FDMA (frequency division multiple access) is a technology that divides the frequency band allocated for wireless communication into multiple channels, with each channel assigned to a single user. It allows more than one user to share the radio frequency spectrum by allocating different frequency channels. In FDMA, each call is placed on a separate frequency channel. It separates the spectrum into uniform chunks of bandwidth for voice channels. While capable of digital transmission, FDMA is not efficient for digital transmission.

1. (frequency division
multiple access)

2. What is FDMA ?
• FDMA (frequency division multiple access) is the
division of the frequency band allocated for wireless
cellular telephone communication into 30 channels,
each of which can carry a voice conversation or, with
digital service, carry digital data.
• FDMA is a basic technology in the analog Advanced
Mobile Phone System (AMPS), the most widely-
installed cellular phone system in North America.
• With FDMA, each channel can be assigned to only one
user at a time.

3. • FDMA is a method that lets more than one user to
share a single radio frequency spectrum. This is done
by assigning active users a different frequency channel.
• FDMA puts each call on a separate frequency.
• The Digital-Advanced Mobile Phone Service (D-AMPS)
also uses FDMA but adds time division multiple access
(TDMA)

4. • Frequency division Multiple Access (FDMA) is a
technology whereby the total amount of
spectrum is divided in a number of channels.
• Between the different used frequency channels is
a small amount of bandwidth not used. This
space is called a guard band.
• This bandwidth is necessary to cater for
instability of the sender, frequency shifts due to
movement (the Doppler effect) and no-ideal
filtering.

5. • FDMA separates the
spectrum into distinct
voice channels by
splitting it into uniform
chunks of bandwidth.
• While it is certainly
capable of carrying digital
information, FDMA is not
considered to be an
efficient method for
digital transmission.

6. FDMA
• All channels in a cell are available to all the mobiles. Channel
assignment is carried out on a first-come first- served basis.
• The number of channels, given a frequency spectrum BT , depends
on the modulation technique (hence Bw or Bc ) and the guard
bands between the channels 2Bguard . These guard bands allow for
imperfect filters and oscillators and can be used to minimize
adjacent channel interference.
• FDMA is usually implemented in narrowband systems.

7. Single-carrier FDMA
• Single-carrier
FDMA (SCFDMA)- SC-
FDMA can be interpreted
as a linearly precoded
OFDMA scheme, in the
sense that it has an
additional DFT processing
preceding the
conventional OFDMA
processing

8. Main features
• Continuous transmission : the channels, once assigned, are
used on a non-time-sharing basis
• Narrow bandwidth : Analog cellular systems use 25-30 kHz.
Digital FDMA systems can make use of low bit rate speech
coding techniques to reduce the channel band even more.
• Low overhead : Carry overhead messages for control,
synchronization purposes
• Simple hardware at mobile unit and BS : (1) no digital
processing needed to combat ISI (2) ease of framing and
synchronization.

9. Main Features
• In FDMA all users share the satellite transponder or frequency
channel simultaneously but each user transmits at single frequency.
• FDMA can be used with both analog and digital signal.
• FDMA requires high-performing filters in the radio hardware, in
contrast to TDMA and CDMA.
• FDMA is not vulnerable to the timing problems that TDMA has.
• Due to the frequency filtering, FDMA is not sensitive to near-far
problem which is pronounced for CDMA.

10. Thank You