This is ppt includes a basic idea about OCDMA and OTDMA.

1. Presented by -
Er. Kush Singla
Roll No. – 192606
ME(1st Semester) , NITTTR
CHD

2. CONTENTS
 Introduction
 Brief history about multiple access communication
systems and evolution of CDMA and TDMA
 What is optical TDMA & CDMA and how is it
implemented ?
 Advantages & Disadvantages
 References

3. INTRODUCTION
 Multiplexing – The process of combining multiple
signal to single transmission link. We can also say
that to accommodate more data on single channel
user.
 Types of multiplexing :
I. FDM – Frequency Division Multiplexing [oldest
multiplexing technique]
II. TDM – Time Division Multiplexing
III. CDM – Code Division multiplexing

4. BRIEF HISTORY ABOUT MULTIPLE ACCESS COMMUNICATION SYSTEMS
AND EVOLUTION OF CDMA & TDMA
• FDMA was introduced at the time of 1st G [generation] of
Mobile Communication system or Wireless Communication
Systems in late 70s.
• TDMA was introduced at the time of 2nd G [generation] of
Wireless Communication systems in late 90s.
• CDMA was introduced at the time of 3rd G [generation] of
Wireless Communication systems in 2001.

5. WHAT OPTICAL TDMA & CDMA AND HOW IS IT
IMPLEMENTED ?
OTDMA
Optical Time Division Multiplexing Access
Time Division Multiplexing is done by passing multiple
optical signals into a single data stream.
Above diagram shows high bit rate multiplexed data
Streams using OTDMA technique.

6. BLOCK DIAGRAM OF OTDMA [TRANSMISSION SIDE]

7. ADVANTAGES
 Provides higher bit rate of the order of 100Gb/s.
 Can be operated at both 1500nm and 1300nm.
 It can easily adapt to transmission of data as well
as voice communication.

8. DISADVANTAGES
 The users have a predefined time slot for receiving
data.
 It is subjected to multipath distortion.

9. OCDMA
Optical Code Division Multiple Access
It means that users share the same frequency band at
the same time in the light pulse transmitted and user
receives its data on the basis of multiplexed code.
Here in OCDMA the data is send in the form of light
pulse instead of electromagnetic waves.

10. BLOCK DIAGRAM OF OCDMA

11. ADVANTAGES
 It does not need any time or frequency
management because all the user can transmit
using the whole BW at the same time.
 Slot allocation problems are not needed here in
contradiction to OTDMA , simple implementation
using existing fibre network.
 Reduce the cost in aspect as security, since the
data is transmitted being coded so the security of
the data also increases.
 Provision of value added services is also available

12. DISADVANTAGES
 Since it has a lot of advantages over OFDMA ,
OTDMA and OWDM , burst noise (which is a type
of electronic noise that occurs in semiconductors )
is observed at the receiver.
 Error correction is costly in OCDMA because the
speed for carrying the information in electrical and
optical cables is not the same.
 Encoding broadband and decoding hardware is
expensive for OCDMA. To generate the intensity to
handle an OCDMA, LED’s are not enough so it
comes in LASERS where both laser array and
EDFA have the required power but currently they
are costly.

13. REFERENCES
 https://www.youtube.com/watch?v=TJNKoRPn-G8
 https://www.slideshare.net/12012112/optical-code-division-multiple-
access?qid=0255e57c-fa6b-4eea-8125-
7a2e787192a0&v=&b=&from_search=11
 https://www.slideshare.net/Amandeepkaur144/optical-time-division-
multiplexing
 https://www.google.com/search?q=optical+tdma+slide+share&newwindow=
1&safe=active&sxsrf=ACYBGNSSli_LFJQA0U_PrUCMOJAAatq3Mg:15747
89201325&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjUpMP3sojmAhW
IfSsKHcXhCC4Q_AUoAXoECCsQAw&biw=1288&bih=665
 https://www.slideshare.net/shadabsiddiqui7/multiplexing-tdma-fdma-cdma-
wdma/8
 https://www.tutorialspoint.com/gsm/tdma_and_cdma.htm
 https://www.facebook.com/EngineeringBuddy/posts/advantages-and-
disadvantages-of-ocdmaadvantages-of-ocdma1equal-distribution-of-
a/167654580048343/