Device and method for sensing using reference objects

Abstract

The present disclosure relates to integrated sensing and communications. A mechanism for calibrating sensing nodes in a mobile radio network using reference objects is provided. A sensing control entity is configured to provide assistance information to sensing nodes for bias-free sensing measurements. The assistance information provided to a sensing transmitter includes information associated with one or more reference objects. The assistance information provided to a sensing receiver includes information for obtaining sensing measurements. The sensing nodes, such as user equipment, base stations, and roadside units, may be dynamically selected to perform bistatic sensing in downlink, uplink, sidelink, or cross-link configurations. The system ensures robust calibration by leveraging environmental reference objects. The disclosure can improve sensing accuracy, and enhances the reliability of joint communication and sensing systems.

Description

[0001] DEVICE AND METHOD FOR SENSING USING REFERENCE OBJECTS

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to the field of wireless technology. For instance, the disclosure relates to a control entity and a sensing device.

[0004] BACKGROUND

[0005] Radio access networks (RAN) are deployed for communication purposes, enabling the transmission of information between nodes via radio signals. As these radio signals propagate through the environment, interacting with various objects and surfaces, they may also be utilized to extract information about the environment. This capability has paved the way for the evolution of next-generation RANs, where radio nodes are envisioned as multifunctional devices capable of both communication and sensing.

[0006] In an integrated sensing and communication system, radio nodes, such as base stations, user devices (or user equipment, UE), and any other entities capable of transmitting and / or receiving radio signals, play a pivotal role. These radio nodes can leverage their sensing capabilities to extract detailed environmental information, opening new opportunities for applications beyond traditional communication systems.

[0007] SUMMARY

[0008] Environment sensing can be realized using different sensing configurations within a RAN. For instance, monostatic sensing involves a co-located transmitter and receiver, while bistatic sensing deploys the transmitter and receiver on separate nodes. Among these configurations, UE-assisted bistatic sensing introduces significant advantages by leveraging the mobility of UEs. A moving UE can function as a dynamic sensing node, enabling the creation of large synthetic antenna apertures that enhance sensing resolution. Furthermore, activating a UE as a sensing node allows coverage of occluded areas that may not be accessible from the perspective of a base station, thereby extending the network's sensing capabilities.

[0009] One critical challenge to employ user devices as sensing nodes is synchronization. Each user device operates using its own local oscillator and hardware, which means the clocks at the RAN nodes and the UEs are not locked. This lack of clock synchronization introduces time-varying carrier frequency offsets and sampling clock offsets. Such asynchronization between sensing nodes can result in timing and frequency offsets, ultimately causing biases in range and Doppler shift estimations, which can adversely impact the accuracy and reliability of the sensing process.

[0010] In a communication-oriented RAN, synchronization is primarily implemented at the receiver side to align symbol timing, mitigate inter-carrier and inter-symbol interference, and eliminate unwanted phase variations caused by frequency offsets.

[0011] In radar systems designed for remote sensing, persistent scatterers — dominated by strong, consistent reflecting objects — provide radar responses that remain constant over time. These coherent scatterers, or coherent pixels when reflected on a radar image, are used to align multiple radar images, enabling finer sensing resolutions. This approach facilitates the monitoring of micro-displacements, such as subtle changes in the Earth's surface over time. In communication systems, synchronization does not require differentiation between the effects of frequency offset and Doppler shift, nor between timing offset and tap delay. Instead, these effects are often combined into a single effective channel which is estimated and used for equalization to demodulate data symbols.

[0012] In contrast, environment sensing aims to extract information about the surroundings based on measurements obtained at sensing nodes. For this purpose, it is critical to separate time and frequency offsets from tap delay and Doppler shift on individual paths. This separation is essential for accurately inferring the distance to, and dynamic behavior of, the scatterers in the environment. Unfortunately, this level of granularity is not supported by state-of-the-art communication system designs.

[0013] While synchronization among radar images can be achieved using permanent scatterers, applying such techniques directly to an integrated sensing and communication system is challenging. This is because radar systems are often proprietary, and components in an integrated sensing and communication system may be manufactured by different vendors. As a result, the functionality and interactions between sensing nodes must be explicitly specified to ensure effective operation.

[0014] This disclosure provides a mechanism for calibrating sensing nodes in a mobile radio network by leveraging arbitrary reference objects (or scatterers) present in the environment. The method focuses on utilizing reference objects to remove timing and / or frequency errors between the sensing nodes. This may be realized by cancelling or compensating the timing and frequency bias. A further objective is to identify and manage arbitrary reference objects present in the environment.

[0015] These and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the drawings.

[0016] A first aspect of the present disclosure provides a control entity for sensing. The control entity is configured to provide first assistance information to a first sensing transmitter. The first assistance information comprises information associated with one or more reference objects.

[0017] The first assistance information provided to the first sensing transmitter includes details associated with the one or more reference objects. The one or more reference objects are used to facilitate sensing calibration of a first sensing transmitter corresponding to the first sensing transmitter by enabling creation of one or more reference paths. The reference paths, scattered or reflected by the reference objects, serve as a basis for compensating synchronization errors, such as timing offsets and frequency offsets, that may arise during sensing operations. By calibrating these offsets, the first sensing receiver can obtain bias-free sensing measurements, thereby improving the accuracy of range and Doppler shift measurements and enhancing the reliability of the sensing process.

[0018] In an implementation form of the first aspect, the information associated with the one or more reference objects comprises, for each reference object, one or more of: location information, a quality indicator, an associated sensing node, an associated sensing region, type information, and time information.

[0019] Notably, the location information may comprise geographical or spatial coordinates of the reference object. The quality indicator may comprise metrics representing the reliability of the reference object. The associated sensing region may indicate geographical or spatial area where the reference object is observed and / or used for calibration. The type information may indicate a classification of the reference object, such as whether it is an environmental scatterer, a pre-deployed comer reflector, or a Reflective Intelligent Surface (RIS). The time information may indicate when the reference object was identified or measured.

[0020] In a further implementation form of the first aspect, the information associated with the one or more reference objects comprises reference signal configuration information for the first sensing transmitter to transmit one or more reference signals. In general, the first assistance information provided by the control entity includes the reference signal configuration information. This configuration information allows the first sensing transmitter to transmit one or more reference signals in a controlled and precise manner. By including this configuration information, the control entity ensures that the transmitted signals can interact with the reference objects in a way that measurements associated to the reference objects may be obtained by a sensing receiver, therefore enabling accurate sensing calibration.

[0021] In a further implementation form of the first aspect, the reference signal configuration information comprises a time window and / or a spatial filter configuration.

[0022] The time window indicates a time duration during which the sensing transmitter transmits reference signals. This ensures that the signals are sent within a controlled timeframe, enabling a corresponding sensing receiver to accurately acquire and measure the reference paths.

[0023] The spatial filter configuration comprises information to configure the spatial directionality of the reference signal transmission. By applying spatial filtering, the sensing transmitter can focus the reference signals in specific directions of interest, targeting potential reference objects for calibration purposes.

[0024] These configurations allow precise control over the reference signal transmission, ensuring effective interaction with reference objects for sensing calibration.

[0025] In a further implementation form of the first aspect, the control entity is further configured to provide second assistance information to a first sensing receiver. The second assistance information configures the first sensing receiver to obtain sensing measurements associated with the one or more reference objects. The second assistance information comprises a set of time windows and / or a set of quality indicators.

[0026] The second assistance information can be used by the first sensing receiver to detect the one or more reference paths associated with the one or more reference objects. For instance, the time windows are predefined time durations during which the sensing receiver is expected to detect and measure the reference path(s) based on the received reference signal. The quality indicators may comprise criteria or thresholds that the sensing receiver uses to assess the quality of the received paths. These quality indicators may comprise amplitude dispersion, phase stability, mean Doppler shift, Doppler variance, and delay variance. By acquiring the reference paths based on these indicators and the corresponding thresholds, the sensing receiver ensures that valid and reliable reference objects are used for calibration.

[0027] In a further implementation form of the first aspect, the control entity is configured to obtain the information associated with one or more reference objects by: configuring a second sensing transmitter to transmit reference signals; configuring a second sensing receiver to report sensing measurements based on one or more thresholds with respect to one or more quality indicator; and determining the information associated with the one or more reference objects based on the sensing measurements.

[0028] It is noted that the second sensing transmitter may be the same as or different from the first sensing transmitter. The second sensing receiver may be the same as or different from the first sensing receiver. The control entity configures the second sensing receiver to measure the transmitted reference signals and generate measurement reports based on thresholds defined for one or more quality indicators. These quality indicators may comprise amplitude dispersion, phase stability, mean Doppler shift, Doppler variance, and delay variance.

[0029] The control entity is configured to determine the reference object information (e.g., location, quality metrics, etc.) by analyzing the sensing measurements reported by the second sensing receiver.

[0030] A second aspect of the present disclosure provides a first sensing transmitter configured to receive first assistance information from a control entity. The first assistance information comprises information associated with one or more reference objects. The first sensing transmitter is further configured to transmit one or more reference signals based on the first assistance information.

[0031] In an implementation form of the second aspect, the information associated with the one or more reference objects comprises, for each reference object, one or more of: location information, a quality indicator, an associated sensing node, an associated sensing region, type information, and time information.

[0032] In a further implementation form of the second aspect, the information associated with the one or more reference objects comprises reference signal configuration information for the first sensing transmitter to transmit one or more reference signals.

[0033] In a further implementation form of the second aspect, the reference signal configuration information comprises a time window and / or a spatial filter configuration.

[0034] The first sensing transmitter of the second aspect may share the same or corresponding features and technical effect as the control entity of the first aspect, which are not repeated herein.

[0035] A third aspect of the present disclosure provides a system comprising a control entity according to the first aspect, a first sensing transmitter according to the second aspect, and a first sensing receiver. The first sensing receiver is configured to detect the one or more reference signals transmitted by the first sensing transmitter, and obtain sensing measurements of the detected reference signal(s). Optionally, the first sensing receiver is configured to receive the second assistance information from the control entity, and the sensing measurements are obtained according to the second assistance information. Optionally, the second assistance information comprises a set of time windows and / or a set of quality indicators.

[0036] A fourth aspect of the present disclosure provides a method for (facilitating) sensing. The method is applied to a control entity and comprises providing first assistance information to a first sensing transmitter. The first assistance information comprises information associated with one or more reference objects.

[0037] In an implementation form of the fourth aspect, the information associated with the one or more reference objects comprises, for each reference object, one or more of: location information, a quality indicator, an associated sensing node, an associated sensing region, type information, and time information.

[0038] In a further implementation form of the fourth aspect, the information associated with the one or more reference objects comprises reference signal configuration information for the first sensing transmitter to transmit one or more reference signals.

[0039] In a further implementation form of the fourth aspect, the reference signal configuration information comprises a time window and / or a spatial filter configuration.

[0040] In a further implementation form of the fourth aspect, the method comprises providing second assistance information to a first sensing receiver. The second assistance information configures the first sensing receiver to obtain sensing measurements associated with the one or more reference objects. The second assistance information comprises a set of time windows and / or a set of quality indicators.

[0041] In a further implementation form of the fourth aspect, the information associated with one or more reference objects can be obtained by: configuring a second sensing transmitter to transmit reference signals; configuring a second sensing receiver to report sensing measurements based on one or more thresholds with respect to one or more quality indicator; and determining the information associated with the one or more reference objects based on the sensing measurements.

[0042] A fifth aspect of the present disclosure provides a sensing method applied to a first sensing transmitter. The method comprising receive first assistance information from a control entity. The first assistance information comprises information associated with one or more reference objects. The method further comprises transmitting one or more reference signals based on the first assistance information.

[0043] In an implementation form of the fifth aspect, the information associated with the one or more reference objects comprises, for each reference object, one or more of: location information, a quality indicator, an associated sensing node, an associated sensing region, type information, and time information.

[0044] In a further implementation form of the fifth aspect, the information associated with the one or more reference objects comprises reference signal configuration information for the first sensing transmitter to transmit one or more reference signals.

[0045] In a further implementation form of the fifth aspect, the reference signal configuration information comprises a time window and / or a spatial filter configuration.

[0046] A sixth aspect of the present disclosure provides a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to the fourth / fifth aspect or any implementation form thereof.

[0047] A seventh aspect of the present disclosure provides a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to the fourth / fifth aspect or any implementation form thereof.

[0048] An eighth aspect of the present disclosure provides a chipset comprising instructions which, when executed by the chipset, cause the chipset to carry out the method according to the fourth / fifth aspect or any implementation form thereof.

[0049] It has to be noted that all entities, devices, elements, units, and means described in the present disclosure could be implemented in software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity, which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. BRIEF DESCRIPTION OF DRAWINGS

[0050] The above-described aspects and implementation forms will be explained in the following description in relation to the enclosed drawings, in which:

[0051] FIG. 1 shows a signaling diagram of assistance information provisioning;

[0052] FIG. 2 shows an example of a reference object list;

[0053] FIG. 3 shows an example of sensing regions and corresponding reference objects;

[0054] FIG. 4 shows a signaling diagram of reference object identification;

[0055] FIG. 5 shows a signaling diagram of reference object identification in downlink;

[0056] FIG. 6 shows a signaling diagram of reference object identification in uplink;

[0057] FIG. 7 shows application scenarios of the present disclosure; and

[0058] FIG. 8 shows an example of sensing node selection.

[0059] DETAILED DESCRIPTION OF EMBODIMENTS

[0060] In FIGs. 1-8 below, corresponding elements may share the same features and function likewise.

[0061] FIG. 1 shows a signaling diagram of assistance information provisioning. The assistance information is to facilitate sensing nodes calibration in a mobile radio network. A system 100 is provided and includes a sensing control entity 110, a first sensing transmitter 120, and a first sensing receiver 130. The first sensing transmitter 120 and the first sensing receiver 130 are collaborated for sensing, such as bistatic sensing. The sensing control entity 110 is configured to provide first assistance information 101 (also referred to as transmitter (TX) assistance information) to the first sensing transmitter 120. The first assistance information includes information associated with one or more reference objects. The one or more reference objects, such as rigid structures or metallic surfaces, are capable of producing strong reflection peaks in range-Doppler measurements, making them suitable for calibration.

[0062] The sensing control entity 110 may optionally provide second assistance information 102 (also referred to as receiver (RX) assistance information) to the first sensing receiver 130. This second assistance information configures the first sensing receiver 130 to acquire sensing measurements associated with the one or more reference objects. The sensing measurements are related to the reference signals 103. The second assistance information 102 may specify parameters such as expected time windows and quality indicator thresholds. These configurations provided by the second assistance information 102 allow the first sensing receiver 130 to accurately identify and measure reference paths necessary for calibration.

[0063] Once the reference signals 103 are transmitted by the first sensing transmitter 120, the first sensing receiver 130 performs measurements on any received signals detected according to the second assistance information 102. This is depicted as step

[0064] 104, wherein the first sensing receiver 130 processes the received signals and obtains sensing measurements. These measurements are then utilized to calibrate timing and frequency offsets, ensuring bias-free sensing data.

[0065] The calibrated sensing measurements obtained in step 104 may be further processed in two alternative approaches. In alternative

[0066] 105, the first sensing receiver 130 may be configured to provide the calibrated sensing measurements directly to the first sensing transmitter 120 for further use. Alternatively, in alternative 105', the first sensing receiver 130 may be configured to provide the calibrated sensing measurements to the sensing control entity 110. This flexibility allows the system to adapt to different calibration and processing needs depending on the operational context.

[0067] By providing the first assistance information 101 to the first sensing transmitter 120, it enables robust and flexible calibration. Leveraging environmental scatterers as reference objects for calibration reduces the reliance on specialized infrastructure, such as comer reflectors or Reflective Intelligent Surfaces (RIS), and minimizes deployment costs. Furthermore, the ability to identify and use multiple reference objects ensures robust calibration, as it avoids reliance on any single reference path, such as a Line-of-Sight (LoS) path, which may be prone to occlusion. This improves the overall reliability of the sensing process in dynamic or complex radio environments.

[0068] FIG. 2 shows an example of a reference object list, which can be managed by the sensing control entity. The information comprised in the reference object list may be applied to FIG. 1. Specifically, the first assistance information 101 provided by the control entity 110 to the first sensing transmitter 120 may be built according to the reference object list. This list comprises information about candidate reference objects identified for use in sensing node calibration. The reference object list includes, for each reference object, key details such as location information (e.g., position coordinates, x-y-z), quality indicators, and the time at which the reference object information was captured. The reference object information may be indexed using an ID, which is unique for each reference object in the list. Accordingly, the information associated with one or more reference objects comprised in the first assistance information 101 may comprise a subset of the information as in the list. The information associated with one or more reference objects may also comprise an associated sensing region and / or an associated sensing node. This information can also be retrieved from the list, as each list may be associated with a sensing region and / or a sensing node. The sensing node used to associate a reference object is typically a stationary sensing node, e.g., a Transmit Receive Point (TRP) of a base station.

[0069] Optionally, the information associated with the one or more reference objects may comprise reference signal configuration information, which can be used for the first sensing transmitter 120 to transmit one or more reference signals 103. For instance, the reference signal configuration information may comprise a time window and / or a spatial filter configuration of each reference signal associated with a respective reference object.

[0070] In addition to candidate reference objects that can be dynamically identified in the environment, such as natural or man-made structures exhibiting reflective characteristics, the list may also include other types of reference objects that are pre-deployed in the network. Examples of pre-deployed reference objects include comer reflectors and Reflective Intelligent Surfaces (RIS). These objects may be strategically placed within the network to provide reliable calibration paths when environmental reference objects are insufficient or unavailable. For this purpose, the list may further comprise a “Type” field to indicate the type of each reference object.

[0071] The reference object list allows the sensing control entity 110 to efficiently manage and utilize reference objects for various sensing regions, facilitating flexible and accurate calibration of sensing nodes. The inclusion of information such as quality indicators enables the sensing control entity 110 to prioritize or filter reference objects based on their suitability for calibration tasks, ensuring robust system performance in diverse environmental conditions.

[0072] FIG. 3 shows an example of sensing regions and their corresponding reference objects. A sensing region may be referred to as a proximity around a sensing transmitter 120 and / or a sensing receiver 130 that is used to identify one or more reference objects for calibration. This proximity may vary depending on the location and capabilities of the sensing nodes and the availability of reference objects in the environment. As illustrated in FIG. 3, reference objects 1 and 2 are associated with UE sensing region 1; reference objects 3 and 4 are associated with UE sensing region 2. All reference objects 1 to 4 are associated with TRP X. Optionally, it is also possible that a reference object is associated with two or more sensing regions. For instance, the reference object 3 may be associated with both sensing regions 1 and 2.

[0073] Since candidate reference objects are typically environmental scatterers — such as buildings, metal structures, or other reflective surfaces — they may exhibit non-ideal reflection characteristics and are only observable from specific perspectives. FIG. 3 demonstrates how the visibility and usability of a reference object for calibration depend on the relative positions of the sensing nodes. For example, a reference object may be observable and usable within one sensing region but may fall outside the line- of-sight or reflective range of another sensing region.

[0074] The sensing control entity 110 can consider these limitations when managing the reference object list and assigning reference objects to specific sensing regions and / or sensing nodes. By dynamically selecting and assigning reference objects based on the proximity of the sensing nodes and the reference object characteristics, the system ensures bias-free calibration and robust operation, even in complex or dynamic radio environments.

[0075] FIG. 4 shows a signaling diagram for reference object identification, which is performed by the sensing control entity 410 in coordination with a further sensing transmitter 420 and a further sensing receiver 430. It is noted that the sensing control entity 410 in FIG. 4 may correspond to the sensing control entity 110 in FIG. 1. However, the further sensing transmitter 420 and the further sensing receiver 430 in FIG. 4 may be the same as or different from the sensing transmitter 120 and the sensing receiver 130 in FIG. 1. For instance, TRP X may be used as the sensing transmitter 420 for reference object identification. The same TRP X may be used as the sensing transmitter 120 for sensing calibration. UE 1 in sensing region 1 may be used as the sensing receiver 430 for reference objection identification. However, UE 2 (other than UE 1) in sensing region 1 may be used as the sensing receiver 130 for sensing calibration. The reference object list managed by the control entity 110 / 410 may be obtained through multiple couples of sensing transmitter and sensing receiver for reference object identification as shown in FIG. 4.

[0076] The reference objection identification procedure begins with the sensing control entity 410 configuring the further sensing transmitter 420 through TX configuration to transmit reference signals over a designated time period. This configuration includes parameters such as the direction of interest and time period. The direction of interest may be derived from a-priori channel sounding, so that spatial filtering settings for directing the transmitted signals toward potential reference objects may be utilized. The time period specifies a duration during which the reference signals are to be transmitted.

[0077] The further sensing receiver 430 is configured to perform measurements on the transmitted reference signals through RX configuration and report the measurements. The RX configuration may comprise reference signal information or identity, which indicates a reference signal to be measured at the further sensing receiver 430. The RX configuration may comprise contents or conditions for the static path report, e.g. tap delays / range, receiver power levels, quality indicating factors, thresholds, etc.

[0078] The further sensing transmitter 420 then transmits a number of reference signals with the same spatial filter over time period T. The further sensing receiver 430 measures the reference signals and reports static path information including delay and receiver power, as well as the corresponding quality indicators. The static paths may be selected based on but not limited to the following quality indicators: amplitude dispersion index: DA= — < a phase stability: ati, < h mean Doppler shift, and variance thereof: | < c, Of < d: and delay variance: uT< e, where aAis the standard deviation, and iAis the mean of the amplitude of the received signals. Here, the coefficients a, b, c, d, e are provided by the sensing control entity 410, e.g., through the RX configuration. Finally, the sensing control entity 410 identifies one or more candidate reference objects by computing the position of the static objects based on the measurements. The identified one or more candidate reference objects may be managed and stored in the reference object list shown in FIG. 2 and utilized in FIG. 1 for sensing calibration.

[0079] FIG. 5 shows a signaling diagram of reference object identification in downlink. The reference object identification may be initiated by a sensing control entity 410 / 110 before selecting two sensing nodes to perform bistatic sensing. Based on the capability of the candidate sensing nodes, e.g., a TRP or a UE, different implementations may apply so that reference object information can be accurately computed based on the obtained measurements.

[0080] In scenarios where a TRP and a UE are employed, limitations arise due to the constraints on user devices, such as size, power, and cost. Unlike a TRP, which can utilize a large antenna array to obtain high-quality Angle of Arrival (AoA) measurements, user devices often cannot achieve the same level of accuracy due to their smaller antenna size. To address this, the sensing control entity 410 / 110 instead relies on the Angle of Departure (AoD), which can be obtained at the TRP side.

[0081] The signaling procedure proceeds as follows. In steps 1 to 3, the sensing control entity 410 / 110 obtains the AoD information corresponding to the potential directions. This AoD information helps determine the spatial regions of interest for identifying reference objects.

[0082] In step 4, the sensing control entity 410 / 110 configures the TRP to transmit reference signals with specific spatial filtering. The spatial filtering ensures that the transmitted signals are directed toward the potential candidate reference objects to gather accurate ranging information.

[0083] Correspondingly, the UE is configured to measure the reference signals transmitted by the TRP (and reflected / refracted by a potential reference object). The configuration provided to the UE includes criteria such as expected time windows, delay / range thresholds, and quality indicators, as described above in FIG. 4.

[0084] In step 5, the TRP transmits the reference signals over a specified time duration, allowing sufficient signal propagation for measurement by the UE.

[0085] In step 6, the UE measures the received signals and generates a measurement report containing static path information. The measurement report includes details such as the delay, range, and relevant quality indicators (e.g., amplitude dispersion, phase stability, Doppler shift, and delay variance) as introduced above in FIG. 4. This report is sent to the sensing control entity 410 / 110 for further analysis.

[0086] In step 7, based on the received measurement reports, the sensing control entity 410 / 110 calculates the location and characteristics of the candidate reference objects. The identified objects are then added to a reference object list for sensing calibration.

[0087] The signaling procedure shown in FIG. 5 highlights the efficient identification of candidate reference objects through coordination between the TRP, the UE, and the sensing control entity 410 / 110. In the example of FIG. 5, the TRP corresponds to the further sensing transmitter 420 in FIG. 4, and the UE corresponds to the further sensing receiver 430 in FIG. 4. By leveraging AoD at the TRP side and utilizing spatially filtered reference signals, the system overcomes constraints associated with limited AoA measurement accuracy at user devices. This ensures accurate and reliable identification of reference objects, which can subsequently be used for bias-free calibration of sensing measurements.

[0088] FIG. 6 shows a signaling diagram of reference object identification in uplink. In this example, the sensing control entity 410 / 110 configures a UE to act as the further sensing transmitter 420 in FIG. 4, while a TRP is configured to function as the further sensing receiver 430 in FIG. 4. This uplink-based approach leverages the TRP’s capability to obtain Angle of Arrival (AoA) measurements directly using its deployed antenna array.

[0089] The procedure begins with the sensing control entity 410 / 110 configuring the UE to transmit reference signals over a specified time duration. The configuration provided to the UE includes details such as the transmission duration, reference signal parameters, and spatial filters (if applicable) to ensure effective signal transmission towards potential candidate objects.

[0090] The TRP, acting as the sensing receiver, is configured by the sensing control entity 410 / 110 to measure the transmitted reference signals and report the corresponding static path information. The TRP obtains high-quality AoA measurements of the received reference signals due to its large antenna array, enabling accurate spatial identification of the static paths.

[0091] Once the transmitted reference signals are received, the TRP generates a measurement report that includes key parameters associated with the static paths, such as path delays, AoA, etc.

[0092] The TRP sends the measurement report to the sensing control entity 410 / 110, which analyzes the static path information to compute the location and characteristics of candidate reference objects.

[0093] The uplink-based signaling procedure shown in FIG. 6 demonstrates an efficient method for identifying reference objects using a user device as the transmitting node and a TRP as the receiving node. This approach is particularly advantageous in scenarios where the TRP’s antenna array enables high-accuracy AoA measurements, overcoming the limitations associated with smaller antenna arrays on user devices.

[0094] FIG. 7 shows application scenarios of the present disclosure. Various implementations of bistatic sensing in a mobile radio network are shown in FIG. 7, showcasing various configurations where two radio nodes are selected to perform sensing tasks, as described in the following. a) Downlink Bistatic Sensing

[0095] In this configuration, a Transmit Receive Point (TRP) of a base station (BS) acts as the sensing TX, and a user device (UE) functions as the sensing RX. The TRP transmits reference signals to illuminate the environment, and the UE receives and processes these signals to perform bistatic sensing. This downlink configuration is suitable for scenarios where the TRP provides strong transmission capabilities and the UE is positioned to collect and analyze reflected signals. b) Uplink Bistatic Sensing

[0096] In the uplink scenario, the UE acts as the sensing TX, while the TRP serves as the sensing RX. The UE transmits reference signals, and the TRP, with its advanced antenna array, receives these signals and measures their reflections from the environment. The TRP’s ability to obtain high-quality Angle of Arrival (AoA) measurements enhances the accuracy of uplink bistatic sensing. c) Sidelink Bistatic Sensing

[0097] In this configuration, a user device serves as the sensing TX, while another user device operates as the sensing RX. This sidelink configuration allows direct communication and sensing between UEs, enabling flexible deployment in scenarios where BS involvement may be limited or unnecessary, such as in vehicle-to-vehicle communication. d) Cross-Link Bistatic Sensing

[0098] In the cross-link configuration, one TRP functions as the sensing TX, and another TRP operates as the sensing RX. This setup enables TRPs to collaboratively perform bistatic sensing, leveraging their extensive coverage areas and advanced signal processing capabilities. The cross-link configuration is ideal for network deployments requiring coordinated sensing over large or complex environments.

[0099] The sensing control entity 410 / 110, which orchestrates the selection and configuration of the sensing nodes, may be implemented as a computing entity. It may reside in various network locations, such as a network function in the core network or radio access network, an application running on a user device, or a computing platform like a cloud or edge server. This flexibility in deployment ensures that the sensing control entity can adapt to the specific requirements of different network architectures and use cases.

[0100] FIG. 8 shows an example of sensing node selection, where a deployment environment is depicted in the upper side of FIG. 8 and a corresponding signaling diagram is depicted in the lower side of FIG. 8. In the deployment environment, a transmit receive point of a base station (BS-TRP) and two Road Side Units (RSUs) are positioned around a road intersection. The sensing control entity 410 / 110 is configured to dynamically select candidate sensing nodes for bistatic sensing based on the sensing requirements, the location and capability of the available nodes, and the quality of identified reference objects.

[0101] In this example, the sensing control entity 410 / 110 selects RSU 1 to perform bistatic sensing with the TRP. Accordingly, the sensing control entity 410 / 110 provides corresponding assistance information to the TRP and RSU 1 respectively, as described above in FIG. 1.The selection of RSU 1 is based on the availability of reference objects previously identified within the sensing region of RSU 1. The identified reference objects facilitate the calibration of sensing measurements, ensuring bias-free estimations of delay and Doppler shift. These measurements are critical for achieving accurate sensing results in the environment.

[0102] The sensing control entity 410 / 110 evaluates several factors when selecting the candidate sensing nodes, such as: sensing requirements, including the resolution and accuracy needed for the sensing task; geographic location and sensing capabilities of the available nodes (e.g., RSUs, UEs, or TRPs); and the availability and quality of the reference objects in the corresponding sensing region.

[0103] By leveraging UE-assisted bistatic sensing, the system allows flexible node selection, enabling UEs, RSUs, or TRPs to be dynamically activated as sensing nodes. This approach extends the network's sensing coverage and improves its robustness, particularly in complex environments such as urban intersections where occlusion may occur.

[0104] Overall, the present disclosure provides a robust and flexible mechanism for calibrating sensing nodes in a mobile radio network using reference objects. By leveraging environmental reference objects, accurate and bias-free delay and Doppler shift sensing measurements can be ensured. The devices (e.g., the control entity, sensing transmitter, and sensing receiver) in the present disclosure may comprise processing circuitry configured to perform, conduct or initiate the various operations of the devices described herein, respectively. The processing circuitry may comprise hardware and software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors. Optionally, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the respective device to perform, conduct or initiate the operations or methods described herein, respectively.

[0105] The present disclosure has been described in conjunction with various aspects as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed subject matter, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or another unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

CLAIMS1. A control entity (110) for sensing, wherein the control entity (110) is configured to provide first assistance information (101) to a first sensing transmitter (120), wherein the first assistance information (101) comprises information associated with one or more reference objects.

2. The control entity (110) according to claim 1, wherein the information associated with the one or more reference objects comprises, for each reference object, one or more of: location information; a quality indicator; an associated sensing node; an associated sensing region; type information; and time information.

3. The control entity (110) according to claim 1 or 2, wherein the information associated with the one or more reference objects comprises reference signal configuration information for the first sensing transmitter (120) to transmit one or more reference signals.

4. The control entity (110) according to claim 3, wherein the reference signal configuration information comprises a time window and / or a spatial filter configuration.

5. The control entity (110) according to any one of claims 1 to 4, further configured to provide second assistance information (102) to a first sensing receiver (130), wherein the second assistance information (102) configures the first sensing receiver (130) to obtain sensing measurements associated with the one or more reference objects, the second assistance information (102) comprising a set of time windows and / or a set of quality indicators.

6. The control entity (110) according to any one of claims 1 to 5, configured to obtain the information associated with one or more reference objects by: configuring a second sensing transmitter to transmit reference signals; configuring a second sensing receiver to report sensing measurements based on one or more thresholds with respect to one or more quality indicator; and determining the information associated with the one or more reference objects based on the sensing measurements.

7. A first sensing transmitter (120) configured to: receive first assistance information (101) from a control entity (110), wherein the first assistance information (101) comprises information associated with one or more reference objects; and transmit one or more reference signals based on the first assistance information (101).

8. A system (100) comprising a control entity (110) according to any one of claims 1 to 6, a first sensing transmitter (120) according to claim 7, and a first sensing receiver (130), wherein the first sensing receiver (130) is configured to: receive the second assistance information (102) from the control entity (110); and obtain sensing measurements based on the second assistance information (102).

9. A method for sensing, wherein the method is applied to a control entity (110) and comprises: providing first assistance information (101) to a first sensing transmitter (120), wherein the first assistance information (101) comprises information associated with one or more reference objects.

10. The method according to claim 9, wherein the information associated with the one or more reference objects comprises, for each reference object, one or more of: location information; a quality indicator; an associated sensing node; an associated sensing region; type information; and time information.

11. The method according to claim 9 or 10, wherein the information associated with the one or more reference objects comprises reference signal configuration information for the first sensing transmitter (120) to transmit one or more reference signals.

12. The method according to claim 11 , wherein the reference signal configuration information comprises a time window and / or a spatial filter configuration.

13. The method according to any one of claims 9 to 12, further comprising providing second assistance information (102) to a first sensing receiver (130), wherein the second assistance information (102) configures the first sensing receiver (130) to obtain sensing measurements associated with the one or more reference objects, the second assistance information (102) comprising a set of time windows and / or a set of quality indicators.

14. A method for sensing, wherein the method is applied to a first sensing transmitter (120) and comprises: receiving first assistance information (101) from a control entity (110), wherein the first assistance information (101) comprises information associated with one or more reference objects; and transmitting one or more reference signals based on the first assistance information (101).

15. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to perform the method according to any one of claims 9 to 14.

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