An Investigation of the Impact of Signal Strength on Wi-Fi Link ...

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35 30 25 20 15 10 5 0 A-R (WDS with AP Mode) Throughput / Distance with Different AP Configuration and Placement A-J (WDS with AP Mode) G-R (WDS with AP Mode) AP Position - 80 - G-J (WDS with AP Mode) E-3m-N-3m (WDS with AP Mode) Figure 5.17: Comparison with different AP configurations and placements. E-3m-N-3m (AP with E<strong>the</strong>rnet Connection) Distance (Meter) Throughput (Mbps) Figure 5.17 shows <strong>the</strong> throughput with different AP configurations and placements. When <strong>the</strong> APs were configured as “WDS with AP” mode and placed at position “E-3M” and “N-3M”, throughput was better than <strong>the</strong> o<strong>the</strong>r positions. This is because <strong>the</strong> distance between positions “E-3M” and “N-3M” is shorter than <strong>the</strong> o<strong>the</strong>r positions. Also, <strong>the</strong> radio propagation environment <strong>of</strong> “E-3M” and “N-3M” was less harsh than o<strong>the</strong>r positions. We verified <strong>the</strong> impact <strong>of</strong> distance on WLAN performance again. The results show that <strong>the</strong> distance between two APs had a slight impact on AP-to-AP throughput in LOS condition. In table 5.3, <strong>the</strong> throughput decreased with an increased in <strong>the</strong> distance between two APs, except for APs at positions “G and “R”. Thus, <strong>the</strong> measurement results revealed that <strong>the</strong> location <strong>of</strong> APs, and radio propagation environment would be <strong>the</strong> major factors to influence throughput ra<strong>the</strong>r than <strong>the</strong> distance in LOS condition.
The throughput <strong>of</strong> “WDS with AP mode” (5.61 Mbps) was only half <strong>of</strong> <strong>the</strong> estimated throughput <strong>of</strong> a signal AP (11 Mbps). This is due to <strong>the</strong> fact that <strong>the</strong> APs need to deal with traffic between wireless stations and to exchange data with o<strong>the</strong>r APs in <strong>the</strong> “WDS with AP mode”. On <strong>the</strong> o<strong>the</strong>r hand, when two APs were configured as “AP mode” and a Cat-5 E<strong>the</strong>rnet cable was used to link two BSSs, throughput increased to 164% (from 5.61 Mbps to 14.834 Mbps). The “AP mode” with E<strong>the</strong>rnet connection used a Cat-5 cable to link two BSSs. The traffic between BSSs was served by E<strong>the</strong>rnet (100 Mbps). There was only one hop between <strong>the</strong> AP to <strong>the</strong> wireless nodes on both BSSs. Thus, throughput <strong>of</strong> “AP mode” with <strong>the</strong> E<strong>the</strong>rnet connection was much better than <strong>the</strong> “WDS with AP mode”. The optimal positions (E-3M and N-3M) for two APs placement were obtained from phase 2 measurements. The position “E-3M” and “N-3M” were <strong>the</strong> candidate measurement points for <strong>the</strong> third phase measurements. The results <strong>of</strong> phase 3 measurement are presented next. 5.4 Phase 3 Measurement The APs were configured as “WDS with AP mode” in scenario 10 and “AP mode” with E<strong>the</strong>rnet connection in scenario 11. Both APs were placed at position “E-3M” and “N-3M”. Two laptops were connected to different APs. TX was placed at a fixed position and RX was moved around to different measurement points in <strong>the</strong> <strong>of</strong>fice. The results <strong>of</strong> “WDS with AP mode” and <strong>the</strong> results <strong>of</strong> “AP mode” with E<strong>the</strong>rnet connection - 81 -
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An Investi
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2.3.5 Signal <stro
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Attestation of Aut
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Abstract Wireless local area networ
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List of Abbreviati
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List of Figures Fi
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List of Tables Tab
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Chapter 1 Introduction There has be
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WLAN performance evaluation and ana
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Chapter 2 Background and Related Wo
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The IEEE 802.11 networks have two o
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The coverage of a
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2.2.1 Physical Layer Figure 2.8 sho
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throughput significantly at higher
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DCF is designed to provide “best-
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Figure 2.11: Backof</strong
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modulation in [37]. According to si
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Figure 2.12: Net throughput <strong
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As highlighted in [46, 47], distanc
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2.3.2 Base Station Placement <stron
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gained an insight that this would m
Page 43 and 44: proposed to improve WLAN performanc
Page 45 and 46: specifications of
Page 47 and 48: dynamic and complicated. As argued
Page 49 and 50: In addition, we surveyed and review
Page 51 and 52: 4.1 Performance Metrics A stopwatch
Page 53 and 54: Model: DWL-G132 Specification: Sta
Page 55 and 56: Figure 4.1: WY building layout. - 4
Page 57 and 58: Figure 4.2 shows wireless configura
Page 59 and 60: 4.4.2 Wireless Adapter Configuratio
Page 61 and 62: 4.4.3 AP Operation Mode Two APs (D-
Page 63 and 64: meeting room with different distanc
Page 65 and 66: Scenario 4 In figure 4.12, two APs
Page 67 and 68: “(H-3.5m)F-H” is the</s
Page 69 and 70: Figure 4.16: Phase 2 measurement: A
Page 71 and 72: performed the prop
Page 73 and 74: The receiver sensitivity is an impo
Page 75 and 76: In table 5.1, the
Page 77 and 78: Ethernet connectio
Page 79 and 80: sufficient signal coverage and thro
Page 81 and 82: throughput decreases along with low
Page 83 and 84: In table 5.1, when RSS is larger th
Page 85 and 86: (for example, measurement point “
Page 87 and 88: AP at Position “R” Figure 5.13
Page 89 and 90: The measurement results indicated t
Page 91 and 92: 5.2.2 Throughput An</strong
Page 93: impact on RSS and throughput. Resul
Page 97 and 98: The RSS of “WDS
Page 99 and 100: The average throughput of</
Page 101 and 102: The average data size of</s
Page 103 and 104: 5.6.1 SOHO Environment Due to <stro
Page 105 and 106: The following notes are needed to b
Page 107 and 108: when APs were placed at positions
Page 109 and 110: Real and accurate results for AP pl
Page 111 and 112: Chapter 7 Summary and Conclusions W
Page 113 and 114: planning. Propagation measurement (
Page 115 and 116: deployment. Many WLANs are deployed
Page 117 and 118: placement in indoor wireless system
Page 119 and 120: Communications, vol. 2, no. 5, pp.
Page 121 and 122: [56] J. K. L. Wong, M. J. Neve, and
Page 123 and 124: eceived signal strength of<
Page 125 and 126: Appendix A Preliminary Experimental
Page 127 and 128: 2. AP Mode Measurement in t
Page 129 and 130: 7. The Ad-Hoc Mode Measurement on <
Page 131 and 132: Appendix B Phase 1 Experimental Res
Page 133 and 134: (P-1.5m)O-P 32.78 -86 193.6 0.453 N
Page 135 and 136: 3. Access Point at Position “E-3M
Page 137 and 138: (C-5m)C-D 21.63 -83 46.8 1.875 NLOS
Page 139 and 140: J 9.00 -44 8.2 10.703 LOS (J-1.5m)J
Page 141 and 142: 7. Access Point at Position “H”
Page 143 and 144: Figure B.2: Throughput map for AP a
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60 40 20 0 -20 -40 -60 -80 -100 Acc
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(N-3m)N-O 15.00 -72 15.6 5.626 NLOS
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(C-3m)C-D 14.32 -74 13.6 6.453 NLOS
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Figure B.8: Throughput map for AP a
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60 40 20 0 -20 -40 -60 -80 -100 Acc
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AP at A RX Position Left-Hand Area
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AP at L RX Position Left-Hand Area
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Appendix D Phase 3 Experimental Res
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TX at 2M from E-3M Data File: 153.6
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IEEE 802.11 b/g Access Point DWL-21
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Standards • IEEE 802.11g • IEEE
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1 Maximum wireless signal rate deri
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Wireless 108G Standards • 802.11b
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Wireless 108G Add 802.11g Wireless
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2.4GHz Omni-Directional 7dBi Indoor
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