Planet WNAP-7350, Руководство пользователя

Страница: 87 / 101

User Manual of WNAP-7350
-80-
Solutions to overcome the interferences:
 Minimizing the number of walls and ceilings.
 Position the WLAN antenna for best reception.
 Keep WLAN devices away from other electrical devices, eg: microwaves, monitors, electric
motors…etc.
 Add additional WLAN Access Points if necessary.
A.8 What are the Open System and Shared Key authentications?
IEEE 802.11 supports two subtypes of network authentication services: open system and shared key. Under
open system authentication, any wireless station can request authentication. The station that needs to
authenticate with another wireless station sends an authentication management frame that contains the identity
of the sending station. The receiving station then returns a frame that indicates whether it recognizes the
sending station. Under shared key authentication, each wireless station is assumed to have received a secret
shared key over a secure channel that is independent from the 802.11 wireless network communications
channel.
A.9 What is WEP?
An option of IEEE 802.11 function is that offers frame transmission privacy similar to a wired network. The Wired
Equivalent Privacy generates secret shared encryption keys that both source and destination stations can use to
alert frame bits to avoid disclosure to eavesdroppers.
WEP relies on a secret key that is shared between a mobile station (e.g. a laptop with a wireless Ethernet card)
and an access point (i.e. a base station). The secret key is used to encrypt packets before they are transmitted,
and an integrity check is used to ensure that packets are not modified in transit.
A.10 What is 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