introduction to ad hoc networking
DESCRIPTION
Introduction to Ad Hoc Networking. Perkin’s book: Ch 1 and Ch 2. Some data collected from the Internet by Prof. Yu-Chee Tseng. Model of Operations. Assumptions. Symmetric Links : unidirectional links are difficult to dealt with, and sometimes at the verge of failure Layer-2 Routing: - PowerPoint PPT PresentationTRANSCRIPT
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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 stationarylargely homogeneouspower 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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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 routesattempt to maintain consistent, up-to-date routing
informationwhen 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
ON-DEMAND-DRIVEN REACTIVE
HYBRIDDSDV
CGSR
TABLE DRIVEN/ PROACTIVE
DSR
AODV
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 destinationSequence 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
C3
M2
C2
C1
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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
N4N1
N3
N5
N6
N7
N8
Source
Destination
N2
N4N1
N3
N5
N6
N7
N8
Source
Destination
(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
N2
N4N1
N3
N5
N6
N7
N8
N1
N1
N1-N2
N1-N3-N4
N1-N3-N4
N1-N3-N4-N7
N1-N3-N4-N6N1-N3
N1-N3-N4
N1-N2-N5
N2
N4N1
N3
N5
N6
N7
N8N1-N2-N5-
N8N1-N2-N5-
N8
N1-N2-N5-N8
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ZRP Zone Routing Protocol
Hybrid protocolOn-demandProactive
ZRP has three sub-protocolsIntrazone Routing Protocol (IARP)Interzone Routing Protocol (IERP)Bordercast Resolution Protocol (BRP)
Zone Radius =
r Hops
Zone of Node Y
Zone of Node Y
Node X
Zone of Node X
Node Z
Zone of Node Z
Border Node
Border Node
Bordercasting
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LAR Location-Aided Routing
Location information via GPS Shortcoming
GPS availability is not yet worldwidePosition information come with deviation
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LAR
(Xs,Ys)
SRC
Request Zone Expected Zone
DEST
R
(Xd+R, Yd+R)
(Xd,Yd)
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PAR Power-Aware Routing
+
–
+
–
+
–
+
–
+
–
+
–
SRCN1 N2
DEST
N4N3