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arxiv: 2604.06408 · v1 · submitted 2026-04-07 · 💻 cs.NI

Towards Realistic Waveform-Level IoT Network Simulation via IQ Mixing

Alexis Delplace , Samer Lahoud , Kinda Khawam , Dominique Quadri This is my paper

Pith reviewed 2026-05-10 18:01 UTC · model grok-4.3

classification 💻 cs.NI
keywords IoTnetwork simulationwaveform simulationIQ mixingphysical layercoexistenceISM bandbaseband
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The pith

IQSim replaces abstract packet collision models with shared IQ waveform mixing to capture realistic radio impairments in IoT simulations.

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

Traditional IoT network simulators rely on packet-level discrete-event models with analytical interference rules. These approximations overlook waveform-level phenomena such as adjacent-channel leakage and receiver imperfections that affect performance in shared radio bands. The paper presents IQSim as an alternative that maintains a shared complex baseband IQ stream. Transmissions are added as processed waveforms to this stream and then demodulated to determine outcomes. Preliminary results indicate this method can operate in real time while providing higher fidelity for coexistence studies.

Core claim

By maintaining a shared complex baseband IQStream into which simulated transmissions are inserted as IQ waveforms after propagation processing, and then demodulating the resulting stream, IQSim reproduces waveform-level effects like adjacent-channel leakage and cross-modulation that abstract models miss.

What carries the argument

The shared complex baseband IQStream, which accumulates propagated IQ waveforms from multiple transmitters for superposition and delivery to demodulators.

If this is right

  • More accurate prediction of packet errors in scenarios with multiple coexisting IoT protocols.
  • Ability to test interactions with actual hardware receivers or gateways within the simulation.
  • Support for both real-time online simulation and offline detailed analysis.
  • Feasibility of scaling the approach without losing the benefits of waveform detail.

Where Pith is reading between the lines

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

  • Developers of IoT protocols could use this to simulate and mitigate interference issues before deployment.
  • Connecting IQSim to full network stacks might reveal higher-layer impacts of physical impairments.
  • Optimizations for waveform processing could extend its use to very large simulated networks.

Load-bearing premise

That the propagation processing and IQ superposition in the simulation accurately reflect the main impairments encountered in real radio environments.

What would settle it

An experiment comparing the bit or packet error rates produced by IQSim for a specific interference scenario against direct measurements from a hardware testbed using the same signals and receivers.

Figures

Figures reproduced from arXiv: 2604.06408 by Alexis Delplace, Dominique Quadri, Kinda Khawam, Samer Lahoud.

Figure 1
Figure 1. Figure 1: General framework of packet-level wireless network simulators. [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: High-level architecture of IQSim illustrating IQ-based signal genera [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Prototype IQSim used in the preliminary feasibility experiments. [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
read the original abstract

Most Internet of Things (IoT) network simulators are packet-level discrete-event systems in which physical-layer (PHY) behavior is approximated through analytical interference rules and precomputed error models. While this enables scalable experiments, it can miss key waveform-level effects such as adjacent-channel leakage, cross-modulation interference between coexisting signals, and receiver imperfections, which are critical in heterogeneous sub-GHz ISM-band coexistence scenarios. This paper discusses these limitations and introduces IQSim, a simulation paradigm based on in-phase/quadrature (IQ) stream mixing. Instead of predicting packet outcomes from abstract collision models, IQSim maintains a shared complex baseband IQStream into which simulated transmissions are inserted as IQ waveforms after propagation processing, and then demodulated by software-based receivers or hardware gateways. We outline the end-to-end workflow, including online or offline waveform generation, IQ-domain propagation, waveform superposition, and delivery to gateways. We also report preliminary prototype results supporting the feasibility of real-time execution.

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 paper critiques conventional packet-level IoT network simulators for missing waveform-level effects such as adjacent-channel leakage and cross-modulation in heterogeneous sub-GHz ISM-band coexistence. It introduces IQSim, which maintains a shared complex baseband IQStream into which simulated transmissions are inserted as IQ waveforms after propagation processing; the superposed stream is then demodulated by software receivers or hardware gateways. The manuscript outlines the end-to-end workflow (waveform generation, IQ-domain propagation, superposition, delivery) and reports preliminary prototype results supporting real-time execution feasibility.

Significance. If validated with quantitative evidence, the approach could meaningfully advance IoT simulation fidelity by directly modeling PHY impairments that packet-level abstractions approximate, enabling more reliable coexistence studies. The potential for hardware-in-the-loop integration is a strength. However, the current absence of error metrics or hardware comparisons limits the assessed significance to conceptual promise rather than demonstrated improvement.

major comments (2)
  1. [Abstract] Abstract (preliminary prototype results paragraph): The results are described only as supporting real-time execution feasibility, with no quantitative validation data, error metrics (e.g., BER/PER), or comparisons against over-the-air captures or full RF-chain simulations. This is load-bearing for the central claim that simplified IQ mixing reproduces dominant real impairments, as the introduction explicitly contrasts the method against models that miss leakage and cross-modulation.
  2. [Workflow description] Workflow description (IQ-domain propagation and superposition steps): No explicit models are provided for transmitter/receiver nonlinearities, phase noise, or frequency-dependent antenna effects, despite the introduction noting that traditional packet models miss these. Without such components, the superposition step risks omitting the very hardware-specific impairments the paradigm aims to capture.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments on our manuscript. We address each major comment below and indicate the revisions we will make to strengthen the paper.

read point-by-point responses

  1. Referee: [Abstract] Abstract (preliminary prototype results paragraph): The results are described only as supporting real-time execution feasibility, with no quantitative validation data, error metrics (e.g., BER/PER), or comparisons against over-the-air captures or full RF-chain simulations. This is load-bearing for the central claim that simplified IQ mixing reproduces dominant real impairments, as the introduction explicitly contrasts the method against models that miss leakage and cross-modulation.

    Authors: We agree that the abstract and results section focus on feasibility of real-time execution rather than providing quantitative validation metrics such as BER or comparisons to hardware. The paper introduces the IQSim concept and demonstrates its basic operation through a prototype. To address this, we will revise the abstract to explicitly state that the results are preliminary and support feasibility, while noting that comprehensive validation of impairment reproduction is part of ongoing work. revision: yes

  2. Referee: [Workflow description] Workflow description (IQ-domain propagation and superposition steps): No explicit models are provided for transmitter/receiver nonlinearities, phase noise, or frequency-dependent antenna effects, despite the introduction noting that traditional packet models miss these. Without such components, the superposition step risks omitting the very hardware-specific impairments the paradigm aims to capture.

    Authors: The introduction highlights that packet-level models miss waveform effects including leakage and cross-modulation, which the IQ mixing approach captures through direct superposition of waveforms. However, we acknowledge that the current workflow description does not explicitly detail models for nonlinearities, phase noise, or frequency-dependent effects. The prototype uses a linear propagation model to establish the core mixing mechanism. We will revise the workflow section to include a discussion on how these additional impairments can be incorporated into the framework via modular processing blocks, and clarify the scope of the initial implementation. revision: partial

Circularity Check

0 steps flagged

No circularity detected in IQSim workflow or claims

full rationale

The paper proposes a new simulation paradigm (IQ stream mixing for waveform-level IoT networks) without any mathematical derivation chain, fitted parameters, or predictions. The core description—maintaining a shared complex baseband IQStream, inserting pre-processed waveforms after propagation, superposing them, and delivering to demodulators—is presented as an independent workflow. No equations, self-citations, or ansatzes are invoked in a load-bearing way that reduces the method to its own inputs by construction. Preliminary feasibility results are cited only for execution speed, not as self-referential validation of accuracy. This is a standard non-circular conceptual/methodological contribution.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 1 invented entities

The approach rests on the domain assumption that waveform-level effects dominate performance in heterogeneous sub-GHz scenarios and on the unproven claim that IQ superposition can be performed efficiently at useful scale. No free parameters are fitted and no new physical entities are postulated beyond the IQStream data structure itself.

axioms (1)
  • domain assumption Waveform-level effects such as adjacent-channel leakage and cross-modulation interference are critical in heterogeneous sub-GHz ISM-band coexistence scenarios
    Explicitly stated as the motivation for moving beyond packet-level models.
invented entities (1)
  • IQStream no independent evidence
    purpose: Shared complex baseband container that receives inserted waveforms and enables superposition before receiver processing
    Core data structure of the new simulation method; no independent evidence of its accuracy beyond the abstract's feasibility claim.

pith-pipeline@v0.9.0 · 5472 in / 1354 out tokens · 70933 ms · 2026-05-10T18:01:55.124813+00:00 · methodology

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Reference graph

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