CP-OFDM vs DFT-S-OFDM Using MTALAB Plots

Why It Matters

Lower PAPR in DFT‑S‑OFDM enables more power‑efficient uplink transmission, directly extending device battery life and reducing amplifier costs in 5G networks.

Key Takeaways

• CP-OFDM used for downlink, DFT‑S‑OFDM for uplink transmissions.
• DFT‑S‑OFDM adds pre‑coding DFT step before subcarrier mapping.
• DFT‑S‑OFDM reduces PAPR, improving power‑amplifier efficiency for uplink.
• Simulations show 1.86 dB PAPR reduction (~35% lower) versus CP‑OFDM.
• CP‑OFDM offers higher spectral efficiency and simpler processing chain.

Summary

The video walks through a MATLAB‑based comparison of two orthogonal‑frequency‑division multiplexing (OFDM) variants used in 5G New Radio: cyclic‑prefix OFDM (CP‑OFDM) for the downlink and DFT‑spread OFDM (DFT‑S‑OFDM) for the uplink. It outlines each scheme’s processing chain, highlighting that CP‑OFDM follows data → subcarrier mapping → IFFT → CP insertion, while DFT‑S‑OFDM inserts a DFT precoding step before the same subcarrier‑mapping and IFFT stages.

Key technical insights include the role of DFT precoding in spreading each symbol across multiple subcarriers, effectively turning the signal into a single‑carrier‑like waveform. This reduces the peak‑to‑average power ratio (PAPR), making the uplink transmitter more power‑efficient. CP‑OFDM, by contrast, carries independent QAM symbols on each subcarrier, delivering higher spectral efficiency but higher PAPR.

The presenter cites simulation results: CP‑OFDM exhibits an 8.16 dB PAPR versus 6.30 dB for DFT‑S‑OFDM, a 1.86 dB (≈34.8 %) reduction. Monte‑Carlo runs of about a thousand trials generate complementary cumulative distribution function (CCDF) plots confirming the PAPR advantage. The MATLAB code visualizes the first three symbols of each waveform and their instantaneous power, reinforcing the quantitative findings.

For network designers, the trade‑off is clear: CP‑OFDM remains optimal for downlink enhanced mobile broadband (eMBB) due to its spectral efficiency, while DFT‑S‑OFDM is preferred for uplink where lower PAPR translates to reduced distortion and longer battery life. Selecting the appropriate OFDM variant therefore balances performance, hardware complexity, and power consumption in 5G deployments.

Original Description

CP-OFDM vs DFT-S-OFDM using MATLAB Plots | Time Domain, Spectrum, and PAPR Insight

In this video, I compare CP-OFDM and DFT-S-OFDM using MATLAB plots to help you understand the practical and visual difference between these two important waveform techniques used in wireless communication systems.

This video covers:

What is CP-OFDM

What is DFT-S-OFDM

Time-domain signal comparison

Frequency-domain / spectrum comparison

Why DFT-S-OFDM has lower PAPR

Why CP-OFDM is widely used

Use of DFT-S-OFDM in uplink transmission

Basic conceptual difference with simple explanation

This video is useful for:

LTE learners

5G NR learners

Engineering students

Interview preparation

MATLAB-based wireless communication understanding

If you want to understand waveform comparison visually through plots, this video will help you a lot.

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