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

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SNR was used to determine delivery probability and packet loss rates in [65]. The study indicated that link distance and SNR had a significant effect on packet loss rate. SIR is a parameter to measure <strong>the</strong> signal strength and interference in <strong>the</strong> communication channel. Higher SIR means lower interference in <strong>the</strong> radio propagation environment. Higher SIR could also have large signal coverage <strong>of</strong> APs in <strong>the</strong> IEEE 802.11g environment [66]. The study proved that using “symbol erasures” would improve <strong>the</strong> coverage <strong>of</strong> an AP from 40% to 300% when Bluetooth device is operating close to wireless station within 1 meter to 10 meters. In addition, <strong>the</strong> “interference avoidance procedure” was developed to minimize <strong>the</strong> interference and increase SIR by optimizing output waveform [67]. SIR is also a benchmarking parameter for WLAN design. SIR performance has significant impacts on signal quality [68]. <strong>Signal</strong> coverage and transmission power <strong>of</strong> mobile nodes are insufficient during base station placement. It also requires a consideration <strong>of</strong> SIR performance. Inadequate SIR performance leads to path loss between base station and mobile nodes. BER is a ratio to measure <strong>the</strong> number <strong>of</strong> error bits received to <strong>the</strong> number <strong>of</strong> total bits sent within a fixed time interval. The IEEE 802.11 DCF protocol is strongly influenced by BER. Increasing BER would result in poor throughput, longer delay and higher packet drop probability [69]. BER can be used for optimizing packet size to reduce packet drop probability and delay. A scheme called Error Recover Service Medium-Access Control (ERSMAC) was - 28 -
proposed to improve WLAN performance specially in higher BER condition [70]. Both BER and <strong>the</strong> number <strong>of</strong> re-transmitting frames are key factors to influence WLAN performance. Noise and interference have a significant impact on throughput and coverage <strong>of</strong> AP. To achieve higher data rate and throughput, it requires lower BER and higher SNIR threshold. Understanding SNR, SIR, SNIR and BER would be helpful in WLAN design. The studies have significant implications for assessing and enhancing WLAN performance. 2.3.4 Recommendations for WLAN Performance Measurement Due to <strong>the</strong> complex and dynamic characteristics <strong>of</strong> signal propagation, conducting propagation measurement in WLAN is a difficult work. Various rules to improve accuracy <strong>of</strong> measurement results was identified in [71]. They are: Use short distance ra<strong>the</strong>r than long distance to ensure <strong>the</strong> signal strength could not be a factor to influence saturation throughput. Scan radio channel prior to experiment to avoid interference from o<strong>the</strong>r wireless stations or APs. Use small and closed room for reducing multiple-path effect when conducting experiment in open and free space is not possible. Turn <strong>of</strong>f <strong>the</strong> unnecessary services in <strong>the</strong> AP configuration to reduce additional overhead. Use appropriate packet size. Pre-test and find out optimal orientation <strong>of</strong> <strong>the</strong> AP. Use appropriate file size for measuring AP throughput. - 29 -
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: gained an insight that this would m
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 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
Page 145 and 146:
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
Page 165 and 166:
Standards • IEEE 802.11g • IEEE
Page 167 and 168:
1 Maximum wireless signal rate deri
Page 169 and 170:
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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An Investigation of the Impact of Signal Strength on Wi-Fi Link ...

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