



CATS WG                                                    CJ. Bernardos
Internet-Draft                                                      UC3M
Intended status: Standards Track                               A. Mourad
Expires: 4 January 2026                                     InterDigital
                                                                T. Jiang
                                                                    CMCC
                                                             3 July 2025


         Integrated Sensing and Communications (ISAC) for CATS
                    draft-bernardos-cats-isac-uc-01

Abstract

   Integrated Sensing and Communications (ISAC) represents a paradigm
   shift in wireless networks, where sensing and communication functions
   are jointly designed and optimized.  By leveraging the same spectral
   and hardware resources, ISAC enables advanced capabilities such as
   environment perception, object tracking, and situational awareness,
   while maintaining efficient and reliable data transmission.  This
   integration holds great potential for applications in areas such as
   autonomous systems, smart cities, and industrial automation, where
   precise sensing and low-latency communication are critical.  This
   document presents the ISAC as a typical CATS scenario to facilitate
   discussions on the potential challenges and requirements.

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   This Internet-Draft will expire on 4 January 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Computing Aware distributed sensing for Integrated Sensing and
           Communications  . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  CATS of ETSI ISAC . . . . . . . . . . . . . . . . . . . .   3
     2.2.  CATS of 3GPP ISAC . . . . . . . . . . . . . . . . . . . .   6
     2.3.  Relation to CATS  . . . . . . . . . . . . . . . . . . . .   7
     2.4.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   7
     2.5.  Additional remarks  . . . . . . . . . . . . . . . . . . .   8
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Informative References  . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Integrated Sensing and Communications (ISAC) is emerging as a key
   enabler for next-generation wireless networks, integrating sensing
   and communication functionalities within a unified system.  By
   leveraging the same spectral, hardware, and computational resources,
   ISAC enhances network efficiency while enabling new capabilities such
   as high-resolution environment perception, object detection, and
   situational awareness.  This paradigm shift is particularly relevant
   for applications requiring both reliable connectivity and precise
   sensing, such as autonomous vehicles, industrial automation, and
   smart city deployments.  Given its strategic importance, ISAC has
   gained significant traction in standardization efforts.













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   While the ETSI Industry Specification Group (ISG) on ISAC has been
   established to explore technical requirements and use cases, the 3GPP
   organization has approved the 5G study work in its release 20 (rel-
   20) and initiated the investigation on ISAC-related features
   [TR.23.700-14].  Moreover, 3GPP has agreed to continue the sensing
   related research on future 6G systems.  Furthermore, research
   initiatives within the IEEE and IETF are investigating how ISAC can
   be integrated into network architectures, spectrum management, and
   protocol design, making it a critical area of development in the
   evolution of wireless networks.

   This document presents the ISAC as a typical CATS scenario, being
   supplementary to the CATS use cases as in
   [I-D.ietf-cats-usecases-requirements], to facilitate discussions on
   the potential challenges, and requirements.  Further, the document
   references the new draft on CATS reference model
   [IETF-CATS-RefModel-ACN] to briefly discuss how the ISAC case may
   leverage the model.

2.  Computing Aware distributed sensing for Integrated Sensing and
    Communications

   Integrated Sensing and Communications (ISAC) enables wireless
   networks to perform simultaneous data transmission and environmental
   sensing.  In a distributed sensing scenario, multiple hardware
   network entities, such as base stations, access points, or edge
   devices (e.g., wireless terminal equipment), and intelligent agents
   deployed as software instances on the entities (e.g., AI-agents) --
   collect raw sensing data from the environment.  These data can
   include radio frequency (RF) reflections, Doppler shifts, channel
   state information (CSI), or other physical-layer features that
   provide insights into object movement, material composition, or
   environmental conditions.  To extract meaningful information, the
   collected raw data must be aggregated and processed by a designated
   computing node with sufficient computational resources.  This
   requires efficient coordination between sensing nodes and computing
   resources to ensure timely and accurate analysis, making it a
   relevant scenario for Computing-Aware Traffic Steering (CATS) in
   IETF.

2.1.  CATS of ETSI ISAC

   This use case aligns with ongoing efforts in standardization bodies
   such as the ETSI ISAC Industry Specification Group (ISG),
   particularly Work Item #5 (WI#5), titled 'Integration of Computing
   with ISAC'.  WI#5 focuses on exploring different forms of computing
   integration within ISAC systems, including sensing combined with
   computing, communications combined with computing, and the holistic



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   integration of ISAC with computing.  The considerations outlined in
   this document complement ETSI's work by examining how computing-aware
   networking solutions, as developed within CATS, can optimize the
   processing and routing of ISAC sensing data.

   As an example, we can consider a network domain with multiple sites
   capable of hosting the ISAC computing "service", each with
   potentially different connectivity and computing characteristics.
   Figure 1 shows an exemplary scenario.  Considering the connectivity
   and computing latencies (just as an example of metrics), the best
   service site is #n-1 in the example used in the Figure.  Note that in
   the figure we still use the old terminology in which by ICR we mean
   Ingress CATS-Forwarder [I-D.ietf-cats-framework], and by ECR we mean
   Egress CATS-Forwarder.





































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                                ________________
                               (     ---------- )
                              (      |        |  )
                            (     ---------- |   )
      ________________     (     |        | |    )     _______________
     (     ---------- )    (   ---------- | |    )    (    ---------- )
    (      |        |  )   (   |service | |-     )   (     |        |  )
   (     ---------- |   )  (   |contact | |      )  (    ---------- |  )
   (     |        | |   )  (   |instance|--      )  (    |        | |  )
   (   ---------- | |   )   (  ----------       )   (  ---------- | |  )
   (   |service | |-    )    ( Serv. site #N-1 )    (  |service | |-   )
   (   |contact | |     )     -------+----------     (  |contact | |   )
   (   |instance|--    )   Computing  \              (  |instance|--   )
    (  ----------     )    delay:4ms   \              ( ----------     )
     ( Serv. site #1 )           --------+--           ( Serv. site #N )
      -------+--------       ----| ECR#N-1 |----        ---------+-----
              \  Computing --     -----------    --  Computing  /
               \ delay:10ms      Networking          delay:5ms /
             ---+-----           delay:7ms              ------+--
           ( | ECR#1 |            //                    | ECR#N | )
          (  ---------           //                     ---------  )
         ( Networking           //                       Networking )
        (  delay:5ms           //                         delay:15ms )
       (                      //                                      )
       (                     //                                       )
        (                   //                                       )
         (                 //                                       )
          (               //                                       )
           (       ---------                     ---------        )
            -------| ICR#1 |---------------------| ICR#2 |--------
                   ---------           __         ---------
                   (·)   (·)        / (  )           (·)
                  (·)   -------   -  (    )         (·)
                 (·)    | UE2 | /     (__) \      (·)
                (·)     -------    /         -   -------
               (·)               /  (sensing  \  | UE3 |
             -------   ---------                 -------
             | UE1 | /
             -------

                        Figure 1: Exemplary scenario










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2.2.  CATS of 3GPP ISAC

   3GPP has specified in the stage-1 document [TR.22.870] the
   requirements & objectives of ISAC service.  Fundamentally, the ISAC
   service includes offering wide area multi-dimensional sensing that
   provides spatial information about non-connected objects as well as
   connected devices and their movements and surroundings.
   Successively, the 3GPP SA2 WG has approved a study item (SID) in its
   rel-20 and initiated the investigation on ISAC-related features
   [TR.23.700-14].  Moreover, 3GPP has agreed to continue the sensing
   related research on the on-going 6G studies.

   The Figure 2 describes a possible sensing architecture that conforms
   to the architectural assumptions as in [TR.23.700-14].  The figure
   shows that there could be multiple authorized sensing entities, e.g.,
   (R)ANs, TEs (with sensors).  Also, a new sensing function, i.e.,
   SeNF, is promoted.  Note the name of the sensing function is still up
   for discussion.

          SeNF: Sensing Network Function
          Sensing Entities: TE (Terminal Equip), (g)RAN
                 ...........................................
                 :                                +-----+  :   +-------+
                 :                                | NEF |------| AF/AS |
                 :      +-----+                   +-----+  :   +-------+
                 :      | AMF |                     |      :
                 :      +-----+                     |      :
                 :         |       +------+      +-----+   :
                 :   ......|.......| SeNF |------| PCF |   :
                 :   :     |       +------+      +-----+   :
                 :   :     |      /                        :
       +------+  :   :     |     /                         :
       | TE#1 |......:     |    /                          :
       +------+  :   :     |   /                           :
       +------+......:  +------+        +-----+            :  +--------+
       | TE#2 |--:------|(g)RAN|--------| UPF |------------:--|  Data  |
       +------+  :      +------+        +-----+            :  | Network|
                 :                                         :  +--------+
                 :.........................................:


                  Figure 2: 3GPP ISAC exemplary scenario

   There might be multiple SeNFs in a wireless network, with each SeNF
   capable of handling both the CP and UP of the sensing service.  A
   SeNF can process received sensing data, aggregate sensing reports,
   run detection algorithms, and filter noise - to produce the sensing
   result that meets the service request.  A SeNF may also expose the



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   sensing results to external App servers (namely AS'es).  Given the
   complex yet computationally-heavy tasks as conducted by the SeNF, the
   selection of an optimal SeNF (among all SeNF candidates) embodies the
   principles of CATS.

   Sensing entities on (authorized) UEs may instantiate as software AI-
   agents with sensing functionality.  If there is a large amount of
   collected sensing measurement data, then there might be a need to
   expose (i.e., transmit) the data to (external) service instances
   (e.g., in local premise) for optimized processing (if the local
   compute power at an agent is insufficient or is overloaded).  After
   that can the processed sensing results be sent to the original
   sensing requestor for further processing.  This kind of task
   redirection for better processing efficiency conforms to what the
   CATS strives for.

2.3.  Relation to CATS

   In the distributed sensing scenario, the sensed data collected by
   multiple nodes must be efficiently routed to a computing node capable
   of processing it.  The choice of the computing node depends on
   several factors, including computational load, network congestion,
   and latency constraints.  CATS mechanisms can optimize the selection
   of the processing node by dynamically steering the traffic based on
   computing resource availability and network conditions.
   Additionally, as sensing data is often time-sensitive, CATS can
   ensure low-latency paths while balancing computational demands across
   different processing entities.  This capability is essential for
   real-time applications such as cooperative perception for autonomous
   systems, industrial monitoring, and smart city infrastructure.

   Further, the draft [IETF-CATS-RefModel-ACN] has proposed a CATS
   reference model that operates on general reference points for the
   signaling exchanges of various types of metrics, i.e., network,
   compute and the new AI-agent metrics as defined in the draft.  The
   ISAC scenario for CATS may leverage the model for better operations.
   For example, the IETF Draft of CATS reference model for ACN defines
   the reference points or RPs, e.g., the RPs between C-PS --- C-NMA,
   C-PS --- C-SMA, and AIA (AI-agent) --- C-PS, etc.  The ISAC scenario
   may leverage the AI-agent logics and extend the RPs to sensing: AIA
   (sensing) --- C-PS.  In some scenario in the context of 3GPP, here
   the C-PS can even be a 3rd-party entity like AF/AS.

2.4.  Requirements

   Several challenges need to be addressed for efficient distributed
   sensing in ISAC-enabled networks:




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   *  Traffic Steering and Resource Allocation: Ensuring that sensing
      data is directed to the most suitable computing node while
      considering both network conditions and processing availability.

   *  Latency Sensitivity: Many ISAC applications require near-real-time
      processing, necessitating low-latency and high-reliability data
      forwarding strategies.

   *  Data Synchronization: Sensing nodes may have different
      perspectives on the environment, requiring synchronization and
      fusion of data streams before processing.

   *  Scalability: As the number of participating sensing nodes
      increases, mechanisms must efficiently distribute and balance the
      computational workload.

   *  Security and Privacy: Sensed data may contain sensitive
      information, requiring mechanisms for secure transmission and
      processing.

   *  Holistic Reference Model: Potentially a general CATS reference
      model with reference points for the signaling exchanges of various
      types of metrics among CATS entities and sensing entities.

2.5.  Additional remarks

   The integration of ISAC-based distributed sensing into CATS
   frameworks may require enhancements in computing-aware routing
   protocols, traffic steering algorithms, signaling mechanisms, and
   potentially the integration of the CATS reference model.
   Standardization efforts could focus on defining metrics for
   computing-aware path selection that is based not only on the existing
   CATS metrics but also with any future extensions (e.g., 'AI-agent
   metrics' in [IETF-CATS-RefModel-ACN]), developing mechanisms for
   real-time coordination between sensing and computing nodes, and
   ensuring interoperability with existing network architectures.
   Furthermore, coordination with ETSI & 3GPP may help align the
   development of computing-aware ISAC networking solutions with ongoing
   standardization efforts in computing integration, ensuring cross-
   industry compatibility and deployment feasibility.

3.  IANA Considerations

   N/A.







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4.  Security Considerations

   TBD.

5.  Acknowledgments

   The work of Carlos J.  Bernardos in this document has been partially
   supported by the Horizon Europe MultiX (Grant Agreement No.
   101192521) and Hexa-X-II (Grant Agreement No. 101095759) projects.

6.  Informative References

   [I-D.ietf-cats-framework]
              Li, C., Du, Z., Boucadair, M., Contreras, L. M., and J.
              Drake, "A Framework for Computing-Aware Traffic Steering
              (CATS)", Work in Progress, Internet-Draft, draft-ietf-
              cats-framework-10, 24 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cats-
              framework-10>.

   [I-D.ietf-cats-usecases-requirements]
              Yao, K., Contreras, L. M., Shi, H., Zhang, S., and Q. An,
              "Computing-Aware Traffic Steering (CATS) Problem
              Statement, Use Cases, and Requirements", Work in Progress,
              Internet-Draft, draft-ietf-cats-usecases-requirements-07,
              10 June 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-cats-usecases-requirements-07>.

   [IETF-CATS-RefModel-ACN]
              Jiang, T., et al., "CATS Reference Model for AI-Agent
              Communication Network",  
              https://datatracker.ietf.org/doc/draft-jiang-cats-
              reference-acn, June 2025.

   [TR.22.870]
              "3GPP TR 22.870 v0.3.0: Study on 6G Use Cases and Service
              Requirements; Stage 1, Rel-20",  3GPP TR 22.870, May 2025.

   [TR.23.700-14]
              "3GPP TR 23.700-14 v0.2.0: Study on Stage 2 for Integrated
              Sensing and Communication",  3GPP TR 23.700-14, June 2025.

Authors' Addresses








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   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av. Universidad, 30
   28911 Leganes, Madrid
   Spain
   Phone: +34 91624 6236
   Email: cjbc@it.uc3m.es
   URI:   http://www.it.uc3m.es/cjbc/


   Alain Mourad
   InterDigital Europe
   Email: Alain.Mourad@InterDigital.com
   URI:   http://www.InterDigital.com/


   Tianji Jiang
   China Mobile
   Email: tianjijiang@yahoo.com
































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