PLANET WNL-U555HA - Manual (Page 50)

PLANET 802.11n Wireless High Power USB Adapte r
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19. Transmit / Receive
The wireless throughput in Bytes per second averaged over two seconds.
20. Wi-Fi Alliance
The Wi-Fi Alliance is a nonprofit international association formed in 1999 to certify interoperability of
wireless Local Area Network products based on IEEE 802.11 specification. The goal of the Wi-Fi
Alliance’s members is to enhance the user experience through product interoperability. The
organization is formerly known as WECA.
21. Wi-Fi Protected Access (WPA)
The Wi-Fi Alliance put together WPA as a data encryption method for 802.11 wireless LANs. WPA is an
industry-supported, pre-standard version of 802.11i utilizing the Temporal Key Integrity Protocol (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