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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-375C5C68-67C0-5414-9D41-DDD76692DC81" xml:lang="en"><title>Traffic
Classes</title><shortdesc> Traffic Classes are used to categorise the types of communication
carried by a Universal Mobile Telephone System (UMTS).</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>When implementing QoS within a UMTS you can divide the types of traffic
that can be carried into classes based on their characteristics. Also, with
the bandwidth, latency, and reliability there are some characteristics that
the network needs to adapt if it has to carry the traffic effectively. Two
of these are whether the traffic comes intermittently and whether the upstream
and downstream traffic characteristics are symmetric or asymmetric. </p>
<p>The traffic classes carried by a UMTS are divided into the following categories: </p>
<ul>
<li id="GUID-6FA20E30-9FB2-5E94-A927-5761E2E102B8"><p> <b>Conversational Traffic
Class (Voice telephony)</b> - This is characterized by a fixed, and relatively
small bandwidth with a small latency and comparatively less number of transmission
errors. The upstream and downstream data rates are symmetrical. </p> </li>
<li id="GUID-06BD9213-2841-5325-AC89-66F0FEAF6ED4"><p> <b>Streaming Traffic
Class</b> - This class of traffic is continuous data such as streaming video.
Some errors can be tolerated for example, dropped lines in a single video
frame. The data rates are high and generally asymmetrical. </p> </li>
<li id="GUID-A2708944-1C45-5C5C-A62D-8BB41B3D9C22"><p> <b>Interactive Traffic
Class</b> - This class of traffic handles user request or server response
traffic such as web browsing. It is medium bandwidth, must be reliable and
is intermittent asymmetric data. Unlike the other classes different priorities
can be attached to interactive traffic. </p> </li>
<li id="GUID-DD1AC5DC-BE61-5C7D-A91E-164B813AF9FA"><p> <b>Background Traffic
Class</b> - This traffic is low volume occasional traffic such as an Email.
A reasonable delay is acceptable to the user but reliability must be high. </p> </li>
</ul>
<p>The following table illustrates the characteristics of these classes: </p>
<table id="GUID-A640819E-C63F-583B-9C73-6252BE86D789">
<tgroup cols="6"><colspec colname="col0"/><colspec colname="col1"/><colspec colname="col2"/><colspec colname="col3"/><colspec colname="col4"/><colspec colname="col5"/>
<thead>
<row>
<entry>Traffic Class</entry>
<entry>Acceptable Bandwidth</entry>
<entry>Acceptable Latency</entry>
<entry>Acceptable Reliability</entry>
<entry>Intermittent Data</entry>
<entry>Asymmetric</entry>
</row>
</thead>
<tbody>
<row>
<entry><p>Conversational </p> </entry>
<entry><p>Low </p> </entry>
<entry><p>Low </p> </entry>
<entry><p>Low </p> </entry>
<entry><p>No </p> </entry>
<entry><p>No </p> </entry>
</row>
<row>
<entry><p>Streaming </p> </entry>
<entry><p>High </p> </entry>
<entry><p>Medium </p> </entry>
<entry><p>Medium </p> </entry>
<entry><p>No </p> </entry>
<entry><p>Yes </p> </entry>
</row>
<row>
<entry><p>Interactive </p> </entry>
<entry><p>Medium </p> </entry>
<entry><p>Medium </p> </entry>
<entry><p>High </p> </entry>
<entry><p>Yes </p> </entry>
<entry><p>Yes </p> </entry>
</row>
<row>
<entry><p>Background </p> </entry>
<entry><p>Low </p> </entry>
<entry><p>High </p> </entry>
<entry><p>High </p> </entry>
<entry><p>Yes </p> </entry>
<entry><p>Yes </p> </entry>
</row>
</tbody>
</tgroup>
</table></conbody></concept>