Appendix D Wireless LANs

Preamble Type

Preamble is used to signal that data is coming to the receiver. Short and long refer to the length of the synchronization field in a packet.

Short preamble increases performance as less time sending preamble means more time for sending data. All IEEE 802.11 compliant wireless adapters support long preamble, but not all support short preamble.

Use long preamble if you are unsure what preamble mode other wireless devices on the network support, and to provide more reliable communications in busy wireless networks.

Use short preamble if you are sure all wireless devices on the network support it, and to provide more efficient communications.

Use the dynamic setting to automatically use short preamble when all wireless devices on the network support it, otherwise the NBG-418N uses long preamble.

Note: The wireless devices MUST use the same preamble mode in order to communicate.

IEEE 802.11g Wireless LAN

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 70 IEEE 802.11g

DATA RATE (MBPS)MODULATION

1

DBPSK (Differential Binary Phase Shift Keyed)

 

 

2

DQPSK (Differential Quadrature Phase Shift Keying)

 

 

5.5 / 11

CCK (Complementary Code Keying)

 

 

6/9/12/18/24/36/48/

OFDM (Orthogonal Frequency Division Multiplexing)

54

 

 

 

Wireless Security Overview

Wireless security is vital to your network to protect wireless communication between wireless clients, access points and the wired network.

Wireless security methods available on the NBG-418N are data encryption, wireless client authentication, restricting access by device MAC address and hiding the NBG-418N identity.

 

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NBG-418N User’s Guide