This document discusses Orthogonal Frequency Division Multiplexing (OFDM), a key technology for high data rate transmission in wireless communications, highlighting its features, applications, and challenges. OFDM offers advantages such as high spectral efficiency and robustness against multipath fading, making it widely used in standards like digital audio and video broadcasting. Despite its benefits, it faces issues such as sensitivity to frequency errors and inter-carrier interference.

1. Presented by:
Ashish Soni
ashish.soni.2016@ieee.org
Orthogonal Frequency Division
Multiplexing
(OFDM)

2. Content
 Motivation
 Introduction
 Origin
 Principle
 Features
 Applications
 Problems & ResearchArea
 Conclusion
 References

3. Motivation
 The demand for multimedia wireless communication is
growing today at an extremely rapid pace.
 Multiplexing Schemes: FDM,TDM & CDM [1].

4.  Evolution of Mobile Communication [2].
Generation Standard Data Rate Features
2G GSM 10 kbps DigitalVoice,
SimpleText,
Simple News,
Feeds etc.
2G CDMA 10 kbps
2.5G GPRS 50 kbps
2.5G EDGE 200 kbps
3G WCDMA ~400 kbps DigitalVoice,
Mobile Broadband3.5G HSDPA/HSUPA 4-50 Mbps
4G LTE/WiMAX 100-200 Mbps Live HDTV,
Online Gaming,
High Speed.
4G LTE > 1 Gbps

5. Introduction
 OFDM is promising technique for achieving high data rate
transmission in mobile environment [3].
 It is a special form of multicarrier modulation (MCM),
where a single data stream is transmitted over a number of
subcarriers.

6.  It offers high spectral efficiency, multipath delay tolerance,
robustness to channel fading, immunity to impulse
interference [4].
 Therefore it has been widely deployed in many wireless
communication standards such as Digital Video Broadcasting
(DAB), Asymmetrical Digital Subscriber Line (ADSL),
DigitalTerrestrialTelevision Broadcasting etc.

7. Origin
 Concept of OFDM has existed since 1966.
 But in 1985, Cimini [5] proposed a cellular mobile radio
system based on OFDM.
 In 1995, Wu [4] suggested some high frequency military
systems using OFDM.
 In 1998, Fernando proposed application of OFDM to the
satellite mobile channel.

8. Principle
 Orthogonal Frequency Division Multiplexing technique is
very much alike to Frequency Division Multiplexing.
 Figure shows variation among FDM & OFDM:

9.  Orthogonal sub carriers in OFDM:

10.  OFDMTransceiver

11. Data coded in Frequency Domain Transformation toTime Domain Channel Frequency Response
Frequency Domain SignalTime Domain Signal

12. Features
 High spectral efficiency.
 Can be efficiently implemented using FFT.
 Low efficiency to time synchronization technique.
 OFDM has improved quality of narrowband interference.
 Can easily adapt to severe channel conditions without
complex equalization.
 Robust against inter-symbol interference (ISI) and fading
caused by multipath propagation.
 OFDM has the better resistant quality to fading.

13. Applications
 Digital Audio Broadcasting
 DigitalVideo Broadcasting
 IEEE 802.11 a/g
 IEEE 802.16
 IEEE 802.20 [6].

14. Problems
 Very sensitive to Frequency errors.
 Inter Carrier Interference: Due to Doppler Spreading
 Carrier FrequencyTiming Synchronization: Causes ICI
 Peak toAverage Power Ratio: Reduces power Efficiency.

15. Conclusion
 OFDM has promising Future in wireless networks and
mobile communication.
 OFDM is already playing an important role in WLAN and
will be part of MAN too.
 OFDM with the use of WiMAX and LTE advanced is the
future cellular packet data network.

16. References
1. GSMA Intelligence,April 2014
2. Aditya K Jagannatham, “Principles of Wireless Communication Systems”,
McGrawhill Education
3. Orthogonal Frequency Division Multiplexing (OFDM)-Applications for
Wireless Communications with Coding.
4. Y.Wu and W. Y. Zou, “Orthogonal frequency division multiplexing: A multi-
carrier modulation scheme,” IEEE Trans. Consumer Electronics, vol. 41, Aug.
1995.
5. Leonard J. Cimini, JR.,“Analysis And Simulation Of A Digital Mobile
Channel Using Orthogonal Frequency Division Multiplexing”, Ieee
Transactions On Communications,Vol. Com-33, July-1985.
6. Ramjee Prasad “OFDM for wireless communication system”, universal
personal communication.

17. ThankYou..