This document summarizes a seminar presentation on estimating channels in OFDM systems using a cyclic prefix and two dimensional prolate function. The presentation covers an introduction to OFDM, a literature review on channel estimation techniques for OFDM, identified issues with OFDM including synchronization and phase noise, the motivation and need for research into new channel estimation methods. It describes defining the problem to develop a low complexity channel estimation algorithm, the proposed methodology using pilot-aided channel estimation with QAM modulation, and simulations to test the system. The presentation shows results on BER performance and compares estimation using a cyclic prefix versus unique word. It concludes that comb pilot channel estimation performs better in fast fading channels.

1. A SEMINAR ON
TERNA COLLEGE OF ENGINEERING
Department of Electronics & Telecommunication
Engineering
Presented By-
Manisha Mohite
ME (E & TC)
Estimation of Channels in OFDM Systems Employing Cyclic Prefix Using
Prolate Function
GUIDE
Prof.N.S.Killarikar
CO-GUIDE
Dr.L.K.Ragha

2. TALKFLOW
INTRODUCTION
LITERATURE SURVEY
ISSUES IDENTIFIED
MOTIVATION
NEED FOR RESEARCH
PROBLEM DEFINATION
OBJECTIVES
METHODOLOGY
DESIGN THEORY
RESULTS
RESEARCH FINDINGS

8. LITERATURE SURVEY
REASON FOR
ADAPTION
• High Rate Data Transmission
• Robustness
RELATION
WITH OFDM
• Pilot-based channel estimation
MITIGATION
EFFECT OF ICI
• Remove the mitigation Effect

9. ISSUES IDENTIFIED IN OFDM
1.Synchronization:
2.Phase Noise:
3.Inter Carrier Interference

11. NEED FOR RESEARCH

14. PROBLEM DEFINITION
BASE (OFDM)
LMMSE
estimator
at receiver
side of
OFDM
Analysis of OFDM
with CP
Low
complexit
y channel
estimation
algorithm
using two
dimension
al prolate
function

15. METHODOLOGY
PACE
( Pilot Aided
Channel
Estimation )
• Pilot symbols are used to gather knowledge about
the channel and try to estimate it.
QAM
• QAM modulation technique
SIMULATIO
N
PARAMETE
R
• FFT size, Sampling frequency, Guard bands,
Bandwidth, Modulation, Channel Model.

17. SYSTEM ARCHITECTURE
1. Input to time domain
2. Guard Interval
3. Channel
4. Guard Removal
5. Output to frequency
domain
6. Output
7. Channel Estimation
     1,...,2,1,0  NnkXIDFTnx
 
 
 





1,...,1,0,
1,...,1,,
Nnnx
NNnnNx
nx gg
f
     nwnhnxy ff 
    1,...,1,0  Nnnyny f
     1,...,2,1,0  NknyDFTkY
         
1,...,1,0 

Nk
kWkIkHkXkY
ICI AWGNChannel
   
 
1,...,1,0  Nk
kH
kY
kX
e
e
Estimated
Channel

18. DESIGN THEORY
Pilot Arrangement
Block Pilot Comb Pilot

19. GRAPHICAL REPERESENTATION

20. RESULTS

21. BER Vs SNR with CP

22. BER Vs SNR with UW

23. COMPARISON

24. OFDM offers better performances in wireless fading
channel
Comb type channel estimation is better in fast fading channel
BER performance decreases as no. of taps increases
Channel estimation using UW is better than cp
CONCLUSION

25. REFERENCES
1. F. Pe˜na-Campos, Roberto Carrasco-Alvarez, O. Longoria-Gandara, and R. Parra-Michel,”
Estimation of Fast Time-Varying Channels in OFDM Systems Using Two-Dimensional Prolate”,
IEEE transactions on wireless communications, vol. 12, no. 2, February 2013
2. Yuan Ouyang, Chen,Wu,Chang University Taiwan” Channel Estimation For Mimo-Ofdm Systems
Using A Novel Stbc Pilot Pattern”,IEEE-2012.
3. Yuan Ouyang, Chen,Wu,Chang University Taiwan” Pilot-Assist Channel Estimation for Multi-
input Multi-output (MIMO) 2x2 OFDM System”,2007,white paper
4. Laurent Cariou, Jean-Francois Helard,” A Simple And Efficient Channel Estimation For Mimo
Ofdm Code Division Multiplexing Uplink Systems”, 2005 IEEE 6th Workshop on Signal
Processing Advances in Wireless Communications
5. F.Delestre and Y.Sun,” Pilot Aided Channel Estimation for MIMO-OFDM Systems”, London
Communications Symposium 2009
6. Kala Praveen Bagadi” MIMO-OFDM Channel Estimation using Pilot Carries”, International
Journal of Computer Applications (0975 – 8887) Volume 2 – No.3, May 2010

26. 1] Estimation Of Channels In Ofdm Employing Cyclic Prefix
International Journal of Technical Research and Applications e-
ISSN: 2320-8163, www.ijtra.com Volume 3, Issue4 (July-August 2015), PP.
249-254.
2] Enhanced Estimation Of Channels In Ofdm Using Cyclic Prefix
And Two Dimensional Prolate Function
International Journal of Technical Research and Applications e-
ISSN: 2320-8163, www.ijtra.com Volume 3, Issue 5 (September-October,
2015), PP. 194-197
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