging for multicast communications is
easier Drawback - There is no direct incentive to
refrain from overloading the network
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Security

• Use PKI (Public Key Infrastructure)
• Vulnerability of adopting PKI in ad-hoc networks
• to establish a key management service using a
  single CA (Certification Authority)

A self-organization mobile ad hoc network has no
infrastructure and therefore no server
no certification authority
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Security
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Security
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Conclusion

• Present a global description of some aspects of
  the project called Terminodes
• Self-organized routing, location management,
  GPS-free positioning, and nuglets
• Nuglet is used as the basis for inciting users to
  cooperate, and as a congestion control mechanism
  for discovery and routing mechanisms