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 6 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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Architectural OutlookEmphasis on Cross-Layer
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/Channel State Estimation
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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.
• Under what conditions should we shift between
  different forms of diversity?
• Eg. PHY diversity could be used to combat fast
  fading effects, while network diversity can be
  used against slow fading
• 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 (2)

• 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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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 PHY
  layer diversity at the network layer.
• Waveforms must be resistant to jamming and
  intercept
• Antenna configurations must account for
  imperfections encountered in combat
  conditions-mutual coupling of elements, antenna
  heights, non-ideal spacing, etc.
• Multihop transmissions required to overcome
  shadowing and allow network reconfigurability.
  How many hops are desirable for robustness? for
  capacity? How do nodes cooperate?
• Which links are maintained and used? How much
  power is required to discover and maintain links?
  How can distributed scheduling be accomplished?

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Technical Issues (2)

• Time-scales associated with routing and
  scheduling are longer than the time scales for
  channel variations at the PHY layer. How is the
  frame format modified to incorporate CSI
  information from the PHY layer?
• How is MIMO channel estimation incorporated into
  MAC protocol design? How do the MAC and routing
  layers interact?
• Maintenance of link requires maintenance of CSI
  but how detailed must the CSI be for scheduling
  and routing? Are channel statistics sufficient?
  When do you require CSIR? CSIT? How much
  time/power should be devoted to channel
  estimation in mobile channels?
• How much feedback between transmitters and
  receivers is required? How many bits of
  information and how frequently must they be
  transmitted in different time varying channel
  conditions? What is the effect of latency and
  noisy CSI for mobile nodes?

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Technical Issues (3)

• Frame formats need to be adjusted to facilitate
  simultaneous transmissions and receptions when
  spatial multiplexing is used. What are the
  tradeoffs between network throughput and
  robustness?
• Can diversity and spatial multiplexing co-exist?
  If so, how do they interact? How do you combine
  the benefits of diversity/coding gain from STC
  with the array gain from beamforming?
• How do you control multi-access interference and
  jamming? Beamforming, waveform selection,
  space-time coding, MAC layer,?
• CSMA collision rules that hold for SISO no longer
  hold for MIMO.
• A key issue is determining which transmitters are
  active at any time.
• How do you provide broadcast and multi-access
  unicasting network capabilities with QOS
  guarantees?

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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

• "Temporal Variation of the MIMO Channel State
  and Channel Distribution Information"  Mike
  Jensen, BYU and James Zeidler, UCSD
• Quantifying Performance Improvements Due to
  Spatial-Temporal Diversity in MIMO
  Spread-Spectrum Tactical Mobile Ad-hoc Networks
  James Zeidler, UCSD
• "Channel State Estimation in Rapidly Time
  Varying Environments"  Lee Swindlehurst, BYU,
  and Simon Haykin, McMaster University
• Low Rate Feedback MIMO Systems Theoretical
  Bounds "  Bhaskar Rao, UCSD
• Low Rate Feedback MIMO Systems Code Design"
   Hamid Jafarkhani, UCI
• "Waveform Selection"  Larry Milstein and
  John Proakis, UCSD

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Agenda

• " PHY-Aware MAC Protocol Design for MIMO Ad Hoc
  Networks " Michele Zorzi, UCSD
• " Performance Issues for Relays in Ad Hoc
  Networks Power Control, Interference Mitigation,
  and Throughput Analysis "  Yingbo Hua, UCR
• "Cross-Layer PHY/MAC/Routing Protocols for MIMO
  and Virtual MISO Ad Hoc Networks"   Srikanth
  Krishnamurthy, UCR
• " Cross-Layer Optimal Resource Allocation in
  MIMO Networks"   Tara Javidi and Rene Cruz,
  UCSD
• " Self-Organizing Opportunistic MIMO Systems in
  MANETs"   JJ Luna-Garcia-Aceves, UCSC

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Posters

• Non-Traditional Antenna Arrays for Military MIMO
  Communications
• N. Bikhazi and M. Jensen
• Temporal characteristics of the MIMO Channel
• A. Anderson, J. Wallace (post-doc), M. Jensen
  and J. Zeidler
• Effects of Noisy Channel State Estimates on the
  Performance of Convolutionally Coded Systems with
  Transmit Diversity
• Jittra Jootar, James Zeidler and John Proakis
• Analysis of MIMO Systems with Finite Rate Channel
  State Information Feedback
• Jun Zheng and Bhaskar Rao
• Performance Analysis of Transmit Beamforming for
  MISO systems with Imperfect Feedback
• Yoga Isukapalli and Bhaskar Rao
• Modified Particle Filtering for Tracking MIMO
  Wireless Channels with Impulsive Noise
• Ienkaran Arasaratnam and Simon Haykin
• A Novel Wideband MIMO Channel Model and McMasters
  Wideband MIMO Software Defined Radio

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Posters

• Performance Analysis of a Pre-BLAST-DFE Technique
  for MISO Channels with Decentralized Receivers
• Patrick Amihood, John Proakis and Laurence B.
  Milstein
• Combining Beamforming and Space-Time Coding Using
  Noisy Quantized Channel Direction feedback
• Siavash Ekbatani and Hamid Jafarkhani
• Optimal Routing and Scheduling in Wireless
  Networks
• Javad Kazemitabar and Hamid Jafarkhani
• Weighted Max-Min Fair Scheduling for
  Multi-antenna Wireless Networks
• Bongyong Song, Rene Cruz and Laurence B.
  Milstein
• Information efficiency of Ad Hoc Networks with
  FH-MIMO Transceivers
• Kostas Stamatiou and John Proakis
• Distributed Power Control and Scheduling for Ad
  Hoc Networks
• Qi Qu and Laurence B. Milstein
• Solutions to Packet Forwarding in Ad Hoc Network

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Posters

• Topology Control With Smart Antennas
• Gentian Jakllari, Ece Gelai, Srikanth
  Krishnamurthy and Neal Young
• Distributed Scheduling Algorithm for Multi-hop
  MIMO Networks with Minimum Performance Guarantees
• Yih-Hao (Ethan Lin), R. L. Cruz, T. Javidi, L.
  Milstein
• Optimal Operating Point for MIMO Multiple Access
  Channel with Bursty Traffic
• S. Kittipiyakul and T. Javidi
• Joint Source and Relay Optimization for a
  Non-Regenerative MIMO Relays
• Zheng Fang, Yingbo Hua, and John Koshy
• Optimal Power Schedule for Multiple Distributed
  MIMO Links
• Yue Rong and Yingbo Hua
• Throughput of Large Wireless Networks on Square,
  Hexagonal and Triangular Grids
• Kezhu Hong and Yingbo Hua
• Opportunistic Distributed Medium Access Control
  for a Large Network of Wireless Routers