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Mobile and Ad hoc Networks
Background of Ad hoc
Wireless Networks
Wireless Communication
Technology and Research
Ad hoc Routing and
Mobile IP and Mobility
Wireless Sensor and Mesh
Networks
Student Presentations
Introductory Lecture
http://web.uettaxila.edu.pk/CMS/SP2012/teAWNms/
Objectives
 Where is Wireless Communication today? Where has it come from in the
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last decade? What is its future potential?
Introduction to Mobile Ad hoc, Sensor and Mesh networks
What are key research areas in wireless communication?
How do the features in Ad hoc wireless networks different from traditional
wireless systems (WiFi: 802.11a/b/g/n, 3G, mobile WIMAX: 802.16e)?
Mobility issues
Security and other issues
Research topics
Text Books
 AD HOC NETWORKS
Technologies And Protocols
by Prasant Mohapatra and
Srikanth Krishnamurthy
 The handbook of AD HOC
WIRELESS NETWORKS
by Mohammad Ilyas
Text Books
 Ad Hoc Mobile Wireless
Networks Protocols and
Systems
by C.K. Toh
 Mobile Ad hoc Networking
by Stefano Basagni, Marco Conti,
Silvia Giordano and Ivan
Stojmenovic
Overview of the Course
 Introduction
 Foundations of Wireless
Communications - Wireless Channel
 Foundations of Wireless
Communications – Modulation
 Review of Networking
 Wireless Physical and MAC layer
 Wireless Area Networks (WPAN,
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WLAN, WWAN) and MAC Layer
Wireless MAC protocols
Wireless Routing
Wireless TCP
Mobile IP
Quality of service
Wireless Sensor Networks
Mobile Ad hoc Networks
Vehicular Ad hoc Networks
Mesh Networks
Wireless Network Security
Standardization
 Research Papers
 Physical and MAC layer
 Routing in Wireless
 Opportunistic routing and
network coding
 Network Layer and Routing
 Routing Metrics
 Geographic Routing
 Routing and Scalability
 Routing Algorithms
 Algorithmic foundations for
scalability
 Energy issues
 Sensor Networks
 Wireless Routing Security
 Trust and Reputation systems
 Incentives, mechanisms, etc.
 Physical and link level
issues
 Presentations
Objectives of course
 Learn about challenges in wireless networking
 What forces us to reconsider many traditional
designs?
 Understand state-of-the-art in wireless/ubiquitous
systems
 Get a broad view of the ongoing research in the
wireless domain
 Have a good understanding of their capabilities and
limitations
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Course Materials
 Course Web page
 http://web.uettaxila.edu.pk/CMS/SP2012/teAWNms
 Visit regularly
 Announcements
 Lecture Notes and Assignments
 Research papers
 Pdf/ps version of the papers will be on the Web page
 ~30 papers, Combination of classic and recent work.
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Reading Papers
 Is this a vision/position/direction paper, or just a
measurement/implementation?
 How the paper is compared to others?
 Can I mentally categorize this paper somewhere in the
taxonomy? “Differs from X as follows; has the following
in common with Y”
 What is the most important contribution?
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Reading Papers (2)
 Does this advance the state of the art?
 Did you learn anything new?
 Does it provide evidence which supports/contradicts
hypotheses?
 Is there experimental validation?
 Any technical flaws?
 Will the paper generate discussion in the class?
 How readable is the paper?
 Is the paper relevant to a broader community?
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Covered Topics (will try!)
 Overview
 The challenges, technologies, and trends
 Wireless Fundamentals
 Source and channel coding
 Frequency spectrums
 Wireless LAN
 MAC protocols
 Wireless Internet – Mobile IP
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Covered Topics (2)
 Routing for Wireless
 Ad Hoc Routing
 TCP in wireless enviroment
 Power Management
 wireless Sensor Networks
 Quality of Services (QoS)
 Hybrid Wireless Networks – Architectures– Pricing,
Power Control, Load Balancing
 Special Topics
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Why wireless networks?
 Mobility: to support mobile applications
 Costs: reductions in infrastructure and operating
costs: no cabling or cable replacement
 Special situations: No cabling is possible or it is
very expensive.
 Reduce downtime: Moisture or hazards may cut
connections.
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Why wireless networks? (cont.)
 Rapidly growing market attests to public need for
mobility and uninterrupted access
 Consumers are used to the flexibility and will
demand instantaneous, uninterrupted, fast access
regardless of the application.
 Consumers and businesses are willing to pay for it
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The Two Hottest Trends in
Telecommunications Networks
Millions
700
600
500
400
Mobile
Telephone
Users
Internet Users
300
200
100
0
1993 1994 1995 1996 1997 1998 1999 2000 2001 Years
Source: Ericsson Radio Systems, Inc.
Growth of Home wireless
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Wireless is THE Key Driver
for the Future Internet
 Historic shift from PC’s to mobile computing and embedded
devices…
 >2B cell phones vs. 500M Internet-connected PC’s in 2005
 >400M cell phones with Internet capability, rising rapidly
 Sensor deployment just starting, but some estimates ~5-10B units by
2015
~750M servers/PC’s, >1B laptops, PDA’s, cell phones, sensors
~500M server/PC’s, ~100M laptops/PDA’s
Wireless
Edge
Network
INTERNET
INTERNET
Wireless
Edge
Network
2005
2010
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Market Size
 Wireless as the common case vs.
the exception
 Laptop (54%) vs. desktop sales
(46%)
 >2B cell phones vs. 500M Internetconnected PCs
 Estimates of ~5-10B wireless
sensors by 2015
Staggering Market Statistics
• 9 million hotspot users in
2003 (30 million in 2004)
• Approx 4.5 million WiFi
access points sold in 3Q04
• Sales have tripled by 2009
• Many more non-802.11
devices
 Rapid deployment of new
technology
 Highly dynamic environment
 Must accommodate
new/unexpected technologies
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Why is it so popular?
 Flexible
 Low cost
 Easy to deploy
 Support mobility
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Applications ?
 Ubiquitous, Pervasive computing or nomadic access.
 Ad hoc networking: Where it is difficult or impossible to
set infrastructure.
 LAN extensions: Robots or industrial equipment
communicate each others. Sensor network where
elements are two many and they can not be wired!.
 Sensor Networks: for monitoring, controlling, e
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Infostations
 Mobile hosts traveling through fixed network
 Good for periodic download or upload of bulky data
 Wireless islands (interconnected by wired network)
 Gas stations
 Here and there on the freeway
 Possibly an invisible infrastructure with mobile-aware
applications
 In reality, you may need to know to go to it
 Original paper assumes this: information kiosks
 Coverage is spotty
 Cost is lower than complete coverage
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Ad hoc networks
 Collection of wireless mobile nodes dynamically
forming a temporary network without the use of any
existing network infrastructure or centralized
administration.
 Hop-by-hop routing due to limited range of each node
 Nodes may enter and leave the network
 Usage scenarios:
 Military
 Disaster Relief
 Temporary groups of participants (conferences)
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Sensor networks
 Deployment of small, usually wireless sensor nodes.
 Collect data, stream to central site
 Maybe have actuators
 Hugely resource constrained
 Internet protocols have implicit assumptions about
node capabilities
 Power cost to transmit each bit is very high relative to
node battery lifetime
 Loss / etc., like other wireless
 Ad-hoc: Deployment is often somewhat random
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Ad hoc networks, continued
 Very mobile – whole network may travel
 Applications vary according to purpose of
network
 No pre-existing infrastructure. Do-it-yourself
infrastructure
 Coverage may be very uneven
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Networked Embedded Computers
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Connected to
network
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send and/or receive
May be embedded only for
network access
 networked appliances
Network
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sensors
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historical sites & other
locations
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Embedded Peer
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Composite devices (HW+SW)
 security system
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Distributed composites vs.
hardwired devices
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Network
client-defined composites
reuse of constituents
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ease of change
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extendibility & scalability
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Networked Embedded Computers
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Issues
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Late binding
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Network
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Naming
Discovery
IPC
User-interface deployment
Multi-appliance control
Access control
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Existing social protocols not supported by
existing mechanisms
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All co-located users can use
appliance
Restriction to contents per user
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Location-Aware Computing
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Motivation
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location-based action
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nearby local printer, doctor
nearby remote phone
directions/maps
location-based
information
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real
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virtual
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person’s location
history/sales/events
walkthrough
story of city
augmented
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touring machine
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Pose-Aware Computing
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Operations based
on locations and
orientations of
users and devices
Motivation
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Augmented reality
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Wearable Pose-Aware Computers
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Computers on body
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track body relative
movements
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monitor person
train person
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Beyond Desktops/Servers
Embedded
Mobile
Location
Interactive
Sensor
Flight
Simulator
Wearable
Active
badge
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Summary
 Need to be connected from everywhere and
anytime.
 Need to be connected on movement
 Need to good quality service on those situation.
 Interworking with the existing networks
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Classification of Wireless Networks
 Mobility: fixed wireless or mobile
 Analog or digital
 Ad hoc (decentralized) or centralized (fixed base
stations)
 Services: voice (isochronous) or data (asynchronous)
 Ownership: public or private
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Classification of Wireless Networks
 Area: wide (WAN), metropolitan (MAN), local
(LAN), or personal (PAN) area networks
 Switched (circuit- or packet-switched) or broadcast
 Low bit-rate (voice grade) or high bit-rate (video,
multimedia)
 Terrestrial or satellite
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What is special on wireless?
 Channel characteristics
 Half-Duplex
 Location dependency
 Very noisy channel, fading effects, etc.,
 Resource limitation
 Bandwidth
 Frequency
 Battery, power.
 Wireless problems are usually optimization problems.
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What is special on wireless?
 Mobility in the network elements
 Very diverse applications/devices.
 Connectivity and coverage (internetworking) is a
problem.
 Maintaining quality of service over very unreliable
links
 Security (privacy, authentication,...) is very serious
here. Broadcast media.
 Cost efficiency
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Big issues!
 Integration with existing data networks sounds very
difficult.
 It is not always possible to apply wired networks design
methods/principles here.
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Internet Design Goals
1. Connect existing networks
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initially ARPANET and ARPA packet radio network
2. Survivability
- ensure communication service even in the presence of
3.
4.
5.
6.
7.
network and router failures
Support multiple types of services
Must accommodate a variety of networks
Allow distributed management
Allow host attachment with a low level of effort
Allow resource accountability
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Problems
 Host mobility is not considered in the design.
 There is a hierarchal design. How Ad hoc wireless
networks can be handled
 A layered design. Layer should be independent of
each other. It is not work at all in wireless
 TCP
 Battery shortages;
 Etc,.
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Disconnection / store & forward
 Many Internet protocols assume frequent
connectivity
 What if your node is only on the Internet for 5
minutes every 6 hours?
 How do you browse the web?
 Receive SMTP-based email?
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High availbility requirements
 No QoS assumed from below
 Reasonable but non-zero loss rates
 What’s minimum recovery time?
 1 RTT
 But conservative assumptions end-to-end
 TCP RTO
 Interconnect independent networks
 Federation makes things harder:
 My network is good. Is yours? Is the one in the middle working?
 Scale
 Routing convergence times, etc.
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Trends
 Multimedia over IP networks
 Next Generation Internet with features for “soft” QoS
 RSVP, Class-based Queuing, Link Scheduling
 Voice over IP networks
 Packet Voice and Video
 RTP and ALF
 Intelligence shifts to the network edges
 Better, more agile software-based voice and video codecs
 Programmable intelligence inside the network
 Proxy servers intermixed with switching infrastructure
 Java code: “write once, run anywhere”
Implications for cellular network infrastructure of the 21st century?
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Issues
 Scalability
 Must scale to support hundreds of thousands of
simultaneous users in a region.
 Functionality
 Computer-phone integration
 Real-time, multipoint/multicast, location-aware
services, security
 Home networking, “active” spaces,
sensors/actuators
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Issues(2)
 Leverage evolving IP traffic models
 Provisioning the network for the extrapolated traffic and
services
 Proactive Infrastructure
 Computing resources spread among switching
infrastructure
 Computationally intensive services: e.g., voice-to-text
 Service and server discovery
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Wireless Differences 1
 Physical layer: signals travel in open space
 Subject to interference
 From other sources and self (multipath)
 Creates interference for other wireless devices
 Noisy  lots of losses
 Channel conditions can be very dynamic
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Wireless Differences 2
 Need to share airwaves rather than wire
 Don’t know what hosts are involved
 Hosts may not be using same link technology
 Interaction of multiple transmitters at receiver
 Collisions, capture, interference
 Use of spectrum: limited resource.
 Cannot “create” more capacity easily
 More pressure to use spectrum efficiently
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Wireless Differences 3
 Mobility
 Must update routing protocols to handle frequent
changes
 Requires hand off as mobile host moves in/out
range
 Changes in the channel conditions.
 Coarse time scale:
distance/interference/obstacles change
 Fine time scale: Doppler effect
 Other characteristics of wireless
 Slow
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Growing Application Diversity
Collision Avoidance:
Car Networks
Mesh Networks
Wired Internet
Access
Point
Sensor
Relay Node
Ad-Hoc/Sensor
Networks
Wireless Home
Multimedia
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Challenge: Diversity
Wireless
Edge
Network
INTERNET
INTERNET
Wireless
Edge
Network
2005
2010
 New architectures must accommodate rapidly
evolving technology
 Must accommodate different optimization goals
 Power, coverage, capacity, price
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Spectrum Scarcity
 Interference and unpredictable behavior
 Need better management/diagnosis tools
 Lack of isolation between deployments
 Cross-domain and cross-technology
Why is my
802.11 not
working?
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Other Challenges
 Performance: Nothing is really working well
 Security: It is a broadcast medium
 Cross layer interception
 TCP performance
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Assignment #1
 Introduce Yourself:
 Name: Adeel Akram
 Department: Telecom Engineering Department
 Email Address: [email protected]
 Cell/Contact Number: 0323-5030712/051-9047566
 Define terms highlighted in Yellow colour
Q&A
 ?