ASUS WLAN Card
63
Chapter 5
Chapter 5 - Glossary
Glossary
Each subchannel in the COFDM implementation is about 300 KHz wide. At
the low end of the speed gradient, BPSK (binary phase shift keying) is used to
encode 125 Kbps of data per channel, resulting in a 6,000-Kbps, or 6 Mbps,
data rate. Using quadrature phase shift keying, you can double the amount of
data encoded to 250 Kbps per channel, yielding a 12-Mbps data rate. And by
using 16-level quadrature amplitude modulation encoding 4 bits per hertz, you
can achieve a data rate of 24 Mbps. The 802.11a/g standard specifies that all
802.11a/g-compliant products must support these basic data rates. The standard
also lets the vendor extend the modulation scheme beyond 24 Mbps. Remember,
the more bits per cycle (hertz) that are encoded, the more susceptible the signal
will be to interference and fading, and ultimately, the shorter the range, unless
power output is increased.
Device Name
Also known as DHCP client ID or network name. Sometimes provided by an
ISP when using DHCP to assign addresses.
DHCP (Dynamic Host Configuration Protocol)
This protocol allows a computer (or many computers on your network) to be
automatically assigned a single IP address from a DHCP server.
DNS Server Address (Domain Name System)
DNS allows Internet host computers to have a domain name and one or more
IP addresses. A DNS server keeps a database of host computers and their
respective domain names and IP addresses, so that when a user enters a domain
name into the Internet browser, the user is sent to the proper IP address. The
DNS server address used by the computers on your home network is the location
of the DNS server your ISP has assigned.
DSL Modem (Digital Subscriber Line)
A DSL modem uses your existing phone lines to transmit data at high speeds.
Direct-Sequence Spread Spectrum (for 802.11b)
Spread spectrum (broadband) uses a narrowband signal to spread the
transmission over a segment of the radio frequency band or spectrum. Direct-
sequence is a spread spectrum technique where the transmitted signal is spread
over a particular frequency range.
Direct-sequence systems communicate by continuously transmitting a redundant
pattern of bits called a chipping sequence. Each bit of transmitted data is mapped
into chips and rearranged into a pseudorandom spreading code to form the
chipping sequence. The chipping sequence is combined with a transmitted
data stream to produce the output signal.
