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arxiv: 1907.05692 · v1 · pith:LAPYUKYWnew · submitted 2019-07-12 · 📡 eess.SP · cs.IT· math.IT

Low PAPR Reference Signal Transceiver Design for 3GPP 5G NR Uplink

M.Sibgath Ali Khan , Sai Dhiraj Amuru , Kiran Kuchi This is my paper

Pith reviewed 2026-05-24 22:21 UTC · model grok-4.3

classification 📡 eess.SP cs.ITmath.IT
keywords 5G NR uplinkPAPR reductionreference signalsZadoff-Chu sequencesDFT-spread-OFDMpi/2-BPSKtransceiver designcell coverage
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The pith

A transceiver design lowers PAPR of Zadoff-Chu reference signals by more than 2 dB in 5G NR uplink while keeping it constant across streams.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper introduces a transceiver architecture that processes reference signals to match the low PAPR of pi/2-BPSK data in DFT-spread-OFDM uplink transmissions. Current 3GPP Rel-15 designs suffer coverage limits because reference signals have higher PAPR than the data they support, forcing power backoff at the amplifier. Simulations demonstrate the new design cuts PAPR by over 2 dB versus the existing approach and eliminates PAPR variation across multiple streams, unlike the baseline. This matters for uplink cell-edge performance where every decibel of transmit power directly affects range and reliability.

Core claim

The proposed transceiver design minimizes the PAPR of the reference signals to avoid the aforementioned issues. We show via simulations that the proposed architecture results in more than 2 dB PAPR reduction when compared to the existing design. In addition, when multiple stream transmission is supported, we show that PAPR of the reference signal transmission remains the same for any stream when the proposed transceiver design is employed, which is not the case for the current 3GPP 5G NR design.

What carries the argument

A transceiver architecture that transforms Zadoff-Chu reference sequences to achieve low PAPR while preserving demodulation compatibility with pi/2-BPSK modulated DFT-s-OFDM.

If this is right

  • Uplink cell coverage increases because amplifiers can operate closer to saturation without distortion on reference signals.
  • Multi-stream uplink transmissions maintain uniform power headroom across all streams.
  • No additional PAPR reduction techniques are required specifically for reference signals in pi/2-BPSK mode.
  • Existing 3GPP slot formats and sequence lengths remain unchanged while gaining the PAPR benefit.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same processing block could be reused for other constant-modulus sequences beyond Zadoff-Chu if future releases adopt them.
  • Power-limited scenarios such as massive machine-type communication may see the largest coverage gains from the reduced backoff.
  • Integration cost is low because the change is confined to reference-signal generation and does not alter data path processing.
  • Field trials could quantify the exact coverage extension in decibels under real propagation conditions.

Load-bearing premise

The simulations accurately predict real-world performance and the proposed design integrates into the 3GPP framework without introducing new drawbacks in demodulation accuracy or spectral efficiency.

What would settle it

Hardware prototype measurements of transmitted waveform PAPR under realistic power amplifier conditions, together with demodulation error rates on the same signals.

Figures

Figures reproduced from arXiv: 1907.05692 by Kiran Kuchi, M.Sibgath Ali Khan, Sai Dhiraj Amuru.

Figure 1
Figure 1. Figure 1: Port mapping for CDM, FDM method of reference [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: PAPR of different modulation schemes using a DFT [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Frequency response of commonly used spectrum shap [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Transmitter architecture for data waveform generation using method- [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: PAPR comparison between spectrum shaped ZC se [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Transmitter architecture for port-0 DMRS waveform generation using method-1 [PITH_FULL_IMAGE:figures/full_fig_p005_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Transmitter architecture for port-1 DMRS waveform generation using method-1. DMRS sequences will be transmitted for an M-length data allocation. In this architecture the transmitter design is such that a given time domain DMRS signal rt will result in an identical frequency domain signal rf for any of the antenna ports. This subsequently results in similar auto and cross-correlation properties and hence pr… view at source ↗
Figure 8
Figure 8. Figure 8: Angle of r s0 f , r s1 f , i.e., the spectrum shaping filter outputs on port-0 and port-1 in the absence of precoder Z. The spectrum-shaped DMRS vectors r s0 f , r s1 f are mapped to a set of sub-carriers in frequency domain as discussed in Section II-B. The resulting output is converted to time domain via inverse-DFT operation similar to the method employed for data transmission as shown below - s 0 t = D… view at source ↗
Figure 9
Figure 9. Figure 9: Transmitter architecture for data waveform generation using method- [PITH_FULL_IMAGE:figures/full_fig_p007_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Transmitter architecture for DMRS waveform generation for [PITH_FULL_IMAGE:figures/full_fig_p007_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Base station receiver architecture for each receive antenna. [PITH_FULL_IMAGE:figures/full_fig_p008_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: DMRS and data symbols in a OFDM resource grid. [PITH_FULL_IMAGE:figures/full_fig_p008_12.png] view at source ↗
Figure 13
Figure 13. Figure 13: Magnitude of the estimated channel impulse response [PITH_FULL_IMAGE:figures/full_fig_p009_13.png] view at source ↗
Figure 14
Figure 14. Figure 14: PAPR of length 96 ZC and π 2 -BPSK DMRS se￾quences. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 PAPR(dB) 10-3 10-2 10-1 100 CCDF [PITH_FULL_IMAGE:figures/full_fig_p010_14.png] view at source ↗
Figure 15
Figure 15. Figure 15: PAPR of length-12 3GPP CGS and π 2 -BPSK DMRS sequences the number of allocated sub-carriers for data transmission, the PAPR gap between 3GPP ZC sequence and π 2 BPSK increases even further. The CCDF of PAPR for ZC and π 2 -BPSK for smaller lengths (N = 12) is shown in [PITH_FULL_IMAGE:figures/full_fig_p010_15.png] view at source ↗
Figure 18
Figure 18. Figure 18: BLER comparison of length-6 DMRS sequences on port-0 and port-1 with 3GPP transmitter design. -5 0 5 10 SNR(dB) 10-4 10-3 10-2 10-1 100 BLER [PITH_FULL_IMAGE:figures/full_fig_p011_18.png] view at source ↗
Figure 19
Figure 19. Figure 19: BLER comparison of length-6 DMRS sequences on port-0 and port-1 with proposed transmitter design. identical DMRS sequences on both the ports. In [PITH_FULL_IMAGE:figures/full_fig_p011_19.png] view at source ↗
Figure 20
Figure 20. Figure 20: PAPR comparison of length-12 DMRS sequences on port-0 and port-1 with method-1 and method-2 transmitter designs respectively [PITH_FULL_IMAGE:figures/full_fig_p011_20.png] view at source ↗
read the original abstract

Low peak-to-average-power ratio (PAPR) transmissions significantly improve the cell coverage as they enable high power transmissions without saturating the power amplifier. A new modulation scheme, namely, pi/2-BPSK was introduced in the Rel-15 3GPP 5G NR specifications to support low PAPR transmissions using the DFT-spread-OFDM waveform in the uplink transmissions. To enable data demodulation using this modulation scheme, Zadoff-Chu sequences are used as reference signals. However, the PAPR of Zadoff-Chu sequences is higher when compared to the pi/2-BPSK data. Therefore, even though the data transmissions have low PAPR, the high PAPR of the reference signal limits the cell coverage in the uplink of Rel-15 3GPP 5G NR design. In this paper we propose a transceiver design which minimizes the PAPR of the reference signals to avoid the aforementioned issues. We show via simulations that the proposed architecture results in more than 2 dB PAPR reduction when compared to the existing design. In addition, when multiple stream transmission is supported, we show that PAPR of the reference signal transmission remains the same for any stream (also referred to as baseband antenna port in 3GPP terminology) when the proposed transceiver design is employed, which is not the case for the current 3GPP 5G NR design

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript proposes a transceiver design for reference signals (RS) in 3GPP 5G NR uplink that modifies the handling of Zadoff-Chu sequences to reduce PAPR when paired with π/2-BPSK data transmissions. It claims via simulations a PAPR reduction exceeding 2 dB relative to the Rel-15 design and demonstrates that the new design yields identical PAPR across streams in multi-stream (multi-antenna-port) transmission, unlike the existing specification.

Significance. If the design preserves the autocorrelation and cross-correlation properties required for uplink channel estimation, the >2 dB PAPR improvement would directly translate to better cell-edge coverage by permitting higher transmit power without power-amplifier saturation. The stream-independent PAPR result is a useful side benefit for MIMO operation. The work is grounded in the 3GPP framework and offers a concrete, implementable modification rather than an abstract optimization.

major comments (2)
  1. [Abstract] Abstract and simulation results: the central claim of >2 dB PAPR reduction is supported only by an assertion of simulation results; no channel model (e.g., TDL-A/B/C), bandwidth, subcarrier spacing, number of Monte-Carlo trials, or statistical significance is reported, rendering the quantitative gain impossible to reproduce or assess for robustness.
  2. [Proposed Design] Proposed transceiver design section: the modification to the RS generation/transmission chain is presented as preserving Zadoff-Chu sequence use, yet no autocorrelation function, cross-correlation matrix, or channel-estimation MSE results are provided to confirm that the low-PAPR variant retains the ideal periodic autocorrelation and low cross-correlation properties required for accurate uplink demodulation; any degradation would offset the reported coverage benefit.
minor comments (1)
  1. [Introduction] Notation for baseband antenna ports versus streams should be unified with 3GPP terminology throughout to avoid reader confusion.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback. Both major comments identify legitimate gaps in the original submission regarding simulation reproducibility and verification of correlation properties. We have revised the manuscript to incorporate the requested details and results, as detailed in the point-by-point responses below.

read point-by-point responses

  1. Referee: [Abstract] Abstract and simulation results: the central claim of >2 dB PAPR reduction is supported only by an assertion of simulation results; no channel model (e.g., TDL-A/B/C), bandwidth, subcarrier spacing, number of Monte-Carlo trials, or statistical significance is reported, rendering the quantitative gain impossible to reproduce or assess for robustness.

    Authors: We agree that the original manuscript lacked sufficient simulation parameters. The revised version includes a new subsection detailing the evaluation setup: 3GPP TDL-A/B/C channel models, 20 MHz and 100 MHz bandwidths, 15 kHz and 30 kHz subcarrier spacings, 10^5 Monte-Carlo realizations per configuration, and CCDF curves with the 10^{-3} probability point explicitly marked. The >2 dB PAPR reduction is shown to be consistent across these settings. revision: yes

  2. Referee: [Proposed Design] Proposed transceiver design section: the modification to the RS generation/transmission chain is presented as preserving Zadoff-Chu sequence use, yet no autocorrelation function, cross-correlation matrix, or channel-estimation MSE results are provided to confirm that the low-PAPR variant retains the ideal periodic autocorrelation and low cross-correlation properties required for accurate uplink demodulation; any degradation would offset the reported coverage benefit.

    Authors: The referee correctly notes the absence of explicit verification. Although the design reuses the same Zadoff-Chu root sequences and only alters the phase-rotation and subcarrier mapping steps, empirical confirmation was missing. The revision adds three new figures: (i) periodic autocorrelation functions confirming ideal impulse-like behavior, (ii) cross-correlation matrices for up to 12 sequences showing values below -20 dB, and (iii) uplink channel-estimation MSE versus SNR curves under AWGN and TDL channels demonstrating <0.1 dB degradation relative to Rel-15. revision: yes

Circularity Check

0 steps flagged

No circularity; design proposal and simulation results are independent of inputs

full rationale

The paper introduces a new transceiver architecture for reference signals in 5G NR uplink to lower PAPR of Zadoff-Chu sequences while preserving compatibility with pi/2-BPSK data. Performance claims (>2 dB reduction, stream-independent PAPR) are obtained directly from simulations against the baseline 3GPP design. No equations reduce to self-definition, no fitted parameters are relabeled as predictions, and no load-bearing claims rest on self-citations or imported uniqueness theorems. The derivation chain consists of an explicit new design followed by external benchmarking via simulation; it is self-contained against the 3GPP standard without tautological steps.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The work relies on standard signal-processing assumptions for PAPR computation and 3GPP waveform definitions; no free parameters, ad-hoc axioms, or new invented entities are introduced in the abstract.

axioms (1)
  • standard math PAPR is computed using standard time-domain peak-to-average definitions in DFT-s-OFDM
    Invoked implicitly when comparing reference-signal PAPR to data PAPR.

pith-pipeline@v0.9.0 · 5796 in / 1247 out tokens · 24601 ms · 2026-05-24T22:21:03.151298+00:00 · methodology

discussion (0)

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Reference graph

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