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

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Acknowledgements First <strong>of</strong> all, I would like to express my sincere gratitude to my supervisor Nurul I. Sarkar. Without his kind guidance, comments and encouragement during my research, I would not complete my dissertation. Especially, because <strong>the</strong> experimental measurements cannot be performed during weekdays and it is a time consuming task, my supervisor spent more than 10 weekends to help me in data collection. I take advantage to thank all <strong>of</strong> my friends: Sandeep Patil, Kang Sun, Dun Yong Jin, Ryan Sentosa and Feng Liu. They also provide many supports and inspire me during my research. I would like to express special gratitude to Colligo Networks Inc. for providing me two licenses <strong>of</strong> Colligo Workgroup Edition S<strong>of</strong>tware and PassMark S<strong>of</strong>tware Pty Ltd for a license <strong>of</strong> WirelessMon s<strong>of</strong>tware to support my research. Finally, I would like to thank my parents and family who are always playing an important role no matter <strong>the</strong> distance to encourage me during my difficult time. Without all <strong>of</strong> <strong>the</strong>ir support, I could not achieve my goals. - v -
Abstract Wireless local area networks (WLANs) play an increasingly significant role in providing ubiquitous network services in contemporary society due to <strong>the</strong>ir mobility and cable free usage. It is more challenging to maintain higher throughput <strong>of</strong> WLANs than wired networks. In this dissertation, an experimental investigation <strong>of</strong> <strong>the</strong> impact <strong>of</strong> signal strength on Wi-Fi link throughput in an obstructed <strong>of</strong>fice environment is reported. Due to <strong>the</strong> complexity and unpredictable nature <strong>of</strong> radio signal propagation, it is difficult to derive real and accurate signal strength and link throughput by analytical modeling and computer simulation. The received signal strength (RSS), attenuation and path loss depends on <strong>the</strong> propagation environment. The location <strong>of</strong> an access point (AP) has a significant effect on WLAN performance. <strong>An</strong> appropriate AP placement is required to obtain greater performance <strong>of</strong> WLANs. Through extensive radio propagation measurements, <strong>the</strong> results demonstrated both <strong>the</strong> relationship <strong>of</strong> signal strengths with <strong>the</strong> Wi-Fi link throughput; and optimum AP placement. This research carried out some significant contributions. Firstly, <strong>the</strong> results revealed that not only WLAN throughput depends on RSS, but also on factors such as <strong>the</strong> distance and <strong>the</strong> obstruction between a transmitter and a receiver, and <strong>the</strong> nature <strong>of</strong> radio - vi -
Page 1 and 2: An Investi
Page 3 and 4: 2.3.5 Signal <stro
Page 5: Attestation of Aut
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 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
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4.4.2 Wireless Adapter Configuratio
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4.4.3 AP Operation Mode Two APs (D-
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meeting room with different distanc
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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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