10-09-2013, 03:24 PM
Guided Transmission and Unguided Wireless Transmission
Guided Transmission.pdf (Size: 286.86 KB / Downloads: 47)
Signals
Signals from a system transmit through a
fibre, wire, or wireless medium.
According to defined regulations,
recommended standards, and protocols
Mobile Communication
Entails transmission of data to and from
handheld devices
Two or more communicating devices
At least one is handheld or mobile
Location of the device can vary either
locally or globally
Communication takes place through a
wireless, distributed, or diversified
network
Guided Transmission Advantages
Transmission along a directed path from
one point to another
Practically no interference in
transmission from any external source or
path
Using multiplexing and coding, a large
number of signal-sources simultaneously
transmitted along an optical fibre, a
coaxial cable, or a twisted-pair cable
Unguided─ Wireless Transmission
Electrical signals transmitted by
converting them into electromagnetic
radiation
Radiation transmitted via antennae that
radiate electromagnetic signals
Antennae
Devices that transmit and receive
electromagnetic signals
Most function efficiently for relatively narrow
frequency ranges
If not properly tuned to the frequency band in
which the transmitting system connected to it
operates, the transmitted or received signals
may be impaired. The forms of antennae are
chiefly determined by the frequency ranges
they operate in and can vary from a single
piece of wire to a parabolic dish