Page 114 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Unit 6: Data Communication

6.1.2.3 Wireless Networks (WLAN, WWAN) Notes
A wireless network is basically the same as a LAN or a WAN but there are no wires between hosts
and servers. The data is transferred over sets of radio transceivers. These types of networks are
beneficial when it is too costly or inconvenient to run the necessary cables. For more information,
see Wireless LAN and Wireless wide area network. The media access protocols for LANs come
from the IEEE.
The most common IEEE 802.11 WLANs cover, depending on antennas, ranges from hundreds
of meters to a few kilometers. For larger areas, either communications satellites of various types,
cellular radio, or wireless local loop (IEEE 802.16) all have advantages and disadvantages.
Depending on the type of mobility needed, the relevant standards may come from the IETF or
the ITU.

Figure 6.3: Wireless LAN

To internet Cable Modem

Wireless
router
Laptop with
Desktop with wireless
PCl wireless adapter card
adapter

6.2 Data Communication with Standard Telephone Lines

The public switched telephone network (PSTN) is the world wide telephone system and usually this
network system uses the digital technology. In the past, it was used for voice communication only
but now it is playing very important role for data communication in the computer network such as
in the Internet. There are different types of telephone lines that are used for data communication
in the network. These are discussed below.

6.2.1 Dial-Up Lines
It is a temporary connection that uses communication. Modern is used at the s telephone number
is dialed from the sender the receiving end answers the call. In the communication between
computers or e the cost of data communication is very Internet through this connection.
6.2.2 Dedicated Lines

It is a permanent connection that is establish connection between two permanently. It is better
than dial-up lines connection because dedicated lines provide a constant connection. These types
of connections may be digital or analog. The data transmission speed, of digital lines is very fast
as compare to analog dedicated line. The data transmission speed is also measured in bits per
second (bps). In dial-up and dedicated lines, it is up to 56 Kbps. The dedicated lines are mostly
used for business purposes. The most important digital dedicated lines are described below.

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