ZyXEL Communications NWA1121NI manual 92

Chapter 6 Wireless LAN

TERM	DESCRIPTION
Roaming	If you have two or more NWA1121-NIs (or other wireless access points) on your
	wireless network, you can enable this option so that wireless devices can change
	locations without having to log in again. This is useful for devices, such as notebooks,
	that move around a lot.
Antenna	An antenna couples Radio Frequency (RF) signals onto air. A transmitter within a
	wireless device sends an RF signal to the antenna, which propagates the signal
	through the air. The antenna also operates in reverse by capturing RF signals from
	the air.
	Positioning the antennas properly increases the range and coverage area of a wireless
	LAN.

6.9.2 WMM QoS

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 NWA1121-NI uses WMM QoS to prioritize traffic streams according to the IEEE 802.1q or DSCP information in each packet’s header. The NWA1121-NI 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).

6.9.2.1 WMM QoS Priorities

The following table describes the WMM QoS priority levels that the NWA1121-NI uses.

Table 27 WMM QoS Priorities

Priority Level	description
voice	Typically used for traffic that is especially sensitive to jitter. Use this priority to
(WMM_VOICE)	reduce latency for improved voice quality.
video	Typically used for traffic which has some tolerance for jitter but needs to be
(WMM_VIDEO)	prioritized over other data traffic.
best effort	Typically used for traffic from applications or devices that lack QoS capabilities. Use
(WMM_BESTEFFORT)	best effort priority for traffic that is less sensitive to latency, but is affected by long
	delays, such as Internet surfing.
background	This is typically used for non-critical traffic such as bulk transfers and print jobs
(WMM_BACKGROUND)	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.

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	NWA1121-NI User’s Guide