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arxiv: 2606.30407 · v1 · pith:2CFCI2JMnew · submitted 2026-06-29 · 💻 cs.IT · math.IT

Preprocessing for Physical-Layer Security in Wireless THz-Communication

Rebekka Schulz , Robert F.H. Fischer This is my paper

Pith reviewed 2026-06-30 03:30 UTC · model grok-4.3

classification 💻 cs.IT math.IT
keywords physical-layer securityTHz communicationMIMOpreprocessingsecrecy ratelattice reductionerror performancewireless security
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The pith

Optimizing preprocessing in THz-MIMO systems can achieve both reliable communication for the intended receiver and security against eavesdroppers.

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

The paper examines preprocessing at the transmitter to support physical-layer security in wireless THz multiple-input multiple-output links. It compares optimization criteria based on error performance versus transmission rate, with versions that use only the legitimate receiver's channel and versions that also incorporate the eavesdropper. For each criterion, both standard linear preprocessing and lattice-reduction-aided versions are evaluated through numerical simulations that track secrecy rates and error ratios. A reader would care because THz bands offer high data rates for future wireless systems but need built-in ways to limit information leakage without extra cryptographic overhead.

Core claim

Optimization of the preprocessing matrix, performed either to improve error performance or transmission rate and either with or without the eavesdropper channel, yields positive secrecy rates together with acceptable error ratios at the legitimate receiver when linear or lattice-reduction-aided designs are applied in the THz-MIMO setting.

What carries the argument

The preprocessing matrix at the transmitter, optimized under error or rate criteria and with or without eavesdropper information, using either linear or lattice-reduction-aided designs.

If this is right

  • Including the eavesdropper channel in the optimization improves the achieved secrecy rate compared with receiver-only designs.
  • Lattice-reduction-aided preprocessing produces lower error ratios than linear preprocessing under the same optimization criterion.
  • Optimizing for error performance tends to favor reliability while optimizing for rate tends to favor secrecy in the simulated scenarios.
  • All variants produce positive secrecy rates in the considered THz-MIMO channel models.

Where Pith is reading between the lines

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

  • The same preprocessing approach could be tested in other high-frequency bands if similar channel statistics apply.
  • Adding explicit modeling of hardware impairments would show how much the simulated gains shrink in practice.
  • Combining the preprocessing with power allocation or antenna selection might further raise the secrecy rates.

Load-bearing premise

The simulated channel models and optimization criteria accurately capture the security-performance trade-offs that would occur in a real THz deployment with hardware impairments and imperfect channel knowledge.

What would settle it

A real THz-MIMO hardware test showing secrecy rates well below the simulated values when hardware impairments or channel estimation errors are present would falsify the claim that the optimized preprocessing delivers the reported security and reliability.

Figures

Figures reproduced from arXiv: 2606.30407 by Rebekka Schulz, Robert F.H. Fischer.

Figure 1
Figure 1. Figure 1: Considered transmission scenario. arXiv:2606.30407v1 [cs.IT] 29 Jun 2026 [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Block diagram of the communication setup. The left [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Lattice reduction is done based on the cascade of [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Comparison of LP-EB, LRP-EB, LP-RB, and LRP￾RB over the SNR for Bob and Eve1. Top: SER, bottom: rates and secrecy rate. B. Exemplary Positions Firstly, we consider an exemplary position of an eavesdropper, who is placed at the same height as Bob with a small distance in position [1 m, 1 m, 0]. For the exemplary positions 100 random rotations are considered for the antenna arrays of Eve and 800 different ro… view at source ↗
Figure 6
Figure 6. Figure 6: Secrecy rates and Bob’s SER of different prepro [PITH_FULL_IMAGE:figures/full_fig_p007_6.png] view at source ↗
Figure 5
Figure 5. Figure 5: Comparison of LP-ES, LRP-ES, LP-RS, and LRP￾RS over the SNR for Bob and Eve1. Top: SER, bottom: rates and secrecy rate. The lower part of [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
Figure 7
Figure 7. Figure 7: Comparison of the SER different preprocessing [PITH_FULL_IMAGE:figures/full_fig_p008_7.png] view at source ↗
read the original abstract

In this paper, the usage of preprocessing to achieve physical-layer security in a wireless THz-MIMO scenario is investigated. The goal is a reliable and secure communication. Optimization of the preprocessing is done either based on the error performance or the transmission rate. For both criteria, we present a variant that is based only on the legitimate receiver or also includes the eavesdropper. For each variant, linear and lattice-reduction-aided approaches are considered. Numerical simulations are used to assess the resulting secrecy rates and error ratios. A comparison between all variants is compiled and the possible trade-offs are discussed.

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 / 0 minor

Summary. The manuscript investigates preprocessing techniques to achieve physical-layer security in a THz-MIMO wireless scenario. The goal is reliable and secure communication via optimization of preprocessing based on either error performance or transmission rate. Variants are considered that account only for the legitimate receiver or also include the eavesdropper; for each, both linear and lattice-reduction-aided approaches are examined. Performance is evaluated exclusively through numerical simulations of secrecy rates and error ratios, followed by comparisons and discussion of trade-offs.

Significance. If the simulation results prove robust, the work offers practical comparisons of preprocessing variants for PLS in THz systems, an area of growing interest due to high-frequency propagation challenges. The explicit inclusion of both error- and rate-based criteria, with and without eavesdropper knowledge, provides useful design insights. No machine-checked proofs, parameter-free derivations, or reproducible code are present, so the significance remains tied to the validity of the underlying simulation assumptions.

major comments (2)
  1. [Abstract] Abstract (and implied simulation sections): the central claim that the listed preprocessing variants achieve reliable+secure communication rests on unspecified channel models and a perfect-CSI assumption; this is load-bearing because, as noted in the stress-test, mismatch with real THz effects (molecular absorption, phase noise, estimation errors) can nullify the reported positive secrecy rates while the optimization still executes.
  2. [Numerical simulations] Numerical simulations (throughout): no sensitivity analysis or discussion of hardware impairments is provided, so the reported secrecy-rate and error-ratio improvements cannot be assessed for stability under the imperfect-CSI conditions that the weakest-assumption note identifies as critical.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback highlighting the importance of clearly stating modeling assumptions. We address the two major comments below and will revise the manuscript to improve clarity on the idealized conditions used.

read point-by-point responses

  1. Referee: [Abstract] Abstract (and implied simulation sections): the central claim that the listed preprocessing variants achieve reliable+secure communication rests on unspecified channel models and a perfect-CSI assumption; this is load-bearing because, as noted in the stress-test, mismatch with real THz effects (molecular absorption, phase noise, estimation errors) can nullify the reported positive secrecy rates while the optimization still executes.

    Authors: The full manuscript specifies a standard THz-MIMO channel model (including molecular absorption) in the system model section, with all results derived under the perfect-CSI assumption at the transmitter. The reported secrecy rates and error ratios hold only under these conditions, which is standard for initial studies of preprocessing techniques. We will revise the abstract to explicitly state the perfect-CSI assumption and add a clarifying sentence in the introduction noting that real-world effects such as phase noise or CSI mismatch are outside the current scope. revision: yes

  2. Referee: [Numerical simulations] Numerical simulations (throughout): no sensitivity analysis or discussion of hardware impairments is provided, so the reported secrecy-rate and error-ratio improvements cannot be assessed for stability under the imperfect-CSI conditions that the weakest-assumption note identifies as critical.

    Authors: We agree a discussion of robustness would be beneficial. The paper's focus is the comparison of linear and lattice-reduction-aided preprocessing under ideal conditions; a full sensitivity analysis with hardware impairments would require substantial additional simulation campaigns beyond the present scope. We will add a dedicated paragraph in the numerical results section discussing the impact of potential impairments (e.g., estimation errors) as a limitation and direction for future work. revision: partial

Circularity Check

0 steps flagged

No circularity: simulation-based comparison of preprocessing variants is independent of inputs

full rationale

The paper presents an empirical study of linear and lattice-reduction-aided preprocessing optimizations for THz-MIMO physical-layer security. Optimizations are performed on standard criteria (error performance or transmission rate) with variants that optionally include the eavesdropper; results are evaluated via numerical simulations of secrecy rates and error ratios. No derivation chain, fitted parameters renamed as predictions, self-citations used as load-bearing uniqueness theorems, or ansatzes smuggled via prior work are present. The central claims rest on direct simulation outputs rather than any reduction to the paper's own definitions or inputs. This is the expected non-finding for a simulation-driven engineering paper whose assumptions (channel models, perfect CSI) are stated as modeling choices rather than derived results.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review; no explicit free parameters, axioms, or invented entities are stated. The central claim implicitly rests on standard assumptions about MIMO channel models and perfect knowledge of legitimate and eavesdropper channels during optimization.

pith-pipeline@v0.9.1-grok · 5615 in / 1106 out tokens · 30389 ms · 2026-06-30T03:30:52.763356+00:00 · methodology

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