EnergySaving Conflict Resolution in Wireless AdHoc Networks

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Energy-Saving Conflict Resolution in Wireless
Ad-Hoc Networks
Yalin Evren Sagduyu / Anthony Ephremides

• Objective, Motivation and Approach
• Objective Analysis of collision resolution
  (CR) problem
• for wireless networks from energy-efficiency
  perspective
• Starting Point Collision resolution in
  energy-limited
• access for single-cell uplink channel with
  uniformly
• distributed energy levels.
• Motivation Scheduling of packet
  retransmissions
• according to residual energy levels of
  corresponding nodes
• limits the contention for low-energy nodes
• enables more efficient use of level skipping and
  tree
• pruning methods
• reduces the energy consumption due to
  unsuccessful
• retransmission of backlogged nodes.

• Simulation Environment
• Independent Poisson Packet Arrivals
• Mobile Nodes with Omni-directional Antennas
• Uniformly Distributed Initial Energy Levels
• Uniformly Located Nodes on Square Unit Area

Hybrid REBS/FCFS Method REBS for
Unbacklogged Case
Cumulative Packet Volume for REBS,
First-Come-First-Served (FCFS) and Random
Splitting (RS) Algorithms Classical
Collision Channel Physical
Model
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• Unlimited (or Renewable) Energy for Physical
  Model
• Perfect distance and channel estimation
  assumed
• Transmission power is adjusted to minimum
  value to exceed SINR requirement if no
  interference
• Distance-Based tree-splitting (DBS) CRA
  Packets that arrived at nodes with distance (to
  their intended receiver) between r (k) and r (k)
  ? (k) are transmitted in kth slot.

•  
• Details of the Residual-Energy-Based Tree
  Splitting
• (REBS) Collision Resolution Algorithm
• At kth time slot, the algorithm specifies the
  packets to be transmitted as the set of packets
  that arrived to nodes with residual energy of
  (T(k) - ?(k) , T(k).
• Algorithm determines parameters T(k), ?(k) and
  status
• ? (k) R or L (right or left branch on the tree)
  in terms of feedback, T (k-1), ?(k-1) and ?
  (k-1).

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• Multi-Hop Wireless Ad-Hoc Network with Uniform
  Initial Energy Distribution

• Equal Initial Energy Case (for Collision Channel)
• Performance of REBS algorithm is poor.
• Instead use a Dynamic Hybrid CR method
• Employ quaternary tree splitting jointly using
  time and energy windows with gradual changes
  implemented as functions of system energy
• Start with a very small ?0 for energy window
  (i.e. we start with a FCFS-like algorithm)
• Gradually increase ?0 in energy window to Emax
• Gradually decrease number that divides temporal
  allocation interval from 2 to 1 (i.e. we
  eventually end up with REBS-like algorithm)

• 10 mobile transmitter-
• receiver nodes each with
• single transceiver
• Distributed Bellman-Ford routing algorithm with
• energy-efficient link metric
• Two-node based CR tree decoupling method is
  used

• Single-Cell System Model
• One receiver and multiple transmitters
• Independent Poisson packet arrivals
• Fixed packet transmission power
• Error-free ternary feedback (idle, success,
  collision)
• Packet Collision Models
• Collision Channel idle, success and collision
  refer to
• 0, 1 or more than one packet are transmitted
• SNR-based physical model node i successfully
  transmits to node j if

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The material presented in this poster is based
on the paper Energy-Efficient Collision
Resolution in Wireless Ad-Hoc Networks, Yalin
Evren Sagduyu, Anthony Ephremides, to appear in
the proceedings of INFOCOM 2003.
Pi Transmission power of node i ?
Path loss coefficient ri,j Distance between
nodes i and j N Ambient noise power r0
Antenna far-field region radius