You May Use the Same Channel Knowledge Map for Environment-Aware NLoS Sensing and Communication
Pith reviewed 2026-05-19 06:04 UTC · model grok-4.3
The pith
The same channel knowledge map built for communication can be reused for non-line-of-sight sensing by converting its priors.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
By treating the sensing targets as virtual user equipments, the wireless communication channel priors stored in the channel knowledge map are transformed into the sensing channel priors. This allows a single map, such as the channel angle-delay map, to provide the necessary angle-delay information for sensing target localization in non-line-of-sight scenarios.
What carries the argument
The channel angle-delay map (CADM) that stores environment-specific angle and delay distributions from communication channels and converts them into equivalent priors for the sensing channel.
If this is right
- Sensing accuracy improves over classic geometry-based methods in blocked environments.
- A single map supports both communication and sensing, cutting the need for separate databases.
- The framework enables integrated sensing and communication in urban low-altitude airspace with signal blockages.
- Cramer-Rao Lower Bound analysis confirms the performance advantage of the shared priors.
Where Pith is reading between the lines
- The reuse strategy could reduce overall mapping overhead when deploying integrated sensing and communication in future networks.
- Similar prior transformations might work for other channel features if stable relationships can be established.
- Joint updates to the shared map from both communication and sensing observations could improve long-term accuracy in changing environments.
Load-bearing premise
The angle-delay distributions for communication and sensing channels are related in a stable and known way that permits accurate prior transformation.
What would settle it
Real-world measurements or simulations in an NLoS urban setting where localization error using the transformed priors from the communication map shows no improvement over geometry-based methods would disprove the claimed benefit.
Figures
read the original abstract
As one of the key usage scenarios for the sixth generation (6G) wireless networks, integrated sensing and communication (ISAC) provides an efficient framework to achieve simultaneous wireless sensing and communication. However, traditional wireless sensing techniques mainly rely on the line-of-sight (LoS) assumptions, i.e., the sensing targets are directly visible to both the sensing transmitter and receiver. This hinders ISAC systems to be applied in complex environments such as the urban low-altitude airspace, which usually suffers from signal blockage and non-line-of-sight (NLoS) multi-path propagation. To address this challenge, in this paper, we propose a novel approach to enable environment-aware NLoS ISAC by leveraging the new technique called channel knowledge map (CKM), which was originally proposed for environment-aware wireless communications. One major novelty of our proposed method is that the same CKM built for wireless communication can be directly used to enable NLoS wireless sensing, thus enjoying the benefits of ``killing two birds with one stone''. To this end, the sensing targets are treated as virtual user equipment (UE), and the wireless communication channel priors are transformed into the sensing channel priors, allowing one single CKM to serve dual purposes. We illustrate our proposed framework by a specific CKM called \emph{channel angle-delay map} (CADM). Specifically, the proposed framework utilizes CADM to derive angle-delay priors of the sensing channel by exploiting the relationship between communication and sensing angle-delay distributions, enabling sensing target localization in the challenging NLoS environment. Extensive simulation results demonstrate significant performance improvements over classic geometry-based sensing methods, which is further validated by Cram\'er-Rao Lower Bound (CRLB) analysis.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes using a single channel knowledge map (CKM), specifically the channel angle-delay map (CADM) built from communication measurements, for environment-aware NLoS integrated sensing and communication (ISAC). Sensing targets are treated as virtual UEs, allowing communication angle-delay priors to be transformed into sensing channel priors for target localization in blocked environments. Simulations show performance gains over geometry-based methods, with validation against the Cramér-Rao lower bound (CRLB).
Significance. If the prior transformation is reliable, the work enables efficient dual-use of communication CKMs for NLoS sensing, reducing overhead in 6G ISAC systems operating in complex urban or low-altitude settings where LoS assumptions fail. The reported simulation gains and CRLB analysis constitute concrete, falsifiable evidence supporting the central claim.
major comments (2)
- [Framework for CADM-based NLoS sensing prior derivation] The central transformation step (invoked when deriving angle-delay priors for the sensing channel from the CADM) assumes a stable, environment-independent mapping between communication and sensing angle-delay distributions. No explicit functional form, invariance proof, or sensitivity result with respect to target position, scatterer geometry, or blockage patterns is supplied, which is load-bearing for the claim that one CKM serves both purposes without prior mismatch.
- [Simulation results and CRLB validation] The abstract and results section report significant performance improvements over geometry-based sensing methods. However, the simulation setup lacks explicit details on NLoS channel generation rules, data exclusion criteria, and whether any parameters in the prior transformation were tuned post-hoc, undermining confidence that the gains are not artifacts of the evaluation design.
minor comments (2)
- [Introduction] The distinction between general CKM and the specific CADM instantiation is introduced late; moving a concise definition to the introduction would improve readability.
- [System model] A few sentences on how the virtual-UE treatment interacts with multi-path components in the sensing channel would clarify the model assumptions.
Simulated Author's Rebuttal
We thank the referee for the constructive and detailed comments on our manuscript. We address each major comment below and indicate the corresponding revisions planned for the updated version.
read point-by-point responses
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Referee: [Framework for CADM-based NLoS sensing prior derivation] The central transformation step (invoked when deriving angle-delay priors for the sensing channel from the CADM) assumes a stable, environment-independent mapping between communication and sensing angle-delay distributions. No explicit functional form, invariance proof, or sensitivity result with respect to target position, scatterer geometry, or blockage patterns is supplied, which is load-bearing for the claim that one CKM serves both purposes without prior mismatch.
Authors: We agree that an explicit functional form and supporting analysis would improve clarity. Section III of the manuscript describes the transformation by modeling sensing targets as virtual UEs and mapping the shared angle-delay distributions from the CADM based on common scatterers. To strengthen this, we will add the explicit mathematical expression for the prior mapping, a short invariance argument under the fixed-environment assumption, and a sensitivity study with respect to target position and blockage variations in the revised manuscript. revision: yes
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Referee: [Simulation results and CRLB validation] The abstract and results section report significant performance improvements over geometry-based sensing methods. However, the simulation setup lacks explicit details on NLoS channel generation rules, data exclusion criteria, and whether any parameters in the prior transformation were tuned post-hoc, undermining confidence that the gains are not artifacts of the evaluation design.
Authors: We acknowledge the need for greater transparency in the evaluation setup. The NLoS channels are generated via a geometry-based stochastic model with fixed blockage patterns, as outlined in Section IV. In the revision we will expand this section to specify the exact channel generation parameters, the criteria used to exclude invalid multipath components, and an explicit statement that all transformation parameters were obtained directly from the CADM without post-hoc tuning. revision: yes
Circularity Check
No circularity: framework proposes external relationship exploitation without self-referential reduction
full rationale
The paper's central step treats sensing targets as virtual UEs and transforms communication angle-delay priors into sensing priors by exploiting the relationship between the two distributions. This is presented as domain knowledge applied to the CADM rather than a quantity fitted inside the paper or defined in terms of the output. No equations reduce the claimed localization gains to a parameter estimated from the same sensing data, nor does any self-citation chain supply an unverified uniqueness result that forces the mapping. Simulations and CRLB analysis provide independent validation checks. The derivation therefore remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption A stable and exploitable relationship exists between communication and sensing angle-delay distributions that permits direct transformation of priors from the communication CKM to the sensing channel.
Lean theorems connected to this paper
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IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
the wireless communication channel priors are transformed into the sensing channel priors... exploiting the relationship between communication and sensing angle-delay distributions (eqs. 29-31, CADM Gaussian model (35), FCNN (36))
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IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
CADM... learn the mapping from location to these statistical parameters... N(θl′; μθ,l′(q), σ²θ,l′(q)) ... for target sensing, we perform maximum likelihood (ML) estimation
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Forward citations
Cited by 1 Pith paper
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Channel Knowledge Map-Enabled NLoS ISAC Localization
A CKM-based framework learns scatterer priors offline from path signatures and uses online matching plus NLS to localize users in NLoS ISAC scenarios, outperforming fingerprinting in simulations.
Reference graph
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discussion (0)
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