1. OFDM (Orthogonal Frequency Division Multiplexing )

2. Objectives  What is OFDM  How OFDM works  Types of OFDM  Differences from other multiplexing techniques  Applications

3. What is OFDM  Definition  The first OFDM schemes presented in 1966  Development of OFDM over years

4. A F

5. How OFDM works It distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the "orthogonality" in this technique which prevents the demodulators from seeing frequencies other than their own.

6. Types of OFDM  C-OFDM  MIMO-OFDM  V-OFDM  W-OFDM  Flash-OFDM

7. C-OFDM  Coded OFDM  Digital Audio Broadcasting (DAB)  Digital Video Broadcasting (DVB-T)  COFDM offers real benefit in the presence of isolated narrow-band interfering signals

8. Multiple Input, Multiple Output OFDM (MIMO-OFDM)  Developed by Iospan Wireless  Uses multiple antennas to transmit and receive radio signals  Spatial multiplexing

9. V-OFDM  Vector OFDM  Developed by CISCO  Increases subscriber coverage  Lowers the cost of provisioning and deploying infrastructure  Employs both frequency and spatial diversity  Creates a robust processing technique for multi-path fading and narrow band interference

10. … Subscriber Base Station Paths …

11. W-OFDM  Wideband OFDM  Invented by Wi-LAN  Large spacing between carriers  Advantages: - Optimal performance against Multi-path - Less sensitive to carrier offset -Optimal power efficiency of the transmitter amplifier - More immune against fading

12. Flash-OFDM  Fast-hopped OFDM  Wide-band spread-spectrum technology  Avoids the compromises inherent in other mobile data systems  Capability to work around interfering signals

13. Differences from other multiplexing techniques  OFDM versus WDM -more flexible -higher bandwidth efficiency

14. Differences from other multiplexing techniques  OFDM versus TDM -number of carriers -synchronization-sensitivity -capacity/efficiency advantages -complexity and cost issues

15. Applications  Digital Audio and Video Broadcasting  Asymmetric Digital Subscriber Line (ADSL)  Wireless Networking  Power-line Technology