User's Manual

53
What is BSSID?
A six-byte ad
dress that distinguishes a parti
cular a particular access point from others. Also know as just SSID.
Serves as a network ID or name.
What is ESSID?
The Extended Service Set
ID (ESSID) is the name of the network you want to access. It is used to identify different
wire
less networks.
What are potential factors that may causes interference?
Facto
rs of interference:
Obstacles: walls, ceiling
s, furniture… etc.
Building Materials: metal door, aluminum studs.
Electrical devices: microwaves, monitors and electrical motors.
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.
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 a
uthentication, 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.
What is WEP?
An optional I
EEE 802.11 function 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.
What is Fragment Threshold?
The proposed protocol uses the fram
e fragmentation mechanism defined in IEEE 802.11 to achieve parallel
tran
smissions. 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.