Prof. Guevara Noubir, [e-mail]

1

• Prof. Guevara Noubir, noubir_at_ccs.neu.edu
• Background
• 1996 PhD from ETH-Lausanne
• 1997-2000 senior research scientist at CSEM
  (Neuchâtel)
• Participated to the main 3G-UMTS European
  Projects (FRAMES, RAINBOW, SLATS) and other
  projects on wireless networks (European Space
  Agency IPSAT, MAD Hiperlan 2, etc.)
• Main Research Area Quality of Service for
  Wireless Systems
• Optimal resource management
• Reliability, fault-tolerance
• Security
• Current Research
• Development of adaptive schemes for optimal
  resource management in wireless systems with
  applications in multi-hop wireless ad-hoc
  networks and cellular wireless communication
  systems
• Underlying technology IEEE802.11, Bluetooth
  (scatternets), home built low-power wireless
  interfaces

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Constraints in Wireless Multi-Hop Ad Hoc
Networks (MANET)

• Limited radio spectrum
• Broadcast Medium (resulting in collisions and
  interference)
• Limited power available at the nodes (i.e.,
  energy, computation)
• Limited storage memory
• Connection QoS requirements (e.g., delay, packet
  loss)
• Unreliable network connectivity (depends on the
  channel)
• Dynamic topology (i.e., mobility of nodes gt
  variable density)
• Need to provide a full coverage
• Need to enforce fairness

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Parameters Available to System Designer in MANET

• Use of various coding/modulation schemes
• Use of packets fragmentation
• Use of various transmission power level
• Use of a single hop or multiple hops
• Use of multiple RF interfaces (multiple IF
  characteristics)
• Clustering and backbone formation
• Planning of the fixed nodes location
• Packets scheduling schemes
• Application adaptivity

4
Approach Adaptivity and Cooperation

• Classical networking stacks have only minimum
  interaction between adjacent layers
• Multi-hop wireless ad hoc networks require more
  cooperation between layer because
• Channel variation and network topology changes
  affect the application
• Routing versus single hop communication
  considerably affects the medium access control
  (MAC) performance and physical layer interference
• Collisions versus channel fading affects both the
  physical layer and the MAC
• Battery power has implications on all layers