OFDM (Orthogonal Frequency Division Multiplexing )
Objectives <ul><li>What is OFDM </li></ul><ul><li>How OFDM works </li></ul><ul><li>Types of OFDM </li></ul><ul><li>Differe...
What is OFDM <ul><li>Definition </li></ul><ul><li>The first OFDM schemes presented in  1966   </li></ul><ul><li>Developmen...
A   F
How OFDM works <ul><li>It distributes the data over a large number of carriers that are spaced apart at precise frequencie...
Types of OFDM <ul><li>C-OFDM   </li></ul><ul><li>MIMO-OFDM   </li></ul><ul><li>V-OFDM   </li></ul><ul><li>W-OFDM   </li></...
C-OFDM <ul><li>Coded OFDM </li></ul><ul><li>Digital Audio Broadcasting (DAB) </li></ul><ul><li>Digital Video Broadcasting ...
Multiple Input, Multiple Output OFDM (MIMO-OFDM)   <ul><li>Developed by Iospan Wireless   </li></ul><ul><li>U ses multiple...
V-OFDM   <ul><li>Vector OFDM  </li></ul><ul><li>Developed by CISCO   </li></ul><ul><li>Increases subscriber coverage   </l...
… Subscriber Base Station Paths …
W-OFDM   <ul><li>Wideband OFDM  </li></ul><ul><li>Invented by Wi-LAN  </li></ul><ul><li>Large spacing between carriers  </...
Flash-OFDM <ul><li>Fast-hopped OFDM  </li></ul><ul><li>Wide-band spread-spectrum technology  </li></ul><ul><li>Avoids the ...
Differences from other multiplexing techniques <ul><li>OFDM versus WDM   </li></ul><ul><li>-more flexible  </li></ul><ul><...
Differences from other multiplexing techniques <ul><li>OFDM versus  TDM   </li></ul><ul><li>-number of carriers  </li></ul...
Applications <ul><li>Digital Audio and Video Broadcasting   </li></ul><ul><li>Asymmetric Digital Subscriber Line (ADSL)   ...
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Ofdm

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Ofdm

  1. 1. OFDM (Orthogonal Frequency Division Multiplexing )
  2. 2. Objectives <ul><li>What is OFDM </li></ul><ul><li>How OFDM works </li></ul><ul><li>Types of OFDM </li></ul><ul><li>Differences from other multiplexing techniques </li></ul><ul><li>Applications </li></ul>
  3. 3. What is OFDM <ul><li>Definition </li></ul><ul><li>The first OFDM schemes presented in 1966 </li></ul><ul><li>Development of OFDM over years </li></ul>
  4. 4. A F
  5. 5. How OFDM works <ul><li>It distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the &quot;orthogonality&quot; in this technique which prevents the demodulators from seeing frequencies other than their own. </li></ul>
  6. 6. Types of OFDM <ul><li>C-OFDM </li></ul><ul><li>MIMO-OFDM </li></ul><ul><li>V-OFDM </li></ul><ul><li>W-OFDM </li></ul><ul><li>Flash-OFDM </li></ul>
  7. 7. C-OFDM <ul><li>Coded OFDM </li></ul><ul><li>Digital Audio Broadcasting (DAB) </li></ul><ul><li>Digital Video Broadcasting (DVB-T) </li></ul><ul><li>COFDM offers real benefit in the presence of isolated narrow-band interfering signals </li></ul>
  8. 8. Multiple Input, Multiple Output OFDM (MIMO-OFDM) <ul><li>Developed by Iospan Wireless </li></ul><ul><li>U ses multiple antennas to transmit and receive radio signals </li></ul><ul><li>S patial multiplexing </li></ul>
  9. 9. V-OFDM <ul><li>Vector OFDM </li></ul><ul><li>Developed by CISCO </li></ul><ul><li>Increases subscriber coverage </li></ul><ul><li>Lowers the cost of provisioning and deploying infrastructure </li></ul><ul><li>Employs both frequency and spatial diversity </li></ul><ul><li>Creates a robust processing technique for multi-path fading and narrow band interference </li></ul>
  10. 10. … Subscriber Base Station Paths …
  11. 11. W-OFDM <ul><li>Wideband OFDM </li></ul><ul><li>Invented by Wi-LAN </li></ul><ul><li>Large spacing between carriers </li></ul><ul><li>Advantages: </li></ul><ul><li>- Optimal performance against Multi-path </li></ul><ul><li>- Less sensitive to carrier offset </li></ul><ul><li>-Optimal power efficiency of the transmitter amplifier </li></ul><ul><li>- More immune against fading </li></ul>
  12. 12. Flash-OFDM <ul><li>Fast-hopped OFDM </li></ul><ul><li>Wide-band spread-spectrum technology </li></ul><ul><li>Avoids the compromises inherent in other mobile data systems </li></ul><ul><li>Capability to work around interfering signals </li></ul>
  13. 13. Differences from other multiplexing techniques <ul><li>OFDM versus WDM </li></ul><ul><li>-more flexible </li></ul><ul><li>-higher bandwidth efficiency </li></ul>
  14. 14. Differences from other multiplexing techniques <ul><li>OFDM versus TDM </li></ul><ul><li>-number of carriers </li></ul><ul><li>-synchronization </li></ul><ul><li>-sensitivity </li></ul><ul><li>-capacity/efficiency advantages </li></ul><ul><li>- complexity and cost issues </li></ul>
  15. 15. Applications <ul><li>Digital Audio and Video Broadcasting </li></ul><ul><li>Asymmetric Digital Subscriber Line (ADSL) </li></ul><ul><li>Wireless Networking </li></ul><ul><li>Power-line Technology </li></ul>

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