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Disadvantages of using OFDM for downlink in LTE?

+2 votes
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What are the benefits and drawbacks of OFDM?

posted Apr 21, 2014 by Madhavi Latha

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2 Answers

+1 vote

Benefit: By using OFDMA, more data throughput can be achieved.
Drawbacks: Transmission of data in the form of OFDM requires more power. eNodeB in lte doesn't have any power problem but UE has limited power source (battery) that's why eNodeB uses OFDM for downlink and UE doesn't use OFDM for uplink.

answer Apr 22, 2014 by Ganesh Kumar
0 votes

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.
  • OFDM is computationally efficient by using FFT techniques to implement the modulation and demodulation functions.
  • Is less sensitive to sample timing offsets than single carrier systems are.
  • Provides good protection against cochannel interference and impulsive parasitic noise.

DISADVANTAGES :

  • 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.
answer Apr 22, 2014 by Maninder Bath
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