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1 Interplay of Spatial Reuse and SINR-determined Data Rates in CSMACA-based, Multi-hop, Multi- rate 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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2 Outline 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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3 Introduction How does the collision be avoided in CSMA-CA-based wireless network? Physical carrier sense Binary exponential back off mechanism Data rate adjustment Network throughput : 1. Transmission time 2. Spatial reuse
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4 Spatial reuse Tuning the carrier-sensing threshold Tcs Spatial reuse Computes the accumulated interference Tcs vs. Data rate Increase simultaneous transmissions Within carrier sense range
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5 Network Model and Signal Propagation/Interference Model Network Model Multi-hop Multi-rate Based on IEEE 802.11 DCF
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6 Network Assumption
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7 Virtual transmission time
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8 Network Capacity as A Function of Tcs, SINR and β[i]
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9 Attempt Probability is derived in Calí’s model Radio propagation
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10 Interference d pg d cs
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11 Interference Model 1st –tier interference nodes
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12 Signal Propagation SINR Model SINR of different data r i t ’ : concurrent transmitter
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13 SINR vs. β[i]
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14 Collision Zone Extra interference By simultaneous transmissions within the d cs SINR perceived at the receiver >β[i] Accumulative interference
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15 Revision all accumulated interference P rcv ≧ (I sim,dcz,dcs + I con,dcs,dpg +η) *β Spatial Reuse
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16 Numerical Results-1 Setting 500 nodes 500*500 m 2 1125 Bytes/packet D SR =50m d pg =302m dcs = 153m CW=64
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17 Numerical Results-2_1 200 nodes 500*500 m 2 dcs=153 m CW =64~128
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18 Numerical Results-2_2 62 nodes 500*500 m 2
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19 Numerical Results-2_3 10 nodes 500*500 m 2
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20 Experiments with Settings (Tcs, CW, r) Tcs : Optimal value r= 6 or 54 Number of nodes: 25 125 Field : 500*500 Single hop CBR connection (225Bytes)
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21 Validation of Analytic Model
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22 Conclusions In this paper Investigate Relation between PHY- and MAC-layer parameters Derive Analytic model about the characters of IEEE 802.11 DCF A corresponding SINR Achieve Spatial reuse Sustainable data rates
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