Weidmuller WI-MOD-945-E: 900Mhz Wireless Ethernet & Device Server v2.16 - Manual (Page 101)

Weidmuller Technologies Wireless Ethernet Modem & Device Server 945U-E User Manual
Page 101 www.weidmuller.com Rev 2.136
Appendix B - GLOSSARY
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.
Antenna Gain Antennae don ’t increase the transmission power, but focus the signal more. So instead of
transmitting in every direction (including the sky and ground) antenna focus the signal
usually 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 is used to connect two local area networks together. Bridges are typically used to
connect wireless networks to wired networks. Typically, bridges will transfer messages
between networks only when the message destination is on the other network. Messages
that are destined for the same network as they originated on are not passed to the other
network, therefore reducing traffic on the entire network.
Collision
avoidance A network node procedure for proactively 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 special 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 collision avoidance method rather than collision
detection must be used, because the standard employs half duplex radios
—radios
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 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 have 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, it automatically gets an IP address assigned to it.