r144 - community/trunk/en-US
sradvan at fedoraproject.org
sradvan at fedoraproject.org
Thu Jul 1 00:17:42 UTC 2010
Author: sradvan
Date: 2010-07-01 00:17:40 +0000 (Thu, 01 Jul 2010)
New Revision: 144
Modified:
community/trunk/en-US/Book_Info.xml
community/trunk/en-US/Communication.xml
community/trunk/en-US/Hardware.xml
community/trunk/en-US/Introduction.xml
community/trunk/en-US/Revision_History.xml
Log:
bump, review
Modified: community/trunk/en-US/Book_Info.xml
===================================================================
--- community/trunk/en-US/Book_Info.xml 2010-06-30 23:27:45 UTC (rev 143)
+++ community/trunk/en-US/Book_Info.xml 2010-07-01 00:17:40 UTC (rev 144)
@@ -7,8 +7,8 @@
<subtitle>Wireless and mobile networking overview for Fedora Linux</subtitle>
<productname>Fedora</productname>
<productnumber>13</productnumber>
- <edition>1.3</edition>
- <pubsnumber>1</pubsnumber>
+ <edition>1.4</edition>
+ <pubsnumber>0</pubsnumber>
<abstract>
<para>An overview of IEEE 802.11-based and other mobile networking technologies and their implementation in Fedora Linux.</para>
</abstract>
Modified: community/trunk/en-US/Communication.xml
===================================================================
--- community/trunk/en-US/Communication.xml 2010-06-30 23:27:45 UTC (rev 143)
+++ community/trunk/en-US/Communication.xml 2010-07-01 00:17:40 UTC (rev 144)
@@ -7,6 +7,20 @@
<para>
stuff
</para>
+<section id="sect-Wireless_Guide-Hardware-Data_Rates_and_Throughput">
+<title>Data Rates and Throughput</title>
+ <para>
+ Several metrics and measurements are used to define elements of wireless LANs. Some of these include terms to define data rate, throughput, signal to noise ratio, antenna gain, signal loss and encryption strength. One commonly misunderstood set of measurements is <emphasis>data rate</emphasis> and <emphasis>throughput</emphasis>. To use the IEEE 802.11g standard as an example, it is often referred to and marketed as having a 54Mbps (megabits/s) connection speed. This is however only a theoretical maximum speed under perfect conditions defined in the standard. Unfortunately, the real world is not a perfect environment, and in some cases can be outright hostile to facilitating wireless communication.
+ </para>
+ <para>
+ Continuing to use the IEEE 802.11g standard to define these terms, the standard is actually capable of negotiating its connection with other devices at several different <emphasis>data rates</emphasis>. This ability to change data rates is known as <command>Dynamic Rate Switching</command>, and a properly functioning card will negotiate the best possible speed depending on the distance from the Access Point, the amount and type of other devices that are connecting, and overall environmental conditions.
+ </para>
+ <para>The IEEE 802.11g standard can operate under the following data rates: 6, 9, 12, 18, 24, 36, 48 and 54 Mbps, and can use 802.11b speeds if in a mixed-mode environment. This series of speeds, and the current connected rate is usually intepreted in a graphical form in your operating system as a graph or bar or other text, representing signal strength (this is known as the <command>Received Signal Strength Indicator</command>). So, while the standard defines 54Mbps as the maximum speed, the data rate is actually negotiating one of the above speeds based on environmental conditions. This data rate is related to, but different from the <emphasis>actual amount</emphasis> of network data coming through the connection at any given time. This actual data transfer speed is known as <emphasis>throughput</emphasis>.
+ </para>
+ <para>
+ As mentioned, the full 54Mbps throughput as defined in the standard can never be achieved in the real world. Your actual throughput of network data is typically 15-40% of this maximum level. <emphasis>Data rate</emphasis> is the negotiated, variable, maximum possible link to other devices, and <emphasis>throughput</emphasis> is the real-world speed of actual data flow.
+ </para>
+</section>
<section id="sect-Wireless_Guide-Hardware-Connection_Modes">
<title>Connection Modes</title>
<para>
Modified: community/trunk/en-US/Hardware.xml
===================================================================
--- community/trunk/en-US/Hardware.xml 2010-06-30 23:27:45 UTC (rev 143)
+++ community/trunk/en-US/Hardware.xml 2010-07-01 00:17:40 UTC (rev 144)
@@ -81,7 +81,7 @@
</listitem>
<listitem>
<para>
- Semidirectional - <emphasis>Semidirectional antennas</emphasis> are designed to provide specific, directed signal coverage over large areas. An example of a semidirectional antenna is a <emphasis>Yagi antenna</emphasis>.
+ Semidirectional - <emphasis>Semidirectional antennas</emphasis> are designed to provide specific, directed signal coverage over large areas. Examples of a semidirectional antenna are <emphasis>Yagi</emphasis> or <emphasis>patch</emphasis>.
</para>
</listitem>
<listitem>
Modified: community/trunk/en-US/Introduction.xml
===================================================================
--- community/trunk/en-US/Introduction.xml 2010-06-30 23:27:45 UTC (rev 143)
+++ community/trunk/en-US/Introduction.xml 2010-07-01 00:17:40 UTC (rev 144)
@@ -5,7 +5,7 @@
<chapter id="chap-Wireless_Guide-Introduction">
<title>Introduction</title>
<para>
- Due to increased demand for convenient networking and more flexible access to both the Internet and company resources via more geographically widespread coverage areas, wireless networking use has flourished in recent years. Mobile access to data services previously unavailable is now common. The sales and penetration of wireless access have resulted in a recent projection by <ulink url="http://www.abiresearch.com/">ABI Research</ulink> that one billion Wi-Fi chipsets <ulink url="http://www.infoworld.com/d/networking/one-billion-wi-fi-chipsets-in-2011-216">will ship in the year 2011</ulink>.</para>
+ Due to increased demand for convenient networking and more flexible access to both the Internet and company resources via more geographically widespread coverage areas, wireless networking use has increased dramatically in recent years. Mobile access to data services previously unavailable is now common. The sales and penetration of wireless access have resulted in a recent projection by <ulink url="http://www.abiresearch.com/">ABI Research</ulink> that one billion Wi-Fi chipsets <ulink url="http://www.abiresearch.com/press/1474-One+Billion+Wi-Fi+Chipsets+to+Ship+in+2011+Alone">will ship in the year 2011</ulink>.</para>
<para>
Not only has wireless data access achieved a great deal of market penetration in recent years, but the price of the related hardware has dropped dramatically, making it even more accessible. Wi-Fi seems to be everywhere; in laptops, desktops, PDAs, cell phones and routers, and there is such a large amount of wireless networks in many urban areas that complete overcrowding of the public wireless radio spectrum in use can occur.
</para>
Modified: community/trunk/en-US/Revision_History.xml
===================================================================
--- community/trunk/en-US/Revision_History.xml 2010-06-30 23:27:45 UTC (rev 143)
+++ community/trunk/en-US/Revision_History.xml 2010-07-01 00:17:40 UTC (rev 144)
@@ -34,7 +34,7 @@
</simplelist>
</revdescription>
</revision>
-<revision>
+ <revision>
<revnumber>1.2</revnumber>
<date>6 Jan 2010</date>
<author>
@@ -48,7 +48,7 @@
</simplelist>
</revdescription>
</revision>
-<revision>
+ <revision>
<revnumber>1.3</revnumber>
<date>1 Mar 2010</date>
<author>
@@ -62,6 +62,20 @@
</simplelist>
</revdescription>
</revision>
+ <revision>
+ <revnumber>1.4</revnumber>
+ <date>1 Jul 2010</date>
+ <author>
+ <firstname>Scott</firstname>
+ <surname>Radvan</surname>
+ <email>sradvan at redhat.com</email>
+ </author>
+ <revdescription>
+ <simplelist>
+ <member>Add rate switching, difference between data rate and throughput.</member>
+ </simplelist>
+ </revdescription>
+ </revision>
</revhistory>
</simpara>
</appendix>
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