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

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AP at Position “A” Figure 5.5 shows propagation measurement results <strong>of</strong> distance, RSS and throughput when <strong>the</strong> AP was located at position “A”. RSS and throughput were sufficient between measurement points “B” and “I”. However, RSS and throughput were decreasing from measurement point “L”, because <strong>of</strong> <strong>the</strong> number <strong>of</strong> obstructions and distance were increasing between <strong>the</strong> AP and RX. RSS <strong>of</strong> measurement points “O” was <strong>the</strong> lowest (-90 dBm, refer table B.1). Although measurement points “O” were not <strong>the</strong> fur<strong>the</strong>st point from <strong>the</strong> AP, some obstructions were located between <strong>the</strong> AP and RX, resulting in <strong>the</strong> lowest RSS and throughput (0.393 Mbps, refer table B.1) at measurement point “O”. 40 20 0 -20 -40 -60 -80 -100 Access Point at position "A" : Distance/RSSI/Throughput B C D E F H G I L M J K N O P Q R S RX Position Figure 5.5: Distance/RSSI/Throughput for AP at position “A”. - 66 - Throughput (Mbps) <strong>Signal</strong> strength (dBm) Distance (Meter) We found that RSS had significant impact on Wi-Fi link throughput. For example, RSS at measurement point “H” was -59 dBm with throughput 10.088 Mbps (refer table B.1). When RSS was -76 dBm at “M”, <strong>the</strong> throughput was only 3.134 Mbps. In general,
throughput decreases along with lower RSS. In fact, <strong>the</strong> change <strong>of</strong> throughput was not only determined by RSS, but also by o<strong>the</strong>r factors. These factors will be discussed later in this section. The real throughput in <strong>the</strong> obstructed <strong>of</strong>fice environment is shown in <strong>the</strong> form <strong>of</strong> a map (as shown in figure 5.6). The various colors were used to demonstrate different throughputs, for example, lower throughput (0~2 Mbps) between measurement points “N” and “R” was presented by <strong>the</strong> color tan. Figure 5.6: Throughput map for AP at position “A”. In figure 5.6, overall throughput was better on <strong>the</strong> “left-hand side” <strong>of</strong> <strong>the</strong> <strong>of</strong>fice and <strong>the</strong> center <strong>of</strong> <strong>the</strong> <strong>of</strong>fice. The throughput <strong>of</strong> “right-hand side” <strong>of</strong> <strong>the</strong> <strong>of</strong>fice was very low. However, due to no obstructions between AP and measurement points “R” and “S”, <strong>the</strong> throughput and RSS were acceptable at measurement points “R” and “S”. - 67 -
Page 1 and 2:
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
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 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: sufficient signal coverage and thro
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<
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 <
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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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