Download manet-intro

Introduction to Ad Hoc Networking


Perkin’s 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 (DoD’s 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
AD-HOC MOBILE
ROUTING PROTOCOLS
TABLE DRIVEN/
PROACTIVE
DSDV
ON-DEMAND-DRIVEN
REACTIVE
HYBRID
DSR
AODV
CGSR
ZRP
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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
C2
C1
M2
C3
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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
N2
Source N1
N5
Destination
N7
N4
N3
N8
N2
N5
N6
(a) RREQ
Source N1
Destination
N7
N4
N3
N8
N6
(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 reinitiate 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
N1-N2
N1-N2-N5
N2
N8
N5
N1
N1-N3-N4
N1
N7
N4
N1
N1-N3-N4
N1-N3
N3
N1-N3-N4-N7
N1-N3-N4
N2
N1-N3-N4-N6
N6
N1-N2-N5N8
N5
N1-N2-N5N8
N8
N1-N2-N5N8
N1
N7
N4
N3
N6
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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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Zone of Node Y
Border Node
Zone of Node Y
Bordercasting
Zone Radius =
Border Node
Node X
r Hops
Node Z
Zone of Node X
Zone of Node Z
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
Request Zone
Expected Zone
(Xd+R, Yd+R)
DEST
R
(Xd,Yd)
SRC
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(Xs,Ys)
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
N1
+
N2
–
SRC
+
–
DES
T
+
+
–
–
N3
+
–
N4
+
–
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