Table 93 Ieee 802.11B; Preamble Type - ZyXEL Communications ZyXEL ZyAIR G-3000H User Manual

A large Fragmentation Threshold is recommended for networks not prone to interference
while you should set a smaller threshold for busy networks or networks that are prone to
interference.
If the Fragmentation Threshold value is smaller than the RTS/CTS value (see previously)
you set then the RTS (Request To Send)/CTS (Clear to Send) handshake will never occur as
data frames will be fragmented before they reach RTS/CTS size.

Preamble Type

A preamble is used to synchronize the transmission timing in your wireless network. There are
two preamble modes: Long and Short.
Short preamble takes less time to process and minimizes overhead, so it should be used in a
good wireless network environment when all wireless stations support it.
Select Long if you have a 'noisy' network or are unsure of what preamble mode your wireless
stations support as all IEEE 802.11b compliant wireless adapters must support long preamble.
However, not all wireless adapters support short preamble. Use long preamble if you are
unsure what preamble mode the wireless adapters support, to ensure interpretability between
the AP and the wireless stations and to provide more reliable communication in 'noisy'
networks.
Select Dynamic to have the AP automatically use short preamble when all wireless stations
support it, otherwise the AP uses long preamble.
Note: The AP and the wireless stations MUST use the same preamble mode in order
to communicate.
IEEE 802.11b Wireless LAN
The 802.11b data rate and corresponding modulation techniques are shown in the table below.
The modulation technique defines how bits are encoded onto radio waves.

Table 93 IEEE 802.11b

DATA RATE (MBPS)
1
2
5.5 / 11
Note: The ZyAIR may be prone to RF (Radio Frequency) interference from other 2.4
GHz devices such as microwave ovens, wireless phones, Bluetooth enabled devices,
and other wireless LANs.
Appendix G Wireless LANs
MODULATION
DBPSK (Differential Binary Phase Shifted Keying)
DQPSK (Differential Quadrature Phase Shifted Keying
CCK (Complementary Code Keying)
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