DFT-s-OFDM Waveform for 5G PBCH
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In 5G NR systems operating above 52.6 GHz, existing waveforms face challenges with low power amplifier efficiency and large phase noise, requiring a single carrier-based waveform that effectively handles these issues while maintaining low peak-to-average power ratio (PAPR) for downlink transmission.
Innovation Solution
The implementation of a Discrete Fourier Transform-spread-orthogonal frequency-division multiplexing (DFT-s-OFDM) waveform for transmitting the physical broadcast channel (PBCH) and its associated demodulation reference signal (DMRS) in a time division multiplexing (TDM) manner, with specific SSB patterns and DMRS designs to optimize bandwidth allocation and power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CP-OFDM waveform is used for downlink transmission in 5G NR, then spectral efficiency is improved, but peak-to-average power ratio increases causing low power amplifier efficiency
Solution Approach 1:
The patent changes the waveform parameter from CP-OFDM to DFT-s-OFDM, which fundamentally alters the signal structure by applying DFT spreading to the data symbols before OFDM modulation. This parameter change reduces the PAPR while maintaining spectral efficiency, directly resolving the contradiction between productivity and energy loss.
2Speed
If CP-OFDM waveform is used for downlink transmission, then data rate is improved, but phase noise becomes problematic at high frequencies
Solution Approach 1:
The patent changes the waveform parameter from CP-OFDM to DFT-s-OFDM, which fundamentally alters the signal structure by applying DFT spreading to the data symbols before OFDM modulation. This parameter change reduces the PAPR while maintaining spectral efficiency, directly resolving the contradiction between productivity and energy loss.
3Loss of energy
If single carrier waveform is used to reduce PAPR, then power amplifier efficiency is improved, but spectral efficiency decreases
Solution Approach 1:
The patent creates a composite waveform structure by combining DFT spreading (single-carrier characteristic) with OFDM modulation (multi-carrier characteristic). This composite approach inherits the low PAPR property from single-carrier waveforms while maintaining the high spectral efficiency of multi-carrier waveforms, resolving the contradiction between energy loss and productivity.
4Loss of energy
If DFT-s-OFDM waveform is used for PBCH transmission, then PAPR is reduced improving power amplifier efficiency, but waveform compatibility with existing OFDM structures must be maintained
Solution Approach 1:
The patent makes the DFT-s-OFDM waveform design universal by ensuring it can be integrated into the existing 5G NR OFDM-based framework. The waveform maintains compatibility with existing resource element mapping, reference signal structures, and physical layer processing, allowing it to serve multiple functions without requiring complete system redesign.
Data Source
AI summary
Devices, systems and methods for a fifth generation (5G) or new radio (NR) system comprising multiplexing, by a gNodeB (gNB), a physical broadcast channel (PBCH) and an associated demodulation reference signal (DMRS) in a time division multiplexing (TDM) manner; and transmitting, by the gNB, the PBCH by employing a Discrete Fourier Transform-spread-orthogonal frequency-division multiplexing (DFT-s-OFDM) waveform and its associated DMRS.