Technique for determining a wireless propagation path

Abstract

A technique for determining a path (302) of a wireless communication between a first station (304) and a second station (306) in an environment (300) comprising a first grid (314) and a second grid (316). More specifically a device (100) and a method (200) for determining a path (302) between the first station (304) and the second station (306). The method (200) obtains (S206) one or more paths (302) between a selected (S204) point in the first grid (314) point near the first station (304) and a selected (S204) point in the second grid (316) point near the second station (306), wherein the path (302) comprises a start point and an end point, and wherein each of the one or more obtained (S206) paths (302) comprises path (302) properties. The method (200) further translates (S212) the start point of the one or more obtained (S206) paths (302) to the spatial position of the first station (304), and translate (S212) the end point of the one or more obtained (S206) paths (302) to the spatial position of the second station (306) and determines (S216) a shortest path (302) between the first station (304) and the second station (306) for each of the one or more obtained (S206) paths (302), wherein each of the shortest determined (S216) paths (302) comprises unique path (302) properties.

Description

[0001] TECHNIQUE FOR DETERMINING A WIRELESS PROPAGATION PATH

[0002] Technical Field

[0003] The present disclosure relates to a wireless communication technique based on rapidly determining a wireless communication path between a first station and a second station in an environment. More specifically, and without being limited thereto, a device and a method are disclosed for determining a path of a wireless communication between a first station and a second station in an environment.

[0004] Background

[0005] A ray optical approximation predicts electromagnetic propagation efficiently 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 reflection and refraction at interfaces in the environment. Ray optical approximation can predict optical wireless communications (OWC) as well as radio wave propagation, e.g. if the dimensions of objects and the distances between objects in the environment are significantly larger than a carrier wavelength. Electromagnetic propagation can also be predicted in an environment, which comprises objects that block a direct line-of-sight, based on paths circumventing the blocking object by reflections from neighboring objects or diffraction at edges of any object.

[0006] Predicting wireless channels is highly useful for planning and operating a wireless communication network and for a wireless communication when the influence of deterministic features of the wireless channels needs to be captured, such as reflective or diffractive objects moving in the environment on predictable trajectories. A city bus running on schedule is an example for such a predictable object in the cellular environment of a radio access network (RAN). The RAN may provide radio access according a radio access technology (RAT) specified by the Third Generation Partnership Project (3GPP), such as Fourth Generation (4G) Long Term Evolution (LTE) and Fifth Generation (5G) New Radio (NR). The ray optical approximation becomes more relevant and more accurate with higher frequencies, larger bandwidths, and more antennas used to develop and deploy RATs for mobile and wireless communication of the Fifth Generation (5G), the Sixth Generation (6G) and beyond as this technique enables "an analysis of what the behaviors of linear wave equation solutions may be in a short wavelength or asymptotic limit" (Introduction to quantum chaos, D. Ullmo and S. Tomsovic, 2014). In addition to optical access networks and radio access networks, predicting wireless channels is also important for a wireless communication directly between wireless devices and in a mesh network, which are also supported by 3GPP sidelinks.

[0007] Conventional ray optical techniques to predict propagation are based on ray tracing, also referred to as ray launching and "shooting and bouncing rays" (SBR), which requires launching a plurality of rays from an origin such as a transmitter node. Ray tracing is widely used for radio frequency (RF) wave propagation modelling in radio network modelling and simulation tools, and is increasingly being considered for digital twins of radio networks. With higher frequencies, larger bandwidths, and more antennas being used to develop 5G, 6G and beyond, having an accurate RF wave propagation model that provides fast or real-time representation of the multipath propagation channel is becoming a pressing need. The real-time aspect is especially important in the context of the digital twin, where the digitally represented radio channel must be generated and updated at the same rate as its real physical counterpart.

[0008] The launched rays are allowed to interact with the environmental objects representing the environment, until they are captured at one or more receiver nodes. Different types of interactions such as transmission, reflection, diffraction, and scattering may be taken into account by introducing secondary rays when a primary ray intersects an object. Multiple consecutive interactions of the same or different types may occur along a propagation path, which can lead to an exponential growth in the number of rays that need to be traced. This is a known challenge in ray tracing where the trade-off between the computation time and the accuracy and fidelity of the predicted channels must be managed.

[0009] Commonly, a set of propagation paths is determined between one location (representing the transmitter) and another location (representing the receiver). The current and proposed future capabilities of these networks and equipment include utilizing large antenna arrays, wide communication bandwidths, and simultaneous use of multiple frequency bands for communication. The goal of methods such as ray tracing is to quantitatively represent the wireless channel between current or future transmitters and receivers in current or future scenarios of the environments. To be of use, this radio channel representation should have good fidelity compared to a measured wireless channel between the same transmitter and receiver pair in the same environment. The better the fidelity, the more the modeled and computed radio channel can be trusted to have similar or the same characteristics as a measured channel. In addition, the modeled and computed radio channel should be available with minimum waiting time. What is an acceptable waiting time depends on the use and can range from microseconds for real-time applications, to seconds or minutes for interactive work such as radio network planning, to hours or longer for e.g. radio network dimensioning.

[0010] Radio networks need to be able to handle mobility where the users may move around in the world. State of the art ray-tracing simulations attempt to handle this in different ways. The simplest approach is to perform a new ray-tracing simulation whenever something in the deployment of the transmitters or receivers has changed. However, this carries the cost of duplicating or multiplying the computation time with the number of new simulations, and quickly becomes completely impractical for (near) realtime applications such as in a digital twin. An alternative approach is to predefine the mobility, e.g. as predefined tracks along which the users are moving. Then ray tracing can be performed for locations that are sampled along these tracks, while for intermediate locations the propagation paths can be interpolated between nearby locations. This represents an improvement over the previous approach but has two drawbacks: 1) the track and the sampling resolution needs to be predefined which prohibits interactive movement or digital twin use cases where the user's movement is not known in advance, and 2) the interpolated propagation paths may no longer fulfil fundamental physical properties.

[0011] Current and potential future generations of wireless radio networks increasingly utilize larger antenna arrays and wider bandwidths, as well as using multiple frequency bands for communication. The common assumption that propagation paths can be reused over the array and frequency then becomes less valid, e.g. due to partial blocking of the array or due to propagation delay differences between different parts of the array, or due to frequency-dependent properties of the interactions that occur along a propagation path. Similar approaches as for the mobility case are known (e.g., ray-trace separately for different antenna elements and / or frequencies), but these have similar drawbacks that may limit the usefulness especially in near real-time applications such as digital twins.

[0012] Summary

[0013] Accordingly, there is a need for a technique that efficiently determines a wireless propagation path under discontinuous and alternative changes of the environment with realistic complexity in real-time.

[0014] As to a device aspect, a device for determining a path of a wireless communication between a first station and a second station in an environment comprising a first grid and a second grid is provided. The device comprises memory operable to store instructions and processing circuitry operable to execute the instructions, such that the device is operable to select at least one point of the first grid near the first station and at least one point of the second grid near the second station. The device is further operable to obtain one or more paths between the at least one point in the first grid near the first station and the at least one point in the second grid near the second station. The path comprises a start point and an end point. Each of the one or more obtained paths comprises an interaction signature indicative of one or more interactions between the path and one or more interaction objects of the environment. The device is further operable to translate at least one of the start point of the one or more obtained paths to the spatial position of the first station and the end point of the one or more obtained paths to the spatial position of the second station. The device is further operable to determine a shortest path between the first station and the second station along each of the one or more obtained paths, wherein the determining of the shortest path maintains the interaction signature of the respective path.

[0015] Since the device uses the first grid and the second grid in the environment to determine a path between the first station and the second station, the computational power, resources and time for determining the path are efficiently reduced. Therefore, the device may enable real-time operation and / or near real-time operation, optionally with full interactivity and (e.g., three-dimensional) movement of the first station and / or the second station within the environment. Herein, real-time (e.g., determining a multipath propagation in real-time) may mean that if an object of linear size L is moving at a velocity V, the one or more shortest paths of the propagation can be determined (e.g., periodically updated) within less than L / V time.

[0016] By obtaining paths for pairs of grid points in the first and second grids, embodiments of the method can reuse the obtained paths, beyond state-of-the-art approaches to reusing ray-traced propagation paths in dynamic environments (so-called dynamic ray-tracing, DRT), which are limited to use the notion of time and extrapolation in the linear time domain. The one or more obtained paths may be predetermined by ray tracing at a certain time point T. The first station and / or the second station and / or objects moving in the environment may be described (or approximated) by analytical expressions for their movement. A conventional approach would be limited to consider shifts of path interaction points in a small interval AT, and repeating the ray tracing beyond the time T+AT. In contrast, the embodiments of the method have the advantage of capturing dynamic environments (i.e., not only transmitter / receiver mobility, but also moving world objects), and / or producing Doppler frequencies when providing results on the one or more shortest paths that are not merely extrapolated path geometries for a time within the interval [T,T+AT], Qualitatively different shortest paths result from the embodiments, whereas this conventional approach is only valid for small AT, during which no new paths appear, thus still relying on frequent ray tracing.

[0017] Same or further embodiments can efficiently blend between the full reuse of the one or more paths for a short time step (e.g., with a major overlap in the set of paths between sets of paths obtained for consecutive time instances, i.e., only a fraction of ray-tracing results at time T+AT provides new paths) and take into account qualitatively different paths (compared to the set of extrapolated paths from time T) by selecting another grid point for the obtained one or more paths. This enables a low level of utilization of expensive ray-tracing results combined with long term forecasting of channels without requiring pre-defined movements, making it impossible to evaluate arbitrary world states.

[0018] Same or further embodiments of the method can update propagation paths (as the resulting one or more shortest paths) with moving transmitter or receiver positions and / or interaction objects, e.g. without a movement continuity requirement, which is a conventional limitation of real-time DRT that has to recalculate paths when confronted with arbitrary transmitter and receiver positions. Same or further embodiments can operate in a one-dimensional time domain or by analyzing alternative deployments, which results in an efficient reuse of ray-tracing results, e.g. as represented by the one or more obtained paths with grid points as end points and / or independent of any number of time points. The same technique can be applied to update propagation paths over short intervals (when the movement continuity requirement is fulfilled and the signature of interactions is maintained) as well as for long intervals based on the one or more obtained paths without requiring frequent full ray-tracing recalculations. Same or further embodiments are particularly suited in the event of path blocking by other objects, which is not supported by existing techniques for updating propagation paths, where a manual selection of the valid time interval is required.

[0019] Since the path determination includes determining the shortest path along (e.g., interaction elements in the environment defined by interactions of the obtained path, the quality of the determined path is as high as if the path was determined by slow and resource-intensive ray tracing. For example, the determined path may fulfil Fermat's principle. Additionally, the device does not require predefined or predictable movement of the positions of the first station and the second station, therefore embodiments of the device can determine the path with arbitrary positions of the first station and the second station.

[0020] The determining of the one or more shortest paths may maintain all (e.g., pairwisely distinct) interaction signatures of the one or more obtained paths (e.g., remaining after removing duplicates in terms of the interaction signature). In other words, a shortest path determined based on one of the one or more obtained paths has the same interaction signature as the respective one obtained path.

[0021] The determining of the shortest path between the first station and the second station along each of the one or more obtained paths may comprise minimizing a path length of the respective one of the one or more obtained paths in accordance with one or more interactions of the respective obtained path (e.g., a sequence of interactions along the path). For example, the one or more interactions may be represented as the interaction signature of the respective path (e.g., a hash value of the one or more interactions). Each interaction may be associated with an interaction element of one of the one or more interaction objects in the environment, with which interaction element the path interacts (e.g., in the sense of an electromagnetic interaction).

[0022] Determining the shortest path (i.e., minimizing the path length) may maintain the one or more interactions. For example, each interaction may define a constraint for the interaction point, i.e. the point of the path at which its direction changes due to the interaction. The interaction point may be represented as a point linking two subsequent path segments (i.e., straight lines) of the path. For example, for a specular reflection as a type of the interaction, the interaction element may be the surface of reflection and may define a plane (e.g., coplanar with the surface of reflection) to which the interaction point (i.e., the point of the path) is constrained while minimizing the path length of the path. As another example, for an edge diffraction as a type of the interaction, the interaction element may be the edge of diffraction and may define a straight line to which the interaction point is constrained while minimizing the path length of the path.

[0023] Determining a shortest path along each of the one or more obtained paths may mean that one or more shortest paths are determined, wherein "shortest" does not refer to a minimum over different obtained path but refers to the minimizing of the path length of each of the obtained paths (up to removing duplicates) individually. Herein, "minimizing a path length" of any path 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.

[0024] 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 (e.g., a transmissive object in the environment) 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 = JFirst stationn(r) ds (r).

[0025] Minimizing the path length in accordance with the one or more interactions may encompass minimizing the path length consistently with the zero or more (e.g., respectively changed and unchanged) interactions. Each of the one or more interactions may define a constraint of the interaction point of the path when minimizing the path length of the path. The constraint of the interaction point may be a boundary condition of the respective path. Alternatively or in addition, each of the one or more one interactions may constrain the respective interaction point to an edge or a surface according to the interaction element of the respective interaction object.

[0026] The obtained one or more paths between the at least one point in the first grid near the first station and the at least one point in the second grid near the second station may be stored (e.g., saved) as pre-traced paths. Pre-traced path information may be collected from any number of positions of the first station and the second station, as opposed to a maximum of 2 positions in the time-based dynamic ray tracing (DRT), which significantly improves path reuse and minimizes the number of expensive ray-tracing starts required.

[0027] The device may be able to determine a plurality of paths between a plurality of the first stations and a plurality of the second stations.

[0028] The determining of the one or more paths may scale linearly with the number of first stations and may be quite flat in respect to the number of the second stations. For example, the device may determine a path from each of the first stations to all of the second stations. For example, the device may determine a path from one first station to all second stations, e.g., on demand.

[0029] Determining the shortest path along each obtained path (e.g., up to duplicates) may mean that the interaction signature (also referred to as path characteristic) of the respective obtained path (e.g., the one or more interactions at intermediate points each constrained according to an interaction type and an interaction element of the respective interaction object) is maintained.

[0030] The at least one point of the first grid may also be referred to as the at least one first point. The at least one point of the second grid may also be referred to as the at least one second point. For features introduced to include "at least one" or "one or more", such a quantity may be omitted for better readability. That is, the one or more paths may be briefly referred to as the path (or in the context of a feature for each path as the respective path). Similarly, the at least one first point may be referred to as the first point, and the at least one second point may be referred to as the second point. Moreover, referring to "the path" may refer to any or each of the one or more obtained paths or any or each of the one or more determined shortest paths.

[0031] Translating the start point or end point of the one or more obtained paths to the spatial position of the first or second station may mean that the start point or end point is shifted. The start point and the end point of any one of the paths may be collectively referred to as the endpoints of the respective path. Translating the endpoints of the respective path may also be referred to spatially modifying the respective path.

[0032] The points of the first or second grid may also be referred to as grid points or base points.

[0033] The first and / or second grid may be a set of points (point set) in the environment. The first and / or second grid may have a uniform structure (e.g., a regular or symmetric or lattice structure) or a non-uniform structure (e.g., a point set with a density of grid points adapted to the probability of presence of the first station and / or the second station). The points of the first and / or second grid may have been chosen points for pre-calculation (e.g., ray tracing) and / or may be stored (e.g. in volatile or random-access memory). Since the first and second grids may be used for deployment, e.g. of a radio access network (RAN), the first and / or second grid may also be referred to as deployment grid.

[0034] Herein, for clarity of illustration, a uniform two dimensional (2D) or three dimensional (3D) grid is used, which may be readily replaced by a non-uniform grid.

[0035] In the environment, paths may be pre-determined between one or more locations in the first grid (i.e., a first point set) representing first station locations and one or more locations in the second grid (i.e., a second point set) representing second station locations. Moreover, the first and second grids may comprise two different or independent grids, e.g. a transmitter grid and a receiver grid, respectively. Alternatively or in addition, the first and second grids may comprise two different or independent grids, e.g. a mobile device (or UE) grid and a base station (e.g., gNB) grid.

[0036] In this paragraph "first / second" refers to any one or each of the "first" and / or "second". That is, this paragraph may be read with "first" only, or "second" only, or the paragraph discloses the subject-matter for each of "first" and "second": The at least one point of the first / second grid selected near the first / second station may comprise the point in the first / second grid that is closest to the first / second station. Alternatively or in addition, the at least one point of the first / second grid selected near the first / second station may comprise the number of N points in the first / second grid that the N > 1 closest to the first / second station. Alternatively or in addition, the at least one point of the first / second grid selected near the first / second station may comprise the one or more points in the first / second grid that are in a Fresnel zone of the first / second station.

[0037] In an embodiment, the device may be further operable to discard duplicates among the one or more obtained paths. The duplicates among the one or more obtained paths may comprise the same interaction signature as another one of the one or more obtained paths. Each of the one or more determined shortest paths may comprise unique interaction signature.

[0038] Discarding (e.g., removing) duplicates may mean that all but one of the one or more obtained paths remains for each unique interaction signature. The one or more interactions of each path may be represented by the interaction signature of the respective path. Preferably, the interaction signature is (e.g., not only indicative of the interaction points within the respective path but) also indicative of the start point and / or the end point of the respective path.

[0039] In an embodiment, obtaining one or more paths may comprise tracing a ray shot from the at least one selected point of the first grid to the at least one selected point of the second grid. Alternatively or in addition, obtaining one or more paths may comprise tracing a ray shot from the first station to the second station. Alternatively or in addition, obtaining one or more paths may comprise obtaining the one or more paths from one or more previously saved traced rays between the at least one selected point of the first grid and the at least one selected point of the second grid. Alternatively or in addition, obtaining one or more paths may comprise obtaining the one or more paths from one or more previously saved traced rays between the first station and the second station.

[0040] The tracing of the ray (i.e., the ray tracing) may yield the one or more interactions with the environment, e.g. as indicated by the interaction signature. For example, irrespective of the interaction type, the interaction may be associated with an interface between electromagnetically different media, wherein a change in electromagnetic media may correspond to the interaction type being transmission, or a change in a ray direction satisfying certain constraints on incoming and outgoing directions relative to the interface may correspond to specular reflection (e.g., for equal angles) or may correspond to diffusive reflection (e.g., for a certain interval in the interaction points on a surface as the interaction element), or may correspond to edge diffraction (e.g., for both the edge and the outgoing direction being on a Keller cone). Obtaining the one or more paths between the at least one first point and the at least one second point may be based on, or may comprise, ray tracing. For example, a plurality of rays may be launched from each point of the first grid and each ray may be traced (e.g. via the method of shooting and bouncing rays, SBR) in the environment. The computational complexity of the ray tracing may scale linearly with the number of points in the first grid (e.g., a Tx count or a number of Tx base points or Tx candidates) and / or may be essentially flat (e.g., less than linear, e.g. logarithmically or asymptotically constant) with respect to the number of points in the second grid (e.g. a Rx count or a number of Rx base points or Rx candidates). Practically, the obtaining may be based on ray tracing from each point of the first grid to any or all points of the second grid. The ray tracing may lead to all points of the second grid in an ergodic environment.

[0041] For example, the obtaining may be based on, or may comprise, ray tracing from the first point of the first grid to the second point (e.g., on demand, optionally as the method queries paths for each of the at least one first point.

[0042] The paths resulting from ray tracing may be stored, e.g., in volatile or random-access memory of a server.

[0043] Alternatively or in addition, the one or more paths may be obtained from a database (e.g., from memory or a file system), optionally where results of a previous ray tracing (e.g., shoot and bounce ray tracing) are stored.

[0044] In an embodiment, each of the one or more obtained paths and / or each of the one or more determined shortest paths may comprise two or more path segments of the respective path.

[0045] A path comprising one path segment may begin from the first station and end at the second station without changing the direction, i.e., a ray shot from the first station may reach the second station via a direct line. In order to include at least one interaction at an interaction point, the interaction point may link two path segments of the path.

[0046] In an embodiment, the device may be further operable to obtain one or more objects of the environment along the path. For example, the one or more obtained objects include the one or more interaction objects which interact with the path.

[0047] Obtaining one or more objects may mean that the device measures the one or more objects or receives measurement results that indicate a position or a size or an interaction type of (e.g., one or more interaction elements of) the interaction object. The path may be any or each of the one or more obtained paths or the path may be any or each of the one or more determined shorted paths. For example, the objects may be obtained responsive to the determining of the one or more determined shorted paths. The object interacting with the path may be referred to as interaction object. Interacting with the path may mean that a ray (e.g., represented by a path segment) of the path interacts with an interaction element of the interaction object, for example if the path intersects the interaction element or a Fresnel zone of the interaction element.

[0048] A path comprising more than one path segment may begin from the first station and end at the second station with changing its direction at the interaction point of the interaction. For example, a ray shooting from the first station may reach the second station via changing the direction, e.g., via reflection, at the interaction point.

[0049] The one or more objects along the path may interact with the ray defining the path via the one or more interactions (e.g., reflection) and consequently add one or more interaction points and / or one or more path segments to the path.

[0050] In an embodiment, the device may be further operable to determine the interaction signature of each of the one or more obtained paths. For example, the interaction signature of each of the one or more obtained paths may be determined based on the one or more obtained objects of the environment along the respective path.

[0051] In an embodiment, the interaction signature of the respective path may comprise a sequence of path segments of the path and an interaction at an interaction point between each pair of the subsequent path segments of the path. For example, the interaction may be associated with one of the one or more interaction objects in the environment and a type of the interaction. The type of the interaction may be one of reflection, diffraction, transmission, and refraction.

[0052] The interaction may be any one or each of the one or more interactions indicated by the interaction signature disclosed further above.

[0053] One or each of the one or more path segments of the respective path may represent an interaction with one or more interaction objects along the path without changing a direction of the path (i.e., path segment or ray of the path), e.g. if the interaction type of the interaction is the transmission. Alternatively or in addition, the one or more interaction objects along the path may add interaction points (and a corresponding path segment) to the path, e.g. if the interaction type of the interaction is specular reflection (e.g., pinging back from a surface of the interaction object as the interaction element) or diffusive scattering (also referred to as diffusive reflection, e.g., pinging back from a surface of the interaction object as the interaction element) or refraction (entering the interaction object at a surface as the interaction element) or edge diffraction (e.g., kinking from an edge of the interaction object as the interaction element). In an embodiment, the device may be further operable to discard one or more of the one or more determined shortest paths that are inconsistent with the environment.

[0054] One or more of the one or more determined shortest paths may be discarded if one or more interactions of the respective path are inconsistent with one or more interaction objects of the environment.

[0055] In an embodiment, the one or more discarded shortest paths may be inconsistent due to the respective shortest path intersecting with an object of the environment. Alternatively or in addition, the one or more discarded shortest paths may be inconsistent due to an outgoing ray of a reflection (as one of the one or more interactions) being on an opposite side of an incoming ray relative to a surface of the reflection. Alternatively or in addition, the one or more discarded shortest paths may be inconsistent due to a reflection point being outside of the interaction object.

[0056] As an example of the first case, the discarded path may intersect with a non-transmissive (e.g., frequency- selectively opaque) and / or non-reflective object, optionally obtained as disclosed above.

[0057] As an example of the second case, the reflection may be a diffusive reflection (e.g., scattering from a surface) or a specular reflection.

[0058] As an example of the third case, a reflection point as the interaction point may be outside of the interaction object, e.g. outside of a surface or line of the interaction object as the interaction element.

[0059] In an embodiment, the device may be further operable to perform or initiate a physical action that is dependent on the one or more determined shortest paths between the first station and the second station in the environment. For example, the physical action may be based on modeling a channel of the wireless communication along the one or more determined shortest paths and the environment.

[0060] In an embodiment, the device may be further operable to model a channel of the wireless communication along the one or more determined shortest paths in the environment. For example, the modeling of the channel comprises or the device may be further operable to perform or initiate a physical action that is dependent on the modeled channel.

[0061] In an embodiment, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, an amplitude of each path segment of the respective path.

[0062] Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, an amplitude of each interaction point or between subsequent path segments of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, an amplitude of the entire respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a phase shift of a ray for each path segment of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a phase shift of a ray at each interaction point or between subsequent path segments of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a phase shift of the entire respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a polarization change of each path segment of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a polarization change of each interaction point or between subsequent path segments of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a polarization change of the entire respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a path length of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a time of flight of the respective path. Alternatively or in addition, the modeling of the channel may comprise determining, as a path property of the one or more determined shortest paths, a direction of departure with respect to a direction of arrival of the respective path at each interaction point or between subsequent path segments.

[0063] The phase shifts of path segments and interaction points may add up to the phase shift of the entire respective path. Alternatively or in addition, the amplitudes of path segments and interaction points may be multiplication factors for the amplitude of the entire respective path.

[0064] The path property of the entire path may be determined by combining contributions of the two or more path segments (and one or more interaction points there between), e.g. based on segment tracing of the respective path. Alternatively or in addition, the obtaining of the one or more objects may be based on segment tracing of the respective path.

[0065] The amplitude of a path segment may be the amplitude of a ray propagating along the path segment. The phase shift of a path segment may be the phase shift of a ray propagating along the path segment. The polarization change of a path segment may be the polarization change of a ray propagating along the path segment.

[0066] Modeling the channel may mean that the device is further operable to determine an electromagnetic propagation of the wireless communication in the environment from the first station to the second station based on a superposition (e.g., a sum, optionally a vectorial sum for the polarization) of contributions of the one or more determined shortest paths. The contributions may comprise the amplitude, the phase shift, and / or the polarization change of each of the one or more determined shortest paths. The amplitude and the phase shift may be represented by a complex-valued gain. All three may be represented by a complexvalued vectorial gain.

[0067] 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).

[0068] 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 shortest paths. For example, the electromagnetic propagation may be configured to associate to the one or more shortest 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 shortest paths.

[0069] In any aspect, the one or more shortest 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. Alternatively or in addition, the wireless communication may be a radio frequency communication or a visible light communication (VLC).

[0070] The wireless communication in the environment may be performed (e.g., transmitted or received) or controlled (e.g., initiated) based on the determined one or more shortest paths. Alternatively or in addition, controlling the wireless communication may comprise beam management, e.g., steering, tracking or predicting a radio beam based on the determined one or more shortest paths. Alternatively or in addition, controlling the wireless communication may comprise configuring the transmitter node and / or the receiver node of the wireless communication based on the determined one or more shortest paths.

[0071] Emulating the channel (or emulating a channel state, briefly: channel emulation) may comprise physically transmitted signals that are artificially shifted in amplitude and phase based on the modeled channel, rather than naturally shifted based on radio wave propagation and interactions in the real world. Here, artificially shifted may mean that the transmitter node is wired (e.g., in the analog domain) to an emulating device embodying the device aspect, which applies the shift in amplitude and phase based on the determined multipath propagation, and which output is wired (e.g., in the analog domain) to the receiver node. A wireless communication equipment (i.e., transmitter or receiver) may operate (i.e., perform its functions including at least one of channel estimation, decoding, beamforming, possibly channel prediction, etc.) on the emulated channel rather than actual channels. Typical use cases of the emulated channel are in equipment testing or in digital twins (DTs). The computational efficiency increase, which can be brought about by the finite size of the traced rays and / or the reducing the number of first paths or base paths or base points can still enable using more accurate channel models (e.g., detailed or more complex surfaces in the environment), e.g. in equipment testing or DTs, based on the determined one or more shortest paths.

[0072] Alternatively or in addition, modeling or emulating the channel of the wireless communication may comprise predicting the channel, e.g. based on controlled or scheduled motion of objects (e.g., the reflective surfaces or the diffractive edges) in the environment. For example, the environment may be a manufacturing environment, comprising robots that perform a scheduled or controlled motion influencing the multipath propagation.

[0073] The physical action may (e.g., further) comprise deploying at least one transmitter node and / or at least one receiver node in the environment based on the determined multipath propagation, optionally based on the modeled and / or emulated channel.

[0074] The deployed transmitter node may correspond to, or may refer to, the (at least one) transmitter node of the modeling of the channel or the emulating of the channel. Alternatively or in addition, the deployed receiver node may correspond to, or may refer to, the (at least one) receiver node of the modeling of the channel or the emulating of the channel.

[0075] In an embodiment, the device may be further operable to determine the first grid comprising a plurality of grid points and / or the second grid comprising a plurality of grid points in the environment.

[0076] The first grid and the second grid may be different from each other. For example, the first grid and the second grid may be disjoint point sets in the environment. For example, the first grid may comprise grid points at buildings. The second grid may comprise grid points on streets. Alternatively or in addition, the first grid may comprise stationary grid points. The second grid may comprise moving grid points.

[0077] The first grid and the second grid may relate to the same area or vicinity in the environment. For example, a convex hull of the grid points of the first grid may overlap (e.g., by more than 50 % or 80 %) with a convex hull of the grid points of the second grid.

[0078] The first grid and / or the second grid may be a uniform deployment grid. Alternatively or in addition, the first grid and / or the second grid may provide finer resolution around particular locations in the environment. For example, around areas where the first station or the second station are more likely to move, and / or in areas where the environment comprises small details or where it is otherwise expected that the propagation paths may change more rapidly with variations in position; and / or around the first station or the second station which are using antenna arrays with spatial extensions and where it may be expected that a propagation paths may be partially blocked.

[0079] In an embodiment, the first station may be a transmitting device and the second station may be a receiving device. Alternatively, the first station may be a receiving device and the second station may be a transmitting device.

[0080] The first grid may be a transmitter (Tx) grid comprising Tx base points, and the second grid may be a receiver (Rx) grid comprising Rx base points.

[0081] As to a method aspect, a method of determining a path of a wireless communication between a first station and a second station in an environment comprising a first grid and a second grid is provided. The method comprises or initiates a step of selecting at least one point of the first grid near the first station and at least one point of the second grid near the second station. The method further comprises or initiates a step of obtaining one or more paths between the at least one point in the first grid near the first station and the at least one point in the second grid near the second station, wherein the path comprises a start point and an end point, and wherein each of the one or more obtained paths comprises an interaction signature indicative of one or more interactions between the path and one or more interaction objects of the environment. The method further comprises or initiates a step of translating at least one of the start point of the one or more obtained paths to the spatial position of the first station and the end point of the one or more obtained paths to the spatial position of the second station. The method further comprises or initiates a step of determining a shortest path between the first station and the second station along each of the one or more obtained paths, wherein the determining of the shortest path maintains the interaction signature of the respective path.

[0082] The method may be a computer-implemented method, e.g. at the first station and / or the second station.

[0083] The method may further comprise any feature or step (e.g., functionality) disclosed in the context of the device aspect. For example, the method may further comprise performing or initiating a physical action that is dependent on the determined one or more shortest paths in the environment. Alternatively or in addition, the method may further comprise modeling a channel of the wireless communication along the determined one or more shortest paths (and optionally the structural information of the environment).

[0084] The technique may be implemented as a device for, and a method of, up-sampling (also: ray up-sampling) paths available between points of the first and second grids to any pair of points in the environment.

[0085] The device may be part of a system or tool implemented in a virtualized and / or distributed and / or scalable computing network (also referred to as cloud). 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.

[0086] 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.

[0087] 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.

[0088] Alternatively or in addition, the device may be embodied by a core network node configured to communicate with a base station and / or configured to control a radio access network (RAN). 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.

[0089] In a first variant of any embodiment, the same device that is determining the one or more shortest 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 shortest 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.

[0090] In any aspect, the different directions of the finite set of rays launched from the first station may be uniformly or quasi-uniformly (i.e., near-uniformly) distributed in angle, optionally in each of the groups. For example, the rays in the first group may be uniformly distributed. Uniformly may mean that the directions of the plurality of the launched rays may be equally distributed as intersections on a sphere around the first station or on a portion of a sphere (e.g., a hemisphere). The diameter of the sphere may be sufficiently small so that all rays have a point of intersection with said sphere prior to intersecting a (e.g., real) surface in the environment. Moreover, the sphere radius does not matter in this context as the launched rays may be defined in angular space independent of the space of the environment. In more mathematical terms, the launched rays may be elements of a tangent space of the manifold representing the environment, wherein the tangent space is an element of a tangent bundle at the location of the first station.

[0091] Exactly uniformly distributed directions are (in three dimensions) only possible for the five Platonic solids. The uniformly distributed directions may correspond to vertices of a convex regular polyhedron enclosing the launch point, optionally wherein the launch point is at the center of convex regular polyhedron. Quasi-uniformly distributed directions may be defined by the vertices of a uniform convex polyhedron. Alternatively or in addition, further groups of quasi-uniformly distributed directions may be defined by further subdividing each edge (i.e., line between next neighbors) of the previous group. For example, a group So may correspond to an icosahedron. To achieve quasi-uniformity for a further group Si, the directions of the rays in the group Si may correspond to the midpoints of each edge in the group So. The ratio between the longest and shortest distance between neighboring intersections on the sphere can be ensured to be less than some threshold of about 1.2. The rays or directions in any one of the sets may correspond to midpoints of neighboring vertices for the rays in the previous group. The midpoints may be on straight lines or on a great circle on the surface comprising the neighboring vertices.

[0092] Embodiments of the technique (i.e., any aspect of the technique) may be applied for paths including a sequence of one or more specular interactions (e.g., from surfaces of buildings, ground, etc.) and / or one or more diffractive interactions (e.g. from edges). Furthermore, a first point and / or a last point of a subpath, to which the technique is applied independently, may be subject to diffuse interactions modeled as point interactions. For example, a physical path from a transmitter to a receiver may include a point of diffuse scattering, which acts as the point for launching the finite set of rays according to an embodiment of the technique. Same or further embodiments may be used in a ray tracing -based radio frequency (RF) propagation model for deterministic and site-specific radio network modeling and simulation.

[0093] 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.

[0094] Any radio device may be a user equipment (UE), e.g., according to a 3GPP specification.

[0095] 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.

[0096] 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).

[0097] 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.

[0098] 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.

[0099] Whenever referring to the RAN, the RAN may be implemented by one or more network node (e.g., base stations).

[0100] 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).

[0101] 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). The RAN may be implemented according to the Global System for Mobile Communications (GSM), the Universal Mobile Telecommunications System (UMTS), 3GPP Uong Term Evolution (UTE) and / or 3GPP New Radio (NR).

[0102] 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.

[0103] 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.

[0104] As to a still further aspect a communication system including a host computer is provided. The host computer comprises a processing circuitry configured to provide user data, e.g., included in the transmission and / or reception of the physical action. The host computer further comprises a communication interface configured to forward the user data to a cellular network (e.g., the RAN and / or the base station) for transmission to a UE.

[0105] A processing circuitry of the cellular network may be configured to execute any one of the steps of the method aspect. Alternatively or in addition, the UE comprises a radio interface and processing circuitry, which is configured to execute any one of the steps of the method aspect.

[0106] The communication system may further include the UE. Alternatively, or in addition, the cellular network may further include one or more base stations configured for radio communication with the UE and / or to provide a data link between the UE and the host computer using the method aspect.

[0107] The processing circuitry of the host computer may be configured to execute a host application, thereby providing the user data and / or any host computer functionality described herein. Alternatively, or in addition, the processing circuitry of the UE may be configured to execute a client application associated with the host application.

[0108] 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, the 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. Brief Description of the Drawings

[0109] Further details of embodiments of the technique are described with reference to the enclosed drawings, wherein:

[0110] Fig. 1A shows a schematic block diagram of a first embodiment of a device for determining a path of a wireless communication in an environment;

[0111] Fig. IB shows a schematic block diagram of a second embodiment of a device for determining a path of a wireless communication in an environment;

[0112] Fig. 2 shows a flowchart of an embodiment of a method for determining a path of a wireless communication in an environment, which method may be implementable by the device of Fig. 1;

[0113] Fig. 3 shows an exemplary simplified 2D environment comprising a first grid and a second grid;

[0114] Fig. 4 shows further steps of the method 200 of the exemplary simplified 2D environment

[0115] 300 according to Fig. 3;

[0116] Fig. 5 shows further steps of the method 200 of the exemplary simplified 2D environment

[0117] 300 according to Fig. 3 and Fig. 4;

[0118] Fig. 6 shows an exemplary flowchart of an embodiment of a method for determining a path of a wireless communication between a first station and a second station in an environment comprising a first grid and a second grid;

[0119] Fig. 7 shows a block diagram of an emulating embodiment of the device of Fig. 1;

[0120] Fig. 8 shows a block diagram of a radio device embodiment of the device of Fig. 1;

[0121] Fig. 9 shows a block diagram of a base station embodiment of the device of Fig. 1 ; and

[0122] Fig. 10 shows a block diagram of a core network embodiment of the device of Fig. 1. Detailed Description

[0123] 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.

[0124] 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.

[0125] Fig. 1A schematically illustrates a block diagram of an embodiment of a device for wireless communication in an environment, e.g. for determining a path of a wireless communication between a first station and a second station in an environment comprising a first grid and a second grid. The device is generically referred to by reference sign 100.

[0126] The device 100 comprises an Obtainment Module 102A that selects at least one point of the first grid near the first station and at least one point of the second grid near the second station. The obtaining module further obtains one or more paths between the at least one point in the first grid near the first station and the at least one point in the second grid near the second station. The path may comprise a start point and an end point, and each of the one or more obtained paths may comprise an interaction signature.

[0127] The device 100 further comprises a Configuration Module 104A that discards one or more duplicated obtained paths. The duplicated obtained paths may comprise the same interaction signature. The configuration module 104A further translates the start point of the one or more obtained paths to the spatial position of the first station, and translates the end point of the one or more obtained paths to the spatial position of the second station. The Configuration Module 104A further determines a shortest path between the first station and the second station for each of the one or more obtained paths. Each of the shortest determined paths may comprise unique interaction signature.

[0128] Optionally, the device 100 comprises an Action Module 106A. The Action Module 106A may perform or initiate a physical action that is dependent on the determined one or more shortest paths between the first station and the second station in the environment. Alternatively or in addition, the Action Module 106A may optionally model a channel of the wireless communication along the determined one or more shortest paths in the environment. Optionally the modeling of the channel may comprise, or the device 100 may be further be operable to, perform or initiate a physical action that is dependent on the modeled channel.

[0129] Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality.

[0130] The device 100 may be embodied by an emulator or a network node (e.g., a transmitting and / or receiving node) of a RAN.

[0131] Fig. IB illustrates a schematic block diagram of the second embodiment of a device 100 for determining a path of wireless communication in an environment.

[0132] The device 100 optionally comprises a Grid Determination Module 102, which is tasked with defining the structure and parameters of the first grid and the second grid within the environment.

[0133] The Point Selection Module 104 of the device 100 operates (e.g., in conjunction with this module 102) to pick specific points within the first and second grids that are in close proximity to the first station and the second station in each case.

[0134] The Path Obtainment Module 106 of the device 100 is responsible for obtaining one or more feasible (e.g., physical) communication paths between one or more selected points on the first grid near the first station and one or more selected points on the second grid near the second station.

[0135] Based on the one or more obtained paths of this module 106, the optional Interaction Signature Determination Module 108 identifies unique signatures formed by the interactions between the determined paths and various objects in the environment. To reduce redundancy and optimize the path information, the optional Duplicate Discardment Module 110 scrutinizes the interaction signatures to remove any duplicates, ensuring that each path is unique in terms of its interaction characteristics. Subsequently, the Point Translation Module 112 shifts the start and end points of the paths towards the actual spatial positions of the first station and the second station, adapting the paths to real-world deployment scenarios.

[0136] At any point during the method, e.g. when obtaining the one or more paths or determining the one or more shortest paths, the optional Object Obtainment Module 114 gathers information about the physical objects that are situated in the environment, e.g. along the one or more respective paths. These may include interaction elements such as obstacles or surfaces or edges that may impact the wireless communication signal by means of absorption, reflection or diffusion, or diffraction, respectively, or other such interactions.

[0137] With the groundwork laid, the Shortest Path Determination Module 116 enters the process to identify the shortest path (e.g., with minimal path length) based on the obtained and translated one or more paths for the wireless communication signal between the first station and the second station. It does so while maintaining the integrity of the interaction signature, thus ensuring the paths fulfils Fermat's principle for the given one or more interactions as the physical realities of signal propagation.

[0138] The physical plausibility of the one or more shortest paths is further vetted by the optional Shortest Path Discardment Module 118, which eliminates any paths that (e.g., as a result of minimizing the path length) do not agree with the actual environment's layout, ensuring that the remaining paths are possible and realistic.

[0139] In any embodiment, an optional Physical Action Module 120 may be harnessed to carry out or initiate physical actions based on the actionable intelligence derived from the one or more determined shortest paths. This may involve adjusting precoding or antenna orientations or other environmental or deployment manipulations to optimize the wireless communication. Alternatively, a Channel Model Module 122, if implemented, determines or emulates the characteristics of a communication channel along the one or more shortest paths. This allows for an advanced understanding of the communication channel, e.g. applied to better network configurations and enhanced UE performance.

[0140] Fig. 2 shows an example flowchart for a method 200 for determining a path 302 of a wireless communication between a first station 304 and a second station 306 in an environment 300 comprising a first grid 314 and a second grid 316. For a convenient explanation, the description of Fig. 2 also refers to exemplary features of Fig. 3, without being limited to the embodiment of Fig. 3.

[0141] Optionally, the method 200 comprises a step S202 of determining the first grid 314 comprising a plurality of grid points and / or the second grid 316 comprising a plurality of grid points in the environment 300.

[0142] The first grid 314 and / or the second grid 316 may be a three-dimensional (3D) grid in the environment 300. The first grid 314 and / or the second grid 316 may be or may not be equivalent to each other. The first grid 314 and / or the second grid 316 may be a uniform grid, e.g., a lattice. Alternatively or in addition, the first grid 314 and / or the second grid 316 may be a non-uniform (e.g., adaptive) grid. For example, in particular parts of the environment 300, a density of the grid points of the first grid 314 and / or the second grid 316 may be increased (e.g., relative to an average density in the respective grid). Examples of such particular parts are parts of the environment 300 comprising an increased number or density of details (e.g., relative to an average number of the respective grid). For example, parts of the environment with (e.g., relatively) increased density of grid points may include at least one of complex surfaces of stationary objects in the environment 300, moving objects, the first station 314, and / or the second station 316.

[0143] The points and / or the density of the points of the first grid 314, and / or the points and / or the density of the points of the second grid 316, may be obtained based on periodically sampling the environment 300 and / or randomly sampling (e.g., Monte Carlo sampling) of the environment 300.

[0144] The method 200 comprises a step S204 of selecting at least one point of the first grid 314 near the first station 304 and at least one point of the second grid 316 near the second station 306. The first station 304 may be a transmitting device (e.g., transmitter or Tx) and the second station 306 may be a receiving device (e.g., receiver or Rx), or the first station 304 may be a receiving device and the second station 306 may be a transmitting device.

[0145] The method 200 further comprises a step S206 of obtaining one or more paths between the at least one point in the first grid 314 point near the first station 304 and the at least one point in the second grid 316 point near the second station 306. The path 302 comprises a start point and an end point. Each of the one or more obtained S206 paths 302 comprises path 302 an interaction signature indicative of one or more interactions between the path 302 and one or more interaction objects 308 of the environment 300. The obtained one or more paths between the at least one point in the first grid near the first station and the at least one point in the second grid near the second station may be stored (e.g., saved) in memory and / or a database as pre-traced paths.

[0146] Obtaining S206 one or more paths 302 may comprise tracing a ray shot from the selected point of the first grid 314 to the selected point of the second grid 316. Alternatively or in addition, obtaining S206 one or more paths 302 may comprise tracing a ray shot from the first station 304 to the second station 306. Alternatively or in addition, obtaining S206 one or more paths 302 may comprise obtaining S206 the one or more paths 302 from one or more previously saved traced rays between the selected point of the first grid 314 and the selected point of the second grid 316, e.g. retrieved from the database. Alternatively or in addition, obtaining S206 one or more paths 302 may comprise obtain S206 the one or more paths 302 from one or more previously saved traced rays between the first station 304 and the second station 306. The path 302 may comprise one or more path segments of the path 302. For example, a direct (e.g., nonchanging direction) path between the start point and the end point comprises one path segment.

[0147] Optionally, the method 200 further comprises a step S208 of determining the interaction signature of the one or more obtained S206 path 302.

[0148] The method 200 optionally comprises a step S210 of discarding duplicates among the one or more obtained S206 paths 302. The duplicates among the one or more obtained S206 paths 302 may comprise the same interaction signature as one other of the one or more obtained S206 paths 302.

[0149] The method 200 further comprises a step S212 of translating the start point of the one or more obtained S206 paths 302 to the spatial position of the first station 304. Alternatively or in addition, the method 200 further comprises translating S212 the end point of the one or more obtained S206 paths 302 to the spatial position of the second station 306.

[0150] Optionally, the method 200 further comprises a step S214 of obtaining one or more objects 308 of the environment 300, e.g. one or more objects along one or more paths 302, e.g., the one or more paths 302 obtained in the step S206. The obtained S214 one or more objects 308 of the environment 300 may optionally include the one or more interaction objects which interact with the path. Each of the one or more objects 308 may interact with the ray defining the path 302. The obtaining S214 one or more objects 308 may be based on segment tracing of the path 302. Namely, two interaction points may define a segment of the path 302. The interaction point may comprise the start point of the one or more obtained S206 path 302 and the end point of the one or more obtained S206 path 302.

[0151] The method 200 further comprises a step S216 of determining a shortest path 302 between the first station 304 and the second station 306 for each of the one or more obtained S206 paths 302. The determining S216 of the shortest path 302 maintains the interaction signature of the respective path 302. Alternatively or in addition, each of the shortest determined S216 paths 302 may comprise unique path 302 properties.

[0152] For example, each interaction may define a planar or linear constraint for the interaction point of the path when undergoing said interaction.

[0153] Optionally, the method 200 further comprises a step S218 of discarding one or more of the one or more determined S216 shortest paths 302 that are inconsistent with the environment 300. The one or more discarded S218 shortest paths 302 may be inconsistent (i.e., one or more of the shortest paths 302 may be discarded) due to the respective shortest path 302 intersecting with an object 308 of the environment 300, or due to an outgoing ray of a specular reflection (e.g., as one of the one or more interactions) being on an opposite side of an incoming ray of a surface of the reflection, or due to an interaction point (e.g., a reflection point) being outside of the interaction object 308 (e.g., outside of a physical surface of the reflection as the interaction element of the interaction object 308).

[0154] The one or more discarded S218 shortest paths 302 may be inconsistent with the environment 300 due to the path 302 intersecting with an electromagnetically opaque object 308 of the environment 300, or an outgoing ray of a diffusive or specular reflection enters a volume of the interaction object 308, or an interaction point of the interaction (e.g., which maintains the interaction signature by being constrained to a straight line co-parallel to the interaction element of the interaction object or a surface coplanar with the interaction element of the interaction object) is outside of the interaction object 308. A reflection point is an example for the interaction element.

[0155] Furthermore, if an object 308 in the environment 300 is transparent and transmissive when interacting with the ray defining the path 302, the method 200 discards S218 a determined shortest path 302 that includes a reflection from said object 308 (i.e., the object 308 reflects the ray), which is an inconsistency with the environment 300.

[0156] The interaction signature of the path may comprise a sequence of path segments of the path 302, and an interaction between each pair of the subsequent path segments of the path 302. Alternatively or in addition, the interaction may comprise an interaction object 308 and a type of interaction. The type of interaction may be one of reflection, diffraction, transmission, and refraction.

[0157] Any path 302 may further comprise or may be associated with one or more path properties of the path 302, which may comprise an amplitude of each path segments of the respective path 302; an amplitude of each interaction point or between subsequent path segments of the respective path 302; an amplitude of the entire respective path 302; a phase shift of a ray for each path segment of the respective path 302; a phase shifts of a ray at each interaction point or between subsequent path segments of the respective path 302; a phase shift of the entire respective path 302; a polarization change of each path segment of the respective path 302; a polarization change of each interaction point or between subsequent path segments of the respective path 302; a polarization change of the entire respective path 302; a path length of the respective path 302; a polarization changes of the ray between subsequent path segments; a time of flight of the respective path 302 ray; and a direction of departure of the ray in with respect to the a direction of the arrival of the ray respective path 302 at each interaction point or between subsequent path segments.

[0158] The interaction objects 308 may be specular, diffusive, etc. The objects 308 and / or interaction objects 308 may comprises one or more surfaces, one or more edges / wedges. The ray defining the path 302 may pass through surfaces (e.g., selective null interaction) of the one or more objects 308. The determined S216 shortest path 302 may be used for UL or DL (bidirectional). The directional density of launched rays may be adapted so that there may be at least N hit points on the capture surface of each grid (the first grid and / or the second grid) point. Optionally the method 200 further comprises a step S220 of performing or initiating a physical action that is dependent on the one or more determined S216 shortest paths 302 between the first station 304 and the second station 306 in the environment 300. The step S220 may optionally wherein the physical action S220 is based on modeling S222 a channel of the wireless communication along the determined S216 shortest path 302 and the environment 300.

[0159] Optionally the method 200 further comprises a step S222 of modeling a channel of the wireless communication along the one or more determined S216 shortest paths 302 in the environment 300. The modeling S222 of the channel may comprise or the device 100 may be further operable to perform or initiate a physical action that is dependent on the modeled S222 channel.

[0160] Alternatively or in addition, the modeling S222 of the channel may comprising at least one of the path properties of the one or more determined S216 shortest paths 302.

[0161] Optionally the method 200 further comprises a step of storing information comprising information related to the first grid 314 and the second grid 316 and / or the obtained S206 one or more paths 302 and / or the determined S216 shorte st path 302 between the first station 314 and the second station 316. Optionally the method 200 further comprises the step of re-determining S216 (e.g., recalculating) the shortest path 302, based on the previously stored information. Therefore, the method 200 may get faster and use less computation resources over time.

[0162] The method 200 may be performed by the device 100.

[0163] 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.

[0164] 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.

[0165] Embodiments of the device 100 and the method 200 may be used for determining a path 302 between a first station 304 and a second station 306 using pre-traced paths 302 of nearby positions (e.g., points of the first grid 314 and / or the second grid 316). The method 200 may be reciprocal, i.e., both the first station 304 and the second station 306 positions can be up-sampled using method 200.

[0166] Embodiments of the device 100 and the method 200 may exploit an observation that the first station 304 locations and / or the second station 306 locations that are spatially close to each other tend to have many identical propagation paths 302 (or ray / path geometries). The identical paths 302 in this context may be defined as the paths 302 comprising the same path properties (e.g., series of interactions) from the start to the end. The series of interactions may be defined as from the same or sufficiently similar objects 308, though not necessarily at exactly the same points on these objects 308, e.g. as defined by characteristic sequences.

[0167] Embodiments of the device 100 and the method 200 may use pre-tracing (e.g., obtained S206 paths) to a set of positions scattered in the environment 300, to determine S216 paths 302 to any location by reusing geometric information from paths 302 in the nearby results. A single ray-tracing launch may provide enough information to determine S216 paths 302 to an arbitrary location.

[0168] Embodiments of the device 100 and the method 200 may share the initial interaction by different nonequivalent paths 302 (e.g., tree) and consequently results in storage efficiency of path 302 data.

[0169] Since the paths 302 are translated in a physically correct way (e.g., by virtue of the shortest path determining step S216 following the translating step S212, which combination may be referred to as adjusting the path) and the electromagnetic properties are recalculated for the adjusted (propagation) path 302, the paths 302 resulting from the method 200 are identical to, or equivalent in quality to, corresponding paths 302 that would have been found using ray tracing. At the same time, the method 200 is orders of magnitude faster than ray tracing to each individual destination. It is thus computationally superior to the methods of the art. The fact that the properties of the paths 302 are determined S208 and / or the electromagnetic propagation (e.g., modeling the channel) is re-determined (e.g., in step S216) makes the quality of the results superior to any existing solution employing any type of interpolation.

[0170] Embodiments of the method 200 do not require predefined (e.g., deterministic or scheduled) motion of transmitter and / or receiver positions and may be used to query paths with arbitrary transmitter / receiver locations. This mode of computation defined by the method 200 allows near real-time operation with full interactivity and 3D movement of users. Pre-traced path 302 information is collected from an arbitrary number of transmitter / receiver positions, in contrast to maximum 2 positions in the time-based DRT, which significantly improves path 302 re-usage and minimizes the number of expensive raytracing launches needed. 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.

[0171] Embodiments of the device 100 and the method 200 can improve the fidelity of the modeled channel and / or the accuracy of the determined one or more shortest paths (e.g., represent the dominant contribution to the signal propagation of the wireless communication). For example, based on the modeled channel and / or the determined third path, 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.

[0172] In addition, 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. Ray-tracing (and emulation or simulation) in the digital twin can then inform the physical network or equipment about expected behavior of the radio channel. The proposed method 200 as a full ray tracing computation replacement may have several different applications, including:

[0173] - Channel estimation, i.e. the physical receiver can improve its estimation if some a priori information can be obtained from its digital twin;

[0174] - Beam forming and beam management, the transmitter and / or receiver can 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;

[0175] - Channel prediction, similar to the above, informing a transmitter or receiver about likely future time development of the radio channel based on ray tracing;

[0176] - Positioning, can 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;

[0177] - Sensing, for instance if difference between ray-traced channel and measured channel suggests the presence and location of objects of interest;

[0178] - Configuration of (e.g., base station) equipment, which may 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.; and

[0179] - 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. For example, embodiments can determine the transmission power as a 3D field and determine power density peaks, which is advantageous at locations where objects (e.g., persons or UEs) move so that a direct measurement (e.g., by means of a stationary sensor) is not feasible within the stream of moving objects.

[0180] Alternatively or in addition to above use cases, the one or more shortest paths 302 are the basis for the modelling S222 of the wireless communication, which can result in a high-fidelity representation of the wireless (e.g., radio) channel that is quickly computed and can be put to use in at least the following ways. First, in laboratory testing of radio communication equipment, it is desirable to replicate the conditions that are expected when the equipment is deployed and used in the real world. A common practice is to use channel emulation software or hardware to let the equipment experience radio channels of different kinds. A ray -tracer can generate the radio channels to be emulated. Real-time or near real-time computation of radio channel is very important for this use case.

[0181] Second, the dimensioning and provisioning of wireless radio networks relies on estimating e.g. coverage and user experienced throughput for different hypothesis of how the radio base stations are deployed and how capable they are (e.g. what 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 initial stages of this work, high-fidelity channels that are rapidly computed with the help of ray tracing can immensely enhance the quality of the dimensioning and planning process and reduce the need for costly and time-consuming field trials.

[0182] Third, in development of radio network products it is of importance to understand the relative values of different product enhancements. However, the value can only be established either through measurements (which in most cases would require the product to first be built) or through simulations using channel models. The higher the fidelity of the channel models, the higher the likelihood that correct prioritizations are made leading to better products.

[0183] Fourth, standardization of radio network technologies involves forming an industry consensus view on the relative performance of different proposed standard features or enhancements. In the vast majority of 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 (cf. clause 8, Map-based hybrid channel model). Improvements to the ray-tracing methods can improve the sitespecific modeling and therefore open up for better evaluations or even unlock evaluations for new features and scenarios that were previously considered too complicated for 3GPP. Figs. 3A-3D show an exemplary simplified two-dimensional (2D) or top-view of the environment 300 comprising a second grid 316. For simplicity of illustration and not limitation, the second grid 316 is shown as a rectangular lattice, wherein the points the second grid 316 are indicated by cross points. In a variant of the illustrated embodiment, the second grid 316 (and also the first grid) may have spatially varying density of points. The first grid 314 is in the same environment 300 and illustrated separately in Fig. 3E. That is, Figs. 3A and 3E relate to the same situation of the same environment 300 with the first grid 314 and the second grid 316 illustrated separately in different figures for a clear illustration.

[0184] Note that any one (e.g., each) of the steps S204 and S212 of the method 200 may be performed independently for the first grid 314 and the second grid 316. For example, the selecting S204 of the point 304' of the first grid 314, which point 304' is near the first station 304, and the translating S212 of the selected point 304' to the location of the first station 304, as schematically illustrated in Fig. 3E, may be performed prior to applying the steps S204 and S212 of the method 200 for a point 306' of the second grid 316, which is described below with reference to Figs. 3A-3D, wherein the point 306' is selected S204 because it is near the second station 306 (shown in Figs. 4A-4D).

[0185] In an implementation of any embodiment, the first station 304 or the second station 306 may be at the location of one of the points of the first grid 314 and / or the second grid 316. For example, one of the first grid 314 and the second grid 316 may the aligned with the first station 304 or the second station 306 so that one point of the first grid 314 or the second grid 316 coincides with the first station 304 or the second station 306.

[0186] The exemplary environment 300 comprises three objects 308. In an exemplary scenario only zero to two (0-2) specular reflections are allowed per path 302. For example, Fig. 3A shows 0 specular reflection, Fig. 3B shows 1 specular reflection and Figs. 3C and 3D show 2 specular reflections. In this example, a single first station 304 is shown (in a circle with a cross). Within an area covered by the second grid 316 (e.g., a convex hull of the second grid 316), the first station 304 is up-sampled to an arbitrary location in the environment 300. For clarity of illustration, the first grid 314 and the points of the first grid 314 are not shown, and an arbitrary location within the second grid 316 for the first station 304 is assigned.

[0187] It is noted that analogously to the situation shown in Figs. 3A-3D, the second station 306 may be arranged at any location within an area covered by the first grid 314 (e.g., a convex hull of the points of the first grid 314). An example of the latter is illustrated in Fig. 3E for the first grid 314 when viewed in combination with any one of Figs. 4A-4D for the location of the second station 306.

[0188] The device 100 obtains in the step S206 of the method 200 one or more paths 302 between at least one point in the first grid 314 near the first station 304 (e.g., an arbitrary location of the first station 304 within the second grid 316) and at least one point (shown 306' selected in the second grid 316 near the second station 306. For example, Fig. 3A shows three paths 302 with one segment, Fig. 3B shows three paths 302 with two segments and Figs. 3C and 3D show one path 302 with three segments. The "at least one path" obtained S206 according to the method 200 may comprise at least one group (also referred to as a "union", which is not to be confused with a mathematical term "union" for sets) of paths 302, wherein each group of the paths 302 may have similar (e.g., equivalent) interaction signatures path properties. For example, the three paths 302 shown in Fig. 3A (wherein each path 302 comprise only one segment in this exemplary case) have equivalent interaction signatures (namely, zero interaction) so that two duplicates among the three paths 302 may be eliminated according to the step S210 of the method 200. Analogously for the group of three paths 302 shown in Fig. 3B, wherein each path 302 comprise exactly one interaction point between two subsequent path segments for one interaction at the same surface (as the interaction element) of the same interaction object 308. Consequently, two duplicates among the three paths 302 may be eliminated according to the step S210 of the method 200. The further example paths 302 shown in Figs. 3C and 3D have unique interaction signatures.

[0189] Note that the start point of each of the paths 302 illustrated in Figs. 3A-3D and discussed above is translated to the location of the first station 304, which step S212 is illustrated in Fig. 3E, by applying the step S212 for the start point independently from applying the step S212 for the end point. For example, the step S212 may be applied to the start point and end point of the obtained S206 paths at any time prior to determining the shortest path according to the step S216.

[0190] Figs. 4A-4D show further steps of the method 200 of the exemplary simplified 2D environment 300 of Fig. 3, including those related to the end point of the paths. Figs. 4A-4D show collectively the obtained S206 paths (reference sign 302 suppressed for clarity) between the at least one point in the first grid 314 near the first station 304 (here already translated S212 and thus "up-sampled" to the arbitrary location of the first station 304, which location is not limited to the points of the first grid) and the at least one point (e.g., 306' in the case of Fig. 4D) in the second grid 316 near the second station 306.

[0191] The obtained S206 paths may be grouped according to their interaction signature (and optionally the path properties). Within each group (here corresponding to one of the Figs. 4A-4D), any one of the obtained S206 at least one path 302 may be chosen (e.g., to represent the entire group), and its end point 306', which may be originally on the second grid 316, is translated S212 (and thus "up-sampled") to the location of the second station (e.g., receiver) location 306, which is not limited to the points of the second grid 316.

[0192] Each of Fig. 4A and Fig. 4B shows the discarding S210 of two duplicates among the three obtained paths 302 (herein exemplary two left paths). The duplicates among the one or more obtained S206 paths 302 may comprise similar (e.g., equivalent) interaction signature (and optionally the path properties). The interaction signature may be indicative of the path segments and / or the interaction points between subsequent path segments (and / or the interaction objects 308). Under such a definition of the interaction signature, two of the three obtained S206 paths 302 in Fig. 4A, and two of the three obtained S206 paths in Fig. 4B may be discarded.

[0193] Note that although it is possible to consider all obtained S206 paths 302, it is in terms of memory and computational resources efficient to choose only one path 302 per unique group of interactions (e.g., per unique interaction signature), since after recalculating the geometry of the obtained paths in the step S216 of determining the shortest path 302, all the paths 302 with identical sets of interactions or equivalent interaction signature will yield the same shortest path 302. E.g., there is only one shortest path 302 for each group.

[0194] The curved arrow in each of the Figs. 4A-4D further shows the translating S212 of the end point (e.g. reference sign 306' in Fig. 4D) of the obtained S206 paths 302 to the spatial position (e.g., location) of the second station 306. In other words, the step S212 of translating the start and end points may be split up in two sub-steps, e.g. for the translating S212 of the start point of the obtained S206 paths 302 to the spatial position of the first station 304 (e.g., shown as an arbitrary location of the first station 304 in Figs. 3A-3D and the translating S212 in Fig. 3E) and the translating S212 of the end point of the obtained S206 paths 302 (e.g., as shown in each of the Figs. 4A-4D).

[0195] Fig. 5 shows further steps of the method 200 of the exemplary simplified 2D environment 300 according to Fig. 3 and Fig. 4.

[0196] Fig. 5 shows determining S216 a shortest path 302 between the first station 304 and the second station 306 based on the obtained S206 and translated S212 paths 302. Each of the shortest paths 302 maintains the path signature of the respectively underlying obtained S206 path during the determination S216 of the shortest path, e.g., by minimizing a path length of (e.g., a copy of) the respective obtained S206 path 302, wherein each interaction defines a boundary condition for the path. For example, each interaction point of the one or more obtained S206 paths 302 may be constraint to a (e.g., line or plane according to the type of the interaction) that comprises the interaction element of the interaction.

[0197] Alternatively or in addition, (e.g., by virtue of discarding S210 the duplicates) the different shortest paths have different interaction signatures, i.e., the interaction signature may be unique. In other words the method 200 in step S216 determines the shortest path 302 per group of the obtained S206 paths 302.

[0198] For example, Fig. 5A shows the determined S216 shortest path of the group of obtained S206 paths 302 with zero interactions. Here, the determined S216 shortest path 302 comprises an interaction with at least one (e.g., opaque) object 308 of the environment 300. Therefore, this determined S216 shortest path 302 (here with zero interaction) may not be accepted (e.g., may be discarded S218) according to the method 200. As another example, Fig. 5B shows the determined S216 shortest path 302 of the group of obtained S206 paths 302 with one interactions (e.g., two path segments).

[0199] The interaction signature refers to the sequence of zero or more interactions from the obtained paths, which is maintained when determining S216 the shortest path. That is, maintaining the interaction signature includes the requirement to fulfil the constraint posed by the interaction type, i.e. to slide the interaction point along a surface (e.g., for reflection) or an edge (e.g., for diffraction).

[0200] In a preferred first variant of any embodiment, after determining the shortest path, the validity of the shortest path is assessed according to the step S218. When the shortest path is inconsistent with objects 308 in the environment, the shortest path is discarded. By way of example, when the shortest path intersects with an (e.g., opaque) object 308, it is discarded. In the example illustrated in Fig. 5B the shortest path is consistent with the environment 300. In a subvariant of the first variant, the path property includes the electromagnetic gain associated with the respective path. The path is discarded if its (e.g., absolute value or the complex-valued) gain is below a predefined threshold value.

[0201] In a specific second variant of any embodiment, the interaction signature also includes one or more further interactions determined by one or more intersections of the shortest path with one or more objects 308 in the environment 300, as a result of the step S216. That is, a change in the spatial course of the path when minimizing the path length under the constraint of the interaction element may cause such one or more intersections. When such one or more intersections occur, this may correspond to a change in the interaction signature according to the second variant, so that the path is discarded for not maintaining the interaction signature in this specific second variant. In the example illustrated in Fig. 5B, the interaction signature of the determined S216 shortest path 302 did not change in comparison with the obtained S206 path 302. Hence, the determined S216 shortest path 302 of the Fig. 5B is acceptable according to the method 200 (i.e., there is no inconsistency with the environment 300).

[0202] As another example, Fig. 5C shows the determined S216 shortest path of the group of obtained S206 paths 302 with two interactions (e.g., three path segments). Since the path is inconsistent with the environment 300 (e.g., because the path property changed in the first variant, or because the gain in the path property is below the predefined threshold in to the subvariant of the first variant, or because the interaction signature of the determined S216 shortest path 302 did change in comparison with the obtained S206 path 302 (e.g., the second interaction is not reflection anymore) in the specific second variant), the determined S216 shortest path 302 of the Fig. 5B may not be acceptable (e.g., may be discarded S218) according to the method 200.

[0203] As another example, Fig. 5D shows the determined S216 shortest path of the group of obtained S206 paths 302 with two interactions (e.g., three path segments). Since the determined S216 shortest path 302 is consistent with the environment 300 (e.g., because the gain in the path property is above the predefined threshold in to the subvariant of the first variant, or because the interaction signature of the determined S216 shortest path 302 did not change in comparison with the obtained S206 path 302) in the specific second variant, the determined S216 shortest path 302 of the Fig. 5D is acceptable (e.g., is not discarded S218) according to the method 200.

[0204] For the purposes of the present discussion, a shortest path 302 between the first station 304 and the second station 306 is a path that either connects the points directly (by a straight line), or connects them via one or more object interactions, such as transmission (e.g., pass through), reflection (e.g., specular reflection), and / or diffraction (e.g., edge diffraction, also referred to as wedge diffraction), or arbitrary combinations thereof, in such a way as to minimize the travel time (or geometric path length in a homogeneous medium) of the path, in accordance with Fermat’s principle.

[0205] Since ray-tracing samples space discretely (e.g., since no finite number of paths covers any volume or because any finite number of paths has a discrete set of start points and a discrete set of end points), the determined paths 302 (as represented by the combination of path segments between object identified during the tracing) do not in general fulfill Fermat’s principle. Consequently, conventional ray-tracing techniques determine propagation paths 302, which are to be used for modeling the electromagnetic fields, but do not represent the shortest path between the first station 304 (e.g., a source or transmitter) and the second station 306 (e.g. a target or receiver), e.g. as a result of translating the start and end points to the first and second stations.

[0206] In contrast, the fundamental interaction types in electromagnetic (e.g. radio wave) propagation, e.g. specular reflection and edge diffraction, are consistent that the shortest propagation path 302 determined according to the steps S216 of the method 200. Thus, embodiments of the device 100 and the method 200 can avoid that the predicted fields are inaccurate as in conventional ray-tracing. An inaccuracy caused by the finite angular resolution may scale with distance and radio frequency, as the deviation in length causes a phase shift.

[0207] Conventional techniques to compute channel state information based on ray-tracing of radio waves ignore the effect of the obtained S206 paths 302 not being the shortest paths 302, and simply assume that the error due to the finite resolution can be made small enough to be acceptable. However, launching rays with high angular density and / or denser start points (i.e., not using a finite or small) set of traced rays can alleviate the inaccuracy only to a certain extent and at the cost of exponentially increasing computational resources. The denser the rays are launched, the smaller the error in the prediction. However, the problem with launching rays with sufficient resolution, particularly for large environments (such as cities) is that the number of rays must be very large to achieve small prediction errors. In the limit, the required number of rays can be too large to make the ray-tracing feasible, or can be extremely costly, due to the execution time and / or computer memory constraints. Also, launching rays densely results in multiple, similar but not identical, paths representing the same interactions in the propagation channel, which makes pruning (i.e., the removal of duplicate paths) challenging and time-consuming.

[0208] It is noted that in the most common ray-tracing applications for graphical applications, i.e., computer graphics-related applications, Fermat’s principle is not a major issue. In computer graphics, results on pixel-level tend to be composed of multiple overlapping ray or path contributions based on a multiplicity of rays launched in random directions, aggregated to create a final color and intensity, and this computation is almost exclusively based on reflection and refraction. In graphics, diffraction is not generally modeled using the asymptotic models used for wave propagation, since diffraction effects can be safely ignored at optical frequencies. Furthermore, graphics applications rarely, if ever, apply coherent combining of complex-valued vectors. In radio propagation, coherent addition can be essential, for example when summing the contribution from a direct path with the contribution from a diffracted path, since the (coherent) sum of the contributions is what ensures that the total contribution (i.e. the electromagnetic field) is spatially continuous. Fermat’s principle can be stated as: the path taken by a ray between two given points is the path that has a stationary, typically minimum, time with respect to variations of the path.

[0209] Embodiments of the device 100 determine S216 the path 302 as the shortest path 302 between the first station 304 and the second station 306. The obtained S206 path 302 and / or the determined S216 shortest path 302 may define a given set of interactions (e.g., a sequence of objects and types for the interactions). The shortest path 302 can be used for modeling a radio channel according to radio frequency (RF) propagation, e.g. compliant with Fermat’s principle. The channel may be modeled in real-time based on determined S216 path 302. The modeled channel can replace a conventional channel estimation, which is time-delayed and radio-resource consuming due to reference signal measurements.

[0210] In a variant of any embodiment, any number of shortest paths 302 may be determined S216 (e.g., based on a corresponding or greater number of the obtained S206 path 302) between the two stations (e.g., nodes) 304 and 306. Each path 302 may involve a unique combination (or sequence) of interactions, so that each path 302 can be determined according to the method 200.

[0211] Furthermore, while the technique is described for a transmitter and a receiver as the two nodes 304 and 306, the roles of transmitter and receiver may be interchanged. For example, the shortest path 302 may be determined starting from the location of the receiver 306, wherein the ending point is located at the transmitter 304.

[0212] Fig. 6 shows an exemplary flowchart of an embodiment of a method for determining a path 302 of a wireless communication between a first station 304 and a second station 306 in an environment 300 comprising a first grid 314 and a second grid 316. The following steps describe an exemplary embodiment of the method 200 for a single pair of the first station 304 and the second station 306, e.g. as visualized by the flowchart of Fig. 6. The device 100 may be operative to perform at least one of the following steps, independent of any other definition of the device 100 or in combination with any embodiment disclosed herein:

[0213] (i) The device 100 obtains spatial positions in the environment 300 for a first station 304 and a second station 306. This may be a sub-step of the grid determination S202. It may be noted that, since these positions are not limited to be on a (e.g., predefined) first grid 314 and second grid 316, respectively, determining a valid shortest path between the first station 314 and the second station 316 is also referred to as "up-sampling" (e.g., compared to those path linking only grid points). Given the spatial positions, the device 100 selects S204 at least one point of the first grid 314 near the first station 304 and selects S204 at least one point of the second grid 316 near the second station 306.

[0214] (ii) The device 100 assess (e.g., by querying the database of paths) if there are (e.g., pre-calculated) paths 302 available (e.g., in the database of paths and / or resulting from a previous iteration of determining S216 the shortest path). If so, the device 100 obtains S206 the one or more paths 302. If there are no pre-calculated or stored paths 302 available, the device 100 obtains S206 one or more paths 302 between the selected S204 points in the first grid 314 and the second grid 316 by calculating one or more propagation paths, e.g. by ray tracing, between the selected S204 one or more pairs of points.

[0215] It may be noted that including the one or more shorted paths resulting from S216 (e.g., and if not discarded in S218) in the set of pre-calculated paths (e.g., in the data base) can naturally lead to a density distribution of points of the first grid (e.g., defined as the start points of the previously determined shortest paths) and / or a density distribution of points of the second grid (e.g., defined as the end points of the previously determined shortest paths) that adapt to the spatial probability distribution of the first station 304 and the second station 306, respectively. For example, the first and second grids may adapt to a dynamic traffic pattern of UEs (e.g., connected vehicles when traffic is diverted).

[0216] (iii) The device 100 gathers all obtained S206 paths 302 belonging to either or both of the first grid 314 or the second grid 316 selection.

[0217] (iv) The device 100 calculates the union of paths (e.g., by grouping the paths 302 as discussed with reference to the pairs of Figs. 3 A and 4A, 3B and 4B, etc.) by discarding S210 any duplicate paths 302, i.e., paths 302 with the same interaction signature (e.g., series of interactions with the objects 308 of the environment 300). The discarding S210 may be based on determining S208 the interaction signature for each of the one or more obtained paths. The steps S208 and / or S210 may be sub-steps of the step S206 or separate steps.

[0218] (v) The device translates S212 the start point of the paths 302 to the spatial position of the first station 304 and translates S212 the end point to the spatial position of the second station 306.

[0219] (vi) The device 100 adjusts (e.g., shifts) the intermediate interaction points of each path by determining S216 the shortest path 302 between the first station 304 and the second station 306 (e.g., by minimizing the path length under the planar or linear constraint set by each interaction). As a result, the one or more shortest paths 302 make physical sense as a valid contribution to the electromagnetic propagation. The step S216 may be implemented by mirroring the downstream portion of the path (and the objects it is interacting on the downstream portion) with respect to the plane of each reflection interaction.

[0220] Optionally, the device obtains S214 objects 308 along the paths 302. Each of the one or more obtained objects 308 may interacts (e.g., intersect) with a ray defining the path 302, e.g., by using segment tracing techniques. Alternatively or in addition, the device 100 determines path properties, e.g., path loss. This may be a sub-step of the channel modeling S222. Alternatively or in addition, the device 100 discards S218 one or more of the one or more determined S216 shortest paths 302 that are inconsistent with the environment 300, e.g., because the path loss is below a predefined threshold value and / or because the path intersects an (e.g. opaque) object 308.

[0221] Determining S216 the shortest path 302 and determining the path properties may be implemented in the same step as the steps in a full path finding using ray tracing. The up-sampled paths 302, i.e., the nondiscarded shortest paths, can thus be identical to paths 302 that would have been found during a full ray tracing. Therefore, the technique may reach the physically accurate results of the full ray tracing with embodiments of the device 100 and the method 200 that are orders of magnitude faster for determining the shortest path 302 between the first station 304 and the second station 306.

[0222] The steps S214 and / or S218 may be performed by segment tracing and / or may comprise checking every segment (e.g., part) of an adjusted (propagation) path 302 for changes such as the presence of blocking object 308 or semi-transparent objects 308 that were not found along the obtained S206 paths 302.

[0223] Determining the interaction signature and / or the path properties may use the obtained S214 objects 308 in addition to or rather than the obtained S206 paths 302.

[0224] The result of the pre-calculation (e.g., as an optional sub-step of the step S206 when no or not enough paths are available) may be reused in subsequent up-sampling steps. The pre-calculation step may be performed ahead of time and the results may be stored to persistent storage for improved online (e.g., real time) performance.

[0225] According to some embodiments the up-sampling of one of the first or the second stations 304-306 is desired, for example in the case of a moving second station 306. Therefore, the first grid 314 may be assigned to the spatial location of the first station 304. Conversely, in the case of an antenna array or when attempting to optimize placements of e.g. base stations on building roofs, the second grid 316 may be assigned to the spatial location of the second station 306.

[0226] The method 200 according to some embodiments enables reusing previously obtained S206 paths 302 and / or previously determined S216 paths 302 for new spatial positions of the first station 304 and the second station 306 without a complete ray tracing, which would be a computationally heavy operation.

[0227] The efficiency of embodiments of the technique may be illustrated by the following observation: Closely located nodes share many identical paths, i.e., having the same set of interactions along the path, and the interaction points are closely spaced. This implies that if path tracing is first performed on a coarse set of positions covering the area of interest, then an arbitrary nearby position share most, if not all, of its paths with its neighbors.

[0228] The method 200 does not assume nor require any particular structure of chosen points of the first grid 314 and / or the second grid 316 for obtaining S206 the path (e.g., pre-calculation). However, for clarity of illustration, and without being limited thereto, a uniform 3D grid, a “deployment grid”, is chosen in this description. A deployment grid may comprise two independent grids: a first grid 314 and a second grid 316.

[0229] A uniform deployment grid (e.g., lattice) may be used. Alternatively or in addition, the deployment grid may be adjusted to provide finer resolution around particular locations of the environment 300. For example, around areas where the first stations 304 or the second stations 306 are more likely to move; around areas where the environment 300 has small details or where it is otherwise expected that the propagation paths 302 will change more rapidly with variations in position; and around the first stations 304 or the second stations 306 which are using antenna arrays with spatial extensions and where it may be expected that the propagation paths 302 may e.g., be partially blocked by an object 308 in the environment 300.

[0230] For identifying duplicate paths 302, the concept of “same interaction” (e.g., characteristic sequences) may be used. Two paths 302 having respective sequences of interactions A = {Ai, A2, . . . An} and B = {Bi, B2, . . . Bm} may be labeled as identical paths 302 or duplicates only if n = m and every An= Bm. If Anrefers to a reflection, then Bmis identical to Anif Bmis a reflection in the same plane as An. If Anrefers to a diffraction, then Bmis identical to Anif Bmalso refers to a diffraction on the same edge or wedge. Note that the actual reflection or diffraction points for Anand Bmneed not be exactly geometrically the same point. When adjusting two obtained S206 paths 302 with the same series of interactions (e.g., path properties) to determine S216 the shortest path 302, the two obtained S206 paths 302 results to identical shortest path 302.

[0231] The technique may be combined with any suitable method for ray-tracing, e.g. in the step S206 or S216. The shortest path 302 starts in a first station 304 (e.g., the transmitter) and ends in a second station 306. The path 302 is made up of path segments between points of interaction (e.g., points of reflection) which maintain the radius of curvature in at least one dimension, i.e., specular reflection (e.g., wherein the angle of incidence equals the angle of reflection) and edge diffraction (e.g., wherein the diffracted rays are on Keller's cone), not point diffraction. "Maintaining the radius of curvature in at least one dimension" may mean that the tangent vector of the path (e.g., of the first path and / or the second path and / or the third path) is continuous in at least one dimension (i.e., in a linear subspace), preferably in the two-dimensional plane of the reflective surface of an object 308.

[0232] The determining S216 the shortest path 302 (ray-tracing or briefly: tracing) may be re-run along the previously determined S216 shortest path 302 as the shortest path 302 to capture potential other interactions occurring due to a changed interaction points of the previously determined S216 shortest path 302 compared to an interaction point of the previously determined S216 shortest path 302. The device 100 may re-run the determining S216 to check that the shortest path 302 is not blocked by an object 308 in the environment 300. Alternatively or in addition, the device 100 may check that the shortest path 302 falls within the extent (e.g., the size) of the one or more surfaces and / or edges of the interaction object 308 (e.g. in a longitudinal direction of the respective diffractive edge 308) with which the shortest path 302 interacts. The device 100 may discard the shortest path 302 if the reducing of the length (e.g., a shortest path calculation) shifts outside of the extent of any of the reflective surfaces or outside of a finite length of any of the diffractive edges of the object 308. That is, a point on the surface and / or on an edge of the object 308 may only be allowed to be shifted within an extent (e.g., a length) of the object 308, and optionally may be fixed at either end point of the edge if the reducing of the path length (according to a method ignoring the finite size of the edge) results in a point outside the extent of the edge. In short, reducing the path length by shifting may be stopped at the end of an edge. Alternatively or in addition, reducing the path length by alternating a point of reflection on a surface may be restricted to shifting along an edge of the surface, and / or may stop at a comer of the surface, if the shortest path would fall outside of the extent of the surface.

[0233] Discarding duplications in the determined S216 shortest paths 302 is one example of discarding (e.g., not using for modeling the channel) one or more of multiple determined short paths 302.

[0234] In one example of the physical action, the device 100 comprises an emulating unit. 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 determined one or more propagation paths 302 between at least one first station 304 and at least one second station 306. The emulation may be based on the channel modeled in the step S222 based on the one or more shortest path 302. It is noted that "shortest" may refer to a local minimum of the length in the environment 300 or a minimum of the length given the sequence of interactions.

[0235] The embodiment of the device 100 for emulation comprises an RF input and an RF output coupled to the first station 304 and the second station 306, respectively. The technique can be applied in this context by letting the device 100 generate the radio channels to be emulated. Real-time or near realtime determining of the propagation path 302 enables real-time or near real-time emulation of the radio channel, which is very important for this use case.

[0236] 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 determined multipath propagation between at least one first station 304 and at least one second node 306 (which in turn may be based on the channel modeled in the step S222).

[0237] The device 100 comprises an RF input 702 and an RF output 704 coupled to the first station 304 and the second station 306, respectively, to let the equipment 304 and / or 306 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 very important for this use case.

[0238] Fig. 8 shows a schematic block diagram for a radio device 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 102A to 106A or 102 to 122.

[0239] 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, radio device 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.

[0240] As schematically illustrated in Fig. 8, the device 100 may be embodied by a radio device 800, e.g., functioning as a UE. The node 800 comprises a radio interface 802 coupled to the device 100 for radio communication with one or more other nodes, e.g., including base stations or UEs.

[0241] Fig. 9 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 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 102A to 106A or 102 to 122.

[0242] 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, network node functionality. For example, the one or more processors 904 may execute instructions stored in the memory 906. 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.

[0243] As schematically illustrated in Fig. 9, the device 100 may be embodied by a radio device 900, e.g., functioning as a gNB. The node 900 comprises a wired or radio interface 902 coupled to the device 100 for radio communication with one or more other nodes, e.g., including base stations and UEs, respectively.

[0244] Performing the physical action S220 may comprise transmitting or receiving the wireless communication based on the propagation path 302 determined in the step S216. 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 S220 may comprise controlling the wireless communication in the environment 300 based on the determined propagation path 302.

[0245] Alternatively or in addition, the physical action S220 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 determined propagation path 302 and / or the modeled channel of the step S222. Alternatively or in addition, the physical action S220 may comprise controlling directional gain and / or transmit power of the wireless communication in the environment 300. For example, a radio device 800 (e.g., a UE) may determine its position or a network node 900 (e.g., a gNB) may determine the position of a radio device 310 in the environment 300 based on the propagation path 302 determined in the step S216.

[0246] In one embodiment, radio signals received at the radio device 800 in the environment 300 are compared with radio signals expected (e.g., modeled in the step S222) at the at least one position in the environment 300 according to the determined propagation path 302. In another embodiment, the radio signals received from a radio device 310 in the environment 300 at a network node 900 are compared with radio signals expected (e.g., modeled in the step S222) at the at least one position in the environment 300 according to the propagation path 302 determined in the step S216.

[0247] 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 propagation paths 304 determined in the step S216. For example, the position for deploying at least one a base station 900 (e.g. acting as transmitter and receiver node) in the environment 300 may be determined based on the propagation path 302 (e.g., based on the modeled channel and / or the emulated channel as a function of the position).

[0248] In any embodiment, the propagation path 302, 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).

[0249] Fig. 10 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 1004 for performing the method 200 and memory 1006 coupled to the processors 1004. For example, the memory 1006 may be encoded with instructions that implement at least one of the modules 102A to 106A or 102 to 122.

[0250] The one or more processors 1004 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 1006, core node functionality or edge computing functionality. For example, the one or more processors 1004 may execute instructions stored in the memory 1006. 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 800 and / or the network node 900 may alternatively be performed by the core node 1000 or edge computing node 1000.

[0251] 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.

[0252] Unless specified differently in context, reference signs may relate to the following features and steps.

[0253] 100 Device for determining a path of a wireless communication

[0254] 102 Grid Determination Module

[0255] 104 Point Selection Module

[0256] 106 Path Obtainment Module

[0257] 108 Interaction Signature Determination Module

[0258] 110 Duplicate Discardment Module

[0259] 112 Point Translation Module

[0260] 114 Object Obtainment Module

[0261] 116 Shortest Path Determination Module

[0262] 118 Shortest Path Discardment Module

[0263] 120 Physical Action Module

[0264] 122 Channel Model Module

[0265] 102A Obtaining Module

[0266] 104A Configuration Module

[0267] 106A Action Module

[0268] 200 Method of determining a path of a wireless communication

[0269] S202 Determine first grid and second grid

[0270] S204 Select grid points near first station and second station

[0271] S206 Obtain one or more paths between selected grid points

[0272] S208 Determine interaction signature of obtained path(s)

[0273] S210 Discard duplicate(s) among obtained paths

[0274] S212 Translate start and end points to first and second stations, respectively

[0275] S214 Obtain objects along the path

[0276] S216 Determine shortest path(s) between the first station and the second station

[0277] S218 Discard inconsistent path(s)

[0278] S220 Perform or initiate physical action that is dependent on shortest path(s) S222 Model channel of wireless communication along shortest path(s)

[0279] 300 Environment

[0280] 302 Path

[0281] 304 First station

[0282] 306 Second station

[0283] 308 Objects of the environment, e.g., interaction objects

[0284] 314 First grid

[0285] 316 Second grid

[0286] 702 Channel emulator input interface

[0287] 704 Channel emulator output interface

[0288] 800 Radio device embodiment

[0289] 802 Interface, e.g., radio interface

[0290] 804 Processing circuitry of the radio device embodiment

[0291] 806 Memory of the radio device embodiment

[0292] 900 Access network node embodiment

[0293] 902 Interface, e.g., radio interface

[0294] 904 Processing circuitry of the access network node embodiment

[0295] 906 Memory of the access network node embodiment

[0296] 1000 Core network node embodiment

[0297] 1002 Interface

[0298] 1004 Processing circuitry of the core network node embodiment

[0299] 1006 Memory of the core network node embodiment

[0300] 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 determining a path (302) of a wireless communication between a first station (304) and a second station (306) in an environment (300) comprising a first grid (314) and a second grid (316), the device (100) comprising memory (806; 906; 1006) operable to store instructions and processing circuitry (804; 904; 1004) operable to execute the instructions, such that the device (100) is operable to: select (S204) at least one point of the first grid (314) near the first station (304) and at least one point of the second grid (316) near the second station (306); obtain (S206) one or more paths (302) between the at least one point in the first grid (314) near the first station (304) and the at least one point in the second grid (316) near the second station (306), wherein the path (302) comprises a start point and an end point, and wherein each of the one or more obtained (S206) paths (302) comprises an interaction signature indicative of one or more interactions between the path (302) and one or more interaction objects (308) of the environment (300); translate (S212) at least one of the start point of the one or more obtained (S206) paths (302) to the spatial position of the first station (304) and the end point of the one or more obtained (S206) paths (302) to the spatial position of the second station (306); and determine (S216) a shortest path (302) between the first station (304) and the second station (306) along each of the one or more obtained (S206) paths (302), wherein the determining (S216) of the shortest path (302) maintains the interaction signature of the respective path (302).

2. The device (100) of claim 1, wherein the device (100) is further operable to: discard (S210) duplicates among the one or more obtained (S206) paths (302), wherein the duplicates among the one or more obtained (S206) paths (302) comprise the same interaction signature as another one of the one or more obtained (S206) paths (302), and / or wherein each of the one or more determined (S216) shortest paths (302) comprises unique interaction signature.

3. The device (100) of claim 1 or 2, wherein obtaining (S206) one or more paths (302) comprises at least one of: trace a ray shot from the at least one selected (S204) point of the first grid (314) to the at least one selected (S204) point of the second grid (316); trace a ray shot from the first station (304) to the second station (306); obtain (S206) the one or more paths (302) from one or more previously saved traced rays between the at least one selected (S204) point of the first grid (314) and the at least one selected (S204) point of the second grid (316); and obtain (S206) the one or more paths (302) from one or more previously saved traced rays between the first station (304) and the second station (306).

4. The device (100) of any one of claims 1 to 3, wherein each of the one or more obtained (S204) paths (302) and / or each of the one or more determined (S216) shortest paths comprises two or more path segments of the respective path (302).

5. The device (100) of any one of claims 1 to 4, wherein the device (100) is further operable to: obtain (S214) one or more objects (308) of the environment along the path (302), optionally the one or more obtained (S214) objects (308) include the one or more interaction objects (308) which interact with the path (302).

6. The device (100) of any one of claims 1 to 5, wherein the device (100) is further operable to: determine (S208) the interaction signature of each of the one or more obtained (S206) paths(302), optionally wherein the interaction signature of each of the one or more obtained (S206) paths (302) is determined (S208) based on the one or more obtained (S214) objects (308) of the environment along the respective path (302).

7. The device (100) of any one of claims 1 to 6, wherein the interaction signature of the respective path (302) comprises a sequence of path segments of the path (302) and an interaction at an interaction point between each pair of the subsequent path segments of the path (302), optionally wherein the interaction is associated with one of the one or more interaction objects (308) in the environment (300) and a type of the interaction, wherein the type of the interaction is one of reflection, diffraction, transmission, and refraction.

8. The device (100) of any one of claims 1 to 7, wherein the device (100) is further operable to: discard (S218) one or more of the one or more determined (S216) shortest paths (302) that are inconsistent with the environment (300).

9. The device (100) of claim 8, wherein the one or more discarded (S218) shortest paths (302) are inconsistent due to at least one of: the respective shortest path (302) intersecting with an object (308) of the environment (300); an outgoing ray of a reflection as one of the one or more interactions being on an opposite side of an incoming ray of a surface of the reflection; and an interaction point, optionally a reflection point, being outside of the interaction object (308).

10. The device (100) of any one of claims 1 to 9, wherein the device (100) is further operable to: perform or initiate a physical action (S220) that is dependent on the one or more determined(S216) shortest paths (302) between the first station (304) and the second station (306) in the environment (300),optionally wherein the physical action (S220) is based on modeling (S222) a channel of the wireless communication along the one or more determined (S216) shortest paths (302) and the environment (300).

11. The device (100) of any one of claims 1 to 10, wherein the device (100) is further operable to: model (S222) a channel of the wireless communication along the one or more determined (S216) shortest paths (302) in the environment (300), optionally wherein the modeling (S222) of the channel comprises or the device (100) is further operable to perform or initiate a physical action that is dependent on the modeled (S222) channel.

12. The device (100) of claim 10 or 11, wherein the modeling (S222) of the channel comprises determining at least one of the following path properties of the one or more determined (S216) shortest paths (302): an amplitude of each path segment of the respective path (302); an amplitude of each interaction point or between subsequent path segments of the respective path (302); an amplitude of the entire respective path (302); a phase shift of a ray for each path segment of the respective path (302); a phase shift of a ray at each interaction point or between subsequent path segments of the respective path (302); a phase shift of the entire respective path (302); a polarization change of each path segment of the respective path (302); a polarization change of each interaction point or between subsequent path segments of the respective path (302); a polarization change of the entire respective path (302); a path length of the respective path (302); a time of flight of the respective path (302); and directions of departure with respect to a direction of arrival of the respective path (302) at each interaction point or between subsequent path segments.

13. The device (100) of any one of claims 1 to 12, wherein the device (100) is further operable to: determine (S202) the first grid (314) comprising a plurality of grid points and / or the second grid(316) comprising a plurality of grid points in the environment (300).

14. The device (100) of any one of claims 1 to 13, wherein the first station (304) is a transmitting device and the second station (306) is a receiving device, or wherein the first station (304) is a receiving device and the second station (306) is a transmitting device.

15. A method (200) of determining a path (302) of a wireless communication between a first station (304) and a second station (306) in an environment (300) comprising a first grid (314) and a second grid (316), the method (200) comprising or initiating the steps of: selecting (S204) at least one point of the first grid (314) near the first station (304) and at least one point of the second grid (316) near the second station (306); obtaining (S206) one or more paths (302) between the at least one point in the first grid (314) near the first station (304) and the at least one point in the second grid (316) near the second station (306), wherein the path (302) comprises a start point and an end point, and wherein each of the one or more obtained (S206) paths (302) comprises an interaction signature indicative of one or more interactions between the path (302) and one or more interaction objects (308) of the environment (300); translating (S212) at least one of the start point of the one or more obtained (S206) paths (302) to the spatial position of the first station (304) and the end point of the one or more obtained (S206) paths (302) to the spatial position of the second station (306); and determining (S216) a shortest path (302) between the first station (304) and the second station (306) along each of the one or more obtained (S206) paths (302), wherein the determining (S216) of the shortest path (302) maintains the interaction signature of the respective path (302).

16. A computer program product comprising program code portions for performing the functionality of any one of the claims 1 to 14 or the steps of claim 15 when the computer program product is executed on one or more computing devices (804; 904; 1004), optionally stored on a computer-readable recording medium (806; 906; 1006).

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