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

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The positions “I” and “L” had well balance throughputs for both sides, but <strong>the</strong> average throughputs (6.837 and 6.898 Mbps) were inadequate for both sides. Compared to <strong>the</strong> estimated throughput (11Mbps) <strong>of</strong> <strong>the</strong> IEEE 802.11g, <strong>the</strong> AP that was placed at positions “I” and “L” did not <strong>of</strong>fer adequate throughput. In conclusion, <strong>the</strong> measurement results revealed that multiple APs could provide better signal coverage and throughput than a single AP in this <strong>of</strong>fice. The positions “A”, “G”, “E-3M”, “J”, “R” and “N-3M” were potential locations for AP placement in multiple AP scenarios. The detailed results <strong>of</strong> throughput analysis are presented in appendix C. 5.2.3 Comments From extensive measurements and discussion, some important conclusions have been drawn. Firstly, <strong>the</strong> impact <strong>of</strong> RSS on Wi-Fi link throughput is validated. The measurement results revealed that sufficient RSS does not guarantee sufficient throughput. WLAN throughput also depends on distance, <strong>the</strong> location <strong>of</strong> <strong>the</strong> AP, <strong>the</strong> number <strong>of</strong> constructions between <strong>the</strong> AP and <strong>the</strong> RX. A single AP could cover <strong>the</strong> entire <strong>of</strong>fice, but throughput was insufficient in many locations. Fur<strong>the</strong>rmore, with changing AP positions, RSS and throughput were varying at <strong>the</strong> same time. When <strong>the</strong> AP was located at positions “A”, “G” and “E-3M”, signal coverage and throughput were acceptable on <strong>the</strong> “left-hand side” <strong>of</strong> <strong>the</strong> <strong>of</strong>fice. However, RSS and throughput were inadequate on <strong>the</strong> “right-hand side” <strong>of</strong> <strong>the</strong> <strong>of</strong>fice. When <strong>the</strong> AP was located at positions “J”, “R” and “N-3M”, <strong>the</strong> results was opposite. The measurement results revealed that <strong>the</strong> location <strong>of</strong> AP would have a significant - 78 -
impact on RSS and throughput. Results also shows that <strong>the</strong> measurement points <strong>of</strong> “A”, “G”, “E-3M”, “J”, “R” and “N-3M” are appropriate positions for phase 2 measurements. In phase 2 measurements, we configured and placed two APs in <strong>the</strong> different positions which we derived from phase 1 measurements. The phase 2 measurement is discussed next. 5.3 Phase 2 Measurement The phase 2 measurement aims to investigate <strong>the</strong> throughput between two APs. Two basic service sets (BSSs) were configured. Each BSS included an AP and a wireless station. One <strong>of</strong> <strong>the</strong> BSSs covered <strong>the</strong> “right-hand side” and <strong>the</strong> o<strong>the</strong>r one covered <strong>the</strong> “left-hand side” <strong>of</strong> <strong>the</strong> <strong>of</strong>fice. In configuring two BSSs, performance between two BSSs becomes a key factor to influence <strong>the</strong> end-to-end throughput, especially when two wireless stations are located at different BSSs, trying to communicate with each o<strong>the</strong>r. The numerical results are shown in table 5.3. Access Point Configuration - 79 - Distance Throughput (Meter) (Mbps) LOS/NLOS A-R: WDS with AP Mode 32 3.235 LOS A-J: WDS with AP Mode 21 3.663 LOS G-R: WDS with AP Mode 26 5.281 LOS G-J: WDS with AP Mode 17 4.271 LOS E-3m-N-3M: WDS with AP 12 5.61 LOS E-3m-N-3M: AP with E<strong>the</strong>rnet Connection 12 14.834 LOS Table 5.3: Comparison with different AP configurations and placements.
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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
Page 41 and 42: 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: 5.2.2 Throughput An</strong
Page 95 and 96: The throughput of
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”
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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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