Multiple Access Control Protocol allows several terminals connected to the same multi-point transmission medium (Broadcast network ) to transmit over it and to share its capacity. Examples of shared physical media are wireless networks, bus networks, ring networks and point-to-point links operating in half-duplex mode.

1. PROFESSIONAL COMMUNICATION
(BPC-251)
SESSION 2017-18
PRESENTATION
ON
TOPIC- “Multiple Access Control Protocol”
SUBMITTED TO- SUBMITTED BY-
MR. AMRITANSH MISHRA NITISH AWASTHI
Assistant Professor B.TECH.CS
Roll No. 1710303009
INVERTIS UNIVERSITY BAREILLY
Established by Govt. of U.P. u/s 2f of UGC Act, 1956 vide U.P. Act 22 of 2010.

2.  Protocol is a set of rules that govern “Data
Communication”.
 Multiple access method allows several terminals
connected to the same multi-point transmission
medium (Broadcast network) to transmit over it
and to share its capacity.
Examples of shared physical media are wireless
networks, bus networks, ring networks and
point-to-point links operating in half-duplex
mode.

3. Issues in Multiple Access Control Protocol:
 WHO is going to use the channel?
 WHEN the channel is going to be used?
 For HOW much time the channel is used?

4. Random
Access
Protocol
Aloha
CSMA/CD
CSMA/CA
Control
Access
Protocol
Reservation
Pooling
Token
Passing
Channelization
Protocol
FDMA
TDMA
CDMA

5.  Single channel is shared by large number of hosts.
 Each channel can transmit whenever it desires
(check medium is idle or busy).
 No Scheduled time for a station to transmit , that’s
why these methods are called “Random access”.

6.  Anytime you can transmit data.
 Collision occurs, Acknowledgement facility available to know
whether data is successfully transmitted or failed.
 No need for collision detection.
 If failed than after random amount of time (Back off time)
retransmit, if not get ACK.
There are two versions of Aloha System.
 Pure Aloha
 Slotted Aloha

9.  ‘Sense before transmit’ or ‘ Listen before talk’.
 Stations are connected to shared channel

11.  In wireless communication, when a receiver is within the range of
two active transmitters.
The resulting signal will get garbled (Most of the time).
 CSMA/CD is unsuitable in this situation. There are so called
“Hidden Station Problem” and “Exposed Station Problem” that
can be solved by CSMA/CA.
CSMA/CA
 Sender Sends a short frame called “Request to Send” (RTS) to
destination.
 Destination responds with a short “Clear to Send” (CTS) frame.

12. General Principle these Protocol follow:
 Stations consult each other
 Stations cannot send, until it is authorized by others.
Methods-
 Reservation
 Polling Method
 Token Passing Method

13. Features:
 Time is divided into intervals.
In each interval Station makes a reservation, before sending
data.
 If there are ‘N’ stations in the System, there are exactly ‘N’
reservation mini slots in the reservation frame.

14. Features:
 Works with Topologies.
 In this, one device is designated as Primary
Station; and other devices are Secondary
Station.
It has two functions:
 Select function: It is used whenever Primary
has something to send.
 Polling function: It is used when Primary
wants to receive data.

15. Features:
 In this, the stations in a network are
organized in a logical Ring.
 In this method, a special packet called a
Token circulates through ring.
 The possession of the token gives the station
right to access the channel and sends its
data.

16. It is a Multiple-access method in which the
available bandwidth of a link is shared in
‘Time’, ‘Frequency’ or ‘Through Code’.
Methods:
 TDMA (Time Division Multiple Access)
 FDMA (Frequency Division Multiple Access)
 CDMA (Code Division Multiple Access)

17. It is a process of dividing one channel or
bandwidth into multiple individual band for
use by Single User.
Ex- AMPS (1G Cellular Networks)

18. It divides band into time Slot.
Ex- GSM (2G Cellular networks-Europe)

19.  Used in Several wireless broadcast channels
(cellular, satellite, etc) standards
 Same bandwidth is occupied by all the users,
however they are all assigned own “chipping”
sequence (i.e., code) to encode data.
 encoded signal = (original data) X (chipping
sequence)