ADVANTAGES

effective solution to inter symbol

interference.

Less complexity.

Digital transmitter and receivers

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OFDM TECHNOLOGY

Multicarrier modulation technique.

Different from fdm / wdm.

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OFDM TECHNOLOGY….

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OFDM SYSTEMDESCRIPTION

IFFT

OFDM baseband signal can be

implemented by IDFT

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FFT

• At receiver

FFT

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Cyclic Prefix for OFDM

For an OFDM symbol

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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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NEED OF CP???

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OFDM SYSTEMDESCRIPTION…

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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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CO-OFDM

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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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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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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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Any queries ???....

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THANK YOU!!!

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