advantage and disadvantage of ofdm


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The OFDM transmission scheme has the following key advantages:

Makes efficient use of the spectrum by allowing overlap

By dividing the channel into narrowband flat fading subchannels, OFDM is more resistant to frequency selective fading than single carrier systems are.

Eliminates ISI and IFI through use of a cyclic prefix.

Using adequate channel coding and interleaving one can recover symbols lost due to the frequency selectivity of the channel.

Channel equalization becomes simpler than by using adaptive equalization techniques with single carrier systems.

It is possible to use maximum likelihood decoding with reasonable complexity, asndiscussed in OFDM is computationally efficient by using FFT techniques to implement the modulation and demodulation functions.

In conjunction with differential modulation there is no need to implement a channel
estimator.

Is less sensitive to sample timing offsets than single carrier systems are.

Provides good protection against cochannel interference and impulsive parasitic
noise.

In terms of drawbacks OFDM has the following characteristics:

The OFDM signal has a noise like amplitude with a very large dynamic range,
therefore it requires RF power amplifiers with a high peak to average power ratio.

It is more sensitive to carrier frequency offset and drift than single carrier systems
are due to leakage of the DFT.

Re: advantage and disadvantage of ofdm

the answers lies in the definition of ofdm

the basic principle of ofdm is
The basic principle of OFDM is to split a high-rate datastream into a number of
lower rate streams that are transmitted simultaneously over a number of subcarriers. The
relative amount of dispersion in time caused by multipath delay spread is decreased
because the symbol duration increases for lower rate parallel subcarriers. The other
problem to solve is the intersymbol interference, which is eliminated almost completely by
introducing a guard time in every OFDM symbol. This means that in the guard time, the
OFDM symbol is cyclically extended to avoid intercarrier interference.


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