What is CP-OFDM?
CP-OFDM is the primary waveform used in 5G NR for downlink and most uplink transmissions. It extends conventional OFDM by prepending a copy of the end of each symbol (the cyclic prefix) as a guard interval, completely eliminating inter-symbol interference caused by multipath propagation as long as the channel delay spread is shorter than the CP.
How Does CP-OFDM Work?
The CP duration varies with numerology: for 15 kHz subcarrier spacing (µ=0), the normal CP is 4.69 µs; for 120 kHz (µ=3, used in mmWave), it is 0.59 µs. The receiver discards the CP before applying the FFT, which converts the received time-domain signal back into frequency-domain subcarriers for demodulation.
Use Cases
Downlink for all 5G NR deployments in FR1 and FR2. Uplink for most 5G scenarios. DFT-s-OFDM is used as an uplink alternative in coverage-limited scenarios to reduce PAPR.
3GPP / Standards Reference
3GPP TS 38.211 (Physical Channels and Modulation)
Related Terms
OFDM | DFT-s-OFDM | Numerology | NR | PAPR
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
