ZyXEL Communications NWA570N User Manual page 61

Table 13 Wireless Settings: AP (continued)
LABEL
Short GI
Output Power
Management
Data Rate
Management
Channel Mode Select whether the NWA570N uses a wireless channel bandwidth of 20 or 40
Extension
channel
protection
mode
Preamble
Type
ZyXEL NWA570N User's Guide
DESCRIPTION
Select Yes or No to enable or disable GI (Guard Interval). The GI refers to the
interval given between data transmission from users in order to reduce
interference. Reducing the GI increases data transfer rates but also increases
interference. Increasing the GI reduces data transfer rates but also reduces
interference.
Set the output power of the device in this field. The options are Full, 50%, 25%,
12% and Min. Full is recommended. If there is a high density of APs within an
area, decrease the output power of the device to reduce interference with other
APs.
Use this field to select a maximum data rate for the wireless connection(s). The
options are Auto, 1 ~ 54M, or MCS0-7.2[15] ~ MCS15-144.4[300].
Select Auto to let the NWA570N decide the most suitable data transfer rate. If you
are not certain of what setting to choose, choose Auto.
Alternatively select a maximum data transfer rate from 1 to 54 Mbps. Please note
that this is a total rate to be shared by all of the device's wireless connections.
The NWA570N also lets you configure the maximum data transfer rate based on
the IEEE802.1n draft 2.0 modulation and coding scheme (MCS). The MCS lists
data transfer speeds given a set of factors affecting network data transfer rates.
Such factors include GI and bandwidth. The "MCS0" in the MCS0-7.2[15] option
refers to the first set of network conditions and so on. So MCS0-7.2[15] is
appropriate for network conditions which provides data transfer rates of 7.2 Mbps
and 15 Mbps at bandwidths of 20 Mhz and 40 Mhz respectively. For more
information on the MCS see the IEEE802.1n draft 2.0 specifications.
MHz. A standard 20 MHz channel offers transfer speeds of up to 150Mbps
whereas a 40MHz channel uses two standard channels and offers speeds of up to
300 Mbps. Because not all devices support 40 MHz channels, select 20/40MHZ to
allow the NWA570N to adjust the channel bandwidth automatically.
If you have only IEEE wireless 802.1n draft 2.0 compatible devices on your
network, select None.
If you have devices that are not compatible with IEEE wireless 802.1n draft 2.0
and you have selected a Channel Mode of 40 Mhz, select CTS to self. CTS to
self and RTS-CTS are both kinds of protection mechanisms, similar to HT
protect. Both decrease data transfer speeds but CTS to self is more efficient.
Preamble is used to signal that data is coming to the receiver.
Short preamble increases performance as less time sending preamble means
more time for sending data. All IEEE 802.11b compliant wireless adapters support
long preamble, but not all support short preamble.
Select Long preamble if you are unsure what preamble mode the wireless
adapters support, and to provide more reliable communications in busy wireless
networks.
Select Dynamic to have the device automatically use short preamble when all
wireless clients support it, otherwise the device uses long preamble.
Note: The device and the wireless stations MUST use the same
preamble mode in order to communicate.
Chapter 6 Wireless Screens
61