An Investigation of the Impact of Signal Strength on Wi-Fi Link ...
An Investigation of the Impact of Signal Strength on Wi-Fi Link ...
An Investigation of the Impact of Signal Strength on Wi-Fi Link ...
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c<strong>on</strong>crete wall have a greater impact <strong>on</strong> signal attenuati<strong>on</strong> than o<str<strong>on</strong>g>the</str<strong>on</strong>g>r c<strong>on</strong>structi<strong>on</strong>al<br />
materials in <str<strong>on</strong>g>the</str<strong>on</strong>g> indoor envir<strong>on</strong>ment (refer table 2.2).<br />
Materials Attenuati<strong>on</strong><br />
Plasterboard 3 to 5 db<br />
Glass wall with metal frame 6 db<br />
Cinderblock wall 4 to 6 db<br />
<strong>Wi</strong>ndow 3 db<br />
Metal door 6 to 10 db<br />
Structural c<strong>on</strong>crete wall 6 to 15 db<br />
Table 2.2: <str<strong>on</strong>g>Signal</str<strong>on</strong>g> attenuati<strong>on</strong> with different c<strong>on</strong>structi<strong>on</strong>al material [18].<br />
2.3 WLAN <str<strong>on</strong>g>Signal</str<strong>on</strong>g> <str<strong>on</strong>g>Strength</str<strong>on</strong>g> Measurement<br />
This secti<strong>on</strong> reviews recent articles <str<strong>on</strong>g>of</str<strong>on</strong>g> WLAN performance, base stati<strong>on</strong> placement,<br />
signal quality impacts, WLAN measurements, signal strength and its applicati<strong>on</strong>.<br />
2.3.1 WLAN Performance<br />
<strong>Fi</strong>gure 2.12 shows effective throughput with different kinds <str<strong>on</strong>g>of</str<strong>on</strong>g> network overheads. The<br />
overhead <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> IEEE 802.11 is quite high, so that it has a large gap between practical<br />
throughput and data rate. As menti<strong>on</strong>ed in [39], <str<strong>on</strong>g>the</str<strong>on</strong>g> overhead <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> WLAN is around<br />
60%. Only 40% time is used to transmit payload. The reset <str<strong>on</strong>g>of</str<strong>on</strong>g> time is c<strong>on</strong>sumed by<br />
re-transmissi<strong>on</strong> (35%), acknowledgement (15%) and management traffic (10%). Thus,<br />
to obtain an accurate saturati<strong>on</strong> throughput <str<strong>on</strong>g>of</str<strong>on</strong>g> WLAN from experimental measurements,<br />
test envir<strong>on</strong>ment c<strong>on</strong>trol and minimizing possible interfering factors would be helpful to<br />
gain better and realistic saturati<strong>on</strong> throughput. For example, shutdown unnecessary<br />
services (e.g. disable simple network management protocol (SNMP) functi<strong>on</strong>).<br />
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