Skip to main content

OFDM receiver

Short answer

The OFDM receiver down-converts, samples, synchronizes, and removes the cyclic prefix, then uses an N-point FFT to separate orthogonal subcarriers. Channel estimates from pilots allow one-tap equalization per subcarrier, followed by P/S conversion, demapping, and decoding. This avoids complex time-domain equalization.

Explain OFDM receiver in brief.

The OFDM receiver reverses the steps of the transmitter. It uses an FFT to separate the orthogonal subcarriers, after which each subcarrier sees a flat channel and is equalized with one complex gain.

RF->[Down-conv]->[ADC]->[Sync]->[Remove]->[S/P]
                                 [ CP   ]    |
                                             v
bits<-[Decode]<-[Demap]<-[P/S]<-[1-tap EQ]<-[FFT]
                                   ^
                            [Channel est.]
                            [from pilots ]
  1. Down-conversion and ADC – RF to complex baseband samples.
  2. Synchronization – finds the symbol start and corrects carrier frequency offset (often using the CP or preambles).
  3. Remove cyclic prefix – discards the guard part that contains ISI from the previous symbol.
  4. S/P and N-point FFT – converts the time samples back to subcarrier symbols: Y_k = H_k X_k + N_k.
  5. Channel estimation and equalization – H_k is estimated from pilots and X̂_k = Y_k / H_k (zero-forcing) per subcarrier.
  6. P/S, demapping, deinterleaving and decoding – recover the bit stream.

Because equalization is one division per subcarrier, the receiver is far simpler than a time-domain equalizer for the same multipath channel.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Wireless Communication chapter 4 questions →