Session 10: Mobile Ad Hoc and Wireless Sensor Networks Advanced Data Communication Networks Dr. Farhad Faghani Assistant Professor, Department of Electrical Engineering, Najafabad Branch, Islamic Azad University.
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Session 10:Mobile Ad Hoc and Wireless Sensor
Networks
Advanced Data CommunicationNetworks
Dr. Farhad Faghani Assistant Professor, Department of Electrical Engineering,Najafabad Branch, Islamic Azad University.
Outline
I. Classification of Communication NetworksII. Introduction to Ad Hoc and sensor NetworksIII. Wireless sensor Network Design issuesIV. Crosslayer designV. Wireless application and QOSVI. Ad Hoc Routing Protocol
Classification of CommunicationNetworks
�Wired Networks�LAN, MAN, WAN, and Internet
�Wireless Networks�Infrastructured networks (cellular networks)�Infrastructureless networks (Ad Hoc wireless
networks)�Wireless Sensor Networks (WSN)
Infrastructured networks (cellular networks)�Frequencies, time slots, or codes reused at spatially-
separated locations�Decreasing the cell size increases capacity�Resources:
�Channels�Bandwidth�Power�Rate�Base stations�Access
�Dynamic Resource AllocationAllocate resources as user and network conditions change
BASESTATION
Infrastructureless networks(Ad Hoc wireless networks)
�Peer-to-peercommunications.
�No backboneinfrastructure.
�Routing can bemultihop.
�Topology is dynamic.�Fully connected with
different link SINRs
Different channels, distances, mobility, energy, and rate requirements.
Wireless Sensor Networks (WSN)Energy-Constrained Nodes
�Limited nodeprocessing/communication capabilities
�Nodes can cooperate in transmissionand reception.
�Intelligence must be “in the network”�Data flows to centralized location.�Low per-node rates but 10s to 1000s
of nodes�Data highly correlated in time and
space.
dotmag
acoustic
WSN, Energy-Constrained Nodes, (Cont’d)�Sensor modes
�Active mode� Idle mode�Sleep mode
�Major sources of energy waste� Idle listening when no sensing events�Collisions�Control overhead�Overhearing
Solution: Node schedulingPeriodic listen and sleep
Design Principles�Sleep – majority of the time, >99%�Wakeup – quickly start processing�Active – minimize work & return to sleep
processingdata acquisitioncommunication
sleep
Pow
er
Time
WSN, Energy-Constrained Nodes, Cont’d�Each node can only send a finite number of bits.�Short-range networks must consider both transmit
and processing energy.�Sleep modes save energy but complicate networking.
�Changes everything about the network design:�Bit allocation must be optimized across all protocols.�Delay vs. throughput vs. node/network lifetime tradeoffs.�Optimization of node cooperation.
Applications (Ad Hoc / WSN)�Battlefield communications�Wireless LANs�Emergency infrastructures�Communication infrastructure
for automated vehicles�Sensor networks�Medical applications (on-body)�Smart Buildings/Agriculture�Wide area (Environment
monitoring, counter-terrorism,etc.)
Heterogeneous Wireless Sensor Network
PDA
3d ultrasonicanemometer
Temperature,humidity
HPWREN
AnimalMonitoring
Notebook CellularPhone PC
Ship Monitoring
DataDistribution
Network
Precipitation
Solar radiation
In-flight camera
Weather station
Mobile and Stationary Operations
Stationary camera
Seismic
Storage
DataAcquisition
Network
Wireless Applications and QoSWireless Internet accessNth generation CellularWireless Ad Hoc NetworksSensor NetworksWireless EntertainmentSmart Homes/SpacesAutomated HighwaysAll this and more…
Applications have hard delay constraints, rate requirements,and energy constraints that must be met
These requirements are collectively called QoS
Cross Layer DesignChallenges to meeting QoS
� Wireless channels are a difficultand capacity-limited broadcastcommunications medium
� Traffic patterns, user locations,and network conditions areconstantly changing
� No single layer in the protocolstack can guarantee QoS: cross-layer design needed
� It is impossible to guarantee thathard constraints are always met,and average constraints aren’tnecessarily good metrics.
�Hardware�Link�Access�Network�Application
Delay ConstraintsRate RequirementsEnergy Constraints
Mobility
Crosslayer Techniques�Adaptive techniques
�Link, MAC, network, and application adaptation�Resource management and allocation (power control)
�Diversity techniques�Link diversity (antennas, channels, etc.)�Access diversity�Route diversity�Application diversity�Content location/server diversity
�Scheduling�Application scheduling/data prioritization�Resource reservation�Access scheduling
Networking Scenario1(Mesh Network)From Wireless to Wired network Via Multihop
Networking Scenario2 (SkyPilot NeighborNet)
Networking Scenario3(Urban Grid Applications)
Hot Spot
Hot Spot
Hot Spot
Hot Spot
PowerBlackout
STOP
PowerBlackout
STOP
PowerBlackout
STOP
PowerBlackout
STOP
Mobile Ad Hoc Networks (MANET)Routing
�Mechanism for finding paths from source host todestination host.
�Protocols use different metrics to find network paths.�Hop count, bandwidth, delay, power, load, link quality
(wireless).�Most routing protocols for wireless are based on wireline
protocols�Flooding, point-to-point, table-driven, on-demand, etc.
Wireless link
1- Hop 2- Hops 3- Hops
S
Example1: Multi-hop “ad hoc” networking
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example1 (Cont’d)
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Example2: Sensor aggregate routingTTDD (Two Tier Data Dissemination)
�Data dissemination to mobile sinks�Two-tier query & data forwarding�Objectives
�Source proactively builds a grid structure to support dataavailability for mobile sinks� Mobility pattern is unknown a priori
�Localize impacts of sink mobility on data forwarding�Only a small set of sensor nodes maintain forwarding
state
Example2 (Cont’d) TTDD Basics
Source
Dissemination Node
Sink
Data Announcement
Query
Data
ImmediateDisseminationNode
Example2 (Cont’d) TTDD Mobile Sinks
Source
Dissemination Node
Sink
Data
ImmediateDisseminationNode
ImmediateDisseminationNode
TrajectoryForwarding
TrajectoryForwarding
Ad Hoc Routing Protocols�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
Ad Hoc Routing Protocols
AD-HOC MOBILEROUTING PROTOCOLS
ON-DEMAND-DRIVENREACTIVE
HYBRIDDSDV
CGSR
TABLE DRIVEN/PROACTIVE
DSR
AODV
ZRP
DSDV�Destination Sequenced Distance Vector�Table-driven�Each node maintains a routing table�Routing hops to each destination�Sequence number
�Problem�A lot of control traffic in the network
Clustering Protocol�Cluster Gateway Switch Routing (CGSR)
�Table-driven for inter-cluster routing�Uses DSDV for intra-cluster routing
C3
M2
C2
C1
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)
AODV� Problem
�A node along the routemoves
� Solution�Upstream neighbor notices
the move�Propagates a link failure
notification message toeach of its active upstreamneighbors
�The source node receivesthe message and re-initiateroute discovery
N2
N4N1
N3
N5
N6
N7
N8
Source
Destination
N2
N4N1
N3
N5
N6
N7
N8
Source
Destination
ZRP
�Zone Routing Protocol�Hybrid protocol
� On-demand� Proactive
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
Bor
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