Kozumi K-300MWUN, User Manual

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(TKIP), which fixes the problems of WEP, including using dynamic keys.
22. Wide Area Network (WAN)
A WAN consists of multiple LANs that are tied together via telephone services and / or fiber optic
cabling. WANs may span a city, a state, a country, or even the world.
23. Wired Equivalent Privacy (WEP)
Now widely recognized as flawed, WEP was a data encryption method used to protect the
transmission between 802.11 wireless clients and APs. However, it used the same key among all
communicating devices. WEP’s problems are well-known, including an insufficient key length and no
automated method for distributing the keys. WEP can be easily cracked in a couple of hours with
off-the-shelf tools.
24. Wireless LAN (WLAN)
A wireless LAN does not use cable to transmit signals, but rather uses radio or infrared to transmit
packets through the air. Radio Frequency (RF) and infrared are the commonly used types of wireless
transmission. Most wireless LANs use spread spectrum technology. It offers limited bandwidth,
usually under 11Mbps, and users share the bandwidth with other devices in the spectrum; however,
users can operate a spread spectrum device without licensing from the Federal Communications
Commission (FCC).
25. Fragment Threshold
The proposed protocol uses the frame fragmentation mechanism defined in IEEE 802.11 to achieve
parallel transmissions. A large data frame is fragmented into several fragments each of size equal to
fragment threshold. By tuning the fragment threshold value, we can get varying fragment sizes. The
determination of an efficient fragment threshold is an important issue in this scheme. If the fragment
threshold is small, the overlap part of the master and parallel transmissions is large. This means the
spatial reuse ratio of parallel transmissions is high. In contrast, with a large fragment threshold, the
overlap is small and the spatial reuse ratio is low. However high fragment threshold leads to low
fragment overhead. Hence there is a trade-off between spatial re-use and fragment overhead.
Fragment threshold is the maximum packet size used for fragmentation. Packets larger than the size
programmed in this field will be fragmented If you find that your corrupted packets or asymmetric
packet reception (all send packets, for example). You may want to try lowering your fragmentation
threshold. This will cause packets to be broken into smaller fragments. These small fragments, if
corrupted, can be resent faster than a larger fragment. Fragmentation increases overhead, so you'll
want to keep this value as close to the maximum value as possible.
26. RTS (Request To Send) Threshold
The RTS threshold is the packet size at which packet transmission is governed by the RTS/CTS
transaction. The IEEE 802.11-1997 standard allows for short packets to be transmitted without
RTS/CTS transactions. Each station can have a different RTS threshold. RTS/CTS is used when the
data packet size exceeds the defined RTS threshold. With the CSMA/CA transmission mechanism,
the transmitting station sends out an RTS packet to the receiving station, and waits for the receiving
station to send back a CTS (Clear to Send) packet before sending the actual packet data. This setting
is useful for networks with many clients. With many clients, and a high network load, there will be
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.