Ofdm for optical communications

2. ADVANTAGES
 effective solution to inter symbol
interference.
Less complexity.
Digital transmitter and receivers
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3. OFDM TECHNOLOGY
Multicarrier modulation technique.
Different from fdm / wdm.
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4. OFDM TECHNOLOGY….
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5. OFDM SYSTEMDESCRIPTION
 IFFT
OFDM baseband signal can be
implemented by IDFT
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6. FFT
• At receiver
FFT
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7. Cyclic Prefix for OFDM
For an OFDM symbol
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8. NEED OF CP???
CP eliminates ISI,ICI,
Let the received signal at time t be
CP will eliminate ISI if
 receiver FFT window is aligned with the start of
the main symbol period of the first arriving
signal.
 delay spread does not exceed the CP
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9. NEED OF CP???
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10. OFDM SYSTEMDESCRIPTION…
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11. OFDM for Optical Communications
classified into two main categories:
 Coherent detection (DD-OOFDM)
 Direct detection (CO-OFDM)
Each are different according to their underlying
techniques
future of optical communication is the coherent detection .
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12. CO-OFDM
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13. basic functional blocks
RF OFDM signal transmitter,
RF to optical(RTO) up-converter,
Fiber links,
the optical to RF (OTR) down-converter,
RF OFDM receiver
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14. DISADVANTAGES OF OFDM
 High Peak-to-Average Power Ratio.
 Sensitivity to Frequency Offset, Phase
Noise
 Difficulty and Cost of OFDM
Implementation
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15. CONCLUSION
Typical OFDM transmitter and receiver
described and the roles of main signal
processing blocks explained.
Advantages and disadvantages of ofdm
were discussed.
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16. Any queries ???....
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17. THANK YOU!!!
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