Post on 01-Apr-2015
M. Faloutsos UC Riverside 1
Open Problems: What should you work on for
the next 4 years?
Fred Baker, Fellow CISCO
Bob Briscoe, British Telecom
George Varghese, UCSD/entrepreneurJohn Wroclawski, ISI Networking Director
Facilitator: Michalis Faloutsos, UCRFacilitator: Michalis Faloutsos, UCR
ICNP 2006 - Panel
M. Faloutsos UC Riverside
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We wish a quick recovery… to Darleen Fischer (NSF) who would have been here but cannot due to non-threatening health reasons
M. Faloutsos UC Riverside
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The Goal is to Provoke Provoking is an essential human function
I provoke, therefore I think, therefore I exist A good panel should result in a fist-fight Conclusion: We need controversy
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My First Choices for the Panel
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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Final Panel Fred Baker, Fellow CISCO Bob Briscoe, British Telecom George Varghese, UCSD/entrepreneur John Wroclawski, ISI Networking Director
Alphabetical Order
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The Focus of the Panel The most exciting idea you have read recently The right area for a new researcher to tackle A problem the community should solve
You would give money for the research You would invest in the start up You would give $20 out of your pocket
A technology or user trend that will make a splash in 2-5 years
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Playing the Devil’s Advocate
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My Challenge to the Panel: Everything important has already been
discovered We are not reinventing, just renaming Let the industry do the research it needs Academia is consumed by paper-o-lagnia
Greek: Lagnia = desire, lust for We should all change professions
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Something New and Cool I ‘d give $20 to see it fully implemented
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Cooperative Diversity in ad hoc networks
“United we transmit”
A
B
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Synchronous Tx = Contention
So far, overlapping transmissions = BAD Hidden and exposed terminals Self-contention: packets of the same flow
Current Focus: reduce contention
A B
CD
BAD
C
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Cooperative Diversity: A Paradigm Shift
Cooperation instead of Contention
A phy breakthrough Multiple transmissions
can be combined at the receiver
Not only they don’t cancel out
They improve the success of transmission!
A
B
Node A cooperates with neighbors to send the same packet to B
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Cooperative Diversity: Essentials
Solicit/select the cooperation of neighbors
Provide the cooperating neighbors with a copy of the data packet.
Ensure that the receiver has CSI for the links to every cooperating node.
A
B
Node A cooperates with neighbors to send the same packet to B
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Cooperative Diversity is Counter Intuitive
Transmission range is longer than interference range! The transmissions range is
increased by a factor of 5.4 The interference range by a
factor of 1.7 For diversity gain 15 dB,
path loss 3, BER 10^-3A
B
C
Coop Interference
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1.What Cooperation Buys Us1. We can “shorten” our paths
S D
S I D
2. Path using cooperative diversity
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2. What Cooperation Buys Us Can bridge gaps in sparse networks
Connect disconnected networks Enable weak-device networks
The sensor network reach-back problem Many sensors cooperate to reach the sink!
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Can this translate to network performance?
Phy layer has been well studied Recently efforts show big gains in higher
layer performance Implementation is pending…
CooperativePerformance is red
Thruput Delay
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If you want to see more: J.N.Laneman, “Cooperative diversity in wireless networks:
Algorithms and architectures”, Ph.D. Thesis, Massachusetts Institute of Technology, August 2002.
G. Jakllari et al. "A Cross-Layer Framework for Exploiting Virtual MISO Links in Mobile Ad hoc Networks" IEEE Transactions on Mobile Computing to appear.
G. Jakllari et al. "On Broadcasting with Cooperative Diversity in Multi-hop Wireless Networks ” IEEE JSAC to appear.
A. Khandani, et al. “Cooperative routing in wireless networks.”, Allerton Conference on Communications, Control and Computing, October 2003.
X, Li, Space-Time Coded Multi-Transmission Among Distributed Transmitters without Perfect Synchronization, IEEE Signal Processing Letters, 11(12), December 2004.
A. Sendonaris et al. “User Cooperation Diversity--Part II: Implementation Aspects and Performance Analysis”, IEEE Transactions on Communications, 51(11), November 2003.
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Thank You!