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

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larger than -66 dBm, <strong>the</strong> WLAN adapter reaches maximum data rate (54 Mbps). The table provides an important reference to facilitate <strong>the</strong> discussion. 5.1.1 Scenario 1: The Ad-Hoc Mode in <strong>the</strong> Meeting Room Two IEEE 802.11g wireless adapters (D-Link DWL-G132) were used in <strong>the</strong> experiment. However, we would like to emphasize <strong>the</strong> point before arriving at <strong>the</strong> results section that <strong>the</strong> adapter only supports 802.11b with maximum data rate at 11Mbps in <strong>the</strong> ad-hoc mode. The two laptops had better performance and signal strength when kept 2 meters apart than being kept distant by 1 meter (as shown in figure 5.1). This is because if two wireless stations are placed too close, it would cause path loss. Numerical results are presented in appendix A (table A.1). Throughput (Mbps) 5.90 5.80 5.70 5.60 5.50 5.40 5.30 5.20 5.10 5.00 10.9 Data Ad-Hoc Mode Throughput Measurement 21.9 32.9 43.8 54.8 65.8 76.8 87.8 98.7 109.7 120.7 131.6 142.6 153.6 164.6 274 Data File Size (MB) - 60 - 1 Meter / -45 dBm 2 Meters / -41 dBm 3 Meters / -47 dBm Figure 5.1: Throughput measurement under ad-hoc mode. 263 Audio 256 Video
In table 5.1, <strong>the</strong> estimated throughput <strong>of</strong> IEEE 802.11b is 5 Mbps, once <strong>the</strong> receiver sensitivity is large than -82 dBm. Our measurement throughput (average throughput 5.5 Mbps) with RSS (-41 dBm) was slightly better than estimated throughput. As mentioned in [49], <strong>the</strong>oretical maximum user datagram protocol (UCP) throughput <strong>of</strong> <strong>the</strong> IEEE 802.11b is 5.12 Mbps as well as 2.74 Mbps for TCP throughput with large packet size (1024 bytes) without RTS/CTS. In addition, [95] depicts that two wireless stations were configured in <strong>the</strong> direct line-<strong>of</strong>-sight (LOS) with <strong>the</strong> throughput <strong>of</strong> 802.11b (5 Mbps). Comparing <strong>the</strong> results with [49] and [95], our measurement results were very close to <strong>the</strong> <strong>the</strong>oretical UDP throughput (5.12 Mbps) and <strong>the</strong> real-world measurement throughput (5 Mbps). Our measurement results were better than <strong>the</strong> <strong>the</strong>oretical results in [49] and <strong>the</strong> results <strong>of</strong> crowded <strong>of</strong>fice experiment in [95]. The possible reason is that our measurements were conducted under controlled environment. 5.1.2 Scenario 2 to 5: The Infrastructure Mode in <strong>the</strong> Meeting Room We conducted measurements in <strong>the</strong> meeting room and configured an AP as “AP mode” in scenario 2, two APs as “WDS with AP mode” in scenario 3, two APs as “AP mode” with E<strong>the</strong>rnet connection in scenario 4, and two APs as “WDS mode” in scenario 5. Figure 5.2 shows throughput with different AP configurations. Detailed numerical results are presented in appendix A (table A.2 to A.6). In <strong>the</strong> “AP mode”, <strong>the</strong> average throughput is 10.357 Mbps (refer table A.6) when laptops were placed 2 meters away from <strong>the</strong> AP. However, when <strong>the</strong> laptops were placed only 1 meter away from <strong>the</strong> AP, <strong>the</strong> average throughput is dropped by 21% (8.157 Mbps). Similarly, in <strong>the</strong> ad-hoc mode <strong>the</strong> throughput was 5.437 Mbps and 5.634 Mbps at 1m and 2m respectively (refer table - 61 -
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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
Page 23 and 24: The coverage of a
Page 25 and 26: 2.2.1 Physical Layer Figure 2.8 sho
Page 27 and 28: throughput significantly at higher
Page 29 and 30: DCF is designed to provide “best-
Page 31 and 32: Figure 2.11: Backof</strong
Page 33 and 34: modulation in [37]. According to si
Page 35 and 36: Figure 2.12: Net throughput <strong
Page 37 and 38: As highlighted in [46, 47], distanc
Page 39 and 40: 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: The receiver sensitivity is an impo
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 and 94: impact on RSS and throughput. Resul
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<
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Appendix A Preliminary Experimental
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2. AP Mode Measurement in t
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7. The Ad-Hoc Mode Measurement on <
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Appendix B Phase 1 Experimental Res
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(P-1.5m)O-P 32.78 -86 193.6 0.453 N
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3. Access Point at Position “E-3M
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(C-5m)C-D 21.63 -83 46.8 1.875 NLOS
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J 9.00 -44 8.2 10.703 LOS (J-1.5m)J
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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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