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Question 20296
JEE Physics · Hard

Principles of Communication: Digital Communication MCQ

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Digital CommunicationHardQuestion 20296

Question

The bandwidth efficiency (bits/s/Hz) of QAM-16 with half the bandwidth used for filtering guard band is:
  1. A
    1 bps/Hz
  2. B
    2 bps/Hz
    Correct
  3. C
    4 bps/Hz
  4. D
    8 bps/Hz

Correct answer

2 bps/Hz

Explanation

QAM-16: 4 bits/symbol. Nyquist channel capacity = 2B log₂(M) = 2B × 4. With 50% overhead for guard bands, effective BW = 2 × symbol rate → efficiency = 4/2 = 2 bps/Hz. Practical OFDM systems achieve 3–6 bps/Hz.

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