Rosewill RNX-N400LX Manuale Utente

many more collisions. By lowering the RTS threshold, there may be fewer collisions, and 

performance should improve. Basically, with a faster RTS threshold, the system can 

recover from problems faster. RTS packets consume valuable bandwidth, however, so 

setting this value too low will limit performance.  

 

 

In addition to data frames that carry information from higher layers, 802.11 includes 

management and control frames that support data transfer. The beacon frame, which is a 

type of management frame, provides the "heartbeat" of a wireless LAN, enabling stations 

to establish and maintain communications in an orderly fashion. Beacon Interval 

represents the amount of time between beacon transmissions. Before a station enters 

power save mode, the station needs the beacon interval to know when to wake up to 

receive the beacon (and learn whether there are buffered frames at the access point). 

 

 

There are two preamble types defined in IEEE 802.11 specification. A long preamble 

basically gives the decoder more time to process the preamble. All 802.11 devices 

support a long preamble. The short preamble is designed to improve efficiency (for 

example, for VoIP systems). The difference between the two is in the Synchronization 

field. The long preamble is 128 bits, and the short is 56 bits. 

 

 

Broadcast of SSID is done in access points by the beacon. This announces your access 

point (including various bits of information about it) to the wireless world around it. By 

disabling that feature, the SSID configured in the client must match the SSID of the 

access point. Some wireless devices don't work properly if SSID isn't broadcast (for 

example the D-link DWL-120 USB 802.11b adapter). Generally if your client hardware 

supports operation with SSID disabled, it's not a bad idea to run that way to enhance 

network security. However it's no replacement for WEP, MAC filtering or other 

protections. 

 

 

 

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