The Promise of MIMO Mobile Networks: Project Overview

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James Zeidler, UCSD
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Tactical Ad-Hoc Networks

• Baseline System Model
• 30-100 nodes
• Up to 4 antennas/node
• Mobile Nodes
• No centralized control
• Jamming and physical destruction of nodes
• Shadowing of Nodes
• Hostile interception
• Multi and uni-casting
• Wideband Voice/Data

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Tactical Ad-Hoc Networks

• Research Goal
• Define the best way to utilize multiple transmit
  and receive antennas at each node to improve the
  robustness, capacity, and quality of service of
  the network

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Technical Issues

• Many forms of diversity available
• Space, time, frequency, network, etc.
• Diversity is critical to improve the reliability
  and minimize the need for retransmission. This is
  important for delay-sensitive applications
• Cross layer optimization required to exploit
  physical layer diversity at the network level
• Waveforms must be resistant to jamming and
  intercept
• Antenna configurations adaptable to combat
  conditions
• Multihop transmissions required to overcome
  shadowing and allow network reconfigurability
• Real time channel state information for time
  varying mobile channels required

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Architectural OutlookEmphasis on Crosslayer
Design
Discover and Maintain Appropriate Routes
Feedback To Lower Layers on Topology Construction
Network Layer
Support Scheduling based On Interference Zones
and Generated Traffic
MAC Layer
Physical Layer
Adaptive Antennas Provide Feedback To Higher
Layers On Interference Zones/ Tune In Response to
Needs
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Diversity in Networks

• Diversity is inherent in the physical layer PHY
  diversity
• Time, frequency, space and polarization diversity
• Combat the fading channel by trying to stabilize
  the channel
• Diversity can also be achieved in the MAC or
  higher layer Network diversity
• Multiuser diversity (by scheduling or routing)
• Cooperative diversity (by cooperative
  transmission)
• Exploit the channel fluctuation to ride the
  peaks
• The fundamental challenge for this project is to
  utilize combinations of physical and network
  diversity to maximize network capacity and
  robustness in an optimal fashion

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Diversity in Networks (cont)

• One key research issue in utilizing combinations
  of network and physical layer diversity is the
  way to best utilize channel state information
  (CSI).
• Optimizing network capacity will depend on where,
  when, and how accurately the CSI can be obtained.
• The level of available CSI whether it is
  available at the destination node only, source
  and destination node, or across the network.
• The time-scale of available CSI whether it is
  knowledge about the channel experienced by
  symbols, packets, or transmissions (multiple
  packets).
• The accuracy of available CSI different systems
  have different robustness to noisy CSI.

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Diversity in Networks (cont)

• Depending on the coherence time relative to the
  data rate, CSI availability is different and the
  transceivers or protocols need to adapt
  accordingly.
• The use of STC or beamforming in conjunction with
  ad-hoc routing and scheduling remains an open
  research issue.
• The PHY diversity and network diversity could be
  exploited simultaneously in some scenarios.
• For example, PHY diversity could be used to
  combat fast fading effects, which is hard to be
  tracked at higher layer, while network diversity
  can be used against slow fading.
• The key question is under what conditions should
  we shift between different forms of diversity.

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Research Coordination Plan

• Specified concentration areas in the BAA spanned
  the physics of RF propagation and signal
  processing the electrical engineering of antenna
  array design and electronics computer science of
  networking and the mathematics of information
  theory and control theory
• PIs selected from the computer science and
  electrical and computer engineering faculty of
  four campuses of the University of California and
  Brigham Young University to provide expertise in
  all the specified research specialties
• A provision of the BAA allowed the participation
  of Canadian researchers and Professor Haykin of
  McMaster University was invited to join our team.

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MURI Project Team

• University of California, San Diego
• James Zeidler (PI), Larry Milstein, Rene Cruz,
• John Proakis, Bhaskar Rao, Tara Javidi, Michele
  Zorzi
• University of California, Irvine
• Hamid Jafarkhani
• University of California, Santa Cruz
• JJ Garcia-Luna
• University of California, Riverside
• Srikanth Krisnamurthy, Yingbo Hua
• Brigham Young University
• Lee Swindlehurst, Mike Jensen
• McMaster University
• Simon Haykin

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Agenda

• "Understanding Channel Access Control in Ad Hoc
  Nets with MIMO Nodes"  JJ
  Garcia-Luna-Aceves, UC, Santa Cruz
• "Adaptive MAC Protocols for Mobile Ad-Hoc
  Networks"  Rene Cruz, UC, San Diego
• "Cross Layer Protocols for Use with Antenna
  Arrays"  Srikanth Krisnamurthy, UC, Riverside
• "On the Implications of Layered Space--Time
  Multiuser Detection on the Design of MAC
  Protocols for Ad Hoc Networks"  Michele Zorzi,
  UC, San Diego
• "A Formal Approach to Analysis and Design of
  Self-Configuring Wireless Ad-hoc Networks"
   Tara Javidi, UC, San Diego
• "Quantifying Performance Improvements Due to
  Spatial-Temporal Diversity in Mobile MIMO
  Spread-Spectrum Ad-Hoc Networks"  James
  Zeidler, UC, San Diego
• "The Effect of Channel Estimation Errors on
  System Performance"  Larry Milstein, UC, San
  Diego

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Agenda

• "System Design Issues for Mobile Wireless
  Networks" Lee Swindlehurst, Brigham Young
  University
• "Experimental Evaluation of MIMO Channels
  Multi-User Characteristics and Temporal
  Variability"  Michael A. Jensen, Brigham
  Young University
• "The McMaster Contributions to the MURI
  Project"  Simon Haykin, McMaster University,
  Hamilton, Ontario, Canada
• "Channel Equalization for MIMO Systems"  John
  Proakis, UC, San Diego
• "Quantization Algorithms and their Analysis in
  Feedback MIMO systems"  Bhaskar Rao, UC, San
  Diego
• "Beamforming and Space-Time Coding for Ad-Hoc
  Networks"  Hamid Jafakhani, UC, Irvine
• "A Route-Guided SIMO Data Forwarding Policy for
  Wireless Relays"  Yingbo Hua, UC, Riverside