www.cooperbussmann.com/wirelessresources
Cooper Bussmann 945U-E Wireless Ethernet Modem & Device Server User Manual
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Rev Version 2.14
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B - GLOSSarY
Term
Definition
ACK
Acknowledgment.
Access Point
An access point connects wireless network stations (or clients) to other stations
within the wireless network and also can serve as the point of interconnection
between the wireless network and a wired network. Each access point can serve
multiple users within a defined network area. Also known as a base station.
Ad-Hoc Network
Ad hoc network often refers to a mode of operation of IEEE 802.11 wireless
networks. An ad hoc network is any set of networks where all devices have equal
status on a network and are free to associate with any other ad hoc network device
in link range. Each node participates in routing by forwarding data for other nodes,
so the determination of which nodes forward data is made dynamically on the basis
of network connectivity.
Antenna Gain
Antennae do not increase the transmission power, but instead focus the signal.
Rather than transmitting in every direction (including the sky and ground), antenna
focus the signal either more horizontally or in one particular direction. This gain is
measured in decibels.
Bandwidth
The maximum data transfer speed available to a user through a network.
Bridge
A bridge connects two local area networks, and is typically used to connect
wireless networks to wired networks. Bridges usually transfer messages between
networks only when the message destination is on the other network. Messages
destined for the network on which they originated are not passed on to the other
network. This reduces traffic on the entire network
Collision Avoidance
A network node procedure for pro-actively detecting that it can transmit a signal
without risking a collision with transmissions from other network nodes.
Client / Sta / Station
A device on a network that gains access to data, information, and other devices
through a server (access point).
Crossover Cable
A cable used for networking two computers without the use of a hub. Crossover
cables may also be required for connecting a cable or DSL modem to a wireless
gateway or access point. The cable is wired so that the signals “crossover,”
connecting transmit signal on one side to receiver signals on the other.
CSMA/CA
Carrier sense multiple access/collision avoidance is a “listen before talk” method of
minimizing (but not eliminating) collisions caused by simultaneous transmission by
multiple radios. IEEE 802.11 states that a collision avoidance method rather than
collision detection must be used because the standard employs half-duplex radios,
which are capable of transmission or reception‚ but not both simultaneously.
Unlike conventional wired Ethernet nodes, a WLAN station cannot detect a collision
while transmitting. If a collision occurs, the transmitting station will not receive
an ACKnowledge packet from the intended receive station. For this reason, ACK
packets have a higher priority than all other network traffic. After completion of a
data transmission, the receive station will begin transmission of the ACK packet
before any other node can begin transmitting a new data packet. All other stations
must wait a longer pseudo randomized period of time before transmitting. If an
ACK packet is not received, the transmitting station will wait for a subsequent
opportunity to retry transmission.
CSMA/CD
Carrier sense multiple access/collision detection is the access method used on an
Ethernet network. A network device transmits data after detecting that a channel
is available. However, if two devices transmit data simultaneously, the sending
devices detect a collision and retransmit after a random time delay.
DHCP
Dynamic Host Configuration Protocol is a utility that enables a server to
dynamically assign IP addresses from a predefined list and limit their time of use
so that they can be reassigned. Without DHCP, an IT manager would need to
manually enter in all the IP addresses of all the computers on the network. When
DHCP is used, whenever a computer logs onto the network, an IP address is
automatically assigned to it.