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

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Chapter 3 Research Methodology A literature review in <strong>the</strong> areas <strong>of</strong> WLAN performance, signal strength and propagation measurement is represented in chapter 2. This chapter provides a discussion on research methodologies in <strong>the</strong> area <strong>of</strong> telecommunication networks. Real experimental measurement, analytical modeling and computer simulation are well-known research methodologies for modeling and performance evaluation <strong>of</strong> telecommunication networks. <strong>An</strong>alytical modeling is based on ma<strong>the</strong>matical analysis. Although analytical modeling is good for designing new network protocols and tuning network parameters, it cannot control and operate network protocols in details as well as cannot present <strong>the</strong> dynamic nature <strong>of</strong> network systems [71, 82]. Computer simulation uses computer s<strong>of</strong>tware packages, for example, NS-2 [83], OPNET [84], to evaluate network performance or develop new network protocols. However, higher level simulation s<strong>of</strong>tware has difficulty in obtaining detail operation characteristics <strong>of</strong> network protocols. Especially, <strong>the</strong> physical medium <strong>of</strong> WLAN is - 32 -
dynamic and complicated. As argued in [85], “NS-2 does not implement <strong>the</strong> physical layer <strong>of</strong> <strong>the</strong> network stack nor does it implement <strong>the</strong> characteristics <strong>of</strong> <strong>the</strong> physical medium” (p.23). Johnson et al. [86] pointed out that “simulation models do not sufficiently capture radio and sensor irregularity in a complex, real-world environment, especially indoors” (p.1). According to [64], simulation tools are insufficient for an in-depth study <strong>of</strong> WLAN in several aspects and analytical modeling has difficulty in analysis <strong>of</strong> transmission control protocol (TCP) over multiple-hops WLANs. WLAN throughputs are subject to change due to various radio propagation environment (e.g. obstructions, constructional material) [71, 80, 81]. Therefore, it is quite difficult to understand <strong>the</strong> true characteristics <strong>of</strong> WLAN by both <strong>the</strong> analytical modeling and computer simulation. Due to higher cost <strong>of</strong> WLAN equipments and <strong>the</strong> lack <strong>of</strong> WLAN applications, it is a challenge to perform experimental measurements in <strong>the</strong> area <strong>of</strong> WLANs. The real measurement through an experimental approach is also time consuming and labor extensive. Thus, many WLAN researches have used analytical modeling and computer simulation. However, <strong>the</strong> situation has changed in recent years. With <strong>the</strong> wide applications <strong>of</strong> WLANs and <strong>the</strong>ir rapid development, it encourages researchers to adopt radio propagation measurement to investigate <strong>the</strong> performance and deployment issues <strong>of</strong> WLANs. For example, Park et al. [87] investigated radio interference on WLAN throughput by using experimental measurement. Chen et al. [88] conducted public WLAN traffic and throughput measurement at four hotspots. They used measurement results to develop a throughput propagation prediction model. The model can be adopted in design, development and implementation <strong>of</strong> <strong>the</strong> IEEE 802.11 WLANs. - 33 -
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 and 44: proposed to improve WLAN performanc
Page 45: specifications of
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<
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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
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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
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
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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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