Device, method and apparatus for determining a tiling of a surface for ray tracing

Abstract

A device (100) and a method (200) for determining a tiling of a surface (304) for ray tracing of a propagation path (302) of a wireless communication in an environment (300) comprising the surface (304) is provided. The method (200) comprises the steps of obtaining (S202) an interaction point (308) on the surface (304), wherein a ray (306) of the ray-tracing interacts with the surface (304) at the interaction point (308); and obtaining (S204) a pair of linearly independent lattice vectors (312) each perpendicular to a normal vector (314) of the surface (304), wherein the lattice vectors define a lattice (310) parallel to the surface (304) based on a reference point (316) in the environment (300); and determining (S206) a point of the lattice closest to the interaction point (308) of the surface (304).

Description

[0001] DEVICE, METHOD AND APPARATUS FOR DETERMINING A TILING OF A SURFACE FOR RAY TRACING

[0002] Technical Field

[0003] The present disclosure relates to tiling of a surface for ray-tracing of a propagation path of a wireless communication in an environment. More specifically, and without being limited thereto, a device and a method are disclosed for determining a tiling of a surface for ray-tracing of a propagation path of a wireless communication in an environment.

[0004] Background

[0005] In the rapidly evolving landscape of wireless communication, the ability to accurately predict and analyze the behavior of radio waves within various environments has become increasingly critical, for both indoor and outdoor radio propagation (Z. Yun and M. F. Iskander, "Ray Tracing for Radio Propagation Modeling: Principles and Applications," in IEEE Access, vol. 3, pp. 1089-1100, 2015, doi: 10.1109 / ACCESS.2015.2453991). As we push the boundaries of technology, venturing into higher frequencies and more complex network architectures, the need for precise modeling of radio wave propagation has never been more pressing. This is particularly true for the design and operation of the latest wireless networks, such as those based on 5G and the forthcoming 6G standards, where the dense urban environments and intricate topologies present unique challenges for signal propagation.

[0006] Traditionally, the ray -optical approximation has been a popular method for predicting electromagnetic wave propagation. This technique simplifies the complex wave behavior into a more manageable form by treating electromagnetic energy as a collection of rays traveling in straight lines, reflecting and refracting off surfaces and edges within the environment. While this approach has served us well, especially in scenarios where the dimensions of objects and distances between them are significantly larger than the wavelength of the carrier signal, it is not without its limitations. The fidelity of the raytracing models is heavily dependent on the level of detail and accuracy with which environmental features are represented.

[0007] The prior art in ray-tracing for radio frequency wave propagation modeling has faced significant challenges as radio carrier frequencies increase so that the channel state probes more and more details of its environments. One key issue is the trade-off between computational efficiency and the accuracy of the predicted channels. The process of ray launching, which involves tracing the paths of numerous rays as they interact with environmental objects, can lead to an exponential growth in the number of rays that need to be traced, making the process computationally intensive.

[0008] Thus, the technical evolution of quantitative modelling of the physical channel of a wireless communication has entered a stage where ray approximations become more accurate as frequency increases, but for the same reason more resource intensive as smaller length scales of the environment become relevant.

[0009] Summary

[0010] Accordingly, there is a need for a more efficient and accurate method to model the propagation of radio waves, particularly for real-time applications and advanced network planning.

[0011] As to a device aspect a device for determining a tiling of a surface for ray-tracing of a propagation path of a wireless communication in an environment comprising the surface is provided. The device comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the device is operable to obtain an interaction point on the surface, wherein a ray of the ray-tracing interacts with the surface at the interaction point. The device is further operable to obtain a pair of linearly independent lattice vectors each perpendicular to a normal vector of the surface. The lattice vectors define a lattice parallel to the surface based on a reference point in the environment. The device is further operable to determine a point of the lattice closest to the interaction point of the surface.

[0012] By determining the point of the lattice locally (which corresponds to a local tile of the lattice without global dependencies) for ray-tracing of the propagation path, embodiment can avoid determining a global surface tiling and enable the device to determine or represent the flux of the electromagnetic energy on the surface of the environment efficiently, e.g. in real-time.

[0013] Same of further embodiment of the device can enable locally determining the tiling of a surface for raytracing of a wireless communication propagation path within an environment that includes the surface. The technical effect achieved by this embodiment is an efficient and accurate determination of the propagation path based on a pair of inbound ray hit point (as the interaction point) and outbound ray lattice point (as the determined point of the lattice) where the propagation path interacts with the surface for efficient and accurate ray-tracing. This is particularly useful in wireless communication for predicting and analyzing how radio waves propagate in various environments, which is critical for network planning, optimization, and real-time applications.

[0014] The device operates by first obtaining an interaction point on a surface where a ray-tracing ray interacts. It then obtains a pair of linearly independent lattice vectors, each perpendicular to the surface's normal vector, which define a lattice parallel to (optionally in) the surface based on a reference point in the environment. The device determines the lattice point closest to the interaction point. These features work together to create a virtual lattice that allows for the representation of the electromagnetic energy flux on environmental surfaces efficiently and in real-time. By focusing on local tiles of the lattice for ray-tracing rather than a global surface tiling, the device can accurately model the channel of wireless communication and predict the propagation path of the radio waves, which is essential for the design and operation of advanced wireless networks.

[0015] The lattice may be a virtual lattice (e.g., grid), and / or the lattice may span an infinite plane. Thus, embodiments of the device can determine the lattice point as being part of a globally consistent and locally (i.e., on the fly) determined lattice, e.g. for ray scatting.

[0016] The surface may be a finite surface of an object in the environment. The object in the environment may be a stationary object and / or a moving object.

[0017] The tiling of the surface may correspond to a Voronoi cell of the lattice comprising the closest point of the lattice to the interaction point. The closest point of the lattice to the interaction point may be inside the surface and / or outside of the surface.

[0018] The surface (e.g., according to the device aspect) may be a diffusive surface of the environment. The device may be further operable to launch a plurality of rays in different directions from the determined lattice point for the ray-tracing of the propagation path.

[0019] The device (e.g., according to the device aspect) may be further operable to perform or initiate a physical action that is dependent on the determined point of the lattice, optionally model a channel of the wireless communication along the propagation path in the environment.

[0020] The device (e.g., according to the device aspect) may be further operable to model a channel of the wireless communication along the propagation path in the environment, optionally wherein 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.

[0021] The surface (e.g., according to the device aspect) may be planar. Alternatively or in addition, the surface may be a surface without intrinsic curvature.

[0022] The surface (e.g., according to the device aspect) may be piecewise planar. Alternatively or in addition, the normal vector may be perpendicular to a first piece of the piecewise planar surface and indices of the lattice are continuous across an edge between the first piece and a second piece of the piecewise planar surface.

[0023] For example, the surface may be a surface of ideal staircase with piecewise planar surfaces perpendicular to each other. The surface (e.g., according to the device aspect) may be a surface with zero intrinsic curvature. Alternatively or in addition, a first dimension of the lattice may be linearly mapped to a straight first dimension of the surface with zero extrinsic curvature. Optionally, a second dimension of the lattice may be linearly mapped to a geodesic second dimension of the surface, e.g. perpendicular to the straight first dimension of the surface. The first dimension may correspond to a direction indicated by a first vector of the pair of lattice vectors, e.g. at the reference point (or at a projection of the reference point onto the surface). The second dimension may correspond to a direction indicated by a second vector of the pair of lattice vectors, e.g. at the reference point (or at a projection of the reference point onto the surface). The geodesic second dimension may result from a geodesic continuation of the second vector along the geodesic generated by the second vector.

[0024] The lattice (e.g., according to the device aspect) may be hexagonal (e.g., a honeycomb lattice by combining two hexagonal lattices) or rectangular (e.g., square).

[0025] The pair of lattice vectors may be perpendicular to each other defining a rectangular lattice, or making a 120 degree angle with each other defining a hexagonal lattice or making any other angles between 0 to 180 degrees. In a special case the length of the lattice vectors may be equal.

[0026] The reference point (e.g., according to the device aspect) may be a stationary point in the environment. Alternatively or in addition, the reference point may be a moving point in the environment (e.g., a point of a moving object in the environment).

[0027] The surface (e.g., according to the device aspect) may be parallel to (e.g., coplanar with) a surface of an object moving in the environment and / or may be moving with the object (i.e., may be at rest relative to the moving object). The reference point may be a point of the surface (i.e., the surface parallel to, e.g., coplanar with, the surface of the moving object). Herein, "moving with the object" may be implemented by moving in the same way as the moving object. Based on the movement of the object (or indirectly based on the movement of the reference point), a Doppler shift may be included in the interaction at the interaction point 308 when modeling of the channel based on the method 200.

[0028] The lattice (e.g., according to the device aspect) may be independent of a distance between the reference point and the interaction point in the direction of the normal vector. Alternatively or in addition, a projection of the reference point in the environment onto the surface along the normal vector may define a base point of the lattice.

[0029] The determining of the lattice point (e.g., according to the device aspect) may comprise determining a vectorial difference between the interaction point and the reference point. Rounded scalar products between the vectorial difference and a dual pair of the pair of lattice vectors are indices of the lattice point (i.e., the determined point of the lattice). There may be one scalar product between the vectorial difference and each dual vector of the dual pair of the pair of lattice vectors. The result of each of the scalar products may be rounded to an integer value (e.g., . . . , -2, -1, 0, 1, 2, . . . ) corresponding to one of the indices of the determined point of the lattice.

[0030] The environment (e.g., according to the device aspect) may comprise multiple surfaces, e.g., (actual or potential) interaction surfaces of objects in the environment. The pair of lattice vectors may be obtained along the propagation path for each interaction point on one of the multiple surfaces. Alternatively or in addition, for determining a point of the lattice, the pair of lattice vectors may be applied relative to the same reference point in the environment. That is, the same reference point may be used for each of the multiple surfaces.

[0031] The lattice may be defined for each interaction point (e.g., for each surface). Alternatively or in addition, all the different lattices per surfaces may share same reference point in the environment.

[0032] As to a method aspect, a method for determining a tiling of a surface for ray-tracing of a propagation path of a wireless communication in an environment comprising the surface is provided. The method comprises or initiates the step of obtaining an interaction point on the surface. A ray of the ray-tracing interacts with the surface at the interaction point. The method further comprises or initiates the step of obtaining a pair of linearly independent lattice vectors each perpendicular to a normal vector of the surface. The lattice vectors define a lattice parallel to the surface based on a reference point in the environment. The method further comprises or initiates the step of determining a point of the lattice closest to the interaction point of the surface.

[0033] As to another device aspect, a computer program product is provided. The computer program product comprising program code portions for performing the functionality of the device aspect or the steps of the method aspect when the computer program product is executed on one or more computing devices, which may be optionally provided stored on a computer-readable recording medium or may be accessible for download onto such a computing device that is within the territory to which the subject rights apply.

[0034] Embodiments of the device aspect and the method aspect propose a robust and efficient solution for deterministically tiling arbitrary (e.g., planar or piecewise planar) surfaces on-the-fly, i.e. while raytracing (e.g., sequentially along the propagation path), based on only knowing in which plane the surface resides, e.g. as given by a triangle representing a portion of the surface and / or with which a ray of the raytracing interacts (e.g., intersects or falls within a Fresnel zone). In general, no further knowledge (e.g., as to shape or size) about the surface is required or assumed known. Same or further embodiments can inherently provide deterministic and uniform (e.g., spatial or planar) sampling and resolution, e.g. for contiguous coplanar surfaces, by using a common global lattice for a given surface (e.g., by virtue of a common reference point). Same or further embodiments can provide a deterministic “virtual lattice” of points on planes from which points are selected for use in further ray-tracing (e.g. launching of diffusive rays).

[0035] For the purposes of this disclosure, the lattice may be considered “virtual” in the sense that it is determined based on the properties of the plane coplanar with the triangle with which a ray interacts or that it is independently locally determined and still globally coherent. Preferably, a representation of the lattice and / or associated indices to points in the lattice is determined only once or only upon an interaction has happened, and the lattice information is not stored for further use.

[0036] Given an interaction point (e.g., a hit point), e.g., a point where a ray intersects a given triangle (assumed to be the building block from which surfaces are constructed), the determination may comprise projecting the interaction point on the plane through a global origin (e.g., the reference point), which plane is parallel to the surface of the triangle and detect the coordinates of the nearest point in a virtual lattice associated with the plane coplanar with the given triangle. In other words, while the lattice vectors define a lattice parallel to the surface, the lattice may be in the surface of the interaction point in one variant of any embodiment or in another plane parallel to said surface (e.g., as described in this paragraph).

[0037] The physical action may comprise at least one of the following examples. Preferably, a high fidelity, fast computed representation of the (e.g., radio) channel of the wireless communication may be used in at least the following ways:

[0038] • In (e.g., laboratory) testing of radio communications equipment, it is desirable to replicate the conditions expected when the equipment is deployed and used in the real world. A common practice may be to use channel emulation software and / or hardware to expose the equipment to different types of radio channels. An embodiment of the device (which may be colloquially referred to as a ray tracer) may generate radio channels to be emulated (e.g., as an example of the physical action). Real-time or near real-time calculation of the radio channel is very important for this use case.

[0039] • The dimensioning and deployment of wireless radio networks may rely on estimating e.g. coverage and user-experienced throughput for different hypotheses of how the radio base stations are deployed and what their capabilities are (e.g. which frequency bands they are configured to use, their output power and sensitivity, what kind of antennas, etc.). While stochastic channel models are often used in the initial stages of this work, high-fidelity channels rapidly may be computed using ray-tracing can greatly improve the quality of the sizing and planning process and reduce the need for costly and time-consuming field trials.

[0040] • When designing wireless network products, it is important to understand the relative value of different product enhancements. However, this value may only be determined either by measurement (which in most cases would require the product to be built first) or by simulation using channel models. The higher the fidelity of the channel models, the greater the likelihood that correct prioritization will be made, leading to better products. • Standardization of radio network technologies involves forming an industry consensus view on the relative performance of different proposed standard features or enhancements. In most cases the performance is determined through simulations, mainly using stochastic channel models. However, in recent years there has been an increasing understanding of the need for site-specific channel modeling such as ray-tracing. 3GPP TR 38.901 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 (clause 8, Map-based hybrid channel model). Improvements to the ray-tracing methods can improve the site-specific modeling and therefore open for better evaluations or even unlock evaluations for new features and scenarios that were previously considered too complicated for evaluation or standardization, e.g. through the Third Generation Partnership Project (3GPP).

[0041] • Embodiments of the device can ensure fulfilment of regulations, e.g. as to power densities of the wireless communication, e.g., by preemptive or predictive controlling of a radio access network (RAN) and / or as further detailed below.

[0042] In addition to the above mentioned use cases, there is a class of use cases that fall in a “digital twin” category, i.e. a digital representation of the radio network (e.g., RAN) or of some equipment in the radio network (e.g., a network node or a UE). The device may, based on its ray-tracing emulation or simulation in the digital twin, inform the physical network or equipment about an expected behavior of the radio channel as an example of the physical action.

[0043] This physical action may comprise at least one of the following applications:

[0044] • Channel estimation, i.e., the physical receiver can improve its estimation if some a priori information may be obtained from its digital twin;

[0045] • Beam forming (e.g., for transmission and / or reception) and / or beam management, i.e. a transmitter (Tx) and / or a receiver (Rx) may improve how beams are formed and tracked over time if information about likely directions (and changes thereof) of transmitted or received radio waves can be obtained via ray-tracing;

[0046] • Channel prediction, e.g., similar to the above, i.e. the device may inform a Tx or a Rx about likely future time development of the radio channel based on ray tracing;

[0047] • Positioning, i.e., the device may perform or assist (e.g., as a location management function) in positioning (e.g., of any target UE in the environment) e.g. based on fingerprinting, which may comprise comparing actual measured channel conditions with simulated channels in a vast number of potential positions resulting from the subject technique, or may include classification of line of sight (LOS) or non-LOS of different links which can significantly enhance any time-based or time-difference-based positioning methods;

[0048] • Sensing, for instance, a difference between ray-traced channel and measured channel may be indicative of the presence and / or location of one or more objects of interest; • Configuration of equipment, which may entail selecting numerology and / or cyclic prefix length, different choices of antenna and / or MIMO algorithm (e.g., single-use MIMO (SU- MIMO) or multi-user MIMO (MU -MIMO), number of layers, reciprocity and / or codebook), antenna down-tilt, output power levels, etc.; and

[0049] • Ensuring compliance with radio and / or health regulations, e.g. by adjusting output powers and / or directions of a transmission based on assessments (e.g., provided by an embodiment of the device) on how much power reaches locations, e.g. in which there are or may be persons or equipment that need to be protected.

[0050] Also, some of the use cases from the “digital twin” category may equally well be used without a full- fledged digital twin and vice versa.

[0051] Embodiments of the device aspect and the method aspect provide a deterministic scattering point (e.g., the lattice point) for a given interaction point on a given triangle (e.g., within the surface), regardless of the origin, direction, or density of the incoming rays. This can ensure repeatability and / or global consistency.

[0052] Same or further embodiments of the device aspect and the method aspect may provide a continuous lattice of scattering points for all coplanar triangles representing objects in the environment, e.g. which means that subdivided surfaces share a common lattice, hence ensuring a uniform lattice of scattering points for all coplanar surfaces, regardless of subdivision density. This can ensure power conservation for large surfaces consisting of many contiguous triangles. Alternatively or in addition, these embodiments can ensure that the scattering points (i.e., a scattering lattice) are agnostic to a triangulation applied for representing physical objects in the environment and / or ensures uniqueness with respect to the indices representing points in the lattice which allows pruning of duplicate paths.

[0053] Since the determined one or more lattice points (e.g., scattering points) are deterministic, memoization and / or subsequent stitching of sub-paths of the ray-tracing is possible. Memoization can be used to avoid tracing from a given grid (or scattering) point more than once, greatly reducing redundant operations. Stitching means that paths can be combined from previously traced sub paths, removing the need for tracing. These properties differentiates the solution from the prior art solutions.

[0054] The device may be embodied by a user equipment (UE). The UE may be configured to communicate with a network node (e.g., 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 side link). The UE may comprise a radio interface and processing circuitry configured to execute any of the steps and functionality disclosed for the device. Alternatively or in addition, the device may be embodied by a network node (e.g., a base station or a RAN), e.g. acting as a (e.g., transmitting or receiving) first station at one endpoint of the propagation path of the wireless communication and / or acting as a (e.g., transmitting or receiving) second station at another endpoint of the propagation path of the wireless communication. The network node may be configured to communicate with a UE. The network node may comprise a radio interface and processing circuitry configured to execute any of the steps and functionality disclosed for the device.

[0055] Alternatively or in addition, the device may be embodied by a core network (CN) node or function configured to communicate with a network node (e.g., a base station). The core network node may comprise memory operable to store instructions and processing circuitry operable to execute the instructions, such that the core network node is operable to perform any one of the steps and functionality disclosed for the device.

[0056] In a first variant of any embodiment, the same device that is determining the propagation paths based on the determined point of the lattice 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 propagation path based on the determined lattice point. 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.

[0057] Modeling the channel (or modeling a channel state, briefly: channel modeling) may comprise modeling amplitudes and phase shifts of actual or hypothetical signals between actual or hypothetical transmitters and receivers, e.g. based on the determined one or more second paths, rather than a measured channel state. The result of the channel modeling may be a vector or matrix comprising complex-valued gains of the channel between the launch point and the at least one position, e.g. each pair of transmit antenna and receive antenna and / or in a similar format as a channel estimate for a measured channel state.

[0058] Alternatively or in addition, the result of the channel modeling may be polarimetric, i.e., having (potentially) independent complex-valued gains per polarization state, e.g. for orthogonal transmit antennas or orthogonal receive antennas. Any two mutually orthogonal polarization states also orthogonal to the ray (or path direction) may be used to represent the polarimetric properties of the signal associated with the ray.

[0059] 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).

[0060] The modeling of the channel may comprise determining an electromagnetic propagation of an electromagnetic field (e.g., based on the Lienard-Wiechert potential) along the determined one or more second paths. For example, the electromagnetic propagation may be configured to associate to the one or more second paths at least one of a phase shift of the electromagnetic field, a change in an electrical field component of the electromagnetic field, and a change in magnetic field component of the electromagnetic field. The channel may be modeled by superimposing the electromagnetic field propagated along each of the one or more second paths.

[0061] In any aspect, the one or more second paths may be the basis of an electromagnetic propagation (e.g., a radio propagation or an infrared or visual light propagation) used by the wireless communication. Alternatively or in addition, the wireless communication may be a radio frequency communication or a visible light communication (VLC).

[0062] A transmitting node (e.g., at the first or second station) for transmitting the wireless communication may be a radio device (such as a user equipment, UE), e.g. in an uplink (UL) or in a sidelink (SL).

[0063] Alternatively or in combination (e.g., for a duplex wireless communication), the transmitting node for transmitting the wireless communication may be a base station (such as a next generation Node B, gNB) of a radio access network (RAN) in a downlink (DL). Furthermore, a receiving node (e.g., at the second or first station) for receiving the wireless communication may be a radio device, e.g. in a DL or in a SL. Alternatively or in combination (e.g., for a duplex wireless communication), the receiving node for receiving the wireless communication may be a base station of a RAN in an UL.

[0064] The wireless communication in the environment may be performed (e.g., transmitted or received) or controlled (e.g., initiated) based on the propagation path using the determined lattice point.

[0065] The transmitting or receiving may comprise transmitting or receiving data or transmitting or receiving control signaling, e.g. a random access preamble, a random access response, a reference signal (RS, e.g., a sounding RS in the uplink from a radio device to a network node or a channel state information, CSI, RS in the downlink) or a paging signal or radio resource control (RRC) message.

[0066] The determining of the lattice point may support a channel estimation (at a receiver node or at a transmitter node) of the wireless communication. The channel estimation may encompass receiving (e.g., measuring) radio signals and processing the measured radio signals (e.g., comparing to known reference signals, RSs) to estimate an amplitude and phase shifts of signals wirelessly propagated between the transmitter node and the receiver node. 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.

[0067] Any radio device may be a user equipment (UE), e.g., according to a 3GPP specification.

[0068] 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.

[0069] 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-Li). 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).

[0070] 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.

[0071] Any of the radio devices may be a 3GPP user equipment (UE) or a Wi-Li 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.

[0072] Whenever referring to the RAN, the RAN may be implemented by one or more network node (e.g., base stations).

[0073] 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). 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).

[0074] The RAN may be implemented according to the Global System for Mobile Communications (GSM), the Universal Mobile Telecommunications System (UMTS), 3GPP Eong Term Evolution (LTE) and / or 3GPP New Radio (NR).

[0075] 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.

[0076] 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.

[0077] Any one of the devices, the first station, the second station, the transmitting node, the receiving node, the user equipment (UE), the network node, the base station, a communication system or any node or station for embodying the technique may further include any feature disclosed in the context of the method aspect, and vice versa the method aspect may comprise any step or feature disclosed in the context of the device aspects. Particularly, any one of the units and modules disclosed herein may be configured to perform or initiate one or more of the steps of the method aspect, and the devices may comprise a unit or a module performing any of the steps of the method aspect.

[0078] Brief Description of the Drawings

[0079] Further details of embodiments of the technique are described with reference to the enclosed drawings, wherein:

[0080] Fig. 1A shows a schematic block diagram of a first embodiment of a device for determining a tiling of a surface with which a propagation path of a wireless communication in an environment interacts;

[0081] Fig. IB shows a schematic block diagram of a second embodiment of a device for determining a tiling of a surface with which a propagation path of a wireless communication in an environment interacts;

[0082] Fig. 2 shows a flowchart of an embodiment of a method for determining a tiling of a surface with which a propagation path of a wireless communication in an environment interacts, which method may be implementable by the device of Fig. 1A or IB;

[0083] Fig. 3 shows an exemplary environment comprising an interaction point and a reference point, which may be used by any embodiment of the device of Fig. 1 A or IB for performing a first step of an embodiment of the method according to Fig. 2;

[0084] Fig. 4 shows an exemplary environment comprising an interaction point and a reference point, which may be used by any embodiment of the device of Fig. 1 A or IB for performing a second step of an embodiment of the method according to Fig. 2;

[0085] Fig. 5 shows an exemplary environment comprising an interaction point and a reference point, which may be used by any embodiment of the device of Fig. 1 A or IB for performing a third step of an embodiment of the method according to Fig. 2;

[0086] Fig. 6 shows an exemplary environment comprising an interaction point and a projected reference point, which may be used by any embodiment of the device of Fig. 1A or IB for performing a fourth step of an embodiment of the method according to Fig. 2;

[0087] Fig. 7 shows a front view of the surface of Fig. 6 comprising examples of an interaction point and a pair of lattice vectors, which may be used by any embodiment of the device of Fig. 1 A or IB for performing the fourth step of an embodiment of the method according to Fig. 2; Fig. 8 shows a front view of the surface further comprising examples of lattice points, which may be used by any embodiment of the device of Fig. 1A or IB for performing a fifth step of an embodiment of the method according to Fig. 2;

[0088] Fig. 9 shows a front view of the surface comprising examples of an interaction point, a pair of lattice vectors, and lattice points, which may be used by any embodiment of the device of Fig. 1 A or IB for performing a sixth step of an embodiment of the method according to Fig. 2;

[0089] Fig. 10 shows a front view of the surface comprising examples of an interaction point, a pair of lattice vectors, and lattice points, which may be used by any embodiment of the device of Fig. 1A or IB for performing a seventh step of an embodiment of the method according to Fig. 2;

[0090] Fig. 11 shows a front view of the surface comprising examples of an interaction point, a pair of lattice vectors, and lattice points, which may be used by a variant of any embodiment of the device of Fig. 1A or IB for performing steps of a variant of an embodiment of the method according to Fig. 2;

[0091] Fig. 12 shows a front view of the surface comprising examples of an interaction point, a pair of lattice vectors, and lattice points, which may be used by another embodiment of the device of Fig. 1 A or IB for performing steps of another embodiment of the method according to Fig. 2;

[0092] Fig. 13 shows an exemplary flowchart of another embodiment of the method according to

[0093] Fig. 2;

[0094] Fig. 14 shows a block diagram of an emulating embodiment of the device of Fig. 1A or IB;

[0095] Fig. 15 shows a block diagram of a radio device embodiment of the device of Fig. 1A or IB;

[0096] Fig. 16 shows a block diagram of a base station embodiment of the device of Fig. 1A or IB; and

[0097] Fig. 17 shows a block diagram of a core network embodiment of the device of Fig. 1A or IB. Detailed Description

[0098] 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.

[0099] 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.

[0100] Reference signs of the form 3xy (with digits x and y) appearing in below description of Fig 1A, Fig. IB or Fig. 2 indicate features illustrated in Fig. 3 and later for the purpose of exemplary explanation and without limiting the device and the method to the embodiments and scenarios of Fig. 3 and later.

[0101] Fig. 1A schematically illustrates a block diagram of a first embodiment of a device for wireless communication in an environment. The device is generically referred to by reference sign 100.

[0102] More specifically, the device 100 may be a device for determining a propagation path of a wireless communication between a first station and a second station in the environment, wherein the propagation path 302 interacts with a surface 304 in the environment 300 using a tiling of the surface 304 for raytracing of the propagation path 302 of a wireless communication in an environment.

[0103] Herein, lists of the form A, B, and / or C disclose each of A and B and C individually, any pair of listed elements, as well as the combination of all listed elements, and analogously for two or more than three listed elements. The device 100 comprises an Obtainment Module 102A that is configured to obtain data indicative of physical structures in the environment 300, e.g. stationary objects, objects moving in the environment, and / or a ray 306 underlying (e.g., initializing) the propagation path 302. This obtainment may include - or result in - obtaining an interaction point 308 on the surface 304 where the ray 306 of the ray-tracing interacts with the surface 304 at an interaction point 308. The Obtainment Module 102A is further configured to obtain a pair of linearly independent lattice vectors 312 each perpendicular to a normal vector 314 of the surface 304. The lattice vectors 312 define a lattice 310 parallel to the surface 304 based on a reference point 316 in the environment 300.

[0104] It is noted that the lattice vectors defining a lattice 310 "in" the surface 304 based on a reference point 316 in the environment 300 does may or not need not require that the lattice points are implemented or used in the ray-tracing in the surface 304. For example, the lattice points may be "defined" in the surface 304 in the sense that the lattice is parallel to the surface so that each lattice point uniquely corresponds to a point in the surface 304, even if the lattice 310 and the determined lattice point 320 is used offset from the surface 304, e.g. for launching one or more rays without causing a self-interaction at launch, e.g. due to finite numerical precision.

[0105] The device 100 further comprises a Processing Module 104A that is configured to determine a point 320 of the lattice 310 closest to the interaction point 308 of the surface 304. For example, the processing module may perform the ray-tracing for the determining of the propagation path, wherein the propagation path (i.e., the inbound ray of the propagation path) intersects the surface at the interaction point and exits from the surface at the determined point 320 of the lattice 310.

[0106] 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 propagation path between the first station and the second station in the environment, particularly dependent on the determined point 320 of the lattice 310 for the interaction between the propagation path 302 and the surface 304 in the environment 300. Alternatively or in addition, the Action Module 106A may model a channel of the wireless communication along the determined propagation path 302 in the environment 300. 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, e.g. a channel emulation.

[0107] Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality.

[0108] The device 100 may be embodied by an emulator or a network node (e.g., a transmitting and / or receiving node) of a RAN. Fig. IB schematically illustrates a block diagram of an embodiment of a device for wireless communication in an environment 300, e.g. for determining a tiling of a surface 304 for ray-tracing of a propagation path 302 of a wireless communication in an environment 300 comprising the surface 304. The device is generically referred to by reference sign 100.

[0109] The device 100 comprises an interaction point obtaining module 102. The interaction point obtainment module 102 obtains an interaction point 308 on the surface 304. A ray 306 of the ray-tracing interacts with the surface 304 at the interaction point 308.

[0110] The device 100 further comprises a lattice vector obtainment module 104 that obtains a pair of linearly independent lattice vectors 312 each perpendicular to a normal vector 314 of the surface 304. The lattice vectors 312 define a lattice 310 parallel to the surface 304 based on a reference point 316 in the environment 300.

[0111] The device 100 further comprises a lattice point determination module 106. The lattice point determination module 106 determines a point 320 of the lattice 310 closest to the interaction point 308 of the surface 304.

[0112] Optionally, the device 100 further comprises a ray launching module 108 that launches one or more rays from the determined point 320 of the lattice 310. The ray launching module 108 may launch a plurality of rays in different directions from the determined lattice point 320 (i.e., a point 320 of the lattice 310) for the ray-tracing of the propagation path 302. The rays may be launched in different directions according to a diffusive scattering of the propagation path at the surface. Each of the launched rays may correspond to a different continuations of the incoming ray 306. Each of these continuations may be an example of the determined propagation path. Thus, the device 100 may determine a plurality of propagation paths as a result of the interaction at the surface handled according to the determined point of the lattice.

[0113] Alternatively or in addition, the device 100 further comprises a physical action module 110. The physical action module 110 performs or initiates a physical action that is dependent on the determined point 320 of the lattice 310. Examples of the physical action may comprise modeling a channel of the wireless communication along the propagation path 302 in the environment 300.

[0114] Alternatively or in addition, the device 100 comprises a channel model module 112, which models a channel of the wireless communication along the propagation path 302 in the environment 300. Alternatively or in addition, the modeling of the channel comprises - or the device 100 is further operable - to perform or initiate a physical action that is dependent on the modeled channel.

[0115] Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality. The device 100 may be embodied by an emulator or a network node (e.g., a transmitting and / or receiving node) of a RAN.

[0116] Fig. 2 shows an example flowchart for a method 200 of determining a tiling of a surface 304 for raytracing of a propagation path 302 of a wireless communication in an environment 300 comprising the surface 304.

[0117] The method 200 comprises a step S202 of obtaining an interaction point 308 on the surface 304. A ray 306 of the ray-tracing interacts with the surface 304 at the interaction point 308.

[0118] The method 200 further comprises a step S204 of obtaining a pair of linearly independent lattice vectors 312 each perpendicular to a normal vector 314 of the surface 304. The lattice vectors 312 may define a lattice 310 parallel to the surface 304 based on a reference point in the environment 300.

[0119] The method 200 further comprises a step S206 of determining a point 320 of the lattice 310 closest to the interaction point 308 of the surface 304.

[0120] Optionally, the method 200 further comprises a step S208 of launching a plurality of rays in different directions from the determined S206 lattice point for the ray-tracing of the propagation path 302.

[0121] Optionally, the method 200 further comprises a step S210 of performing or initiating a physical action S210 that is dependent on the determined S206 point 320 of the lattice 310, optionally modeling a channel of the wireless communication along the propagation path 302 in the environment 300.

[0122] Optionally, the method 200 further comprises a step S212 of modeling a channel of the wireless communication along the propagation path 302 in the environment 300. Alternatively or in addition, the modeling S212 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 S212 channel.

[0123] The embodiments of the device 100 and the method 200 may be used in a ray-tracer for generating lattice points 310 (i.e., grid points) in a “virtual lattice” on a plane (or at least piecewise planar surface), given a hit point 308 on a triangle on the surface 304. The lattice points 310 may be deterministic and / or fixed. Alternatively or in addition, the determining S206 may be identical and consistent for all triangles of the surface 304 (optionally, and other surface objects), and / or may be determined on-the-fly, e.g. simultaneously with the ray-tracing. The resolution of the lattice points may be parameter-controlled on a triangle-by-triangle basis, or be set globally. In the context of a ray-tracer, the determined S206 lattice points 320 may serve as origins for launching further rays (e.g., for ray-tracing), such as rays associated with non-specular scattering, including diffuse scattering and scattering (or re-radiation) from reconfigurable intelligent surfaces.

[0124] The method 200 may be performed by the device 100. For example, the modules 102 to 112 of the device 100 may perform the steps S202 to S212, respectively.

[0125] 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.

[0126] 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.

[0127] Embodiments of the device 100 and the method 200 may be used for determining a tiling of a surface 304 for ray-tracing of a propagation path 302 of a wireless communication in an environment 300 comprising the surface 304. The method 200 may be reciprocal, i.e., the ray 306 may be uplink (UL) or downlink (DL) using method 200.

[0128] Embodiments of the method 200 can be orders of magnitude faster than raytracing to each individual destination. It is thus computationally superior to methods of the art. The method 200 does not require predefined motion of transmitter / receiver positions and may be used to query paths with arbitrary transmitter and / or receiver locations. This mode of determination S206 (e.g., computation) allows near real-time operation with full interactivity and 3D movement of objects in the environment, e.g. user equipments (UEs).

[0129] 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. Embodiments of the device 100 and the method 200 can improve the fidelity of the modeled channel and / or the accuracy of the determined propagation path 302 (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 path, transmission parameters and / or precoders at the first station (e.g., 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.

[0130] Any embodiment of the device 100 or method 200 may be based on a ray optical approximation to predict (i.e., to model) electromagnetic propagation efficiently in the environment 300. This example of the physical action may rely 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 300. 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 300, which comprises objects that block a direct line-of-sight, based on paths 302 circumventing the blocking object by reflections 308 from neighboring objects or diffraction at edges of any object.

[0131] 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.

[0132] For the purpose of any physical action, e.g. as disclosed herein, embodiments may perform or control ray optical techniques to determine at least one propagation path based on ray tracing, also referred to as ray launching and "shooting and bouncing rays" (SBR), which requires launching a plurality of rays from a first station as an origin of the path (such as a transmitter or receiver 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. This can be achieved by embodiments of the device 100 and the method 200 by determining the lattice point 320 of the lattice 310 along each propagation path 302. The real-time aspect is particularly important in the context of a digital twin, wherein the digitally represented radio channel must be generated and updated at the same rate as its real physical counterpart.

[0133] Embodiments of the subject technique can advance existing ray tracing techniques, which are also known as "ray launching" as well as "shooting and bouncing rays", for predicting the propagation of radio waves in a given environment 300 uses an optical ray approximation. Here, rays are launched from one or more origin points (i.e., first stations, e.g., transmitter nodes), allowed to interact with the world objects such as the surfaces 304 representing the geometry of the environment 300 until the propagation paths 302 are captured at one or more targets (i.e., the second station, e.g. receiver nodes). Different types of interactions such as transmission, reflection, diffraction, and scattering can be taken into account by introducing (i.e., launching) secondary rays from the determined lattice point 320 when a primary ray intersects the surface 304 of an object at the interaction point 308. Multiple consecutive interactions of the same or different types may occur along each propagation path 302, which may lead to an exponential growth in the number of rays that need to be traced. Therefore, the subject technique allows shifting the trade-off between the computation time and the accuracy and fidelity of the predicted channels to the benefit of accuracy and fidelity.

[0134] A common approach is to use “capture objects” that surround the second station (for example, receivers) and record the rays that hit these capture objects. The radio channel between a source (i.e., the first station, e.g., a transmitter) and the target (i.e., the second station, e.g., a receiver) may be constructed from all the propagation paths 302 traveled by the rays that hit the specific capture object. Due to a finite shooting resolution at the source, the capture objects must be of a sufficient size to ensure a hit, so the endpoint of the propagation path is initially on the surface of the capture object rather than at the actual receiver location.

[0135] If the endpoint of the propagation path is shifted to the receiver location, the propagation path may no longer fulfil fundamental physical properties such as, for example, having equal incidence and departure angles from a specular reflection. This can be addressed by shifting the interaction point (or any interaction point of the respective propagation path) on the surface (or on the respective surface for any interaction along the respective propagation path) according to a minimization of a path length of the propagation path. Herein, the length may be weighted by the refractive index (or the square root of the relative permittivity (i.e., the dielectric constant) local in the environment (e.g., within transmissive objects in the environment).

[0136] For example, a set of propagation paths 302 is determined between one location (i.e., the first station, e.g. representing the transmitter) and another location (i.e., the second station, e.g. representing the receiver) using the subject technique 100 and 200, e.g. at each surface causing a diffusive reflection along each of the propagation paths 302. If the wireless communication system uses multiple antennas and / or wideband or even multiband communication, an approach may be to determine the radio channel assuming that the radio channel is stationary over the antenna array and frequency in the sense that the direction of arrival or departure, the propagation time delay, and optionally the amplitude and phase shifts due to interactions at the interaction points along the propagation path (not the amplitude and phase shifts between the interaction points along the propagation path) are independent of the antenna elements (or antenna ports) of the antenna array and the frequency. In an improved approach, the improved computational efficiency of the subject technique 100 and 200 can allow determining the propagation paths for individual pairs of transmit antenna element and receive antenna element, e.g. while still enabling real-time control of the RAN.

[0137] Ray-tracing is becoming increasingly important for simulating and emulating the wireless channel for controlling existing or future generations of wireless networks and devices. The current and proposed future capabilities of these networks and devices include the use of large antenna arrays, wide communication bandwidths and the simultaneous use of multiple frequency bands for communication. To elaborate, the aim of methods such as ray-tracing is to obtain a representation of the radio channel between actual or hypothetical transmitters and receivers in actual or hypothetical scenarios and environments. To be useful, this representation of the radio channel should have good fidelity compared to a measured radio channel between the same (possibly hypothetical) transmitter / receiver in the same (possibly hypothetical) scenarios and environments. The better the fidelity, the more the modelled radio channel can be trusted to have similar or the same characteristics as a measured channel. In addition, the modelled radio channel can be available with minimum latency using embodiment. What is an acceptable latency depending on the application and can range from microseconds for real-time applications, to seconds or minutes for interactive work such as radio network planning, to hours or more for radio network dimensioning.

[0138] The fidelity of a radio channel model may be classified in various ways, both in terms of deterministic measures, such as the existence of specific paths for a given propagation environment, as well as in terms of statistical measures, such as delay spread and angular spread. When modeling deterministic scenarios, based on real-world environments, the level-of-detail (LOD) in the representation of the environment will impact both deterministic and statistical measures. Fundamental wave-object (or, in a ray tracer context, ray-object) interactions such as specular reflection and wedge (e.g., edge) diffraction are captured based on the location, orientation, and properties of surfaces and comers in the models of the environment. These interactions are responsible for the primary deterministic, scenario-specific features of the predicted propagation channel, particularly for models of outdoor propagation in city environments, and may be captured by coarse LOD representations.

[0139] The properties of the propagation channel, particularly in terms of the statistical measures, will also depend on finer details, related to smaller objects and finer LOD representations. Such smaller objects include windows, balconies, drainpipes, lamp posts, and trees, to name a few. For surfaces, such as walls (facades) and roofs, the representation of the environment (as provided by 3D world models) is generally devoid of such details, resulting in environment models that are overly “clean”, which results in a lack of channel “richness”.

[0140] To mitigate the coarse LOD of available models of propagation environments, the fundamental interactions (specular reflection and wedge diffraction) are complemented by interactions 308 that serve to capture the finer LOD of real -world environments. One such interaction is non-specular surface scattering 308, which improves the predicted propagation channel richness. This scattering is generally applied on surfaces 304 that are otherwise represented as being smooth (e.g., planar or piecewise planar), when the corresponding real -world objects are non-smooth. In a real-time context, surface scattering models are applied at discrete scattering points 320 positioned on the surfaces 304, e.g. representing walls. These points 320 are positioned at pre-determined locations of the lattice 310 and selected based on the interaction point 308 of each ray 306 with the corresponding surface 304.

[0141] Conventionally, two methods of choosing points at which to apply non-specular scattering are in use, both with their separate issues. The first conventional method uses the point on a surface at which the incoming ray in the ray-tracer hits or intersects the surface. To maintain richness and power conservation, and to avoid non-uniform spatial sampling, this method needs to be combined with methods to select which points to use and which points to discard of the identified hit points. Since the spatial density of incident rays on a surface is related to the angular density of the incoming rays as well as the orientation of the surface in relation to the incoming rays, there is no way to achieve uniform sampling of a surface when using hit points as the basis for non-specular scattering. In addition, it is impossible to maintain power conservation for such points in isolation since there is no way of knowing the distance to surrounding points (or even if there are any surrounding points) on a per-point basis. A method to achieve power conservation would require calculation of the Voronoi diagram for all points on the aggregate of all co-planar contiguous surfaces, which would require computationally expensive post-processing once all ray-traced paths had been identified. The second conventional method chooses points for scattering based on the concept of splitting a surface into tiles (the points used for scattering are typically the tile centers). Two implementations of the splitting method have been identified. The first type of implementation is based on randomly selecting an origin for a tiling, and then adding further tiles hierarchically around the tile at the origin. This type of implementation is unacceptable from a repeatability point-of-view due to the randomness. The second type of implementation is based on subdividing a surface into multiple tiles. The key issue with this second type is the need to (1) identify individual surfaces, (2) pre-process the tiling for each surface based on the properties of the surface, and (3) assigning tiling information to the surface representation. In a ray-tracer, surface objects are represented by groups of simple building blocks (such as triangles), and during ray tracing there is typically no notion of surface available for a given triangle. Carrying surface-related information in a triangle container (for example a struct with parameters) would be prohibitively expensive in terms of memory usage.

[0142] Fig. 3 schematically shows an exemplary simplified environment 300 comprising a surface 304 and a reference point 316 labeled "O". Fig. 3 further shows an inbound ray 306 of the ray-tracing interacting with the surface 304. The surface 304 may be represented (e.g., triangulated) with arbitrary two- dimensional (2D) shapes, e.g., triangles, which is the example schematically illustrated in Fig. 3. Any ray 306 inbound on the surface 304 interacts with the surface 304 in one of the exemplary triangles. The surface 304, as locally represented by each triangle, has a normal vector 314 that is perpendicular to the respective triangle. The surface 304 of any object in the environment 300 may be represented, e.g. piecewise, by an equation ax + by + cz + d = 0 in Cartesian coordinate system, wherein (a, b, c) is (e.g., proportional to) the normal vector 314.

[0143] The device 100 may determine the interaction point 308 on the surface 304. Alternatively or in addition, the device 100 may span (i.e., cover) the surface 304 by triangles (e.g., or any other closed 2D shapes) for which an interaction has been detected. For example, if an interaction is within a triangle (or any other 2D polygon) in a flat surface 304, the lattice 310 may be referred to as “automatically” spanning an infinite plane or as a “virtual grid”, since points of the lattice that are not neighbors to the interaction point 308 are without relevance for performing the method 200 in relation to one inbound ray 306. Any kinks (e.g., steps or comers) in the underlying physical surface 304, which the triangle is coplanar with (in the nonkink regions), may be unknown at the point of interaction 308, i.e. when performing an embodiment of the method 200 for a given inbound ray 306. This locality of the method 200 can significantly improve the relation between computation resources and accuracy in favor of the latter.

[0144] In an embodiment of the method 200, all that is known (e.g., the local information that has to be obtained) is the interaction point 308 and vertex positions of the respective triangle (or any other polygon locally representing the surface 304). Moreover, the triangle (or the other polygon) may define - e.g. may only intrinsically define (i.e., without additional parameters) - a plane. Hence, the lattice is restricted to said plane. Alternatively or in addition, if the surface 304 has a (e.g., small) kink along a line, the lattice 310 may be continued (e.g., in terms of point-to-point distances within the surface) over that kink line. Therefore, the embodiment of the device 100 and the method 200 may overcome a singular behavior where a small deviation breaks the usage or global consistency. The kink of the surface 304 need not be small. For example, the kink may be 90°, such as the surface 304 of an ideal staircase. The lattice 310 may be placed on such a surface 304 (e.g., spanning the surface like a carpet on the stairs). Alternatively or in addition, the surface 304 with which the interaction takes place may incorporate information of said non-planar behavior, either explicitly in a definition of the surface 304 or implicitly by an index and / or reference to a list and / or table with said information.

[0145] Alternatively or in addition, the surface 304 with which a ray 306 is intersecting has a parameter set, which contains information from which to construct a non-planar lattice 310. For example the device 100 may use the explicit information in the triangle representation (the vertices of the triangle) to span the surface 304.

[0146] Alternatively or in addition, there may be details about which lattice 310 may be applicable depending on the underlying physical surface 304. For example, a rectangular grid is potentially not a good option for a surface which has curvature in two dimensions (e.g., depending on radii of curvature, how large angular space the surface spans seen from imagined focal points, etc.).

[0147] Alternatively or in addition, it may be possible to have a uniform lattice on a smooth, non-flat surface 304 with no intrinsic curvature, such as a cylinder surface. Generally, if the surface 304 is described in sufficient details, and certainly in terms of a function (e.g., a surface with undulations as represented by sine function or a spline), the lattice 310 may be associated via a mapping. The period of the lattice 310 may or need not be coupled to the period of the undulations of the surface 304 (e.g., when the surface 304 has such a property).

[0148] Alternatively or in addition, to mitigate the coarse level of details (LOD) of available models of propagation in the environment 300 (e.g., models of the physical surfaces of the objects in the environment 300), the fundamental interactions (specular reflection and wedge diffraction) are complemented by interactions that serve to capture the finer LOD of real -world environments. One such interaction may be non-specular surface scattering, which improves the predicted propagation channel richness. This scattering may be generally applied on surfaces that are otherwise represented as being smooth when the corresponding real-world objects are non-smooth. Surface scattering interactions may be applied at discrete scattering points (as the lattice points 310) positioned on the surfaces 304, representing walls. This discretization is particularly advantageous in a real-time context. Thus, the points of outgoing rays may be determined S206 as points positioned at pre-determined locations, namely selected from the lattice 310, and based on the interaction point 308 of each ray 306 interacting with the corresponding surface 304.

[0149] Exemplary embodiments of the device 100 and the method 200 in this document mainly use the lattice 310 for determining S206 points 320 for diffuse scattering (e.g., non-specular surface scattering) on the surface 304. However, e.g. a facade of a building (as an example of an object in the environment 300) may have features such as balconies or bay windows that cause specular reflection in other directions than that given by a plane of the facade, like the staircase in the above-mentioned example. One conventional approach may model such detailed structure of the facade with smaller triangles, but that may strain the ray-tracer by requiring a very high (e.g., angular) shooting resolution (e.g., at the first station). Instead, embodiments of the device 100 and the method 200 enable to associate small reflection planes with the lattice points. Therefore, the lattice 310 may be used to create interactions that serve to capture the finer LOD of real-world environments, of which diffuse scattering and specular reflections are two different examples and use cases.

[0150] Fig. 4 shows the exemplary simplified environment 300 comprising a surface 304 and a reference point O of the Fig. 3. Fig. 4 further shows an interaction point 308 on the surface 304 (e.g., inside the respective triangle) that the ray 306 interacts with on the surface 304.

[0151] Fig. 5 shows the exemplary simplified environment 300 comprising a surface 304 and a reference point O of the Fig. 3 or 4. Fig. 5 further shows another plane B in the environment 300 that is parallel to the surface 304 (labelled as plane A) and comprising the reference point O. The reference point O may be projected to the surface 304 as the projected reference point O’, which serves as a base point 318 for the lattice 310.

[0152] Alternatively or in addition, the proj ected reference point 318 at O ’ used for the lattice 310 may be chosen in different ways. For example, a global coordinate system may be chosen (using, e.g., the origin and when required the coordinate system axes), and / or a local coordinate system associated with an object, or a set of objects (e.g., a building or block of buildings) may be chosen. The reference point O may be uniquely defined. Choosing the global origin or any other common reference point has the advantage that no extra information, beyond that of the vertex coordinates, needs to be included in the description of a local representation of the surface (e.g., the respective triangle). Therefore, memory and computation power for the ray tracing may be maintained at a minimum level.

[0153] Fig. 6 shows the exemplary simplified environment 300 comprising the surface 304 of Figs. 3 to 5. While Fig. 5 shows the reference point 316 (labeled O) of the lattice 310, the corresponding projected reference point 318 in the surface 304 serves as a base point (labeled O’) of the lattice 310. The device 100 further obtain (e.g., predefined in memory) a pair of linearly independent lattice vectors 312 (labelled as ai and a2 in Fig. 6), each perpendicular to a normal vector 314 of the surface 304. The lattice vectors 312 may define a lattice 310 parallel to the surface 304 based on the reference point 316 (e.g., by including O as a lattice point in the plane B or by including O’ as a lattice point in the plane A) in the environment 300. That is, the lattice 310 may be on a plane B that is parallel to the surface 304 and outside (e.g., "under" in the view of Fig. 6) the surface 304 and / or on a plane that is parallel to the surface and "above" the surface 304 and / or on a plane A that is coplanar to the surface 304.

[0154] The pair of lattice vectors 312 may make an angle with each other, e.g., any angle between 0 to 180 degrees. The length of the lattice vectors 312 may be or need not be equal to each other.

[0155] Fig. 7 shows a front view of the surface 304 in the exemplary simplified environment 300 of Figs. 3 to 6. The front view is particularly suited in a parallel projection eliminating an implementational degree of freedom of the plane chosen for the lattice 310. For simplicity of the drawing, the pair of lattice vectors 312 are perpendicular to each other.

[0156] Fig. 8 shows the front view of the exemplary simplified environment 300 comprising the surface 304 of Figs. 3 to 7. Fig. 8 shows the lattice 310 comprising plurality of lattice points. The surface 304 of the environment 300 may be finite and the lattice 310 may be an infinite lattice 310, i.e., the lattice points may be extended outside of the surface 304.

[0157] The points of the lattice 310 (e.g., the virtual grid) may be unique for a given surface 304 of an object in the environment 300 due to the reference point 316 or its projection 318. Regardless of where a ray 306 interacts with the surface 304, points from the same lattice 310 may be locally chosen by performing an embodiment of the method 200. Therefore, a constant density of the lattice points 310 ensures that power conservation is maintained for the determined S206 point 320 in the obtained lattice 310. Periodicity of the lattice 310 and / or lattice type (e.g., angle and lengths of the pair of lattice vectors 312) may be parameters of the ray tracing.

[0158] Fig. 9 shows the exemplary simplified environment 300 comprising examples of an interaction point 308 and a pair of lattice vectors 312, e.g. for illustrating the steps S204 and / or S206 of an embodiment of the method 200. For example, Fig. 9 illustrates (e.g., non-integer values of) projection indices (z, j) of the interaction point 308 based on the lattice vectors 312.

[0159] Fig. 10 shows the exemplary simplified environment 300 comprising the interaction point 308 and the pair of lattice vectors 312 of Fig. 9. An example of implementing the step S206 according to an embodiment of the method 200 is illustrated. The interaction point 308 is used to determine S206 the closest lattice point (wherein the closest lattice point exceptionally coincides with the reference point O’ in the example illustrated in Fig. 10). The closest lattice point 320 may be determined S206 by rounding the non-integer values of the projection indices (z, J) to integer values. The determined S206 lattice point 320 may not necessarily be within the triangle of the interaction point 308.

[0160] The triangles may be uneven depending on origin of object generation. In the ray-tracing, a segment tracing (e.g., an electromagnetic analysis of each straight lines between subsequent interactions points of a propagation path and the interaction points 308) may account for a case wherein the determined closest lattice point 320 is outside of the (physical) surface 304 of the object. For example, a Voronoi cell of the lattice point may be associated with the energy (or power) of the diffusive scattering point. Any modelled coplanar surface 304 may have the same (i.e., consistent) lattice 310 in order to ensure energy conservation combined with on-the-fly ray-tracing by virtue of the locality of embodiments of the method 200.

[0161] Fig. 11 shows another exemplary simplified environment 300 comprising an interaction point 308 and a pair of lattice vectors 312, for illustrating exemplary implementations of steps of an embodiment of the method 200. As schematically illustrated in Fig. 11, the lattice points 310 extended beyond (e.g., a physical extent of) the surface 304. It is noted that in a variant of any embodiment, the lattice vectors 312 may have different lengths and they may make an angle smaller than 90 degrees (e.g., as indicated in Fig. 11).

[0162] In the example illustrated in Fig. 11, the determined S206 lattice point 320 falls inside the triangle.

[0163] Fig. 12 shows a further exemplary simplified environment 300 comprising an interaction point 308 and a pair of lattice vectors 312 for illustrating an implementation of steps of an embodiment of the method 200.

[0164] As with Fig. 11, Fig. 12 indicates that the lattice points 310 extended beyond the surface 304, which boundary are schematically indicated by a black rectangular frame in Fig. 12. The lattice vectors 312 may have different length and / or make an angle smaller than 90 degrees.

[0165] The determined S206 lattice point 320 lies both outside the triangle and outside the area 304. In a variant of any embodiment, the one or more rays are launched from the determined S206 lattice point 320 independent of whether or not the determined S206 lattice point 320 lies inside the triangle of the interaction point 308 and / or independent of whether or not the determined S206 lattice point 320 lies inside the surface 304. This can ensure correct energy conservation when determining the wireless communication channel, since energy conservation is associated with the equal size of each lattice cell of the lattice 310, while the effective change in the boundary of the surface 304 is merely a finite size effect of the lattice vectors 312. Fig. 13 shows an exemplary flowchart of an embodiment of the method 200, which may be implemented in combination with any of the above described embodiments.

[0166] For the purposes of concreteness, a three-dimensional (3D) coordinate system (x, y, z) may be implemented with the third dimension (z) representing a vertical dimension, e.g. according to the axes plotted in each of Figs. 3 to 5). Furthermore, the surface 304 may be described by the four real values (a, b, c, d) in the equation of a plane written as ax + by + cz + d = 0, wherein the triple (a, b, c) represents a unit-length normal vector 314 (see, e.g., Fig. 3) to the surface 304 and d is the distance between the plane and the origin 0(0, 0, 0), see x-, y-, and z-axes in Fig. 5 of the 3D coordinate system (wherein the distance is the shortest distance, i.e., the distance from the global coordinate system origin (e.g., the reference point 316) to the perpendicularly projected reference point 318 (labeled O’) to the surface 304 (or the respective triangle) along the normal 314 to the surface 304.

[0167] The exemplary embodiment of the method 200 may be summarized with the following steps, in the context of a lattice-based action for a given interaction 308:

[0168] 1. A ray 306 is identified as hitting (intersecting) a triangle in a surface 304, resulting in an interaction point 308 represented by a ip = (xp, yp, zp);

[0169] • If the triangle does not support lattice-based interactions, do nothing related to the lattice-based solution (i.e., “continue”);

[0170] 2. Get the (a, b, c, d) terms for the surface 304 of the triangle, wherein (a, b, c) is the normal vector 314 of the surface 304 and d is the distance between the surface 304 in plane A and a corresponding parallel surface B passing through for example the global origin 0(0, 0,0) (see Fig. 5);

[0171] • In one variant, (a, b, c, d) may be read as stored in a triangle representation.

[0172] • In another variant, (a, b, c, d) may be computed if a triangle is only represented by its vertices.

[0173] 3. Construct primitive lattice vectors 312 (see Fig. 6) based on the components (a, b, c) of the normal vector 312, with resolution properties as defined either globally or by the triangle parameters.

[0174] • The lattice unit cell defined by the lattice vectors 312 is typically square or (equilateral) triangular, achieved by using an angle between equal length lattice vectors of 90° or 60°, respectively. However, rectangular or non-equilateral triangular grids (i.e., lattices) may also be constructed using non-equal lattice vectors 312 or other angular separations.

[0175] Project the interaction point 308 z on lattice 310 defined by the lattice vectors 312 to get a representation of ip in terms of fractional (i.e., real-valued) lattice indices (cf. Fig. 9) multiplying the lattice vectors 312 in reference to an arbitrary but fixed and unique origin (such as the origin (0,0,0) of a global coordinate system). • The so-called “projection” may be performed implicitly by dot products. The described plane ‘B’ is primarily meant to facilitate the interpretation of the method 200.

[0176] 4. Choose the closest point (different definitions possible) in the discrete lattice 310 defined by the lattice 310 by a rounding-like operation on the lattice coefficients (cf. Fig. 10). The closest point is the desired lattice point in the global lattice of the surface 304, with the projected reference point O’, i.e., 318 on the surface 304 being the projection (along the normal vector (a, b, cj) of the origin in plane ‘B’ on the surface 304.

[0177] Another exemplary embodiment of the method 200 may comprise at least one of the following features:

[0178] 1. Make a first horizontal primitive lattice vector 312, labeled ai, by using the cross product between the normal vector 314, i.e. (a, b, c), and a pure vertical vector, for example (0,0,1) when the third dimension represents the vertical dimension, and normalize the vector to have unit length.

[0179] 2. Make a second primitive lattice vector 312, labeled a2, as the cross product between the normal 314, i.e. (a, b, c), and the first primitive lattice vector (for a rectangular lattice) or by rotating the first primitive lattice vector, e.g. by 60 degrees, around the normal vector 314, i.e. (a, b, c), (for a triangular or rhombic lattice).

[0180] If the normal vector 314 is vertical:

[0181] 1. Choose an arbitrary direction in the horizontal plane to construct the first primitive lattice vector 312, labeled ai.

[0182] 2. Make a second primitive lattice vector 312, labeled a2, by rotating the first primitive lattice vector 90 degrees around the normal (for a rectangular grid) 314 or 60 degrees for a triangular or rhombic grid.

[0183] The embodiments of the device 100 and the method 200 provide a method that guarantees that points in a periodic lattice 310 on coplanar triangles are generated uniformly, such that the intersected power, and the corresponding scattered power, may be determined uniquely for arbitrary locations and orientations of said triangles. Triangles do not carry any information about the lattice points, which are fully defined by the surface 304 of triangle and the (arbitrary) choice of origin for the lattice (e.g., the reference point O’). The reference point O’ may be referred to as “global” as it may be based on a projection of a truly global origin (for an assumed Cartesian coordinate system) on the respective plane, although other ways of choosing a reference point are possible as long as the reference point is one and the same unique origin for a given plane.

[0184] Furthermore, given such a lattice 310, with fixed periodicity and known lattice vectors 312, the decision, if an interaction point 308 on the surface 304 for a given ray 306 shall be associated with one of these unique lattice points or not, may be based on a calculation of distance between the interaction point 308 and candidate lattice points. With an assumed knowledge of ray 306 density, orientation of the surface 304, and total traveled distance of the ray 306 (including all previous path segments from initial launch point via multiple interactions), the method 200 may provide an efficient means to discard rays 306 that should not be associated with a lattice point. This is an extremely important decision for computational efficiency, to avoid oversampling which can stall the path finding.

[0185] Since the lattice points are unique, and may be represented by indices associated with the two lattice vectors 312, pruning of duplicates paths involving such grid points is simply a matter of comparing integer values.

[0186] An example of the physical action is shown in Fig. 14. Fig. 14 shows a block diagram of an emulating embodiment of the device 100. 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 transmitter node 504 and at least one receiver node 506 (which in turn may be based on the channel modeled in the step S212).

[0187] The device 100 comprises an RF input 702 and an RF output 704 coupled to the transmitter node 504 and the receiver node 506, respectively, to let the equipment 504 and / or 506 experience radio channels of different kinds. The technique can be applied in this context by letting the device 100 generate the radio channels to be emulated. Real-time or near real-time determining of the multipath propagation enables real-time or near real-time emulation of the radio channel, which is important for this use case.

[0188] Fig. 15 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 1504 for performing the method 200 and memory 1506 coupled to the processors 1504. For example, the memory 1506 may be encoded with instructions that implement at least one of the modules 102 to 106, and optionally one of the modules 108 to 112.

[0189] The one or more processors 1504 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 1506, radio device functionality. For example, the one or more processors 1504 may execute instructions stored in the memory 1506. 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. As schematically illustrated in Fig. 15, the device 100 may be embodied by a radio device 1500, e.g., functioning as a UE. The node 1500 comprises a radio interface 1502 coupled to the device 100 for radio communication with one or more other nodes, e.g., including base stations or UEs.

[0190] Fig. 16 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 1604 for performing the method 200 and memory 1606 coupled to the processors 1604. For example, the memory 1606 may be encoded with instructions that implement at least one of the modules 102 to 106.

[0191] The one or more processors 1604 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 1606, network node functionality. For example, the one or more processors 1604 may execute instructions stored in the memory 1606. 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.

[0192] As schematically illustrated in Fig. 16, the device 100 may be embodied by a radio device 1600, e.g., functioning as a gNB. The node 1600 comprises a wired or radio interface 1602 coupled to the device 100 for radio communication with one or more other nodes, e.g., including base stations and UEs, respectively.

[0193] Performing the physical action S210 may comprise transmitting or receiving the wireless communication based on the propagation path 302 determined based on the step S206. Alternatively or in addition, the interface 1502 may be a control interface (e.g., a network interface or an Fl interface according to a 3GPP specification). For example, the node 1500 may be a central unit (CU) of network node (e.g., a gNB). Performing the physical action S210 may comprise controlling the wireless communication in the environment 300 based on the determined propagation path 302.

[0194] Alternatively or in addition, the physical action S210 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 propagation path 302 determined based on the step S206 and / or the modeled channel of the step S212. Alternatively or in addition, the physical action S210 may comprise controlling directional gain and / or transmit power of the wireless communication in the environment 300. For example, a radio device 1500 (e.g., a UE) may determine its position or a network node 1600 (e.g., a gNB) may determine the position of a radio device 310 in the environment 300 based on the propagation path 302 determined using lattice points 320 determined in the step S206.

[0195] In one embodiment, radio signals received at the radio device 1500 in the environment 300 are compared with radio signals expected (e.g., modeled in the step S212) for at least one position in the environment 300 according to the propagation path 302 determined based on the step S206. In another embodiment, the radio signals received from a radio device 310 in the environment 300 at a network node 1600 are compared with radio signals expected (e.g., modeled in the step S212) at the at least one position in the environment 300 according to the propagation path 302 determined based on the step S206.

[0196] 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 based on the step S206. For example, the position for deploying at least one a base station 1600 (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).

[0197] 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).

[0198] Fig. 17 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 1704 for performing the method 200 and memory 1706 coupled to the processors 1704. For example, the memory 1706 may be encoded with instructions that implement at least one of the modules 102 to 106.

[0199] The one or more processors 1704 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 1706, core node functionality or edge computing functionality. For example, the one or more processors 1704 may execute instructions stored in the memory 1706. 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 1500 and / or the network node 1600 may alternatively be performed by the core node 1700 or edge computing node 1700.

[0200] 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.

[0201] Unless specified differently in context, reference signs may relate to the following features and steps.

[0202] 100 Device for determining a tiling of a surface for ray-tracing of a propagation path of a wireless communication

[0203] 102 Interaction Point Obtainment Module

[0204] 104 Lattice Vector Obtainment Module

[0205] 106 Lattice Point Determination Module

[0206] 108 Ray Launching Module

[0207] 110 Physical Action Module

[0208] 112 Channel Model Module

[0209] 102A Obtaining Module

[0210] 104A Configuration Module

[0211] 106A Action Module

[0212] 200 Method for determining a tiling of a surface for ray-tracing of a propagation path of a wireless communication

[0213] S202 Obtain an interaction point on the surface

[0214] S204 Obtain lattice vectors

[0215] S206 Determine a point of lattice closest to the interaction point

[0216] S208 Launch a plurality of rays for the ray-tracing of the propagation path

[0217] S210 Perform or initiate physical action that is dependent on the determined point of lattice S212 Model channel of wireless communication along the propagation path

[0218] 300 Environment

[0219] 302 Propagation path

[0220] 304 Surface

[0221] 306 Ray

[0222] 308 Interaction point

[0223] 310 Lattice 312 Lattice vectors

[0224] 314 Normal vector

[0225] 316 Reference point O

[0226] 318 Projected reference point O'

[0227] 320 Determined lattice point

[0228] 504 Transmitter node

[0229] 506 Receiver node

[0230] 702 Channel emulator input interface

[0231] 704 Channel emulator output interface

[0232] 1500 Radio device embodiment

[0233] 1502 Interface, e.g., radio interface

[0234] 1504 Processing circuitry of the radio device embodiment

[0235] 1506 Memory of the radio device embodiment

[0236] 1600 Access network node embodiment

[0237] 1602 Interface, e.g., radio interface

[0238] 1604 Processing circuitry of the access network node embodiment

[0239] 1606 Memory of the access network node embodiment

[0240] 1700 Core network node embodiment

[0241] 1702 Interface

[0242] 1704 Processing circuitry of the core network node embodiment

[0243] 1706 Memory of the core network node embodiment

[0244] 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 tiling of a surface (304) for ray-tracing of a propagation path (302) of a wireless communication in an environment (300) comprising the surface (304), the device (100) comprising memory (1006) operable to store instructions and processing circuitry (1004) operable to execute the instructions, such that the device (100) is operable to: obtain (S202) an interaction point (308) on the surface (304), wherein a ray (306) of the raytracing interacts with the surface (304) at the interaction point (308); obtain (S204) a pair of linearly independent lattice vectors (312) each perpendicular to a normal vector (314) of the surface (304), wherein the lattice vectors (312) define a lattice (310) parallel to the surface (304) based on a reference point (316) in the environment (300); and determine (S206) a point (320) of the lattice (310) closest to the interaction point (308) of the surface (304).

2. The device (100) of claim 1, wherein the surface (304) is a diffusive surface of the environment (300), and wherein the device (100) is further operable to: launch (S208) a plurality of rays in different directions from the determined (S206) point (320) of the lattice (310) for the ray-tracing of the propagation path (302).

3. The device (100) of claim 1 or 2, wherein the device (100) is further operable to: perform or initiate a physical action (S210) that is dependent on the determined (S206) point (320) of the lattice (310), optionally model a channel of the wireless communication along the propagation path (302) in the environment (300).

4. The device (100) of any one of claims 1 to 3, wherein the device (100) is further operable to: model (S212) a channel of the wireless communication along the propagation path (302) in the environment (300), optionally wherein the modeling (S212) of the channel comprises or the device (100) is further operable to perform or initiate a physical action that is dependent on the modeled (S212) channel.

5. The device (100) of any one of claims 1 to 4, wherein the surface (304) is planar.

6. The device (100) of any one of claims 1 to 5, wherein the surface (304) is piecewise planar, optionally wherein the normal vector (314) is perpendicular to a first piece of the piecewise planar surface (304) and wherein indices of the lattice (310) are continuous across an edge between the first piece and a second piece of the piecewise planar surface (304).

7. The device (100) of any one of claims 1 to 6, wherein the surface (304) is a surface with zero intrinsic curvature, optionally wherein a first dimension of the lattice (310) is linearly mapped to a straight first dimension of the surface (304) with zero extrinsic curvature and wherein a second dimension of the lattice (310) is linearly mapped to a geodesic second dimension of the surface (304), further optionally perpendicular to the straight first dimension of the surface (304).

8. The device (100) of any one of the claims 1 to 7, wherein the lattice (310) is one of hexagonal and rectangular.

9. The device (100) of any one of the claims 1 to 8, wherein the reference point (316) is a stationary point in the environment (300).

10. The device (100) of any one of the claims 1 to 9, wherein the surface (304) is parallel to or coplanar with a surface of an object moving in the environment (300) and is moving with the object, and wherein the reference point (316) is moving with the object, optionally on the surface (304) parallel to or coplanar with the surface of the moving object.

11. The device (100) of the claims 1 to 10, wherein the lattice (310) is independent of a distance between the reference point (316) and the interaction point (308) in the direction of the normal vector (314), or wherein a projection of the reference point (316) in the environment (300) onto the surface (304) along the normal vector (314) defines a base point (318) of the lattice (310).

12. The device (100) of the claims 1 to 11, wherein the determining (S206) of the point (320) of the lattice (310) comprises determining a vectorial difference between the interaction point (308) and the reference point (316), wherein rounded scalar products between the vectorial difference and a dual pair of the pair of lattice vectors (312) are indices of the determined (S206) point (320) of the lattice (310).

13. The device (100) of the claims 1 to 12, wherein the environment (300) comprises multiple surfaces (300), and wherein the pair of lattice vectors (312) is obtained (S204) along the propagation path (304) for each interaction point (308) on one of the multiple surfaces (300), optionally wherein the pair of lattice vectors (312) define the lattice (310) based on the same reference point (316) in the environment (300) for all of the surfaces (304).

14. A method (200) for determining a tiling of a surface (304) for ray-tracing of a propagation path (302) of a wireless communication in an environment (300) comprising the surface (304), the method (200) comprising or initiating the steps of:obtaining (S202) an interaction point (308) on the surface (304), wherein a ray (306) of the raytracing interacts with the surface (304) at the interaction point (308); obtaining (S204) a pair of linearly independent lattice vectors (312) each perpendicular to a normal vector (314) of the surface (304), wherein the lattice vectors (312) define a lattice (310) parallel to the surface (304) based on a reference point (316) in the environment (300); and determining (S206) a point (320) of the lattice (310) closest to the interaction point (308) of the surface (304).

15. A computer program product comprising program code portions for performing the functionality of any one of the claims 1 to 13 or the steps of claim 14 when the computer program product is executed on one or more computing devices (1504; 1604; 1704), optionally stored on a computer-readable recording medium (1506; 1606; 1706).

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