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

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Some important environmental factors and characteristics <strong>of</strong> WLAN equipment have significant impacts on WLAN throughput. It was mentioned in [72]. The factors are: Distance between transmitter and receiver. Specifications <strong>of</strong> AP and wireless adapter. Material <strong>of</strong> building and partition. Interference from o<strong>the</strong>r radio equipment. Location <strong>of</strong> AP and signal propagation environment. The number <strong>of</strong> obstructions between <strong>the</strong> transmitter and <strong>the</strong> receiver. <strong>An</strong>tenna type: omni-directional or directional antenna, and gain <strong>of</strong> antenna. In conclusion, <strong>the</strong> studies proposed some guidelines for conducting propagation measurement. The guidelines would be helpful for our measurement study. 2.3.5 <strong>Signal</strong> <strong>Strength</strong> and Indoor Positioning System In <strong>the</strong> IEEE 802.11 standard, <strong>the</strong>re is no specific definition to present <strong>the</strong> relationship between power level and RSS. Generally, RSS can be measured by mW or dBm. RSS and packet error rate (PER) are two important metrics in <strong>the</strong> adaptation algorithm. Two new adaptations were developed in [73]. Receiving-sensitivity adaptation can be used to reduce WLAN collision. Clear-channel-assessment adaptation is used to mitigate <strong>the</strong> hidden/exposed node problems. Both adaptations were based on RSS and PER. The IEEE 802.11 technology is widely deployed for indoor ubiquitous computing and positioning systems in recent years. Many existing literatures indicated that RSS <strong>of</strong> AP can provide sufficient information to determine location <strong>of</strong> objects [74-78]. Many indoor positioning systems are based on RSS; <strong>the</strong>refore, <strong>the</strong> accuracy and reliability <strong>of</strong> <strong>the</strong> positioning systems are influenced by RSS, radio propagation environment, - 30 -
specifications <strong>of</strong> AP and WLAN adapter. As highlighted in [79], <strong>the</strong> first phase <strong>of</strong> creating RSS base positioning systems has to conduct a field measurement to build up location fingerprinting database as known as radio map. The second phase is to obtain precise location from position calculation based on <strong>the</strong> measurement data. Orinoco WLAN cards was used in [74] to conduct a field measurement in a crowded floor for collecting RSS. The RSS results indicated that radio propagation environment and specifications <strong>of</strong> AP had significant impacts on fingerprinting database. The study has a greater implication for conducting RSS measurement. Extensive experiments were conducted in [80, 81] to measure RF energy and RSS range in indoor environment with different WLAN cards: 3Com, D-Link, SMC, Hawking Technology, BUFFLO, PROXIM and Intel. The experimental results showed that using same WLAN cards for collecting <strong>the</strong> location fingerprint and determining <strong>the</strong> location would have consistent and accurate positioning systems. Fur<strong>the</strong>rmore, as mentioned in [77], specifications <strong>of</strong> computers did not affect <strong>the</strong> accuracy <strong>of</strong> positioning system, but wireless adapters had significant impact on accuracy <strong>of</strong> positioning system. In conclusion, <strong>the</strong> studies provide rich guidelines to understand <strong>the</strong> natural characteristics <strong>of</strong> RSS and specifications <strong>of</strong> wireless equipment. The studies also <strong>of</strong>fer great insights into selecting WLAN cards and APs prior to WLAN deployment and using same WLAN devices, which would also provide consistent results in RSS measurement. - 31 -
Page 1 and 2: An Investi
Page 3 and 4: 2.3.5 Signal <stro
Page 5 and 6: Attestation of Aut
Page 7 and 8: Abstract Wireless local area networ
Page 9 and 10: List of Abbreviati
Page 11 and 12: List of Figures Fi
Page 13 and 14: List of Tables Tab
Page 15 and 16: Chapter 1 Introduction There has be
Page 17 and 18: WLAN performance evaluation and ana
Page 19 and 20: Chapter 2 Background and Related Wo
Page 21 and 22: 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: proposed to improve WLAN performanc
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 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 <
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
Page 147 and 148:
(N-3m)N-O 15.00 -72 15.6 5.626 NLOS
Page 149 and 150:
(C-3m)C-D 14.32 -74 13.6 6.453 NLOS
Page 151 and 152:
Figure B.8: Throughput map for AP a
Page 153 and 154:
60 40 20 0 -20 -40 -60 -80 -100 Acc
Page 155 and 156:
AP at A RX Position Left-Hand Area
Page 157 and 158:
AP at L RX Position Left-Hand Area
Page 159 and 160:
Appendix D Phase 3 Experimental Res
Page 161 and 162:
TX at 2M from E-3M Data File: 153.6
Page 163 and 164:
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
Page 171 and 172:
Wireless 108G Add 802.11g Wireless
Page 173:
2.4GHz Omni-Directional 7dBi Indoor
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