ILX34-AENWG
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POINT I/O Platform
Glossary of Terms
Wireless Point I/O Adapter
Setup Guide
Page 64 of 79
ProSoft Technology, Inc.
July 31, 2009
CSMA/CD
Carrier sense multiple access/collision detection is the access method used in
Ethernet. When a device wants to gain access to the network, it checks to see if
the network is quiet (senses the carrier). If it is not, it waits a random amount of
time before retrying. If the network is quiet and two devices access the line at
exactly the same time, their signals collide. When the collision is detected, they
both back off and each waits a random amount of time before retrying.
D
dBi
Decibels referenced to an "ideal" isotropic radiator in free space; frequently used
to express antenna gain
dBm
Decibels referenced to one milliwatt (mW); an "absolute" unit used to measure
signal power (transmit power output or received signal strength)
DCE
Data communications equipment. A modem, for example.
Decibel (dB)
A measure of the ratio between two signal levels; used to express gain (or loss)
in a system.
Default Gateway
The IP address of a network router where data is sent if the destination IP
address is outside the local subnet. The gateway is the device that routes the
traffic from the local area network to other networks such as the Internet.
Determinism
The ability to predict when information will be delivered. Important in time-critical
applications.
DHCP
The dynamic host configuration protocol is an Internet protocol, similar to BootP,
for automating the configuration of computers that use TCP/IP. DHCP can be
used to automatically assign IP addresses, to deliver IP stack configuration
parameters, such as the subnet mask and default router, and to provide other
configuration information, such as the addresses for printer, time, and news
servers.
Direct Sequence Spread Spectrum
One of two approaches (with frequency hopping spread spectrum) for sorting out
overlapping data signals transmitted via radio waves. 802.11b uses DSSS
