SMC Networks SMC2655W User Manual page 16

non-metal barriers. Roaming users can be handed off from one access
point to another like a cellular phone system. Laptops use wireless
network cards that plug into an existing PCMCIA slot or that are self
contained on PC cards, while stand-alone desktops and servers use
plug-in cards (ISA, PCI, etc.).
What is AD-HOC?
An AD-HOC network is a peer to peer network where all the nodes
are wireless clients. As an example, two PC's with wireless adapters
can communicate with each other as long as they are within range. A
wireless extension point can extend the range of an AD-HOC network.
What is the 802.11 standard?
A family of IEEE standards for wireless LANs first introduced in 1997.
802.11 provides 1 or 2 Mbps transmission in the 2.4GHz band using
either a frequency hopping modulation (FHSS) technique or direct
sequence spread spectrum (DSSS), which is also known as CDMA. The
802.11b standard defines an 11 Mbps data rate in the2.4GHz band,
and the 802.11a standard defines 54 Mbps in the 5GHz band.
What is Infrastructure?
In order for your wireless components to interact with traditional
wired networks they need a media bridge to translate for them. This
is where INFRASTRUCTURE or Network mode comes into play. An
ACCESS POINT is attached to the network using CAT-5 Ethernet cable
attaching to a hub, switch or another PC. Wireless PC's can then com-
municate to Wired Ethernet computers through this access point. The
total range of the network is limited to a radius around this Access
Point. To increase the range, extra Access Points may be wired into
the network. These Access Points talk to each other over the hard-
wired Ethernet cables however, they cannot communicate wirelessly
to one another and they must be wired to the same network.
Individual wireless PC's can move between Access Points on the same
network seamlessly due to a feature called ROAMING.
29
What is Tx Rate?
Tx-Rate or TRANSFER RATE is the current speed at which the network
component is operating. SMC-802.11b products can operate at speeds of
1Mb, 2Mb, 5.5Mb, & 11Mbps. A wireless card set to AUTO will attempt to
connect at whatever speed will give the best throughput on the network.
What is RTS Threshold?
(Request To Send) An RS-232 signal sent from the transmitting station
to the receiving station requesting permission to transmit. RTS is a
collision avoidance method used by all 802.11b wireless networking
devices. In most cases you will not need to activate or administer RTS.
Only if you find yourself in an Infrastructure environment where all
nodes are in range of the Access Point but may be out of range of
each other. It is recommended to leave this setting at its default value
leaving this feature disabled.
What is Authentication Algorithm?
Authentication Algorithm is the means by which one station is autho-
rized to communicate with another. In an Open System, any station
can request authorization in accordance with the WECA standard. In a
Shared key system, only stations that possess a secret encrypted key
may participate in the network. This is a low level security key which
allows the equipment with the shared key algorithm to see each
other on the wireless lan.
What is DBI?
The ability of the antenna to shape the signal and focus it in a partic-
ular direction is called Antenna Gain, and is expressed in terms of
how much stronger the signal in the desired direction is, compared to
the worst possible antenna, which distributes the signal evenly in all
directions (an Isotropic Radiator). To express the relationship to the
Isotropic reference, this is abbreviated: "dBi". The typical omni-direc-
tional "stick" antenna is rated at 6-8 dBi, indicating that that by redi-
recting the signal that would have gone straight up or down to the
horizontal level, 4 times as much signal is available horizontally. A par-
abolic reflector design can easily achieve 24 dBi.
30