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Interplay of Spatial Reuse and SINR-determined
Data Rates in CSMACA-based, Multi-hop, Multirate Wirless Networks
Ting-Yu Lin and Jennifer C. Hou
Department of Computer Science University of
Illinois at Urbana-Champaign
IEEE INFOCOM 2007
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Outline
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Introduction
Network Model and Signal
Propagation/Interference Model
Network Capacity as A Function of Tcs, SINR
and β[i]
Validation of Analytic Model
Conclusions
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Introduction
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How does the collision be avoided in
CSMA-CA-based wireless network?
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Physical carrier sense
Binary exponential back off mechanism
Data rate adjustment
Network throughput : 1. Transmission time
2. Spatial reuse
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Spatial reuse
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Tuning the carrier-sensing threshold
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Tcs
Spatial reuse
Computes the accumulated interference
Tcs vs. Data rate
Increase simultaneous transmissions
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Within carrier sense range
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Network Model and Signal
Propagation/Interference Model
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Network Model
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Multi-hop
Multi-rate
Based on IEEE 802.11 DCF
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Network Assumption
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Virtual transmission time
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Network Capacity as A
Function of Tcs, SINR and β[i]
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Attempt Probability
Radio propagation
is derived in Calí’s model
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Interference
dcs
dpg
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Interference Model
1st –tier interference nodes
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SINR vs. β[i]
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Collision Zone
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Extra interference
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By simultaneous transmissions within the dcs
SINR perceived at the receiver >β[i]
Accumulative interference
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Revision all accumulated
interference
Prcv ≧ (Isim,dcz,dcs+ Icon,dcs,dpg +η) *β
GDP

I con ,dcs ,dpg  
  [i ]
Spatial Reuse
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Numerical Results-1
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Setting
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500 nodes
500*500 m2
1125 Bytes/packet
DSR =50m
dpg=302m
dcs = 153m CW=64
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Numerical Results-2_1
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200 nodes
500*500 m2
dcs=153 m
CW =64~128
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Numerical Results-2_2
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62 nodes
500*500 m2
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Numerical Results-2_3
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10 nodes
500*500 m2
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Experiments with Settings
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(Tcs, CW, r)
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Number of nodes:
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Tcs : Optimal value
r= 6 or 54
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125
Field : 500*500
Single hop CBR
connection (225Bytes)
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Validation of Analytic Model
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Conclusions
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In this paper
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Investigate
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Derive
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Relation between PHY- and MAC-layer parameters
Analytic model about the characters of IEEE 802.11 DCF
A corresponding SINR
Achieve
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Spatial reuse
Sustainable data rates
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