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

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<strong>of</strong> radio propagation. In <strong>the</strong> wireless environment, any wireless node can hear radio signal from o<strong>the</strong>r wireless devices, as long as <strong>the</strong>y are within <strong>the</strong> range <strong>of</strong> radio signal coverage. Radio propagation environment is one <strong>of</strong> <strong>the</strong> key factors that influences <strong>the</strong> performance <strong>of</strong> Wi-Fi networks. <strong>Signal</strong> strength becomes weaker in a harsh propagation environment compared to a good propagation environment. With widely deployment <strong>of</strong> Wi-Fi networks, it encourages researchers devote extensive efforts to study <strong>the</strong> performance and issues in <strong>the</strong> area <strong>of</strong> WLAN. Many researches have focused on improving MAC and PHY <strong>of</strong> <strong>the</strong> IEEE 802.11 [1-3], request to send / clear to send (RTS/CTS) handshaking mechanism [4, 5], and transmission power management [6-8]. In addition, base station placement is also an important aspect in terms <strong>of</strong> WLAN performance in <strong>the</strong> indoor environment [9-11]. Base station placement is a challenging task, especially in an obstructed <strong>of</strong>fice environment due to dynamic characteristics <strong>of</strong> radio wave propagation. The infrastructure mode is widely used in <strong>the</strong> WLAN deployment. <strong>An</strong> access point (AP) coordinates transmission in an infrastructure network. The location <strong>of</strong> an AP is an important factor that influences WLAN performance. A single AP may not provide adequate signal coverage in <strong>the</strong> large organization. The deployment <strong>of</strong> multiple APs is quite common in <strong>the</strong> organization. However, <strong>the</strong> placement <strong>of</strong> multiple APs is more complex than a single AP placement. A careful plan <strong>of</strong> WLAN deployment not only saves cost but also enhances network performance and efficient radio resources utilisation. - 2 -
WLAN performance evaluation and analysis can be performed by: (1) propagation measurement; (2) analytical modeling; and (3) computer simulation. To get an insight into <strong>the</strong> signal strength in a crowded <strong>of</strong>fice environment, a radio propagation measurement is required. Propagation measurement enables us to find <strong>the</strong> relationship between Wi-Fi link throughput and signal strength. Many factors affect <strong>the</strong> received signal strength (RSS) in an indoor environment, for example, multiple-path propagation and human motion [12]. The IEEE 802.11 standard provides various WLAN architectures and topologies for WLAN design (e.g. basic service set, extended service set, ad-hoc mode, infrastructure mode). Unlike normal AP mode, advanced APs could provide various AP configuration modes. Wireless distribution system (WDS) mode is example <strong>of</strong> an advanced AP. Different operating modes <strong>of</strong> APs may have different WLAN performance as well as implementation cost. Careful consideration <strong>of</strong> WLAN configuration is needed because o<strong>the</strong>rwise it would impact WLAN performance, implementation cost, and effective management <strong>of</strong> radio resources. The objective <strong>of</strong> this dissertation is discussed next. 1.1 Objective <strong>of</strong> This Research Project The aim <strong>of</strong> this research is to investigate <strong>the</strong> impact <strong>of</strong> signal strength on Wi-Fi link throughput in an obstructed <strong>of</strong>fice environment. We examine <strong>the</strong> relationship between signal strength and Wi-Fi link throughput through propagation measurements. Moreover, to provide a good signal coverage and throughput, we seek <strong>the</strong> optimal locations for - 3 -
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: Chapter 1 Introduction There has be
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 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
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“(H-3.5m)F-H” is the</s
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Figure 4.16: Phase 2 measurement: A
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performed the prop
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The receiver sensitivity is an impo
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In table 5.1, the
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Ethernet connectio
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sufficient signal coverage and thro
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throughput decreases along with low
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In table 5.1, when RSS is larger th
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(for example, measurement point “
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AP at Position “R” Figure 5.13
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The measurement results indicated t
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5.2.2 Throughput An</strong
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impact on RSS and throughput. Resul
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The throughput of
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The RSS of “WDS
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The average throughput of</
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The average data size of</s
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5.6.1 SOHO Environment Due to <stro
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The following notes are needed to b
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when APs were placed at positions
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Real and accurate results for AP pl
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Chapter 7 Summary and Conclusions W
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planning. Propagation measurement (
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deployment. Many WLANs are deployed
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placement in indoor wireless system
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Communications, vol. 2, no. 5, pp.
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[56] J. K. L. Wong, M. J. Neve, and
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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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An Investigation of the Impact of Signal Strength on Wi-Fi Link ...

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