ZyXEL p-334wh Guia Do Utilizador

P-334WH User’s Guide

Appendix E Wireless LANs

239

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 is used to signal that data is coming to the receiver. Short and Long refer to the 
length of the syncronization field in a packet.

Short preamble increases performance as less time sending preamble means more time for 
sending data. All IEEE 802.11b/g 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 Short preamble if you are sure the wireless adapters support it, and to provide more 
efficient communications.

Select Dynamic to have the AP automatically use short preamble when wireless adapters 
support it, otherwise the AP uses long preamble.

Note: The AP and the wireless adapters MUST use the same preamble mode in 

order to communicate.

IEEE 802.11g is fully compatible with the IEEE 802.11b standard. This means an IEEE 
802.11b adapter can interface directly with an IEEE 802.11g access point (and vice versa) at 
11 Mbps or lower depending on range. IEEE 802.11g has several intermediate rate steps 
between the maximum and minimum data rates. The IEEE 802.11g data rate and modulation 
are as follows:

Table 103   IEEE 802.11g

1

DBPSK (Differential Binary Phase Shift Keyed)

2

DQPSK (Differential Quadrature Phase Shift Keying)

5.5 / 11

CCK (Complementary Code Keying) 

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OFDM (Orthogonal Frequency Division Multiplexing)