ZyXEL Communications NWA3160 User Manual

 Chapter 8 Wireless Configuration

ZyXEL NWA-3160 Series User’s Guide

This section discusses the Quality of Service (QoS) features available on the ZyXEL Device.

WMM (Wi-Fi MultiMedia) QoS (Quality of Service) ensures quality of service in wireless 
networks. It controls WLAN transmission priority on packets to be transmitted over the 
wireless network.
WMM QoS prioritizes wireless traffic according to the delivery requirements of the individual 
and applications. WMM QoS is a part of the IEEE 802.11e QoS enhancement to certified Wi-
Fi wireless networks.
On APs without WMM QoS, all traffic streams are given the same access priority to the 
wireless network. If the introduction of another traffic stream creates a data transmission 
demand that exceeds the current network capacity, then the new traffic stream reduces the 
throughput of the other traffic streams.
The ZyXEL Device uses WMM QoS to prioritize traffic streams according to the IEEE 802.1q 
or DSCP information in each packet’s header. The ZyXEL Device automatically determines 
the priority to use for an individual traffic stream. This prevents reductions in data 
transmission for applications that are sensitive to latency and jitter (variations in delay).

The following table describes the WMM QoS priority levels that the ZyXEL Device uses.

Automatic Traffic Classifier (ATC) is a bandwidth management tool that prioritizes data 
packets sent across the network. ATC assigns each packet a priority and then queues the packet 
accordingly. Packets assigned a high priority are processed more quickly than those with low 
priority if there is congestion, allowing time-sensitive applications to flow more smoothly. 
Time-sensitive applications include both those that require a low level of latency and a low 
level of jitter such as Voice over IP or Internet gaming, and those for which jitter alone is a 
problem such as Internet radio or streaming video.

Table 27   WMM QoS Priorities

voice
(WMM_VOICE)

Typically used for traffic that is especially sensitive to jitter. Use this priority 

to reduce latency for improved voice quality.

video
(WMM_VIDEO)

Typically used for traffic which has some tolerance for jitter but needs to be 

prioritized over other data traffic.

best effort
(WMM_BEST_EFFORT)

Typically used for traffic from applications or devices that lack QoS 

capabilities. Use best effort priority for traffic that is less sensitive to latency, 

but is affected by long delays, such as Internet surfing.

background
(WMM_BACKGROUND)

This is typically used for non-critical traffic such as bulk transfers and print 

jobs that are allowed but that should not affect other applications and users. 

Use background priority for applications that do not have strict latency and 

throughput requirements.