Device, method and computer program product for evaluating a radio wave propagation

Abstract

A device (100) and a method (200) for evaluating a radio wave propagation a wireless communication in an environment (300) is provided. The method (200) comprises the step of obtaining (S202) a first path (320) of the radio wave propagation (300) in the environment (300), the first path comprising interaction points of a sequence of interactions of the radio wave propagation with physical objects (308) in the environment (300), the first path (320) further comprising a segment (314; 316) between each pair of the subsequent interaction points. The method (200) further comprises the step of modify (S204) the first path (320) by shifting the at least one interaction point of the first path (320) from a first location (310) to a second location (312), resulting in a second path (322) comprising at least one modified segment (314; 316). The method (200) further comprises the step of determining (S206) at least one adjusted interaction within at least one segment (314; 316) between at least one pair of subsequent interaction points in the second path (322) by tracing the at least one modified segment (314; 316) of the second path (322) in the environment (300). The method (200) further comprises the step of evaluating (S208) the radio wave propagation along the second path (322) for each segment (314; 316) according to the at least one adjusted interaction and each interaction at the at least one shifted interaction point.

Description

[0001] DEVICE, METHOD AND COMPUTER PROGRAM PRODUCT FOR EVALUATING A RADIO WAVE PROPAGATION

[0002] Technical Field

[0003] The present disclosure relates to evaluating a radio wave propagation of a wireless communication in an environment. More specifically, and without being limited thereto, a device and a method are disclosed for evaluating the propagation of a radio wave, e.g. for a wireless communication, in an environment.

[0004] Background

[0005] A ray optical approximation predicts electromagnetic propagation accurately in certain environments. It relies on the assumption that electromagnetic propagation can be treated as a collection of rays, which travel in straight lines and undergo interactions such as reflection, diffraction, scattering, and refraction at interfaces in the environment. This method can predict both optical wireless communications (OWC) and radio wave propagation, especially when the dimensions of objects and the distances between them are much greater than the wavelength of the carrier signal. By including interactions with the environment, e.g. based on paths circumventing a blocking object by reflections or diffraction at edges of any object, electromagnetic propagation can also be predicted in an environment that block a direct line-of-sight.

[0006] The need for accurately and rapidly predicting wireless channels is crucial for planning and operating a wireless communication network, including when non-deterministic features such as individually moving reflective or diffractive objects need to be accounted for, motorized traffic in the vicinity of cellular radio access networks (RANs). These RANs, defined by standards Fourth Generation (4G) Long Term Evolution (LTE) and Fifth Generation (5G) New Radio (NR) from the Third Generation Partnership Project (3GPP), increasingly benefit from ray optical approximation, particularly as they evolve with higher frequencies, larger bandwidths, and more antennas, crucial for technologies beyond 5G and 6G.

[0007] Conventional ray optical techniques rely on ray tracing, sometimes referred to as ray launching or "shooting and bouncing rays" (SBR). These techniques launch a multiplicity of rays from a source, such as a transmitter node, and model their interactions with environmental objects until they reach a receiver. The various interactions - reflection, refraction, diffraction, and scattering - are modeled by generating one or multiple secondary rays upon the intersection of a primary ray with any object in the environment.

[0008] Multiple consecutive interactions may occur, leading to an exponential growth in the number of rays that need to be traced, which is a significant challenge due to the computational complexity involved. This complexity requires careful management to balance the trade-offs between the computation time and the accuracy and fidelity of the predicted channels. Both accuracy and real-time requirement are particularly important in the context of digital twins, wherein the digitally represented radio channel must be generated and updated at the same rate as its real physical counterpart. For ray tracing to be effective, there is a need for high fidelity in the representation of the modeled radio channel compared to actual measurements. Moreover, the modeled channel should be deliverable with minimal latency, the acceptable level of which can vary widely depending on the application, ranging from microseconds to hours.

[0009] Predicting the time-evolution of radio channels becomes especially complex when considering the movement of transmitters, receivers, or objects within the environment. A conventional method is to conduct a complete ray tracing experiment periodically, which is both time-consuming and computationally intensive. Alternatively, propagation paths could be directly modified by mobility in the environment and the law of reflection, but this may lead to inconsistencies, for instance, when paths become obstructed or reflection points slide off the limited size of reflective surfaces of the objects.

[0010] These deviations in traced paths versus actual paths pose critical challenges: a traced path might indicate line-of-sight (LOS) conditions when the actual path is non-line-of-sight (NLOS) due to obstructions, leading to significant discrepancies in calculated path gains.

[0011] Thus, a full new ray tracing process might be required frequently, which is costly in terms of computational resources and may introduce significant latency. Continually updating the modeled radio network, an approach that is attractive for digital twins of radio networks, necessitates real-time or near real-time channel updates to maintain accuracy, further contributing to the computational load.

[0012] Summary

[0013] Accordingly, there is a need for a technique that efficiently determines a high-fidelity radio wave propagation path in a complex and realistic environment in real time. In other words, there is a need for a technique to efficiently predict the complex and time-varying nature of radio channels with high fidelity while mitigating the computational complexity, latency, and power consumption inherent in current ray tracing techniques.

[0014] As to a device aspect, a device for evaluating a radio wave propagation of a wireless communication in an environment is provided. The device comprises memory operable to store instructions and processing circuitry operable to execute the instructions. The device is operable to obtain a first path of the radio wave propagation in the environment, the first path comprising interaction points of a sequence of interactions of the radio wave propagation with physical objects in the environment. The first path further comprises a segment between each pair of the subsequent interaction points. The device is further operable to modify the first path by shifting at least one interaction point of the first path from a first location to a second location, resulting in a second path comprising at least one modified segment. The device is further operable to determine at least one adjusted interaction within (e.g., on) at least one segment between at least one pair of subsequent interaction points in the second path by tracing the at least one modified segment of the second path in the environment. The device is further operable to evaluate the radio wave propagation along the second path for each segment according to the at least one adjusted interaction and each interaction at the at least one shifted interaction point.

[0015] Herein, the wireless communication may comprise transmitting or receiving reference signals, e.g., positioning reference signals.

[0016] Embodiments of the device may be implemented as a segment tracing device and embodiments of the method may be implemented as a segment tracing method, e.g. because at least the step of determining the adjusted interaction and / or the step of evaluating the radio wave propagation may be performed for each segment of the second path independently (e.g., separately) or in parallel (e.g., simultaneously), e.g. using bit-level parallel computing and instruction-level parallel computing. Herein, the method, or particularly the determining of the at least one adjusted interaction, may be referred to as segment tracing.

[0017] Embodiments can efficiently predict the time evolution of radio channels when the transmitters, receivers, or objects in the environment are moving. In contrast to a naive and very slow and complex approach that redoes a full ray launching and tracing experiment as soon as something in the environment has changed, the modifying step may update the first path based on mobility in the environment and may correct the resulting second path to fulfil Fermat's principle. This significantly decreases the computational complexity, and thus, latency in controlling a RAN and the power consumption of the RAN. For example, a full resource-intensive periodic ray tracing may be (e.g. at regular intervals such as every half second) can be avoided. At the same time, the evaluation provided by embodiments remains accurate, since determining the at least one adjusted interaction by tracing the second path for each segment fast and reveals the changes in the at least one interaction, which are conventionally overlooked when the conditions along a modified propagation path change such as paths may become blocked and others may no longer hit e.g. a reflection plane. The determining step can be both fast (e.g. due to parallelization) and can avoid the conventionally false paths or errors in the evaluation of the radio wave propagation compared to when a ray was traced exactly in the environment.

[0018] Hereinbelow, referring to "a path" may refer to any one (e.g., each) of the first path and the second path. Similarly, referring to "the path" may refer to the respective one of the first path and / or the second path. Each segment of a path may comprise a straight line between a pair of interaction points of subsequent interactions in the sequence of interactions of the path. In other words, each segment of the (first or second) path may correspond to the part of the propagation path between two consecutive interaction points. The interaction point may change the direction of propagation of a ray defining the propagation path. The interaction may be a reflection, and / or a refraction and or a diffraction. Optionally, any segment may comprise an interaction that does not change the direction of the path and / or that is not associated with an interaction point, e.g. a transmission interaction. Alternatively or in addition, a start point of the path in the environment and / or an end point of the path in the environment may be examples of the interaction points.

[0019] The obtained first path may result from (e.g., iterative) ray tracing.

[0020] Alternatively or in addition, the obtained first path may comprise the first location that approximates the second location as a physical location when determining at least one of the interaction points. The first location may be an approximate location that approximates a physical location when determining at least one of the interaction points. The approximate location that approximates a physical location may be the physical location at an earlier (e.g., outdated) point in time. Alternatively or in addition, the approximate location may deviate from the physical location because the first path is not a physical path, e.g. because it does not fulfil Fermat's principle. The physical location may be an interaction location in the environment that corresponds to a change in direction of the path due to an interaction that follows physical laws (e.g., geometrical optics and / or electrodynamics).

[0021] The second path may comprise the at least one modified segment that differs from all segments of the first path. Each segment of the second path, which differs from all segments of the first path, may be traced to determine the at least one adjusted interaction.

[0022] In a first variant of any embodiment, only the at least one modified segment of the second path (e.g., that differs from all segments of the first path) is traced to determine the at least one adjusted interaction. In a second variant of any embodiment, each segments of the second path is traced to determine the at least one adjusted interaction.

[0023] When the at least one shifted interaction point is an inner point (i.e., not an end point) of the first or second path, at least two segments may be modified, e.g. since any shifted inner point is an end point of two subsequent segments, i.e. since any shifted inner point links at least two segments of the respective path.

[0024] The determining of the at least one adjusted interaction may comprise adding at least one interaction point for the at least one adjusted interaction, wherein the at least one added interaction point is determined by the tracing of the at least one modified segment of the second path. The adding of an interaction point is an example of adjusting an interaction that is not present in the first path and that is present in the second path. Alternatively or in addition, the determining of the at least one adjusted interaction may comprise adjusting an interaction by removing the interaction that is present in the first path and removed (i.e., not present) in the second path as a result of the tracing of the at least one modified segment.

[0025] The determining of the at least one adjusted interaction within (e.g., in contrast to “in”) a respective one of the at least one segment may exclude the end points of the respective segment, e.g. because these interactions either have already been modified when shifting the end point or are not modified in the second path compared to the first path. Alternatively or in addition, the determining of the at least one adjusted interaction may be performed along the respective one of the at least one segment.

[0026] The determining of the at least one adjusted interaction by tracing the at least one modified segment of the second path in the environment may take a Fresnel zone around the at least one modified segment into account.

[0027] The modifying of the first path resulting in the second path may comprise shifting the interaction points under constraints of the respective interaction to minimize a path length of the second path. For example, an interaction including a (e.g., diffusive or specular) reflection on a plane may shift the interaction point constrained to the plane. As another example, an interaction including an edge diffraction at an edge may shift the interaction point constrained to the edge. Alternatively or in addition, modifying of the first path resulting in the second path may correspond to kinematics of objects in the environment. For example, the first location may correspond to a location of an object or interaction element of said object (with which the first path interacts) at a first point in time. The second location may correspond a location of the same object or the same interaction element (with which the second path interacts) at a second point in time later than the first point in time (e.g., a next time step). The first and / or second locations may be measured in the environment.

[0028] The adjusted interaction may be caused by a changed location (e.g., translation) or orientation (e.g., rotation) of an object in the environment and / or by the change of the respective segment according to the at least one shifted interaction point at the end or the ends of the respective segment. The determining of the at least one adjusted interaction on at least one segment may be performed by tracing each segment of the second path independently.

[0029] The determination of at least one adjusted interaction on at least one segment by tracing each segment of the second path in the environment may be implemented by parallel computing of the determination for each segment. Alternatively or in addition, the evaluation of the radio wave propagation along the second path per each segment may be implemented by parallel computing of the evaluation for each segment. The determination and / or the evaluation may end (e.g., be terminated) if (e.g., as soon as) a segment fulfils a termination criterion, and as an exemplary result, the second path may be discarded (e.g., from a set of second paths that are determined accordingly by a plurality of obtained first paths). For example, the determination may be terminated if the segment intersects an (e.g., for the RF propagation) opaque object in the environment. Alternatively or in addition, the evaluation may be terminated if a gain of the segment (or negative path loss of the segment in terms of a power level) is below predefined threshold value (optionally defined as a path loss per path length). The radio wave propagation may be evaluated using the "IEEE Standard Definitions of Terms for Radio Wave Propagation," in IEEE Std 211-2018. Alternatively or in addition, the evaluating of the radio wave propagation may comprise determining one or more physical properties of the radio wave propagation along the second path, e.g., a phase shift, a (e.g., complex-valued) gain, a channel state, or a channel estimate.

[0030] Herein, listed features of the form A; B; and / or C (or A, B, and / or C for less complex statements of features) disclose the feature A or the feature B or the feature C or the features A and B or the features A and C or the features B and C or the features A and B and C.

[0031] In an embodiment, each interaction point of the first path may correspond to a change in direction of the first path. Alternatively or in addition, each segment of the first path may correspond to a straight line of the first path between a pair of points representing two consecutive direction-changing or terminating interactions of the first path. Alternatively or in addition, each interaction point of the second path may correspond to a change in direction of the second path. Alternatively or in addition, each segment of the second path may correspond to a straight line of the second path between a pair of points representing two consecutive direction-changing or terminating interactions of the second path.

[0032] The terminating interactions may comprise transmitting (e.g., sending or emitting) a signal of the wireless communication and / or receiving (e.g., observing or at least partially absorbing) a signal of the wireless communication.

[0033] The first and / or second path may span between a first station (i.e., the start point of the first path) and a second station (i.e., the end point of the first path) in the environment. The first station and the second station may be represented by points in the environment. The first station may comprise a first (e.g., transmitting and / or receiving) station of the wireless communication. The second station may comprise a second (e.g., transmitting and / or receiving) station of the wireless communication. For example, each of the first station and the second station may comprise an antenna, e.g. an antenna system including multiple antenna elements for beamforming or (e.g., distributed) a multiple-input multiple-output (MIMO) channel of the wireless communication.

[0034] The first station (e.g., as the start point) and the second station (e.g., as the end point) of the first and / or second path may be interaction points of the respective path. The interaction at the first station may comprise a transmission (e.g., emission) of the radio wave propagation, and the interaction at the second station may comprise reception (e.g., partial absorption) of the radio wave propagation. Vice versa, the interaction at the first station may comprise a reception (e.g., partial absorption) of the radio wave propagation, and the interaction at the second station may comprise a transmission (e.g., emission) of the radio wave propagation. The first path and the second path may be compatible to each other, e.g., when the shifting does not change the approximation locations and consequently the physical location and the approximation location are the same location. In such situations, the device may stop evaluating the second path.

[0035] In an embodiment, the device may be further operable to perform or initiate a physical action that is dependent on the evaluated radio wave propagation along the second path. For example, evaluating the radio wave propagation along the second path may comprise modeling a channel of the wireless communication along the evaluated second path in the environment, and / or the physical action may be dependent on the modeled channel. Alternatively or in addition, the device may be further operable to model a channel of the wireless communication along the second path in the environment based on the evaluated radio wave propagation. For example, the modeling of the channel may comprise, or the device may be further operable to perform or initiate, a physical action that is dependent on the modeled channel.

[0036] In an embodiment, the modifying of the first path by shifting the at least one interaction point from the first location to the second location may trigger the determining and / or an adjusting of the at least one interaction on the at least one segment (e.g. resulting in the at least one adjusted interaction). The determining of the at least one adjusted interaction within the at least one segment between at least one pair of subsequent interaction points in the second path may be based on the second path as the modified first path. Alternatively or in addition, the at least one adjusted interaction within the at least one segment may be determined by determining, for each of the at least one segment, if there is an intersection between a straight line representing the respective one of the at least one segment and a geometrical interaction object representing a further physical object in the environment. Alternatively or in addition, the determining and / or adjusting of the at least one interaction on the at least one segment may comprise adding to or removing from the second path the at least one interaction on the respective segment (e.g., the segment of the second path that used to interact or that will interact with one or more objects in the environment). Alternatively or in addition, the radio wave propagation may be evaluated along the second path according to each added or removed interaction and each interaction at the at least one shifted interaction point.

[0037] The removing of the at least one interaction from the second path encompasses excluding an interaction from the second path. The second path needs not to initially include the removed interaction. Rather, the at least one interaction may be removed in the sense of not including the at least one interaction in the second path that is included in the first path.

[0038] The geometrical interaction object may be represented a triangular mesh or other shapes.

[0039] The intersection between the straight line representing the respective segment and the geometrical interaction object may take a Fresnel zone around the straight line into account. Removing an interaction from the segment of the second path may be implemented by not including in the segment of the second path an interaction that is present in the corresponding section of the first path.

[0040] The adjusted interaction may correspond to a further interaction, e.g., because the respective segment of the second path intersects with an object with which the first path did not interact (optionally at least not within the corresponding segment of the first path). Alternatively or in addition, the adjusted interaction may be a change in an interaction type, e.g. from a transmission interaction on the segment of the first path that passes through an object without changing the direction (i.e., the straight line) of the segment to an interaction that introduces a further interaction point on the segment and splits the segment into two sub-segments (i.e., one further segment) linked at the further interaction point of the second path. Alternatively or in addition, the adjusted interaction may correspond to a removed interaction, e.g. by omitting a transmission interaction that corresponds to the respective segment of the first path passing through an object in the environment. The transmission interaction may be absent in the corresponding segment of the second path, e.g. because the segment of the second path does not intersect the object according to the determination step.

[0041] In an embodiment, the added or removed interaction with one or more physical objects in the environment within the respective segment may result from the shifting of the at least one interaction point connected to the respective segment. Alternatively or in addition, the added or removed interaction with physical objects in the environment within the respective segment may result from a mobility of the one or more physical objects in the environment.

[0042] The added interaction may comprise an or any interaction along a or each segment connected to at least one interaction point that is shifted when modifying the first path.

[0043] The adding of an or any interaction along the respective segment may comprise, for each segment, launching (also referred to as transmitting or shooting) a single ray between the two interaction points connected by the respective segment (i.e., between consecutive interaction points).

[0044] The device may stop ray tracing (e.g., segment ray tracing) from the first station when the last interaction point is the second station. Or vice versa, the device may stop ray tracing (e.g., segment ray tracing) from the second station when the last interaction point is the first station.

[0045] In an embodiment, the obtaining of the first path may comprise an iterative ray tracing in the environment resulting in at least one first path. Alternatively or in addition, the device may be operable to modify each of the at least one first path resulting in at least one second path, determine the at least one adjusted interaction, and to evaluate the radio wave propagation along each of the at least one second path.

[0046] Preferably, the ray tracing may yield a plurality of first paths. Iterative ray tracing may mean that each ray launched at the first interaction point (e.g., the start point) of the first path is traced in the environment until it intersects with an object. The intersection may define the second interaction point of the first path, optionally for launching one subsequent ray (e.g., for specular reflection or edge diffraction) or a bundle of subsequent rays in different directions (e.g., for diffusive reflection). Optionally so on for subsequent interactions.

[0047] In an embodiment, the device operable to obtain the first path may comprise the device being operable to launch one or multiple rays of the ray tracing at a first interaction point of the first path as the first location, which is shifted for the modification to a first station in the environment as the second location. Alternatively or in addition, the device operable to obtain the first path may comprise the device being operable to determine the interaction points of the interactions of the first path at intersections of rays of the ray tracing with the objects in the environment. Alternatively or in addition, the device operable to obtain the first path may comprise the device being operable to launch one or multiple rays at one or more of the interaction points of the interactions of the first path as the first location offset to the outside of the object of the respective interaction that approximates the physical location of the respective interaction as the second location. Alternatively or in addition, the device operable to obtain the first path may comprise the device being operable to capture one or multiple rays of the ray tracing for each of the at least one first path on a capture surface enclosing a second station in the environment, the interaction point of the first path on the capture surface being the first location that approximates the second location of the last interaction point of the second path at the second station.

[0048] The first interaction point may be a transmitting (i.e., sending) interaction point. The first station may be a transmitter. Alternatively or in addition, and the first interaction point may be a receiving interaction point and the first station may be a receiver or a receiving interaction point.

[0049] The second location as the physical location of the respective interaction may be on the object of the respective interaction. Alternatively or in addition, the first location (e.g., as an approximate location) on the object of the respective interaction may be shifted to the second location (e.g., as a physical location) outside of the object within a Fresnel zone of the respective interaction.

[0050] In an embodiment, the first interaction point of the first path as the first location may deviate from the second location of a first station of the wireless communication due to a mobility of the first station, optionally due to a time lag in updating the first location of the first station for the ray tracing.

[0051] Alternatively or in addition, the interaction point of the first path as the first location may deviate from the second location of an object of the respective interaction due to a mobility of the object in the environment, optionally due to a time lag in updating the first location of the object for the ray tracing. Alternatively or in addition, the last interaction point of the first path as the first location may deviate from the second location of a second station of the wireless communication due to a mobility of the second station, optionally due to a time lag in updating the first location of the second station for the ray tracing.

[0052] In an embodiment, the device may be further operable to obtain physical locations of a first station as the first interaction point at different points in time and / or physical locations of one or more objects in the environment as one or more intermediate interaction points at different points in time and / or physical locations of a second station as the last interaction point at different points in time.

[0053] In this context, obtaining any of these physical locations may be implement by measuring the physical locations (e.g., positioning the one or more objects and / or the first and / or second stations by means of radio access technologies of the wireless communication) or by receiving the physical locations (e.g., from a digital twin of the respective object or station or from the respective object or station as a node of a radio access network of the wireless communication).

[0054] The first path may correspond to a first point in time and the second path may correspond to a second point in time later than the first point in time.

[0055] The following sentences of this paragraph may apply to any one or each of the first and second paths. Each of the first station and / or the second station may comprise one or multiple antennas as the first and / or last interaction points, respectively. Alternatively or in addition, each of the one or more objects (e.g., moving objects in the environment) may comprise an interaction element (e.g., a surface or an edge) where the interaction point of the one or more intermediate interactions is located or constrained to.

[0056] In an embodiment, the modifying of the first path or the determining of the at least one adjusted interaction of the second paths or the evaluating of the radio wave propagation along the second path may comprise discarding the respective path, or discarding the respective interaction (e.g. and a segment connected to the respective interaction point). The path or the interaction (e.g., and the segment) may be discarded if the first location as the interaction point of the first path on the object of the respective interaction is shifted to the second location as the interaction point of the second path, and the second location is outside of a physical size of the object of the respective interaction or outside of a Fresnel zone of the respective interaction.

[0057] The one or more interaction points of the first path may be stored as a result of the ray tracing. The modifying of the first path or the determining of the at least one adjusted interaction of the second paths or the evaluating of the radio wave propagation along the second path may comprise assessing whether the interaction point is on the object of the respective interaction, e.g., on an edge of a diffractive object or on a surface of a reflective object. In an embodiment, the modifying of the first path may reduce or minimize a path length of the second path compared to the length of the first path by shifting the at least one interaction point from the first location to the second location within a plane or line of the object of the respective interaction.

[0058] The second path may also be referred to as the shortest path (e.g., given the sequence of interactions).

[0059] Each of the at least one interaction point of the respective interaction may be shifted under a constraint defined by the respective interaction. The plane or line of the object of the respective interaction may encompass a plane that is parallel (e.g., co-parallel or offset to avoid self-interaction) to a surface of the object (e.g., if a type of the interaction is specular or diffusive reflection) or a line that is parallel (e.g., coaxial or offset to avoid self-interaction) to an edge of the object.

[0060] In an embodiment, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a phase shift along the second path.

[0061] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a gain along the second path and / or a power loss along the second path and / or received signal strength indicator (RS SI).

[0062] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a time of flight along the second path.

[0063] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise an angle of departure (AoD) and / or an angle of arrival (AoA) of the second path.

[0064] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a Doppler shift or Doppler spread of the second path. Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a signal to noise ratio (SNR) along the second path.

[0065] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a signal to interference plus noise ratio (SINR) along the second path.

[0066] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a channel state information (CSI) of the second path.

[0067] Alternatively or in addition, the evaluating of the radio wave propagation along the second path, the physical action, and / or the modeling of the channel of the wireless communication may comprise determining one or more physical properties of the radio wave propagation. The one or more physical properties may comprise a channel estimate of the second path.

[0068] The evaluating of the radio wave propagation along the second path may comprise optimizing one or more physical properties of the second path, e.g., minimizing the time of flight and / or a precoder (e.g., a precoding matrix) for the wireless communication from the first station to the second station.

[0069] The Doppler shift or Doppler spread of the second path may depend not only on the relative velocity of the start point and end point of the second path due to the interactions of the second path with the objects in the environment.

[0070] In the case of multiple second paths (e.g., resulting from multiple obtained first paths, e.g. after discarding zero or more paths), the one or more physical properties may be determined based on a superposition of a contribution (e.g., a complex-valued and / or vector-valued gain) of each of the multiple second paths.

[0071] In an embodiment, the device may be further operable to store the second path, optionally as resulting from the modifying or the determining or the evaluating. The stored second path may be obtained or obtainable when the device iterates the operable steps or functions disclosed herein.

[0072] As to a method aspect, a method of evaluating a radio wave propagation of a wireless communication in an environment is provided. The method comprises or initiates obtaining a first path of the radio wave propagation in the environment, the first path comprising interaction points of a sequence of interactions of the radio wave propagation with objects in the environment. The first path comprises a segment between each pair of the subsequent interaction points. The method further comprises or initiates modifying the first path by shifting at least one interaction point of the first path from a first location to a second location, resulting in a second path. The method further comprises or initiates determining at least one adjusted interaction on at least one segment between at least one pair of subsequent interaction points in the second path by tracing each segment of the second path in the environment. The method further comprises or initiates evaluating the radio wave propagation along the second path for each segment according to the at least one adjusted interaction and each interaction at the at least one shifted interaction point.

[0073] As to another aspect, a computer program product is provided. The computer program product comprises program code portions for performing any one of the steps of the method aspect and / or any of the functionality of the one device aspect or the other device aspect disclosed herein, when the computer program product is executed by one or more computing devices. The computer program product may be stored on a computer-readable recording medium. The computer program product may also be provided for download, e.g., via the radio network, the RAN, the Internet and / or the host computer. Alternatively, or in addition, the method may be encoded in a Field-Programmable Gate Array (FPGA) and / or an Application-Specific Integrated Circuit (ASIC), or the functionality of the device aspect may be provided for download by means of a hardware description language.

[0074] The embodiments of the device aspect and the method aspect may efficiently perform segmental ray tracing (e.g., in the determining step) using an iterative approach (e.g., in the obtaining step):

[0075] 1. launch a ray in a certain direction, e.g., from the first station to the next interaction point;

[0076] 2. identify a first object that the ray intersects with;

[0077] 3. depending on the type of object, launch one or several new rays, representing e.g. reflection, transmission, diffraction, or diffuse scattering. Each new ray may proceed in a similar way, starting from 1 ;

[0078] 4. construct the full propagation path from an identified object.

[0079] The launch point for the further rays (e.g., from the interaction point) may need to be spatially offset from the hit point (i.e., from the interaction element of the object with which the second path interacts) to avoid self-intersection due to finite numerical precision. Otherwise, the further rays may hit the same object again resulting in an infinite loop. The first location of the shifting may be the spatially offset launch point that is shifted back to the interaction element of the object as the second location of the shifting in the modifying step.

[0080] The objective of the embodiments of the device aspect and the method aspect may be to efficiently establish the conditions, e.g. presence of objects, along the true propagation path (the second path), obtained by modifying a ray traced path (the first path). This may comprise both the presence or absence of objects at the interaction points and the presence or absence of objects between the interaction points. The invention achieves this objective by performing a further but computationally very efficient ray tracing step involving launching (e.g., shooting) a single ray from the start to the finish of each segment of the true propagation paths.

[0081] Each segment may be defined as to start and end at successive interaction points (e.g., including the transmitter location and the receiver location as the first and the last interaction points). Every object in the environment that the ray hits along the segment may be recorded (e.g., stored) so that the transmission properties may later be used in calculations (e.g., determining) of the electromagnetic properties of the radio waves along the radio wave propagation path. The objects that are hit may be determined iteratively (e.g. using what is known in the art as “a closest hit program”). Alternatively or in addition, the objects that are hit may be determined using a parallel approach (which may be referred to as an “any hit program”) that returns all intersected objects. This may prevent the error propagation and resulting deviations from the true path.

[0082] The embodiments of the device aspect and the method aspect may trace a single ray along each segment of a modified first path, and use the objects that this ray interacts when determining the electromagnetic properties of the radio channel.

[0083] The embodiments of the device aspect and the method aspect may disclose a way to determine the presence or absence of objects along the true propagation path (e.g., the second path) using segment tracing. This solves the problem of false paths or paths with erroneous characteristics such as wrong path gain.

[0084] Compared to full ray tracing where many billions of rays are launched and traced, the segment tracing only requires only a single ray to be launched per segment. Hence it is computationally several orders of magnitude more efficient and can therefore be implemented with little additional computational cost. Moreover, since every segment can be traced independently of all others, the segment tracing is very suitable for parallel implementation which further enhances the computational efficiency, e.g. when using modem Graphics Processing Units (GPUs). The use of an Any Hit (AH) Program for determining intersected objects avoids the problems with error propagation and deviations from the intended true path.

[0085] A high fidelity, fast computed representation of the radio channel may be used in at least the following ways:

[0086] • In (e.g., laboratory) testing of radio communications equipment, it is desirable to replicate the conditions expected when the equipment is deployed and used in the real world. The subject technique may be used for channel emulation (e.g., according to the evaluating or modeling step) to expose the equipment to different types of radio channels. An embodiment of the device may generate radio channels to be emulated. Real-time or near real-time calculation of the radio channel is very important for this use case.

[0087] • The dimensioning and deployment of wireless radio networks may rely on estimating e.g. coverage and user-experienced throughput for different hypotheses of how the radio base stations are deployed and what their capabilities are (e.g. which frequency bands they are configured to use, their output power and sensitivity, what kind of antennas, etc.). While stochastic channel models are often used in the initial stages of this work, high-fidelity channels rapidly may be computed using ray tracing can greatly improve the quality of the sizing and planning process and reduce the need for costly and time-consuming field trials.

[0088] • When designing wireless network products, it is important to understand the relative value of different product enhancements. However, this value may only be determined either by measurement (which in most cases would require the product to be built first) or by simulation using channel models. The higher the fidelity of the channel models, the greater the likelihood that correct prioritization will be made, leading to better products.

[0089] • Standardization of radio network technologies involves forming an industry consensus view on the relative performance of different proposed standard features or enhancements. In most cases the performance is determined through simulations, mainly using stochastic channel models. However, in recent years there has been an increasing understanding of the need for site-specific channel modeling such as ray tracing. The 3GPP document TR 38.901, version 17.1.0, contains a specification of the channel models that have been used of most of the NR standardization in RANI, and includes both stochastic models and a site-specific model with ray tracing elements (loc. cit., clause 8, Map-based hybrid channel model). Improvements to the ray tracing methods can improve the site-specific modeling and therefore open for better evaluations or even unlock evaluations for new features and scenarios that were previously considered too complicated for 3 GPP.

[0090] • Furthermore, embodiments can ensure that regulation, e.g. for maximum transmission power, are fulfilled.

[0091] In addition to the above mentioned use cases, there is a class of use cases that fall in the “digital twin” category, i.e. where there is a digital representation of the radio network or of some equipment in the radio network. The one or more digital twins may provide the environment, based on which an embodiment of the method inform the physical network or equipment about expected behavior of the radio channel. This may have several different applications, including:

[0092] • Channel estimation, i.e., the physical receiver can improve its estimation if some a priori information may be obtained from its digital twin;

[0093] • Beam forming and beam management, the transmitter (Tx) and / or receiver (Rx) may improve how beams are formed and tracked over time if information about likely directions (and changes thereof) of transmitted or received radio waves can be obtained via ray tracing • Channel prediction, similar to the above, informing a Tx or Rx about likely future time development of the radio channel based on ray tracing

[0094] • Positioning, may be based on fingerprinting (comparing actual measured channel conditions with simulated channels in a vast number of potential positions), or could include classification of line of sight (LOS) or non-LOS of different links which can significantly enhance any time or time-difference based methods

[0095] • Sensing, for instance if difference between ray traced channel and measured channel suggests the presence and location of objects of interest

[0096] • Configuration of equipment: this could entail selecting numerology and cyclic prefix length, different antenna and MIMO algorithm choices (SU-MIMO / MU-MIMO, number of layers, reciprocity or codebook), antenna down-tilt, output power levels, etc.

[0097] • Ensuring compliance with radio and health regulations by adjusting output powers and directions of transmission based on assessments on how much power reaches locations in which there are or may be persons or equipment that need to be protected.

[0098] Also, some of the use cases from the “digital twin” category may equally well be used without a full- fledged digital twin and vice versa. In the “digital twin” category of use cases, the ray tracing may be performed in a physical base station as well as by a separate computer program product that could be running in a cloud implementation.

[0099] The device may be embodied by a user equipment (UE). The UE may be configured to communicate with a base station (e.g., directly on an uplink or downlink, or through another UE functioning as a gateway or relay) or with a peer UE (e.g., on a sidelink). The UE may comprise a radio interface and processing circuitry configured to execute any of the steps and functionality disclosed for the device.

[0100] Alternatively or in addition, the device may be embodied by a base station, e.g. acting as the first station or the second station and / or configured to communicate with a UE. The base station may comprise a radio interface and processing circuitry configured to execute any of the steps and functionality disclosed for the device.

[0101] Alternatively or in addition, the device may be embodied by a core network node configured to communicate with a base station. The core network node may comprise memory operable to store instructions and processing circuitry operable to execute the instructions, such that the core network node is operable to perform any one of the steps and functionality disclosed for the device.

[0102] In a first variant of any embodiment, the same device that is determining the one or more second paths may also perform the physical action. In a second variant of any embodiment or in combination with the first variant, the device may initiate (e.g., trigger) the physical action, which is accordingly performed by another device other than the device that is determining the one or more second paths. For example, the device and the other device may be distributed nodes or networked (e.g., cloud-based) implementations. The device and the other device may be spaced apart from each other. Moreover, initiating the physical action may comprise outputting instruction (which may be machine readable and / or which may be human readable) for the performing of the physical action.

[0103] Modeling the channel (or modeling a channel state, briefly: channel modeling) may comprise modeling amplitudes and phase shifts of actual or hypothetical signals between actual or hypothetical transmitters and receivers, e.g. based on the determined one or more second paths, rather than a measured channel state. The result of the channel modeling may be a vector or matrix comprising complex-valued gains of the channel between the launch point and the at least one position, e.g. each pair of transmit antenna and receive antenna and / or in a similar format as a channel estimate for a measured channel state.

[0104] Alternatively or in addition, the result of the channel modeling may be polarimetric, i.e., having (potentially) independent complex-valued gains per polarization state, e.g. for orthogonal transmit antennas or orthogonal receive antennas. Any two mutually orthogonal polarization states also orthogonal to the ray (or path direction) may be used to represent the polarimetric properties of the signal associated with the ray.

[0105] A result of the modeling of the channel may be a channel estimate (e.g., a matrix comprising matrix elements, each representing amplitude and phase between any pair of transmit antenna at the transmit node and receive antenna at the receive node, optionally including antennas with orthogonal polarizations). Therefore, the step of modeling may also be referred to as determining a channel estimation (e.g., as opposed to performing a channel estimation that is solely based on measuring reference signals).

[0106] The modeling of the channel may comprise determining an electromagnetic propagation of an electromagnetic field (e.g., based on the Lienard-Wiechert potential) along the determined one or more second paths. For example, the electromagnetic propagation may be configured to associate to the one or more second paths at least one of a phase shift of the electromagnetic field, a change in an electrical field component of the electromagnetic field, and a change in magnetic field component of the electromagnetic field. The channel may be modeled by superimposing the electromagnetic field propagated along each of the one or more second paths.

[0107] In any aspect, the one or more second paths may be the basis of an electromagnetic propagation (e.g., a radio propagation or an infrared or visual light propagation) used by the wireless communication.

[0108] Alternatively or in addition, the wireless communication may be a radio frequency communication or a visible light communication (VLC).

[0109] A transmitting node (e.g., at the first or second station) for transmitting the wireless communication may be a radio device (such as a user equipment, UE), e.g. in an uplink (UL) or in a sidelink (SL). Alternatively or in combination (e.g., for a duplex wireless communication), the transmitting node for transmiting the wireless communication may be a base station (such as a next generation Node B, gNB) of a radio access network (RAN) in a downlink (DL). Furthermore, a receiving node (e.g., at the second or first station) for receiving the wireless communication may be a radio device, e.g. in a DL or in a SL. Alternatively or in combination (e.g., for a duplex wireless communication), the receiving node for receiving the wireless communication may be a base station of a RAN in an UL.

[0110] The wireless communication in the environment may be performed (e.g., transmited or received) or controlled (e.g., initiated) based on the determined one or more second paths.

[0111] The transmiting or receiving may comprise transmiting or receiving data or transmiting or receiving control signaling, e.g. a random access preamble, a random access response, a reference signal (RS, e.g., a sounding RS in the uplink from a radio device to a network node or a channel state information, CSI, RS in the downlink) or a paging signal or radio resource control (RRC) message.

[0112] The determining of the one or more second paths may support a channel estimation (at a receiver node or at a transmiter node) of the wireless communication. The channel estimation may encompass receiving (e.g., measuring) radio signals and processing the measured radio signals (e.g., comparing to known reference signals, RSs) to estimate an amplitude and phase shifts of signals wirelessly propagated between the transmiter node and the receiver node.

[0113] In any radio access technology (RAT), the technique may be implemented for a downlink (DL, transmission from a radio device to a network node), an uplink (UL, transmission from a network node to a radio device) and / or a sidelink (SL, transmission from one radio device to another radio device). The SL may be implemented using proximity services (ProSe), e.g. according to a 3GPP specification.

[0114] Any radio device may be a user equipment (UE), e.g., according to a 3GPP specification.

[0115] The radio device and the RAN may be wirelessly connected in an uplink (UL) and / or a downlink (DL) through a Uu interface. Alternatively or in addition, the SL may enable a direct radio communication between proximal radio devices, e.g., the remote radio device and the relay radio device, optionally using a PC5 interface. Services provided using the SL or the PC5 interface may be referred to as proximity services (ProSe). Any radio device (e.g., a remote radio device and / or a relay radio device) supporting the SL may be a ProSe-enabled radio device.

[0116] The radio device and / or the network node and / or the RAN may form, or may be part of, a radio network, e.g., according to the Third Generation Partnership Project (3GPP) or according to the standard family IEEE 802.11 (Wi-Fi). The method aspect may be performed by one or more embodiments of the radio device, the network node and the RAN (e.g., a base station). The RAN may comprise one or more base stations, e.g., performing the method aspect. Alternatively or in addition, the radio network may be a vehicular, ad hoc and / or mesh network comprising two or more radio devices, e.g., acting as a remote radio device and / or the relay radio device.

[0117] Any of the radio devices may be a 3GPP user equipment (UE) or a Wi-Fi station (STA). The radio device may be a mobile or portable station, a device for machine-type communication (MTC), a device for narrowband Internet of Things (NB-IoT) or a combination thereof. Examples for the UE and the mobile station include a mobile phone, a tablet computer and a self-driving vehicle. Examples for the portable station include a laptop computer and a television set. Examples for the MTC device or the NB-IoT device include robots, sensors and / or actuators, e.g., in manufacturing, automotive communication and home automation. The MTC device or the NB-IoT device may be implemented in a manufacturing plant, household appliances and consumer electronics.

[0118] Whenever referring to the RAN, the RAN may be implemented by one or more network node (e.g., base stations).

[0119] The transmitting or receiving node (e.g., a radio device) may be wirelessly connected or connectable (e.g., according to a radio resource control, RRC, state or active mode) with the receiving node and transmitting node, respectively (e.g., a relay radio device or a network node of the RAN).

[0120] The network node (e.g., a base station) may encompass any station that is configured to provide radio access to any of the radio devices. The base station may be a cell, a transmission and reception point (TRP), a central unit (CU), a distributed unit (DU), a radio access node or an access point (AP). The base station and / or the relay radio device may provide a data link to a host computer providing user data to the (e.g., remote) radio device or gathering user data from the (e.g., remote) radio device. Examples for the base stations may include a 3G base station or Node B (NB), 4G base station or eNodeB (eNB), a 5G base station or gNodeB (gNB), a Wi-Fi AP and a network controller (e.g., according to Bluetooth, ZigBee or Z-Wave).

[0121] The RAN may be implemented according to the Global System for Mobile Communications (GSM), the Universal Mobile Telecommunications System (UMTS), 3GPP Long Term Evolution (LTE) and / or 3GPP New Radio (NR).

[0122] Any aspect of the technique may be implemented on a Physical Layer (PHY), a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, a packet data convergence protocol (PDCP) layer, and / or a Radio Resource Control (RRC) layer of a protocol stack for the radio communication. Herein, referring to a protocol of a layer may also refer to the corresponding layer in the protocol stack. Vice versa, referring to a layer of the protocol stack may also refer to the corresponding protocol of the layer. Any protocol may be implemented by a corresponding method.

[0123] Any one of the devices, the first station, the second station, the transmitting node, the receiving node, the user equipment (UE), the network node, the base station, a communication system or any node or station for embodying the technique may further include any feature disclosed in the context of the method aspect, and vice versa the method aspect may comprise any step or feature disclosed in the context of the device aspects. Particularly, any one of the units and modules disclosed herein may be configured to perform or initiate one or more of the steps of the method aspect, and the devices may comprise a unit or a module performing any of the steps of the method aspect.

[0124] Brief Description of the Drawings

[0125] Further details of embodiments of the technique are described with reference to the enclosed drawings, wherein:

[0126] Fig. 1 shows a schematic block diagram of an embodiment of a device for evaluating a radio wave propagation of a wireless communication in an environment;

[0127] Fig. 2 shows a flowchart of an embodiment of a method for evaluating a radio wave propagation of a wireless communication in an environment, which method may be implementable by the device of Fig. 1;

[0128] Fig. 3 shows a first exemplary embodiment of an environment comprising a first path and a second path;

[0129] Fig. 4 shows second exemplary embodiment of an environment comprising a first path and a second path;

[0130] Fig. 5 shows third exemplary embodiment of an environment comprising a first path and a second path;

[0131] Fig. 6 shows fourth exemplary embodiment of an environment comprising a first path and a second path;

[0132] Fig. 7 shows a block diagram of an emulating embodiment of the device of Fig. 1;

[0133] Fig. 8 shows a block diagram of a base station embodiment of the device of Fig. 1 ; and Fig. 9 shows a block diagram of a core network embodiment of the device of Fig. 1.

[0134] Detailed Description

[0135] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as a specific network environment in order to provide a thorough understanding of the technique disclosed herein. It will be apparent to one skilled in the art that the technique may be practiced in other embodiments that depart from these specific details. Moreover, while the following embodiments are primarily described for a New Radio (NR) or 5G implementation, it is readily apparent that the technique described herein may also be implemented for any other radio communication technique, including a Wireless Local Area Network (WLAN) implementation according to the standard family IEEE 802.11, 3GPP LTE (e.g., LTE-Advanced or a related radio access technique such as MulteFire), for Bluetooth according to the Bluetooth Special Interest Group (SIG), particularly Bluetooth Low Energy, Bluetooth Mesh Networking and Bluetooth broadcasting, for Z-Wave according to the Z-Wave Alliance or for ZigBee based on IEEE 802.15.4.

[0136] Moreover, those skilled in the art will appreciate that the functions, steps, units and modules explained herein may be implemented using software functioning in conjunction with a programmed microprocessor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP) or a general purpose computer, e.g., including an Advanced RISC Machine (ARM). It will also be appreciated that, while the following embodiments are primarily described in context with methods and devices, the invention may also be embodied in a computer program product as well as in a system comprising at least one computer processor and memory coupled to the at least one processor, wherein the memory is encoded with one or more programs that may perform the functions and steps or implement the units and modules disclosed herein.

[0137] While below description of general device and method embodiments refer to Figs. 1 and 2, for convenience of reading and not limitation, the description also includes some reference signs for feature that are exemplified in the later figures.

[0138] Fig. 1 schematically illustrates a block diagram of an embodiment of a device for evaluating a radio wave propagation of a wireless communication in an environment 300, e.g. for ray tracing of a propagation path 320, 322 of a wireless communication in an environment 300 comprising a first station 302 and a second station 304. The environment 300 may further comprise one or more objects 308. The device is generically referred to by reference sign 100.

[0139] The device 100 comprises a first path module 102. The first path module 102 may obtain S202 a first path points of a sequence of interactions of the radio wave propagation with objects 308 in the environment 300. The first path 320 may further comprises a segment 314; 316 between each subsequent pair of the interaction points. The obtaining S202 of the first path 320 may use a first location 310 (e.g. an approximate location) that approximates a second location 312 (e.g., a physical location) for at least one of the interaction points.

[0140] The first path 320 and / or the second path 322 may have a start point 310 and 312, respectively, at the first interaction point referred to by a suffix "F". Analogously, the first path 320 and / or the second path 322 may have an end point 310 and 312, respectively, e.g., the last interaction point referred to by a suffix "L". For convenient terminology (e.g., when referring to a segment between pairs of interaction points), the start point and the end point may be referred to as interaction points.

[0141] The start point may comprise a first station 302 and the end point may comprise a second station 304 or a capture surface 306 thereof.

[0142] The obtaining S202 of the first path 320 may comprise the device 100 being operable to at least one of launching one or multiple rays of the ray tracing at a first interaction point of the first path 320 as the approximate location 310-F for the physical location 312-F of a first station 302 in the environment 300; determining the interaction points of the interactions of the first path 320 at intersections of rays of the ray tracing with the objects 308 in the environment 300; launching one or multiple rays at one or each interaction of the interactions of the first path 320 from a launch point as the approximate location 310 outside of the object 308 of the respective interaction that approximates the physical location 312 of the respective interaction; and capturing one or multiple rays of the ray tracing for each of the at least one first path 320 on a capture surface 306 enclosing a second station 304 in the environment 300, the interaction point of the first path 320 on the capture surface 306 being the approximate location 310-L that approximates the physical location 312-L of the last interaction point of the second path 322 at the second station 304.

[0143] Determining the interaction points of the interactions of the first path 320 may further comprise determining the objects 308 in the environment 300 (e.g., determining the size of objects 308 and / or the types of interactions with the object 308). The objects 308 of the environment may be stationary or moving objects 324. The location of the objects 308 and / or the location of the first station 302 and / or the location of the second station 304 may be moving relative to each other within the environment 300.

[0144] Optionally, the first station 302 and the second station may be referred to as the objects 308 of the environment 300.

[0145] The device 100 further comprises a second path module 104. The second path module 104 may modify S204 the first path 320 by shifting at least one interaction point (e.g., the last interaction point or each intermediate interaction point) from a first location 310 (e.g., an approximate location 310) of one interaction to a second location (e.g., a physical location 312) of the respective one interaction, which results in a second path 322.

[0146] To avoid the conventional interaction inconsistencies of the prior art, which may be cause by the modifying S204 of the first path 320 when shifting the at least one interaction point (e.g., from the approximate location 310 to the physical location 312), the device 100 further comprises a interaction module 106 that determines S206 at least one adjusted interaction, e.g. by changing a type of the interaction or adding to or removing from the pertinent segment of the second path 322 any interaction (e.g., with further objects 324 in the environment 300). This may be performed along any of the segments 314, 316, and preferably in parallel for each segment.

[0147] As a result, the number of the segments along the second path 322 may be more, equal or less than the numbers of the segments along the first path 320.

[0148] For example, the added or removed interaction with objects 324 in the environment 300 along the respective segment 314; 316 results from the shifting of the at least one interaction point connected to the respective segment 314; 316. Alternatively or in addition, the added or removed interaction with objects 324 in the environment 300 along the respective segment 314; 316 may result from a mobility of the objects 324 in the environment 300.

[0149] The modifying S204 of the first path 320 may reduce or minimize a length of the second path 322 compared to the length of the first path 320 by shifting the at least one interaction point from the approximate location 310 to the physical location 312 within a plane or line of the object 308 of the respective interaction. The second path 322 may also be referred to as the shortest path.

[0150] The first path 320 and the second path 322 may have been obtained based on a ray tracing in the environment 300. For example the first path 320 may have been obtained by launching a ray from the first station 302 and iterative ray tracing.

[0151] The first interaction point 310-F of the first path 320 as the approximate location 310 may deviate from the physical location 312-F of a first station 302 of the wireless communication due to a mobility of the first station 302, optionally due to a time lag in updating the approximate location 310 of the first station for the ray tracing. Alternatively or in addition, the interaction point of the first path 320 as the approximate location 310 may deviate from the physical location 312 of an object 308 of the respective interaction due to a mobility of the object 308 in the environment, optionally due to a time lag in updating the approximate location 310 of the object 308 for the ray tracing. Alternatively or in addition, the last interaction point 310-L of the first path 320 as the approximate location 310-L may deviate from the physical location 312-L of a second station 304 of the wireless communication due to a mobility of the second station 304, optionally due to a time lag in updating the approximate location 310 of the second station 304 for the ray tracing.

[0152] The device 100 further comprises an evaluation module 108. The evaluation module 108 may evaluate S208 the radio wave propagation along the second path 322 for each segment 314; 316 according to each interaction at the at least one shifted interaction point. The radio wave propagation may be evaluated S208 along the second path 322 for each segment 314; 316 according to each added or removed interaction and each interaction at the at least one shifted interaction point.

[0153] For example, a complex-valued (and / or vector-valued or matrix-valued) gain may be evaluated for each segment and each intermediate interaction point. The gains may be multiplied according to the sequence of segments and interaction points along the second path. In case of multiple second paths linking the first station 302 and the second station 304, the contributions (resulting from the multiplication along each path) of the multiple second paths are added up, which yields the gain of the radio wave propagation.

[0154] The modifying S204 of the first path 320, the determining S206 of the adjusted interaction and / or the evaluating S208 along the second path 322 may comprise discarding the respective path, or discarding the respective interaction and the connected segment 314; 316, e.g. if the shifting of the first (e.g., approximate) location 310 as the interaction point of the first path 320 (e.g., on an earlier position of the object 308 of the respective interaction) to the second (e.g., physical) location as the interaction point of the second path 322 is outside of a size of the object 308 of the respective interaction or outside of a Fresnel zone of the respective interaction.

[0155] The evaluating S208 of the radio wave propagation along the second path 322 may comprise determining one or more physical properties of the radio wave propagation, optionally per each segment along the first path 320 and / or per each segment along the second path 322. The one or more physical properties comprises at least one of a phase shift; a gain; a time of flight; a Doppler shift; a signal to interference plus noise ratio (SINR); a channel state; and a channel estimate. The evaluating of the radio wave propagation along the second path 322 may comprise optimizing one or more physical properties of the second path, e.g., minimizing the time of flight and / or shortest path.

[0156] The device 100 may obtain S202 the first path 320 and the second path 322 (e.g., modified S204 first path 320) wherein the environment 300 comprise one or more of the physical location 312-F of the first station 302 and / or wherein the environment 300 comprises one or more of the physical location 312-L of the second station 304. The first station 302 and / or the second station 304 may comprise multi antenna (e.g., MIMO).

[0157] In a first variant of any embodiment, the device 100 may further be operable to perform or initiate a physical action S210 that is dependent on the evaluated S208 the radio wave propagation along the second path 322. Alternatively or in addition, the device 100 may model S212 a channel of the wireless communication along the evaluated second path 322 in the environment 300.

[0158] In a second variant of any embodiment, the device 100 may further be operable to model S212 a channel of the wireless communication along the second path 322 in the environment 300. Alternatively or in addition, the modeling S212 of the channel comprises, or the device 100 may be further operable to perform or initiate, a physical action that is dependent on the modeled S212 channel.

[0159] Optionally, the device 100 may further be operable to store S214 the evaluated S208 second path 322. The evaluated S208 second path may be used for further ray tracing in the environment 300 or as the first path in an iteration of the method performed by the device 100.

[0160] The obtaining S202 of the first path 320 may comprise an (e.g., iterative) ray tracing in the environment 300 resulting multiple first paths 320. The device 100 is operable to modify S204 each of the first paths 320 resulting multiple second paths 322, to determine S206 the at least one adjusted interaction for each of the second paths and each segment thereof, and to evaluate S208 the radio wave propagation along each of the second paths 322, which results in combination in the radio wave propagation of the wireless communication.

[0161] Optionally, the device 100 may further detect the interaction point (e.g., first or approximate location 310 and / or second or physical location 312) on the one or more objects 308.

[0162] Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality.

[0163] The device 100 may be embodied by an emulator or a network node (e.g., a transmitting and / or receiving node) of a RAN.

[0164] Fig. 2 shows an example flowchart for a method 200 of evaluating a radio wave propagation of a wireless communication in an environment 300, e.g. for ray tracing of a propagation path 320, 322 of a wireless communication in an environment 300 comprising a first station 302 and a second station 304. The first station 302 may be a transmitter node (e.g., a network node) and the second station may be a receiving node (e.g., a radio device), or vice versa.

[0165] The method 200 comprises a step S202 of obtaining a first path 320 of the radio wave propagation in the environment 300. The first path 320 may comprise interaction points of a sequence of interactions of the radio wave propagation, e.g. including one or more intermediate interactions with objects 308 in the environment 300. The first path 320 may further comprise a segment 314; 316 between each subsequent pair of the interaction points. The obtaining S202 of the first path 320 uses a first (e.g., approximate) location 310 that is shifted to (e.g., because it approximates) a second (e.g., physical) location 312 in the following step S204.

[0166] The method 200 further comprises a step S204 of modifying the first path 320 by shifting the at least one interaction point from the first (e.g., approximate) location 310 to the second (e.g., physical) location 312, resulting in a second path 322.

[0167] Responsive to the modification, at least one of adjusted interaction is determined in the step S206 of the method 200.

[0168] The method 200 further comprises a step S208 of evaluating the radio wave propagation along the second path 322 for each segment 314; 316 according to each interaction at the at least one shifted interaction point as well as the at least one adjusted interaction.

[0169] Optionally, the method 200 may further comprise a step S210 of performing or initiating a physical action that is dependent on the evaluated S208 the radio wave propagation along the second path 322. For example, a channel of the wireless communication may be modeled along the evaluated second path 322 in the environment 300.

[0170] Alternatively or in addition, the method 200 may further comprises a step S212 of modeling a channel of the wireless communication along the second path 322 in the environment 300, optionally wherein the modeling S212 of the channel comprises - or the device 100 is further operable to perform or initiate - a physical action S210 that is dependent on the modeled S212 channel.

[0171] Optionally, the method 200 may further comprises a step S212 of storing the evaluated S206 second path 322. The evaluated S206 second path may be used for further ray tracing in the environment 300.

[0172] The method 200 may be performed by the device 100.

[0173] The technique may be applied to uplink (UL), downlink (DL) or direct communications between radio devices, e.g., device-to-device (D2D) communications or sidelink (SL) communications.

[0174] The device 100 may be embodied by, or may control, a radio device or a network node of a RAN (e.g., a base station). Herein, any radio device may be a mobile or portable station and / or any radio device wirelessly connectable to a base station or RAN, or to another radio device. For example, the radio device may be a user equipment (UE), a device for machine-type communication (MTC) or a device for (e.g., narrowband) Internet of Things (loT). Two or more radio devices may be configured to wirelessly connect to each other, e.g., in an ad hoc radio network or via a 3GPP SL connection. Furthermore, any base station may be a station providing radio access, may be part of a radio access network (RAN) and / or may be a node connected to the RAN for controlling the radio access. For example, the base station may be an access point, for example a Wi-Fi access point.

[0175] Embodiments of the device 100 and the method 200 may be used for evaluating a radio wave propagation of a wireless communication in an environment 300. The method 200 may be reciprocal, i.e., the ray may be uplink (UL) or downlink (DL) using method 200.

[0176] Embodiments of the method 200 are orders of magnitude faster than ray tracing to each individual destination. It is thus computationally superior to the methods of the art. Same or further embodiments of the method 200 do not require a predefined or deterministic motion of the first or second stations (e.g., transmitter or receiver positions) or other objects in the environment and may be used to query paths with arbitrary transmitter / receiver locations. This mode of computation allows near real-time operation with full interactivity and 3D movement of users.

[0177] A conventional channel estimation is based on measuring reference signals, which is time consuming and occupies transmission resources. Due to the delay caused by measuring the channel and processing, at the time of transmission the channel estimate may be already outdated. If the channel is more rapidly modeled using only on a finite set of rays, e.g. a random set for a Monte-Carlo simulation, the fidelity of the modeled channel is low, which can cause inaccurate beamforming and interference at neighboring UEs.

[0178] Embodiments of the device 100 and the method 200 can improve the fidelity of the modeled channel and / or the accuracy of the evaluated second path 322 (e.g., represent the dominant contribution to the signal propagation of the wireless communication). For example, based on the modeled channel and / or the evaluated second path 322, transmission parameters and / or precoders at the first station (for transmitting and / or receiving) the wireless communication can be improved, e.g. a signal -to-noise ratio (SNR) or a signal-to-interference and noise ratio (SINR) at UEs can be increased.

[0179] The paths may also be referred to as propagation paths.

[0180] The second station 304 may be represented by or enclosed by a capture object 306 that surrounds for example a receiver 306. When rays are launched from the first station 302 and traced in the environment 300, the device 100 may record (e.g., in the obtaining step S202) the paths 320 which rays intersect the capture object 306. The radio wave propagation (e.g., the radio channel) between the first station (e.g., a source, optionally a transmitter) and the second station (e.g., a receiver) may be evaluated in the step S208 (e.g., constructed) from all the second paths based on the first paths traveled by the rays that hit the specific capture object (e.g., receiver) after modifying in the step S204 each of the first paths by shifting the last interaction point of the first path (i.e., the first location of the shifting) to the second station (i.e., the second location of the shifting). Due to the finite shooting resolution (i.e., the finite angular density of the rays launched at the first station), the capture objects 306 must be of a sufficient size to ensure a hit (i.e., to have a sufficient cross-section for a sufficient probability per launched ray to yield an intersection), so the end point (i.e., the last interaction point) of the first path is initially at the first location on the surface of the capture object rather than at the physical location, i.e., actual location, of the second station (e.g. a receiver location) as the second location of the shifting. If the end point (i.e., the last interaction point) is moved to the second station (e.g., the receiver location) according to the step S204, the resulting second path 322 as the modified first path 320 may no longer fulfil fundamental physical properties such as for example having equal incidence and departure angles from a specular reflection, or more generally, may not fulfil Femaf s principle.

[0181] To this end, the modifying step S204 may further comprising minimizing the path length of the second path 322, e.g. while maintaining the interaction points under constraints. For example, the first and last interaction points 312-F and 312-L may be pinned to the first station 302 and the second station 304, respectively. The intermediate interaction points (i.e., the other interaction points within the second path 322) may be constrained to a line or plane defined by the respective interaction underlying the interaction point.

[0182] Herein, "minimizing a path length" of any path (e.g., the first and / or the second paths) may mean that the respective path is a physical path that fulfils Fermat's principle (e.g., between the first station and the second station). The minimizing of a path length of a path may result in a local minimum (e.g., local in a path space comprising the path) of the path length or a path which path length is stationary with respect to variations of the path.

[0183] Herein, "a path length" of any path may be a spatial path length or an optical path length. For example, in vacuum or air, the minimization may use "a path length" that is unweighted or corresponds to the spatial length. If the path passes through a medium with a relevant optical density (e.g. a medium that has a dielectric response at a radio frequency of the wireless communication) or any spatially varying index of refraction, n(r), the minimizing may use "a path length" that is weighted by the index of refraction. In other words, the path length of the path may be the optical path length, e.g. path length =

[0184] Minimizing the path length of the second path in accordance with the (intermediate) interactions of the second path may encompass minimizing the path length consistently with the interactions. At least one or each interaction may define a constraint of an interaction point of the first path when minimizing the path length of the second path. The adjusting of the least one interaction of the second path may involve a change (e.g., an addition or removal) of the corresponding constraint. The constraint of the interaction point may be a boundary condition of the respective path. In an implementation, the minimizing of the path length may comprise that the second path is unwrapped for all interactions involving specular reflection (i.e., mirroring the second path and the downstream interaction objects of the environment) to remove the specular interaction points.

[0185] Herein, to "unwrap" may be defined as the replacement of the remainder of a path after (i.e., "downstream" from the first station to the second station) a specular reflection 602 by its mirror image (i.e., a mirrored second path), when mirrored in a plane coplanar with the surface (at the interaction point of reflection) in which the specular reflection takes place. This may be implemented using for example imaging methods and involves imaging of both the interaction points and the interaction objects (e.g., a line along a diffraction edge and a specular reflective surfaces) with which the second path (and thus the mirrored second path) interacts.

[0186] The path length of the mirrored (i.e. unwrapped) second path is reduced, e.g., by apply a "taut string" process to get the shortest unwrapped second path, optionally via the zero or more mirrored diffractive edges of the mirrored second path. Herein "zero or more" refers to all those diffraction edges (if any) with which the second path interacts, so that the mirrored second path also interacts (i.e. remains attached as a boundary condition) with the correspondingly mirrored diffractive edges downstream of the (temporarily) eliminated specular reflection.

[0187] While the minimization of the path length has been described from the first station to the second station, it may as well be performed in the opposite direction along the second path.

[0188] In a sub-step of the minimization of the path length, the path is de-imaged, i.e. the imaging performed in the sub-step prior to the minimization of the mirrored path length is reversed, of course including the effect of reducing of the path length so that the resulting "shortest" second path is different. That comprises reintroducing the one or more reflective surfaces and the zero or more diffractive edges. At each reintroduction of one of the one or more reflective surfaces, the remaining path (and, in a first variant, the zero or more diffractive edges) downstream of the corresponding point of the reintroduced reflection are mirrored (i.e., de-imaged) with respect to a plane coplanar with the reintroduced reflective surface. In a second variant, the zero or more diffractive edges are determined directly from the structural information of the environment, e.g. obtained in the step S202 for the first path.

[0189] The sub-step of de-imaging includes determining updated reflection interaction points (which are different from the reflection interaction points prior to the path length minimization) on the original respective surfaces (e.g., according to the obtained structural information). Furthermore the zero or more diffraction interaction points are updated, e.g. by mirroring the diffraction points of the shorted path back along the original diffractive edges (e.g., according to the obtained structural information). The second path resulting from this minimization of the path length is the shortest path in the original environment with the same sequence of interactions as prior to the minimization of the path length.

[0190] Typically, a set of second paths 322 between the first station (e.g., representing the transmitter) and the second station (e.g., representing the receiver) is determined according to the method. If a wireless communication system (e.g., comprising the first station and / or the second station) uses multiple antennas and / or wideband or even multiband communication, a preferred approach is to determine the radio channel in the step S208 or S212 assuming that the radio channel is stationary over the antenna array and frequency in the sense that the direction of arrival or departure, the propagation delay, and the amplitude and phase shifts due to interactions along the propagation path are all constant (or linearly dependent on frequency in the case of the phase shift).

[0191] Therefore, ray tracing is becoming increasingly important for modeling or emulating the wireless channel for existing or future generations of wireless networks and devices. The current and future capabilities of these networks and devices include the use of large antenna arrays, wide communication bandwidths and the simultaneous use of multiple frequency bands for communication. To elaborate, the aim of methods such as ray tracing is to obtain a representation of the radio channel between real or planned transmitters and receivers in real or planned scenarios of the environment. This can be achieved by embodiments of the device 100 and the method 200 in real-time and with acceptable power consumption due to the improved computational and energy efficiency.

[0192] A simplified environment 300 comprising a first station 302 and a second station 304 is shown in Fig. 3 as a first exemplary embodiment of the device 100 and / or the method 200 comprising only two segments for illustration and without limitation. The environment 300 comprises an object 308. Fig. 3 shows an obtained S202 first path 320 comprising a first segment 314 and a second segment 316 shown with dashed line. The first path 320 starts from the first station 302 and ends at the captured surface 306 of the second station 304.

[0193] Fig. 3 shows a physical location 312-F of the first station 302 in the environment and an approximate location 310-L of the second station 304 that approximate the physical location 312-L of the second station 304. The device 100 may obtain the second path 322 by modifying S204 the first path 320 by shifting the interaction point on the object 308 from the approximate location 310 to the physical location 312. By shifting the interaction point, the second path 322 ends at the physical location 312-L of the second station 304. The modifying S204 further comprises minimizing the path length while maintaining the intermediate interaction point for the reflection in the plane defined by the surface of the object 308 as the interaction element. The minimization of the path length ensures that the angle of reflection of the second path 322 fulfills the law of reflection. In a first variant of the first embodiment, the determination S206 of the adjusted interaction determines that the reflection interaction point at the first location 310 of the first path has been shifted to the second location 312, which is outside of the size of the interaction element (i.e., the reflection surface) of the object 308. Consequently, the second path is discarded as invalid. Discarded may encompass that the second path is excluded from being considered in the evaluation S208 or as a basis for modeling S212 the channel or performing the action S210.

[0194] Thus, Fig. 3 illustrates an example of segment tracing (e.g., segmental ray tracing) where specular reflection found to be invalid.

[0195] In a second variant of the second embodiment, the determination S206 determines that the second location is outside of the physical size of the interaction element, but still within a Fresnel zone of the object 308 (or a Fresnel zone of the second path still overlaps with the interaction element). Consequently, the computation of the gain at the interaction point 312 is adjusted in the step S206. Then, the device 100 further evaluates S208 the radio wave propagation along the second path 322 for each segment 314; 316 according to each interaction at the at least one shifted interaction point.

[0196] Thus Fig. 3 also aids to illustrate an example of segment tracing (e.g., segmental ray tracing) where specular reflection found to be adjusted.

[0197] The embodiment of the device 100 and / or the method 200 may be operable to or operate the following steps:

[0198] I. Launch in the step S202 one or multiple rays of the ray tracing at a first interaction point of the first path 320, e.g. as the approximate location 310 (e.g., from a center point of a first station 302) for approximating the one or more physical locations 312-F of different antennas of the first station 302 in the environment 300).

[0199] II. Perform in the step S202 iterative ray tracing (e.g., from each interaction point to the consecutive one).

[0200] III. Determine in the step 202 the interaction points of the interactions of the first path 320 at intersections of rays of the ray tracing with the objects 308 in the environment 300. Namely capture rays using capture objects 308 and determine complete propagation paths (e.g., the first path 320).

[0201] IV. Modify in the step S204 the one or more first paths 320 a) to achieve physically correct paths (e.g., the second path 322); and b) to account for movement of the transmitter 302 or receiver 304 or any other object 308 or 324 in the environment 300.

[0202] V. Launch in the step S206 one or multiple rays from the start to the finish of each segment 314; 316 of every second path 322 a) to find and store, e.g. in the step S206, all objects 308 or further objects 324 that this ray intersects with, e.g. using an Any Hit program, as adjusted interactions; and b) optionally to trace just past the end of the segment to ensure that the ray hits the object 308 (e.g., at the physical second location 312 while the segment from the first path ends at the approximate first location 310 offset from the interaction object to avoid selfinteractions) that is responsible for the direction-changing interaction (e.g. a finite plane for specular reflections, a wedge for diffractions, etc.). Preferably, if the modified path (e.g., the second path 322) misses the object 308 then discard the modified path.

[0203] VI. Evaluating (e.g., determine) in any of the steps S208 to S212 the electromagnetic properties of rays interacting with all objects 308 along the second path 322, e.g., a polarimetric path gain, a propagation delay, a directions of departure and arrival, etc. a) use the further objects 324 found in step V.a) when determining a transmission loss along the propagation paths (e.g., the second path 322), optionally instead of the objects 308 along the propagation path (e.g., the first path 320) from step III.

[0204] Herein, the segment may be defined as the path (e.g., the direct line) between two consecutive directionchanging interactions (reflection, diffraction, diffuse scattering) in the sequence of interactions, including the first station 302 and the second station 304.

[0205] Fig. 3 shows a scenario with one first station 302 and one second station 304 in the environment 300 including a single object 308 for clarity of illustration and not limitation. Conventional ray tracing (steps I-III above) returns one path (e.g., the first path 320), indicated by the dashed line, that has a specular reflection on object 308. The modified path (e.g., the second path 322) resulting from step IV is shown by the solid line. The segment tracing in step V may be done for each of the two segments 314 and 316 of the second path 322. In the first variant, the determination S206 of the first segment 314 of the second path 322 reveals that the specular interaction point has slid outside of the reflection surface (as the interaction element) on the object 308. Hence, the second path 322 is found to be invalid and may be discarded. In the second variant, the Fresnel zone is taken into account and the interaction is adjusted accordingly.

[0206] According to some embodiments the approximate location 310 may be outside of the reflection surface 318, obtaining S202 the first path 320, and by modifying S204 the first path 320 by shifting the interaction point from the first (e.g., approximation) point 310 to the second (e.g., physical) location 312 that is inside of the reflection surface 318 (not shown here).

[0207] Another simplified environment 300 comprising a first station 302 and a second station 304 is shown in Fig. 4 as a second exemplary embodiment of the device 100 and / or the method 200. The environment 300 comprises an object 308 and a further object 324. Fig. 4 shows an example of segment tracing (e.g., segmental ray tracing) where the ray found blocked. Fig. 4 shows an obtained S202 first path 320 comprising a first segment 314 and a second segment 316 showed with dashed line. The first path starts from the first station 302 and ends at the captured surface of the second station 304.

[0208] Fig. 4 shows a physical location 312-F of the first station 302 in the environment and an approximate location 310-L of the second station 304 that approximate the physical location 312-L of the second station 304. The device 100 may obtain the second path 322 by modifying S204 the first path 320 by shifting the interaction point on the object 308 from the approximate location 310 to the physical location 312. By shifting the interaction point the second path 322 ends at the physical location 312-L of the second station 304. The device 100 may further evaluate S206 the radio wave propagation along the second path 322 for each of the segments 314 and 316 according to each interaction at the at least one shifted interaction point.

[0209] The first path 320 (indicated by the dashed line) with a specular reflection in object 308 has been obtained S202 during ray tracing (e.g. above steps I-III). The modified path 322 from step S204 (e.g., step above IV) is shown by the solid line.

[0210] In the step S206, the result from segment tracing (e.g. in above step V) shows that the segment 314 indeed interacts with a surface for a valid specular reflection on object 308. Ray tracing of segment 316 reveals that the second path 322 is blocked by the further object 324, which allows to consider this adjusted interaction, e.g. when evaluating S208 the electromagnetic properties of the second path 322 in step VI (e.g. by accounting for proper transmission losses). If the object 324 is opaque or a gain of the segment 316 is less than a threshold value, the second path 322 may be discarded in this scenario. Fig. 5 shows another exemplary scenario with one first station 302 and one second station 304 in the environment 300 including a stationary object 308 and a further moving object 324. Fig. 5 shows a third example of segment tracing (e.g., segmental ray tracing). Fig. 5 shows an obtained S202 first path 320 comprising a first segment 314 and a second segment 316 showed with dashed line. The first path starts from the first station 302 and ends at the captured surface 306 of the second station 304.

[0211] Fig. 5 shows a physical location 312-F of the first station 302 in the environment and an approximate location 310-L of the second station 304 that approximate the physical location 312-L of the second station 304. The device 100 may obtain the second path 322 by modifying S204 the first path 320 by shifting the interaction point on the object 308 from the approximate location 310 to the physical location 312. By shifting the interaction point, the second path 322 ends also at the physical location 312-L of the second station 304. The device 100 determines S206 each of the segments 314 and 316 for an adjusted interaction.

[0212] The device 100 may further evaluate S208 the radio wave propagation along the second path 322 according to each interaction at the at least one shifted interaction point and the potentially adjusted interaction.

[0213] The first path 320 (indicated by the dashed line) with a specular reflection in object 308 has been obtained S202 during ray tracing (steps I-III). The modified path 322 from step IV is shown by the solid line. The result from segment tracing in step V shows that the segment 314 indeed interacts with a surface for a valid specular reflection on object 308. Ray tracing of segment 316 reveals that the second path 322 is not blocked by the further object 324 (e.g., due to moving the further object 324 away from the second segment of the second path 322) which allows to consider this when determining the electromagnetic properties of the second path 322 in step VI (e.g. by accounting for proper transmission losses). Therefore the second path 322 may be validated in this scenario.

[0214] In a variant of the third embodiment, if the further object 324 moves in the opposite direction, the step S206 may determine that the segment 316 is blocked and the second path 322 is discarded.

[0215] Fig. 6 shows another exemplary scenario with one first station 302 and one second station 304 in the environment 300 including a stationary object 308 and a further moving object 324. Fig. 6 shows a fourth example of segment tracing (e.g., segmental ray tracing). Fig. 6 shows an obtained S202 first path 320 comprising a first segment 314 and a second segment 316 showed with dashed line. The first path starts from the first station 302 and ends at the captured surface of the second station 304.

[0216] Fig. 6 shows a first physical location 312-F of the first station 302 in the environment 300 and an approximate location 310-L of the second station 304 that approximate the physical location 312-L of the second station 304. The device 100 may obtain the second path 322 by modifying S204 the first path 320 by shifting the interaction point on the object 308 from the approximate location 310 to the physical location 312, and shifting the first physical location 312-F of the first station 302 to a second physical location 312-F of the first station 302. By shifting the interaction point the second path 322 ends also at the physical location 312-L of the second station 304. The device 100 may further evaluate S206 the radio wave propagation along the second path 322 for each segment 314, 316 according to each interaction at the at least one shifted interaction point.

[0217] The first path 320 (indicated by the dashed line) with a specular reflection in object 308 has been obtained S202 during ray tracing (steps I-III). The modified path 322 from step IV is shown by the solid line. The result from segment tracing in step V shows that the segment 314 indeed interacts with a surface for a valid specular reflection on object 308. Ray tracing of segment 316 reveals that the second path 322 is not blocked by the further object 324 (e.g., due to moving the first station) which allows to consider this when determining the electromagnetic properties of the second path 322 in step VI (e.g. by accounting for proper transmission losses). Therefore the second path 322 may be validated in this scenario. For example, a transmission interaction that had attenuated the gain of the segment 314 of the first path 320 may be removed from the segment 314 of the second path 322, which may significant increase the gain contributed by the second path 322 to the radio wave propagation.

[0218] An example of the physical action is shown in Fig. 7. Fig. 7 shows a block diagram of an emulating embodiment of the device of Fig. 1. In developing and testing radio communication equipment, it is desirable to replicate the conditions that are expected when the equipment is deployed and used in the environment 300. To this end, the physical channel of the wireless communication is emulated based on the second path 322 between at least one transmitter node 302 and at least one receiver node 304 (which in turn may be based on the evaluation S208 or the channel modeled in the step S212).

[0219] The device 100 comprises an RF input 702 and an RF output 704 coupled to the transmitter node 302 and the receiver node 304, respectively, to let the equipment 302 and / or 304 experience radio channels of different kinds. The technique can be applied in this context by letting the device 100 generate the radio channels to be emulated. Real-time or near real-time determining of the multipath propagation enables real-time or near real-time emulation of the radio channel, which is important for this use case.

[0220] Fig. 8 shows a schematic block diagram for a network node embodiment of the device 100. The device 100 comprises processing circuitry, e.g., one or more processors 804 for performing the method 200 and memory 806 coupled to the processors 804. For example, the memory 806 may be encoded with instructions that implement at least one of the modules 102 to 108.

[0221] The one or more processors 804 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and / or encoded logic operable to provide, either alone or in conjunction with other components of the device 100, such as the memory 806, network node functionality. For example, the one or more processors 804 may execute instructions stored in the memory 806. Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein. The expression "the device being operative to perform an action" may denote the device 100 being configured to perform the action.

[0222] As schematically illustrated in Fig. 8, the device 100 may be embodied by a network node 800, e.g., a base station optionally functioning as a gNB. The node 800 comprises a wired or radio interface 802 coupled to the device 100 for radio communication with one or more other nodes, e.g., including base stations and user equipments (UEs), respectively.

[0223] Performing the physical action S208 may comprise transmitting or receiving the wireless communication based on the second path 322 evaluated in the step S206. Alternatively or in addition, the interface 802 may be a control interface (e.g., a network interface or an Fl interface). For example, the node 800 may be a central unit (CU) of network node (e.g., a gNB). Performing the physical action S208 may comprise controlling the wireless communication in the environment 300 based on the evaluated second path 322.

[0224] Alternatively or in addition, the physical action S208 may comprise locating or handing-over a radio device in the environment 300. The transmission of the wireless communication, or the controlling of the wireless communication, may be adjusted to ensure compliance with regulations based on the determined multipath propagation. For example, an energy flux in the environment 300 may be determined based on the evaluated second path 322 and / or the modeled channel of the step S210.

[0225] Alternatively or in addition, the physical action S208 may comprise controlling directional gain and / or transmit power of the wireless communication in the environment 300. For example, a radio device (e.g., a UE) may determine its position or a network node 800 (e.g., a gNB) may determine the position of a radio device in the environment 300 based on the second path 322 evaluated in the step S208.

[0226] In one embodiment, radio signals received at the radio device in the environment 300 are compared with radio signals expected (e.g., modeled in the step S212) at the at least one position in the environment 300 according to the second evaluated path 322. In another embodiment, the radio signals received from a radio device in the environment 300 at a network node 800 are compared with radio signals expected (e.g., modeled in the step S212) at the at least one position in the environment 300 according to the second path 322 evaluated in the step S208.

[0227] Alternatively or in addition, a construction or an upgrade of a radio access network (RAN), e.g., when a radio frequency of the RAN is increased, may depend on the one or more second paths 322 evaluated in the step S208. For example, the position for deploying at least one a base station 800 (e.g. acting as transmitter and receiver node) in the environment 300 may be determined based on the second path 322 (e.g., based on the modeled channel and / or the emulated channel as a function of the position).

[0228] In any embodiment, the second path 322, e.g. the modeled or emulated channel, may be determined in real-time, optionally for the transmitting of the wireless communication and / or the receiving of the wireless communication or the controlling of the wireless communication (or for initiating of the transmitting or the receiving of the wireless communication).

[0229] Fig. 9 shows a schematic block diagram for a further embodiment of the device 100. The device 100 comprises processing circuitry, e.g., one or more processors 904 for performing the method 200 and memory 906 coupled to the processors 904. For example, the memory 906 may be encoded with instructions that implement at least one of the modules 102 to 108.

[0230] The one or more processors 904 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and / or encoded logic operable to provide, either alone or in conjunction with other components of the device 100, such as the memory 906, core node functionality or edge computing functionality. For example, the one or more processors 904 may execute instructions stored in the memory 906. Such functionality may include providing any of the steps and functions discussed herein. For example, steps and functions disclosed in the context of the radio device and / or the network node 800 may alternatively be performed by the core node 900 or edge computing node 900.

[0231] As has become apparent from above description, at least some embodiments of the technique can more quickly and / or more accurately model a channel and / or a spatial path of a wireless communication (e.g., in a 5G RAN). This can improve beamforming, MIMO, interference mitigation, adaptive modulation and coding, dynamic resource allocation, and power control. These advantages, individually or collectively, can enhance network performance, increase network capacity, improve data rates, and optimize the overall user experience.

[0232] Unless specified differently in context, reference signs may relate to the following features and steps.

[0233] 100 Device for evaluating a radio wave propagation

[0234] 102 First Path Module

[0235] 104 Second Path Module

[0236] 106 Interaction Module

[0237] 108 Evaluation Module 200 Method of evaluating a radio wave propagation

[0238] S202 Obtain a first path of the radio wave propagation in the environment

[0239] S204 Modify the first path by shifting at least one interaction point, resulting in a second path

[0240] S206 Determine at least one adjusted interaction on at least one segment of the second path

[0241] S208 Evaluate the radio wave propagation along the second path

[0242] S210 Perform or initiate a physical action

[0243] S212 Model a channel of the wireless communication

[0244] S214 Store the second path

[0245] 300 Environment

[0246] 302 First station of the wireless communication, e.g. transmitter node

[0247] 304 Second station of the wireless communication, e.g. receiver node

[0248] 306 Capture surface enclosing a second station in the environment

[0249] 308 Object in the environment, e.g., interaction object

[0250] 310 First location, e.g., an approximate location or an earlier location

[0251] 310-F The first location of a first interaction point of the first path, e.g., the first location of a first station

[0252] 310-L The first location of a last interaction point of the first path, e.g., the first location of a second station

[0253] 312 Second location, e.g., a physical location or a later location

[0254] 312-F The second location of a first interaction point of the second path, e.g., the second location of a first station

[0255] 312-L The second location of a last interaction point of the second path, e.g., the second location of a second station

[0256] 312-L Second location of a second station

[0257] 314 Path segment, e.g., w-th segment of the first or second path

[0258] 316 Path segment, e.g., (n+ 1 )-th segment of the first or second path

[0259] 320 First path

[0260] 322 Second path

[0261] 324 Further object in the environment, e.g., further interaction object

[0262] 700 Channel emulator embodiment of the device

[0263] 702 Channel emulator input interface

[0264] 704 Channel emulator output interface

[0265] 800 Access network node embodiment of the device, e.g. base station

[0266] 802 Interface of access network node embodiment

[0267] 804 Processing circuitry of access network node embodiment

[0268] 806 Memory operable of access network node embodiment 900 Core network node or edge computing device embodiment of the device

[0269] 902 Interface of CN node or edge computing device embodiment, e.g., radio interface

[0270] 904 Processing circuitry of CN node or edge computing device embodiment 906 Memory of CN node or edge computing device embodiment

[0271] Many advantages of the present invention will be fully understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the units and devices without departing from the scope of the invention and / or without sacrificing all of its advantages. Since the invention can be varied in many ways, it will be recognized that the invention should be limited only by the scope of the following claims.

Claims

Claims1. A device (100) for evaluating a radio wave propagation of a wireless communication in an environment (300), the device (100) comprising memory (806; 906) operable to store instructions and processing circuitry (804; 904) operable to execute the instructions, wherein the device (100) is operable to: obtain (S202) a first path (320) of the radio wave propagation in the environment (300), the first path (320) comprising interaction points of a sequence of interactions of the radio wave propagation with physical objects (308) in the environment (300), the first path (320) further comprising a segment (314; 316) between each pair of the subsequent interaction points; modify (S204) the first path (320) by shifting at least one interaction point of the first path (320) from a first location (310) to a second location (312), resulting in a second path (322) comprising at least one modified segment (314; 316); determine (S206) at least one adjusted interaction within at least one segment (314; 316) between at least one pair of subsequent interaction points in the second path (322) by tracing the at least one modified segment (314; 316) of the second path (322) in the environment (300); and evaluate (S208) the radio wave propagation along the second path (322) for each segment (314; 316) according to the at least one adjusted interaction and each interaction at the at least one shifted interaction point.

2. The device (100) of claim 1, wherein each interaction point of the first path (320) corresponds to a change in direction of the first path (320), and / or wherein each segment (314; 316) of the first path (320) corresponds to a straight line of the first path (320) between a pair of points representing two consecutive direction-changing or terminating interactions of the first path (320); and / or wherein each interaction point of the second path (322) corresponds to a change in direction of the second path (322), and / or wherein each segment (314; 316) of the second path (322) corresponds to a straight line of the second path (322) between a pair of points representing two consecutive directionchanging or terminating interactions of the second path (322).

3. The device (100) of claim 1 or 2, wherein the device (100) is further operable to perform or initiate a physical action (S210) that is dependent on the evaluated (S208) radio wave propagation along the second path (322), optionally wherein evaluating (S208) the radio wave propagation along the second path (322) comprises modeling (S212) a channel of the wireless communication along the evaluated second path (322) in the environment (300), the physical action (S210) being dependent on the modeled (S212) channel; and / or wherein the device (100) is further operable to model (S212) a channel of the wireless communication along the second path (322) in the environment (300) based on the evaluated (S208) radio wave propagation, optionally wherein the modeling (S212) of the channel comprises, or the device (100)is further operable to perform or initiate, a physical action (S210) that is dependent on the modeled (S212) channel.

4. The device (100) of any one of claims 1 to 3, wherein the modifying (S204) of the first path (320) by shifting the at least one interaction point from the first location (310) to the second location (312) triggers the determining (S206) and / or adjusting of the at least one interaction on the at least one segment (314; 316); and / or wherein the determining (S206) of the at least one adjusted interaction within the at least one segment (314; 316) between at least one pair of subsequent interaction points in the second path (322) is based on the second path (322) as the modified (S204) first path (320); wherein the at least one adjusted interaction within the at least one segment (314; 316) is determined (S206) by determining, for each of the at least one segment, if there is an intersection between a straight line representing the respective one of the at least one segment and a geometrical interaction object representing a further physical object (324) in the environment (300); and / or wherein the determining (S206) and / or adjusting of the at least one interaction on the at least one segment (314; 316) comprises adding to or removing from the second path (322) the at least one interaction within the segment (314; 316) of the second path (322) with one or more physical objects (324) in the environment (300); and / or wherein the radio wave propagation is evaluated (S208) along the second path (322) according to each added or removed interaction and each interaction at the at least one shifted interaction point.

5. The device (100) of claim 4, wherein the added or removed interaction with one or more physical objects (324) in the environment (300) within the respective segment (314; 316) results from the shifting of the at least one interaction point connected to the respective segment (314; 316), and / or wherein the added or removed interaction with physical objects (324) in the environment (300) within the respective segment (314; 316) results from a mobility of one or more physical objects (324) in the environment (300).

6. The device (100) of any one of claims 1 to 5, wherein the obtaining (S202) of the first path (320) comprises an iterative ray tracing in the environment (300) resulting in at least one first path (320), and wherein the device (100) is operable to modify (S204) each of the at least one first path (320) resulting in at least one second path (322), determine (S206) the at least one adjusted interaction, and to evaluate (S208) the radio wave propagation along each of the at least one second path (322).

7. The device (100) of claim 6, wherein being operable to obtain (S202) the first path (320) comprises the device (100) being operable to at least one of: launch one or multiple rays of the ray tracing at a first interaction point of the first path (320) as the first location (310-F), which is shifted for the modification to a first station (302) in the environment (300) as the second location (312-F);determine the interaction points of the interactions of the first path (320) at intersections of rays of the ray tracing with the objects (308) in the environment (300); launch one or multiple rays at one or more of the interaction points of the interactions of the first path (320) as the first location (310) offset to the outside of the object (308) of the respective interaction that approximates the physical location of the respective interaction as the second location (312); and capture one or multiple rays of the ray tracing for each of the at least one first path (320) on a capture surface (306) enclosing a second station (304) in the environment (300), the interaction point of the first path (320) on the capture surface (306) being the first location (310-L) that approximates the second location (312-L) of the last interaction point of the second path (322) at the second station (304).

8. The device (100) of any one of claims 1 to 7, wherein the first interaction point (310-F) of the first path (320) as the first location (310) deviates from the second location (312-F) of a first station (302) of the wireless communication due to a mobility of the first station (302), optionally due to a time lag in updating the first location (310) of the first station (302) for the ray tracing; wherein the interaction point of the first path (320) as the first location (310) deviates from the second location (312) of an object (308) of the respective interaction due to a mobility of the object (308) in the environment, optionally due to a time lag in updating the first location (310) of the object (308) for the ray tracing; and / or wherein the last interaction point (310-L) of the first path (320) as the first location (310-L) deviates from the second location (312-L) of a second station (304) of the wireless communication due to a mobility of the second station (304), optionally due to a time lag in updating the first location (310) of the second station (304) for the ray tracing.

9. The device (100) of any one of claims 1 to 8, wherein the device (100) is further operable to at least one of: obtain physical locations (310-F, 312-F) of a first station (302) as the first interaction point at different points in time and / or physical locations (310, 312) of one or more objects (324) in the environment (300) as one or more intermediate interaction points at different points in time and / or physical locations (310-L, 312-L) of a second station (304) as the last interaction point at different points in time.

10. The device (100) of any one of claims 1 to 9, wherein the modifying (S204) of the first path (320) or the determining (S206) of the at least one adjusted interaction of the second paths (322) or the evaluating (S208) of the radio wave propagation along the second path (322) comprises discarding the respective path (322), or discarding the respective interaction and a segment (314; 316) connected to the respective interaction point, optionally if the first location (310) as the interaction point of the first path (320) on the objectsecond path (322), wherein the second location (312) is outside of a physical size of the object (308) of the respective interaction or outside of a Fresnel zone of the respective interaction.

11. The device (100) of any one of claims 1 to 10, wherein the modifying (S204) of the first path (320) reduces or minimizes a path length of the second path (322) compared to the length of the first path (320) by shifting the at least one interaction point from the first location (310) to the second location(312) within a plane or line of the object (308) of the respective interaction.

12. The device (100) of any one of claims 1 to 11, wherein the evaluating (S208) of the radio wave propagation along the second path (322), the physical action (S210), and / or the modeling (S212) of the channel of the wireless communication comprises determining one or more physical properties of the radio wave propagation, wherein the one or more physical properties comprise one or more of: a phase shift along the second path (322); a gain along the second path (322) and / or a power loss along the second path (322) and / or received signal strength indicator, RSSI; a time of flight along the second path (322); an angle of departure, AoD, and / or an angle of arrival, AoA, of the second path (322); a Doppler shift or Doppler spread of the second path (322); a signal to noise ratio, SNR, along the second path (322); a signal to interference plus noise ratio, SINR, along the second path (322); a channel state information, CSI, of the second path (322); and a channel estimate of the second path (322).

13. The device (100) of any one of claims 1 to 12, wherein the device (100) is further operable to: store (S214) the second path (322), optionally as resulting from the modifying (S204) or the determining (S206) or the evaluating (S208), and wherein the stored (S206) second path is obtained (S202) or obtainable when the device (100) iterates the operable steps.

14. A method (200) of evaluating a radio wave propagation of a wireless communication in an environment (300), the method (200) comprising or initiating the steps of: obtaining (S202) a first path (320) of the radio wave propagation in the environment (300), the first path (320) comprising interaction points of a sequence of interactions of the radio wave propagation with physical objects (308) in the environment (300), the first path (320) further comprising a segment (314; 316) between each pair of the subsequent interaction points; modifying (S204) the first path (320) by shifting at least one interaction point of the first path (320) from a first location (310) to a second location (312), resulting in a second path (322) comprising at least one modified segment (314; 316);determining (S206) at least one adjusted interaction within at least one segment (314; 316) between at least one pair of subsequent interaction points in the second path (322) by tracing the at least one modified segment (314; 316) of the second path (322) in the environment (300); and evaluating (S208) the radio wave propagation along the second path (322) for each segment (314; 316) according to the at least one adjusted interaction and each interaction at the at least one shifted interaction point.

15. A computer program product comprising program code portions for performing the functionality of any one of the claims 1 to 13 or the steps of claim 14 when the computer program product is executed on one or more computing devices (804; 904), optionally stored on a computer-readable recording medium (806; 906).

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