Localized Algorithms and Their
Applications in Ad Hoc Wireless
Networks
Jie Wu
Dept. of Computer Science & Engineering
Florida Atlantic University
Boca Raton, FL 33431
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Classification of Communication
Networks
• Wired Networks
– LAN, MAN, WAN, and Internet
• Wireless Networks
– Infrastructured networks
(cellular networks)
– Infrastructureless networks
(ad hoc wireless networks)
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Wired/Wireless Networks
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Wireless and Mobile Networks
• 200 million wireless telephone handsets
(purchased annually)
• A billion wireless communication devices in
use
• The first decade of 21st Century: mobile
computing
• "anytime, anywhere"
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Characteristics
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Self-organizing: without centralized control
Scarce resources: bandwidth and batteries
Dynamic network topology
Unit disk graph models: host connection
based on geographical distance
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Unit Disk Graph
A simple ad hoc wireless network of six wireless
mobile hosts.
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Major Issues in Ad Hoc Networks
• Mobility management
– Addressing and routing
• Location tracking
– Absolute vs. Relative, GPS
• Network management
– Merge and split
• Resource management
– Network resource allocation and energy efficiency
• QoS management
– Dynamic advance reservation and adaptive error control
techniques
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Major Issues in Ad Hoc Networks
(Cont’d.)
• MAC protocols
– Contention-base, controlled
• Applications and middleware
– Measurement and experimentation
• Security
– Authentication, encryption, anonymity, and intrusion detection
• Error control and failure
– Error correction and retransmission, deployment of back-up
systems
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Localized Algorithms (Estrin, 99)
• Processors (hosts) only interact with others in a
restricted vicinity.
• Each processor performs exceedingly simple tasks
(such as maintaining and propagating information
markers).
• Collectively these processors achieve a desired
global objective.
• There is no (or limited) sequential propagation of
information.
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Localized Algorithms (Con’t)
• Differ from traditional distributed algorithms
• Complexity
– Communication: number of rounds
– Communication: size of message
– Computation: plays a lesser rule
• Quality
– Average case: probabilistic analysis/simulation
– Worst case: bound/approximation ratio
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Application I: Connected
Dominating Set (CDS)
(Wu and Li, 1999)
• CDS as a virtual backbone
• Marking process: A node is marked true if it
has two unconnected neighbors
.
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Marking Process (Cont’d.)
A sample ad hoc wireless network
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Application II: Broadcasting
(Wu and Dai, 2003 and 2004)
• Promiscuous receive mode
• Coverage & efficiency
• Flooding: each node forwards the message
once
u
w
s
v
(a)
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u
u
w
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(b)
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w
s
v
(c)
Application II: Broadcasting (Con’t)
• Localized solution via self-pruning
(INFOCOM 2003)
• Localized solution via neighbor designation
(ICDCS 2003)
• Mobility management and consistent view
(INFOCOM 2004)
• Computation complexity reduction in dense
mode (ICDCS 2004)
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A Sample Broadcasting
(n=100, d=6, r=16, k=2)
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Other Applications
• Energy-Efficient Communication
• MAC layer protocols
• Topology control
• Directional antenna
• Sensor coverage
• Data gathering and dissemination
•…
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Security in Ad Hoc Networks
• Key
management
• Routing security
• Light-weight cryptography
• Intrusion detection
• Trust: incentive-based
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Cross-Disciplinary Issues
• NSF Sensor Network Program
(March, 2003)
• Sponsored by multiple divisions/programs
(including CISE)
• Encouraging multi-disciplinary team
effort
• 1,000 submissions with an acceptance rate
of around 5%
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Example: Multi-Disciplinary Team
• Hitch-hiking Model (INFOCOM 2004)
• Energy-efficient design in sensor networks
• Multiple institutions: UMass- FAU
• Multiple disciplines
• physical layer
• MAC layer
• network layer
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Vision of the Field
• Convergence of Multiple Disciplines
– Parallel processing
– Distributed systems
– Network computing
• Wireless network and mobile computing as
an important component in
Cyberinfrastructure and Cybertrust
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Vision of the Field
Ultimate Cyberinfrastructure
• Petascale computing, exabyte storage, and terabit
networks
Network-Centric
• Supernetworks: networks are faster than the
computers attached to them
• Endpoints scale to bandwidth-match the network
with multiple-10Gbps lambdas
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Major Conferences in the fields
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General: IEEE INFOCOM
Mobile Computing: ACM MobiCom
Ad Hoc Networks: ACM MobiHoc
Distributed Systems: IEEE ICDCS
Sensor Networks: IEEE MASS (Mobile Adhoc and Sensor Networks)
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Some Related Events
• IEEE Computer
– Special issue on Ad Hoc Networking
– Feb. 2004, guest editors: J. Wu. & I. Stojmenovic
• NSF Workshop on Theoretical Aspects of Ad hoc,
Sensor, and Peer-to-Peer Networks
– Feb. 2004, http://www.cse.fau.edu/~jie
– Book published by CRC and special issue in JPDC
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