Pith. sign in

REVIEW 3 major objections 7 minor 4 cited by

Overview of 3GPP Release 19 Study on Channel Modeling Enhancements to TR 38.901 for 6G

T0 review · 3 major / 7 minor · reviewed 2026-08-15 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read Release 19 study validates and extends the standard channel model TR 38.901 for 6G.

desk verdict A useful insider overview of the Rel-19 TR 38.901 updates, but the headline claim of 'accurate' SMa modeling outruns the evidence the paper itself presents. read the letter →

arxiv 2507.19266 v2 pith:UPTF2AS4 submitted 2025-07-25 cs.IT math.IT

Hitesh Poddar , Dimitri Gold , Daewon Lee , Nan Zhang , Gokul Sridharan , Henrik Asplund , Mansoor Shafi This is my paper · ORCID
classification cs.ITmath.IT
keywords 3GPPRelease19channelmodelingTR38.9016G7-24GHznear-fieldpropagationspatialnon-stationaritysuburbanmacrocell
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

This paper reports what the Release 19 standardization study changed in TR 38.901, the stochastic channel model used as a benchmark for designing and evaluating wireless systems between 0.5 and 100 GHz. The study targeted the 7-24 GHz band, where the model had thin measurement support, and added a suburban macrocell scenario, realistic handset and customer-premises equipment antenna patterns, variable cluster and ray counts, polarization power variability, near-field spherical wavefronts, and spatial non-stationarity from very large antenna arrays and human blockage. If the additions hold up, simulations for 6G will track real propagation more closely in the bands the next generation is expected to use. The paper also records which parameters were validated, which were updated, and which were left unchanged because the contributed data were inconclusive.

What carries the argument

The central object is the cluster-based stochastic channel model of TR 38.901: multipath energy is grouped into clusters and rays, each with delay, angular spread, and a $2\times 2$ polarization matrix, and channel coefficients are assembled per antenna element. The new study extends this machinery with four mechanisms: element-wise near-field phase and angle computation using auxiliary points and the direct LOS distance; a polarization variability factor applied to each matrix element; visibility regions and stochastic attenuation factors for spatial non-stationarity; and a reference user-terminal antenna geometry with fixed device dimensions, candidate locations, and grip-based blockage. These mechanisms carry the added modeling capability while keeping the original far-field stochastic framework intact.

What would settle it

Run an independent measurement campaign in a suburban macrocell at a carrier frequency between 7 and 24 GHz, using channel sounding or ray tracing, and compare measured LOS probability, path loss, delay spread, and angular spreads against the new SMa tables in TR 38.901 v19.0.0; a systematic mismatch would refute the claim that the SMa scenario accurately models suburban deployments.

Watch

Extended reading notes

Core claim

The paper's central claim is that the Release 19 study turned TR 38.901 into a model that covers the 7-24 GHz range with realistic suburban deployments and modern antenna configurations. It introduces a Suburban Macrocell scenario with its own LOS probability, path loss tables extended to 37 GHz, plywood and low-loss outdoor-to-indoor penetration models, and fast-fading parameters drawn from legacy suburban models plus new measurements. It defines a reference handheld (15 cm x 7 cm) and CPE (20 cm x 20 cm) antenna model with eight and nine candidate antenna locations, a directional radiation pattern, per-antenna power imbalance, and user hand/head blockage. It replaces fixed cluster and ray counts with a variable-cluster framework and an updated ray-per-cluster rule that allows fewer than 20 rays for wideband or large-array systems. It adds absolute time-of-arrival models for NLOS paths, a polarization variability model that multiplies each element of the $2\times 2$ polarization matrix by a lognormal factor with 3 dB standard deviation, a near-field model that computes antenna-element-wise phase and angle from a spherical wavefront, and both a blocker-based and a stochastic spatial non-stationarity model for base-station arrays.

Load-bearing premise

The entire update rests on the accuracy and representativeness of the industry-contributed measurement and simulation datasets summarized in the paper's Table I; if those datasets are biased or unrepresentative, the decisions to add SMa, near-field, SNS, and parameter updates are unsupported.

Editorial extensions

If this is right

  • System-level simulations for 6G in the 7-24 GHz band can now use a standard model rather than extrapolating from sub-6 GHz or mmWave data.
  • Evaluations of massive MIMO and extremely large aperture arrays can include near-field spherical wavefronts and spatial non-stationarity instead of assuming a planar wavefront and uniform array illumination.
  • Handset form-factor effects, such as antenna position, power imbalance, and hand or head blockage, can appear in standard evaluations and change predicted MIMO and diversity performance.
  • Variable cluster and ray counts allow models to reflect the sparser multipath seen at higher frequencies and large bandwidths, which matters for rank and beamforming analysis.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A testable extension is to apply the variable-cluster and variable-ray framework to sub-THz bands, where the same fixed-count assumptions would likely fail the same way.
  • The SMa LOS probability approach, which uses an environment-dependent distribution similar to the indoor-factory model, could be imported to rural or urban-fringe deployments where foliage and building density vary similarly.
  • If future measurements show that the 3 dB polarization variability standard deviation depends on environment or frequency, the framework would need per-scenario values rather than a single global constant.
Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 7 minor

Summary. This manuscript is a standards-overview article reporting the outcomes of the 3GPP Release 19 study item on channel modeling enhancements for the 7–24 GHz band, which concluded in June 2025. The paper summarizes the additions to TR 38.901 v19.0.0, including a new Suburban Macrocell (SMa) scenario, realistic handheld-UT and CPE antenna models, variable numbers of clusters and rays per cluster, a polarization-variability framework, near-field propagation modeling, and spatial non-stationarity effects. It also lists updated delay-spread and angular-spread parameters for UMi and UMa, and describes which legacy parameters were considered validated or left unchanged due to inconclusive data. The authors are 3GPP delegates from multiple companies, and the manuscript is largely a descriptive account of a concluded standards study.

Significance. If the reported outcomes are taken at face value, the paper is a useful and timely reference for 6G system designers: it consolidates the key changes in TR 38.901 v19.0.0, names the contributing measurement and simulation datasets in Table I, and explains the rationale behind the updates. Its multi-company authorship and grounding in the public TR lend it credibility as an accurate record of the standardization outcome. The principal weakness is that the abstract claims the study provided the 'ability to accurately model' SMa and 'accurate' modeling of other phenomena, while the body of the paper does not report validation statistics or goodness-of-fit results for the new SMa scenario or for the near-field and SNS frameworks. The paper is therefore more reliable as a catalog of what was standardized than as evidence that the standardized models are accurate in a quantitative sense.

major comments (3)
  1. [Abstract and Section III-A] The abstract states that the study resulted in 'the ability to accurately model a Suburban Macrocell (SMa) scenario,' but Section III-A does not provide evidence for the word 'accurately.' The PL model is reused from ITU-R M.2135-1/WINNER II, the LOS probability model is based only on ray tracing, and all fast-fading parameters are adopted from [4], [8], or the UMa scenario, with several parameters 'derived using the arithmetic mean' of legacy values and Rel-19 contributions. Table I lists only sparse SMa measurement entries (AT&T PL/DS/ASA/ZSA at 7/8/15 GHz, BT/Ericsson and Vodafone/Ericsson ASD/ZSD near 3.5 GHz, Nokia O2I at 28 GHz), with no reported comparison of modeled versus measured distributions for the fast-fading parameters. I recommend either removing 'accurately' from the abstract and the associated claims, or reporting the validation statistics from the TR (e.g., mean error or RMS error versus the submitted data).
  2. [Section III (validation summary)] The paper lists parameters 'considered validated based on provided data' and others for which 'limited data and inconsistent validation results' made changes inconclusive, but it never defines what 'validated' means operationally. No acceptance threshold, statistical test, or error metric is stated. Since the stated purpose of the Rel-19 study is to validate TR 38.901 for 7–24 GHz, this omission prevents readers from judging the strength of the validation claims. Please add one sentence specifying the validation criterion (or cite the specific TR section/annex where the validation plots and fitting residuals are documented), and note that for the SMa fast-fading parameters no validation results are reported.
  3. [Section III-C and Table III] The updated UMi/UMa delay-spread and angular-spread parameters are stated to be 'derived from both legacy datasets ... and newly acquired data ... using either weighted least squares curve fitting or weighted mean,' but the paper does not identify which parameters used which method, how the weights were chosen, or how many datasets contributed to each fit. Table III also changes some UMa ASD values from frequency-dependent expressions to constants (e.g., ASD LOS from 1.06 + 0.1114 log10(fc) to 0.92) without comment. For a paper whose contribution is reporting model refinements, this is a load-bearing gap; please clarify the fitting details or point to the exact TR sections where the datasets and fits are reported.
minor comments (7)
  1. [Section II and Section IV] The bullet list in Section II states that Absolute Time of Arrival modeling was added for UMi, UMa, InH, and RMa, while the conclusion says it was extended to 'UMa, UMi, RMa, InH, and SMa.' Please reconcile the two lists.
  2. [Table I] The company name is misspelled as 'V odafone' in two rows; it should read 'Vodafone.'
  3. [Section III-D] The phrase 'log normal Gaussian distribution' is redundant; use 'lognormal distribution' for clarity.
  4. [Section III-F] The citation 'Eq. (7.6-53, 7.6-54)' should be 'Eqs. (7.6-53) and (7.6-54)' for correctness.
  5. [References] The version numbers in references [9] and [10] are formatted inconsistently ('14.2.0' and '14.4.0' versus the file names with 'e20' and 'e40'); please use a consistent 'v14.x.0' format.
  6. [Figure 1 caption] The caption 'Coverage Decreases Capacity increases' should include punctuation, e.g., 'Coverage decreases; capacity increases.'
  7. [Section II bullet list] The bullet 'Introduction of modeling variable number of clusters per Base Station (BS) and UT link' is grammatically awkward; consider rewriting as 'Introduction of a model for a variable number of clusters per BS–UT link.'

Circularity Check

0 steps flagged · score 0.0 of 10

No circular derivation found: the paper is a descriptive overview of 3GPP Rel-19 standardization outcomes, not a predictive derivation that reduces to fitted inputs.

full rationale

This manuscript is an overview and summary of a 3GPP Release 19 Study Item, not a derivation of a new channel model from equations. The claimed outcomes (SMa scenario, UT antenna model, variable cluster and ray counts, polarization variability, near field, spatial non-stationarity) are presented as standardized model components in TR 38.901 v19.0.0, with parameter values taken from contributed measurements, ray-tracing simulations, or legacy ITU/WINNER/3GPP models. No equation in the paper has its output defined by its fitted input. For example, Section III-A states that SMa fast-fading parameters are adopted from [4], [8], or UMa and that some are arithmetic means of legacy and Rel-19 data; that is a transparent description of model construction, not a prediction masquerading as independent confirmation. The paper explicitly lists cases where validation was inconclusive (UMa PL, InF DS, UMi ZSD, InH angular spreads), showing that data sufficiency, not circularity, is the limiting factor. Self-citations such as [14] (a polarization measurement study) and [11] (a 3GPP discussion summary) are not load-bearing: the polarization variability standard deviation is reported as obtained from measurements, and the power-imbalance range is presented as a proposal in discussion. No uniqueness theorem is imported from the authors to force a choice, and the SMa 'accurate modeling' claim is a descriptive assertion whose evidence is thin rather than a result that reduces by construction to its own inputs. Therefore no significant circularity is present.

Assumptions & free parameters 3 free parameters · 2 assumptions · 0 invented entities

The paper is an overview, so it introduces no new mathematical axioms or entities. Its central claim rests on the empirical validity of measurement data contributed by 3GPP members and on simulation models; these are domain assumptions rather than axioms in the mathematical sense. The free parameters listed are the reported, fitted model coefficients that appear in the updated standard, not parameters used in a derivation within this paper.

free parameters (3)
  • Updated UMa delay spread NLOS model coefficients = mu_lgDS = -6.47 - 0.134 log10(fc)
    Reported in Table III as updated based on weighted least squares fitting to legacy and new measurement data; these coefficients are fits, not predictions.
  • Polarization variability log-normal standard deviation = 3 dB
    Adopted from measurements [14] to model per-element power variability in the polarization matrix (Section III-D).
  • Number of clusters bounds (Dmin, Dmax) = e.g., UMi NLOS 6 to 19
    Chosen as a bounded interval to allow variable cluster counts per link (Section 7.6.15 in [2]).
assumptions (2)
  • domain assumption The industry-contributed measurement and simulation data (Table I) are accurate, representative of the target environments, and sufficient to justify the parameter validation and update decisions.
    The paper's entire account of which parameters were validated or updated depends on the trustworthiness of data from multiple 3GPP member companies; these data are not public.
  • domain assumption The ray tracing simulations used for the SMa LOS probability model are representative of suburban environments with variable foliage and building density.
    Section III-A states the SMa LOS probability model is based on ray tracing simulations; if the simulation scenarios do not cover the variability of suburban environment, the model may be biased.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Overview of 3GPP Release 19 Study on Channel Modeling Enhancements to TR 38.901 for 6G." pith.science (2026). https://pith.science/paper/UPTF2AS4

@misc{pith2026250719266,
  author       = {Pith},
  title        = {Pith review of: Overview of 3GPP Release 19 Study on Channel Modeling Enhancements to TR 38.901 for 6G},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/UPTF2AS4}},
  note         = {Machine review of arXiv:2507.19266}
}
read the original abstract

Channel models are a fundamental component of wireless communication systems, providing critical insights into the physics of radio wave propagation. As wireless systems evolve every decade, the development of accurate and standardized channel models becomes increasingly important for the development, evaluation and performance assessment of emerging technologies. An effort to develop a standardized channel model began around 2000 through the Third Generation Partnership Project (3GPP) and the International Telecommunication Union (ITU) with the aim of addressing a broad range of frequencies from sub-1 GHz to 100 GHz. Prior efforts focused heavily on sub-6 GHz bands and mmWave bands, and there exist some gaps in accurately modeling the 7-24 GHz frequency range, a promising candidate band for 6G. To address these gaps, 3GPP approved a Release (Rel) 19 channel modeling study. This study resulted in several enhancements to the channel models, including the ability to accurately model a Suburban Macrocell (SMa) scenario, realistic User Terminal (UT) antenna models, variability in the number of clusters, variability in the number of rays per cluster, a framework for capturing variability in power among all polarizations, near field (NF) propagation, and spatial non-stationarity (SNS) effects, all of which may be crucial for future 6G deployments. This paper presents the outcomes of this study and provides an overview of the underlying rationale, and key discussions that guided the validation, refinement, and enhancements of the 3GPP TR 38.901 channel models.

Figures

Figures reproduced from arXiv: 2507.19266 by the authors.

Figure 1
Figure 1. Overview of 3GPP channel modeling studies for IMT systems. [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. UT antenna reference radiation pattern with 3 dB beamwidth of 125 [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. UT antenna blockage scenarios (left to right): one hand grip, dual [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figures from the paper (1 more)
Figure 4
Figure 4. Figure 4: NF propagation and SNS effect at both the BS and UT. [PITH_FULL_IMAGE:figures/full_fig_p008_4.png]

Review history (2 revisions) →

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Urban Macro/Microcellular Channel Characterization at 4.85 GHz With Literature-Referenced Upper FR1-to-FR3 Cross-Band Analysis

    eess.SP 2025-11 unverdicted novelty 6.0 of 10

    Urban measurements at 4.85 GHz anchored to literature data produce indicative log-log trends in delay spread, ASA, and ASD across 4-28 GHz that are compared to 3GPP models.

  2. When 5G MIMO Scaling Breaks: Toward 6G Upper-Mid-Band Extreme MIMO

    eess.SP 2026-07 conditional novelty 5.0 of 10

    Scaling 5G MIMO to 256+ ports at 7–8 GHz breaks on common-channel coverage, RF/array power, and CSI overhead; the paper maps a roadmap that decouples radiating elements, RF chains, and acquired channel dimensions.

  3. iBEAMS: A Unified Framework for Secure and Energy-Efficient ISAC-MIMO Systems leveraging Bayesian Enhanced learning, and Adaptive Game-Theoretic Multi-Layer Strategies

    eess.SP 2026-03 conditional novelty 5.0 of 10

    A hierarchical Stackelberg–GNE–Bayesian ISAC controller reports ~4.4–4.7 bps/Hz secrecy rate and 30–70% higher SEE than a Stackelberg baseline from 28 GHz to 3 THz in simulation.

  4. Single and Multi-Frequency Path Loss Models for Indoor Hotspot Scenario Based on Measurements Conducted at 6.75, 16.95, 28, 73 and 142 GHz

    cs.IT 2025-09 conditional novelty 4.0 of 10

    Indoor hotspot path loss measurements at 6.75, 16.95, 28, 73, and 142 GHz are fitted to CI, FI, ABG, and cross-polarization variants, producing parameter tables for 7-24, 0.5-100, and 0.5-150 GHz bands, including new ...

Reference graph

Works this paper leans on

15 extracted references · 15 canonical work pages · cited by 4 Pith papers

  1. [4]

    Guidelines for Evaluation of Radio Interface Tech- nologies for IMT-Advanced,

    ITU-R M.2135-1, “Guidelines for Evaluation of Radio Interface Tech- nologies for IMT-Advanced,” Tech. Rep., 2009

    work page 2009

  2. [8]

    WINNER II Chan- nel Models,

    J. Meinil ¨a, P. Ky ¨osti, T. J ¨ams¨a, and L. Hentil ¨a, “WINNER II Chan- nel Models,” in Radio Technologies and Concepts for IMT-Advanced . Wiley, 2010, pp. 39–92

    work page 2010

  3. [1]

    Study on Channel Model for Frequencies from 0.5 to 100 GHz (Release 18),

    3GPP TR 38.901 v18.0.0, “Study on Channel Model for Frequencies from 0.5 to 100 GHz (Release 18),” Tech. Rep., Apr. 2024

    work page 2024

  4. [2]

    Study on Channel Model for Frequencies from 0.5 to 100 GHz (Release 19),

    3GPP TR 38.901 v19.0.0, “Study on Channel Model for Frequencies from 0.5 to 100 GHz (Release 19),” Tech. Rep., Jun. 2025

    work page 2025

  5. [3]

    Guidelines for Evaluation of Radio Interface Technolo- gies for IMT-2020,

    ITU-R M.2412, “Guidelines for Evaluation of Radio Interface Technolo- gies for IMT-2020,” Tech. Rep., 2017

    work page 2020

  6. [5]

    World Radiocommunications Conference 2023, WRC-23,

    M. Ghosh, “World Radiocommunications Conference 2023, WRC-23,” IEEE Wireless Communications, vol. 30, no. 6, pp. 4–4, 2023

    work page 2023

  7. [6]

    In Memory of Larry Greenstein, Promi nent Wireless Researcher and ComSoc V olunteer,

    A. Goldsmith, M. Shafi, and S. Weinstein, “In Memory of Larry Greenstein, Promi nent Wireless Researcher and ComSoc V olunteer,” IEEE Communications Magazine , vol. 56, no. 10, pp. 12–13, 2018

    work page 2018

  8. [7]

    Study on Channel Modelling Enhancements for 7-24 GHz for NR,

    RP-234018, “Study on Channel Modelling Enhancements for 7-24 GHz for NR,” 3GPP RAN#102 Plenary, Tech. Rep., 2023

    work page 2023

Show all 15 references
  1. [9]

    Study on new radio access technology Physical layer aspects,

    3GPP TR 38.802 14.2.0, “Study on new radio access technology Physical layer aspects,” Tech. Rep., Sep. 2017. [Online]. Available: https: //www.3gpp.org/ftp//Specs/archive/38 series/38.802/38802-e20.zip

    2017

  2. [10]

    Study on new radio access technology: Radio Frequency (RF) and co-existence aspects,

    3GPP TR 38.803 14.4.0, “Study on new radio access technology: Radio Frequency (RF) and co-existence aspects,” Tech. Rep., Oct

  3. [11]

    R1-2503130: Summary #5 of discus- sions for rel-19 7-24 ghz channel modeling validation,

    Moderator (Intel Corporation), “R1-2503130: Summary #5 of discus- sions for rel-19 7-24 ghz channel modeling validation,” 3GPP TSG RAN WG1 Meeting #120-bis, wuhan, China, Apr. 7–11, 2025

    2025

  4. [12]

    2015, appendix C: CTIA Defined Right Hand Phantom, Rev

    CTIA – The Wireless Association, Test Plan for Wireless Device Over- the-Air Performance , CTIA – The Wireless Association, Jan. 2015, appendix C: CTIA Defined Right Hand Phantom, Rev. 3.8.1

    2015

  5. [13]

    White paper on 5G Channel Model for bands up to 100 GHz,

    “White paper on 5G Channel Model for bands up to 100 GHz,” 2016

    2016

  6. [14]

    Propagation Characteristics of Polarized Radio Waves in Cellular Communications,

    H. Asplund, J.-E. Berg, F. Harrysson et al., “Propagation Characteristics of Polarized Radio Waves in Cellular Communications,” in 2007 IEEE 66th Vehicular Technology Conference. IEEE, 2007, pp. 839–843. Hitesh Poddar (poddarh@sharplabs.com) is a Se- nior Communication Systems...

    2007

  7. [2024]

    Available: https://www.3gpp.org/ftp/Specs/archive/38 series/38.803/38803-e40.zip

    [Online]. Available: https://www.3gpp.org/ftp/Specs/archive/38 series/38.803/38803-e40.zip

Pith tools

Reviewed August 15, 2026 · model on record in the stance chip above.