際際滷

際際滷Share a Scribd company logo

Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1

Download as PPTX, PDF
Harish Rajula
Harish Rajula

This document discusses the benefits of adaptive modulation in OFDM systems. It explains that in fixed modulation schemes, each subcarrier is individually attenuated under frequency-selective fading channels, resulting in poor performance. Adaptive modulation schemes address this by allowing the modulation rate to change based on instantaneous signal-to-noise ratio. The document presents simulation results showing adaptive modulation outperforms fixed modulation schemes, with average bit error rates approximately 0.203568 for adaptive modulation versus 0.913545 for higher order fixed modulation. It concludes that adaptive modulation improves the bit error rate performance of OFDM systems operating over frequency-selective fading channels.

1 of 14
Downloaded 30 times
BER PERFORMANCE OF OFDM SYSTEM WITH ADAPTIVE MODULATION Presented by: Harish Rajula P14EC009 SV_NIT-Surat harish.rajula91@gmail.com Ieee Explorer search:BER Performance of OFDM System with Adaptive Modulation
Challenges in Designing OFDM Transmitter: 1. The Number of subcarriers required to send the given data Each subcarriers are centered at frequencies that are orthogonal to each other (usually multiples of frequencies).
2. The second design parameter could be the Modulation format that we wish to use An OFDM signal can be constructed using anyone of the following digital modulation techniques namely BPSK, QPSK, QAM etc..,
Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1
In an OFDM transmission system if the same fixed transmission scheme is used for all OFDM subcarriers, Each subcarrier is attenuated individually under the frequency-selective and fast fading channel It results in highest attenuation and hence poor performance
Adaptive Modulation
Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1
Adaptive modulation comparison is made with fixed modulation system under various IFFT size(N). BER is calculated using following formula: Adaptive modulation is introduced by presenting some of the simpler adaptive Quadrature Amplitude Modulation(QAM) schemes and their performance for both perfectly known and predicted channels.
Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1
Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1
Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1
Here IFFT size is denoted by N. For IFFT size N=64, 128, 256,512 ,1024,2048 BER performance has shown
In adaptive modulation, modulation rate changes based upon value of an instantaneous SNR. The BER performance comparison between fixed and adaptive modulation shows that BER performance for all modulation techniques is better, when IFFT size is greater than 512. For all values of IFFT sizes, average BER of Adaptive modulation is approximately 0.203568 and for higher order fixed modulation it is approximately 0.913545 . Hence, it concludes that BER performance of
Effect of Channel Prediction on Automatic Modulation Classification for Adaptive OFDM Systems Adaptive OFDM for Wireless Interconnect in Confined Enclosures..

More Related Content

Adaptive OFDM_Orthogonal Frequency Dvision Multiplexing_1

  • 1. BER PERFORMANCE OF OFDM SYSTEM WITH ADAPTIVE MODULATION Presented by: Harish Rajula P14EC009 SV_NIT-Surat harish.rajula91@gmail.com Ieee Explorer search:BER Performance of OFDM System with Adaptive Modulation
  • 2. Challenges in Designing OFDM Transmitter: 1. The Number of subcarriers required to send the given data Each subcarriers are centered at frequencies that are orthogonal to each other (usually multiples of frequencies).
  • 3. 2. The second design parameter could be the Modulation format that we wish to use An OFDM signal can be constructed using anyone of the following digital modulation techniques namely BPSK, QPSK, QAM etc..,
  • 5. In an OFDM transmission system if the same fixed transmission scheme is used for all OFDM subcarriers, Each subcarrier is attenuated individually under the frequency-selective and fast fading channel It results in highest attenuation and hence poor performance
  • 8. Adaptive modulation comparison is made with fixed modulation system under various IFFT size(N). BER is calculated using following formula: Adaptive modulation is introduced by presenting some of the simpler adaptive Quadrature Amplitude Modulation(QAM) schemes and their performance for both perfectly known and predicted channels.
  • 12. Here IFFT size is denoted by N. For IFFT size N=64, 128, 256,512 ,1024,2048 BER performance has shown
  • 13. In adaptive modulation, modulation rate changes based upon value of an instantaneous SNR. The BER performance comparison between fixed and adaptive modulation shows that BER performance for all modulation techniques is better, when IFFT size is greater than 512. For all values of IFFT sizes, average BER of Adaptive modulation is approximately 0.203568 and for higher order fixed modulation it is approximately 0.913545 . Hence, it concludes that BER performance of
  • 14. Effect of Channel Prediction on Automatic Modulation Classification for Adaptive OFDM Systems Adaptive OFDM for Wireless Interconnect in Confined Enclosures..

Editor's Notes