tseng:1

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Introduction to Ad Hoc Networking

• Perkins book Ch 1 and Ch 2.
• Some data collected from the Internet
• by Prof. Yu-Chee Tseng

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Model of Operations
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Assumptions

• Symmetric Links
• unidirectional links are difficult to dealt with,
  and sometimes at the verge of failure
• Layer-2 Routing
• Most protocols are presented in layer-3 routing,
  but can be easily retooled as a layer-2 ones.
• Proactive vs. Reactive Protocols
• (to be elaborated later)

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Applications

• ad hoc conferencing
• home networking
• emergency services
• personal area network (PAN)
• ubiquitous computing
• computers are all around us, constantly
  performing mundane tasks to make our lives a
  litter easier
• Ubiquitous intelligent internetworking devices
  that detect their environment, interact with each
  other, and respond to changing environmental
  condition will create a future that is as
  challenging to imagine as a science fiction
  scenario.

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• Sensor Dust
• a large collection of tiny sensor devices
• once situated, the sensors remain stationary
• largely homogeneous
• power is likely to be a scarce resource, which
  determines the lifetime of the network
• can offer detailed information about terrain or
  environmental dangerous conditions.
• Intelligent Transportation System
• may be integrated with cars, positioning devices,
  etc.

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Technical Factors

• scalability
• power budget vs. latency
• protocol deployment and incompatibility standards
• Unless a miracle happens (e.g., the IETF manet
  working group is able to promulgate a widely
  deployed ad hoc networking protocol), ad hoc
  networks will gain momentum only gradually
  because users will have to load software or take
  additional steps to ensure interoperability.
• wireless data rate
• e.g., TCP over multi-hop wireless links
• security issues

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More Extensions (DoDs Perspective)

• could be a group of hosts supported by one or
  more radios
• could across the Internet

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IEFT MANET Working Group

• goal
• to standardize an interdomain unicast routing
  protocol which provides one or more modes of
  operation, each mode specialized for efficient
  operation in a given mobile networking context,
  where a context is a predefined set of network
  characteristics.
• a dozen candidate routing protocols have been
  proposed.

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Applications of Ad Hoc Networks
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Network Architectures

• No Infrastructure (ad hoc networks)
• no base stations no fixed network infrastructure

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MANET

• MANET Mobile Ad Hoc Networks
• multi-hop communication
• needs support of dynamic routing protocols

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Nokia Rooftop Product
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Nokia RoofTop

• RoofTop solution (Nokia, Finland)
• Wireless router
• a radio frequency (RF) modem
• a digital Internet protocol (IP) router

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FHP

• FHP Wireless, USA
• ad hoc network in a campus

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FHP Wireless
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FHP Wireless
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MeshNetworks

• MeshNetworks, USA

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System MeshNetworks

• Architecture

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Networking Scenario To Internet
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SkyPilot NeighborNet

• SkyPilot Network, USA

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Routing Ants Searching for Food
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Three Main Issues in Ants Life

• Route Discovery
• searching for the places with food
• Packet Forwarding
• delivering foods back home
• Route Maintenance
• when foods move to new place

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Proactive vs. Reactive Routing

• Proactive Routing Protocol
• continuously evaluate the routes
• attempt to maintain consistent, up-to-date
  routing information
• when a route is needed, one may be ready
  immediately
• when the network topology changes
• the protocol responds by propagating updates
  throughout the network to maintain a consistent
  view
• Reactive Routing Protocol
• on-demand
• Ex DSR, AODV

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Ad hoc routing protocols
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DSDV

• Destination Sequenced Distance Vector
• Table-driven
• Based on the distributed Bellman-Ford routing
  algorithm
• Each node maintains a routing table
• Routing hops to each destination
• Sequence number

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DSDV

• Problem
• A lot of control traffic in the network
• Solution
• two types of route update packets
• Full dump
• All available routing information
• Incremental
• Only information changed since the last full dump

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Clustering Protocol

• Cluster Gateway Switch Routing (CGSR)
• Table-driven for inter-cluster routing
• Uses DSDV for intra-cluster routing

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AODV

• Ad hoc On-demand Distance Vector
• On-demand driven
• Nodes that are not on the selected path do not
  maintain routing information
• Route discovery
• The source node broadcasts a route request packet
  (RREQ)
• The destination or an intermediate node with
  fresh enough route to the destination replies a
  route reply packet (RREP)

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AODV
(a) RREQ
(b) RREP
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AODV

• Problem
• A node along the route moves
• Solution
• Upstream neighbor notices the move
• Propagates a link failure notification message to
  each of its active upstream neighbors
• The source node receives the message and
  re-initiate route discovery

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DSR

• Dynamic Source Routing
• On-demand driven
• Based on the concept of source routing
• Required to maintain route caches
• Two major phases
• Route discovery
• Route maintenance
• A route error packet

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DSR
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ZRP

• Zone Routing Protocol
• Hybrid protocol
• On-demand
• Proactive
• ZRP has three sub-protocols
• Intrazone Routing Protocol (IARP)
• Interzone Routing Protocol (IERP)
• Bordercast Resolution Protocol (BRP)

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LAR

• Location-Aided Routing
• Location information via GPS
• Shortcoming
• GPS availability is not yet worldwide
• Position information come with deviation

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LAR
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DREAM

• Distance Routing effect Algorithm for mobility
• Position-based
• Each node
• maintains a position database
• Regularly floods packets to update the position
• Temporal resolution
• Spatial resolution

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PAR

• Power-Aware Routing