Open Problems: What should you work on for the next 4 years?

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Open Problems What should you work on for the
next 4 years?

• Fred Baker, Fellow CISCO
• Bob Briscoe, British Telecom
• George Varghese, UCSD/entrepreneur
• John Wroclawski, ISI Networking Director
• Facilitator Michalis Faloutsos, UCR

ICNP 2006 - Panel
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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

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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
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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 Devils 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
B
A

• United we transmit

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Synchronous Tx Contention
A
D
B
B
A
C
C
D

• So far, overlapping transmissions BAD
• Hidden and exposed terminals
• Self-contention packets of the same flow
• Current Focus reduce contention

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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 dont cancel out
• They improve the success of transmission!

B
A

• 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.

B
A

• 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 10-3

Coop Interference
B
A
C
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1.What Cooperation Buys Us

1. We can shorten our paths

1. 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?
Cooperative Performance is red
Delay
Thruput

• Phy layer has been well studied
• Recently efforts show big gains in higher layer
  performance
• Implementation is pending

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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!