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

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The IEEE 802.11a and 802.11b amendments were approved by IEEE 802.11 committee in October 1999. The IEEE 802.11a standard is also known as “high-speed physical layer in <strong>the</strong> 5 GHz band” [14]. The IEEE 802.11a operates at 5 GHz unlicensed band and supports up to 54 Mbps by using orthogonal frequency division multiplexing (OFDM). Due to heavy loading <strong>of</strong> ISM band, <strong>the</strong> IEEE 802.11a standard has an advantage <strong>of</strong> less interference. However, <strong>the</strong> high carrier frequency (5 GHz) results in limited transmitted range than 2.4 GHz [15]. In contrast, <strong>the</strong> IEEE 802.11b (Higher-Speed physical layer extension in <strong>the</strong> 2.4 GHz) was published later than <strong>the</strong> IEEE 802.11a. However, <strong>the</strong> IEEE 802.11b product was launched earlier than <strong>the</strong> IEEE 802.11a product and has much larger radio coverage than <strong>the</strong> IEEE 802.11a product. The IEEE 802.11b adopts high rate direct sequence spread spectrum (HR/DSSS) technique and complementary code keying (CCK) modulation scheme to provide higher data rates (5.5 and 11 Mbps). Since <strong>the</strong> IEEE 802.11b operates in <strong>the</strong> 2.4 GHz ISM band, it also adopts DSSS technique to support low data rates (1 and 2 Mbps). With comprehensive application <strong>of</strong> WLAN, higher data rate and throughput is required by multimedia application. The IEEE 802.11g standard, as known as “fur<strong>the</strong>r higher data rate extension in <strong>the</strong> 2.4 GHz”, was published in June 2003. By comparison with <strong>the</strong> IEEE 802.11b, data rate and throughput <strong>of</strong> <strong>the</strong> IEEE 802.11g has significant improvement (up to 54Mbps) and radio coverage is larger than <strong>the</strong> IEEE 802.11b. Moreover, one <strong>of</strong> <strong>the</strong> advantages <strong>of</strong> <strong>the</strong> IEEE 802.11g is that it is backward compatible with <strong>the</strong> IEEE 802.11b. Therefore, <strong>the</strong> IEEE 802.11g and 802.11b have become mainstream standards <strong>of</strong> WLAN products nowadays. - 6 -
The IEEE 802.11 networks have two operation modes: (1) Ad-Hoc; and (2) Infrastructure [16]. <strong>An</strong> infrastructure network involves an AP as a coordinator between wireless stations (as shown in figure 2.1). On <strong>the</strong> o<strong>the</strong>r hand, an ad-hoc network is formed by two or more wireless stations without AP involved (as shown in figure 2.2). Figure 2.1: <strong>An</strong> infrastructure network. Figure 2.2: <strong>An</strong> ad-hoc network. The IEEE 802.11 networks have three different network architectures: (1) basic service set (BSS); (2) independent BSS (IBSS); and (3) extended service set (ESS) [13]. BSS is - 7 -
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: Chapter 2 Background and Related Wo
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
Page 67 and 68: “(H-3.5m)F-H” is the</s
Page 69 and 70: 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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