User Manual User guide

Rockwell Automation Publication 1783-UM006A-EN-P - May 2014 151
Stratix 5100 Device Manager Parameter Definitions Chapter 4
QoS: Radio Page
This page enables you to define the parameters of Carrier Sense Multiple Access
(CSMA) for each traffic access category. These parameters affect how packets are
delivered for the different classes of service.
See QoS Policies Page
on page 149 to determine the level of service you want.
These parameters must be modified with caution because radio behavior is
affected. To revert to the default values, see Reset the WAP to Default Settings
on
page 55.
Table 54 - Access Category Definition Page Parameter Description
Parameter Description
Min Contention For each access category, enter the minimum contention page value. Channel
access is prioritized by assigning smaller contention page values to a higher
priority traffic class. If a channel is busy or a transmission collides, a node chooses
a random number between 0 and the current contention page minimum.
Max Contention For each access category, enter the maximum contention page value. The
minimum contention page value is doubled each time a collision occurs until the
maximum is reached. A small contention page value decreases the access delay
but increases the probability of a collision.
Fixed Slot Time For each access category, enter the fixed slot time. Channel access can be strictly
prioritized by assigning smaller contention page values to a higher priority traffic
class. Traffic in the access category must wait this fixed number of slots after each
packet received before resuming its random back-off.