Devices and methods for radio resource pool allocation for D2D communication TECHNICAL FIELD

In general, the present invention relates to the field of D2D (device-to-device)

communication. More specifically, the present invention relates to devices and methods for radio resource pool allocation for D2D communication, in particular a D2D

communication device, a network management entity as well as corresponding methods.

BACKGROUND

V2X (Vehicle-to-Everything) services can be provided directly via a so-called PC5 interface (also known as sidelink or D2D communication) and/or indirectly via an LTE-Uu interface (also known as uplink/downlink), as specified in 3GPP TS 36.300 V14.2.0, "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2". Support of V2X services via the PC5 interface is provided by V2X sidelink communication, which is a

communication mode in which User Equipments (UEs) such as vehicles can communicate with each other directly via the PC5 interface. This communication mode is supported when the UE is served by E-UTRAN and when the UE is outside of E-UTRA coverage. More details about V2X sidelink communication can be found in specification 3GPP TS 23.303 V14.1 .0.

A UE supporting V2X sidelink communication can operate in two modes for sidelink radio resource allocation: in a first mode, known as "scheduled resource allocation", a UE requests transmission radio resources from a base station, also known as Evolved Node B (eNB), and the base station allocates dedicated transmission radio resources to the UE. In a second mode, known as "UE autonomous resource selection", the UE on its own selects radio resources from (pre-)configured resource pools.

In order to ensure low interference among V2X sidelink transmissions when using UE autonomous resource selection (also known as "mode 4"), two features are introduced in specification 3GPP TS 36.331 V14.2.2 "Radio Resource Control". The first feature relates to zones: the world is divided into geographical zones, wherein a zone is a periodically repeating geographic region (in latitude and longitude). The UE selects a radio resource pool based on the zone in which it is located. The second feature relates to sensing: based on channel sensing within the selected radio resource pool, the UE selects specific sidelink radio resources within that pool for transmission.

Each radio resource pool is configured with a zonelD identifying the zone in which the pool may be used. Based on its location, a UE derives the identity of the zone in which it is located on the basis of the following equation: zonelD = y ₁ N _x + x ₁ , wherein x ₁ and y _x are defined by the following equations: x ₁ = [x/L\ mod N _x

y ₁ = [y/W\ mod N _y , wherein x denotes the distance between the current location of the UE and geographical coordinates (0, 0) in longitude, y denotes the distance between the current location of the UE and geographical coordinates (0, 0) in latitude, L denotes the zone length

(zoneLength), W denotes the zone width (zoneWidth), N _x denotes the number of zones configured with respect to longitude (zoneldLongiMod) and N _y denotes the number of zones configured with respect to latitude {zoneldLatiMod).

The location of geographical coordinates (0, 0) and the parameters L, w, N _x and N _y can be configured by the network operator or pre-configured in the UE. The UE then selects a radio resource pool configured with the corresponding zonelD.

Figure 1 shows a schematic diagram illustrating an exemplary conventional zone configuration with N _x = N _y = 4 and L = W, wherein the number within each square indicates the identity of the zone, i.e. zonelD. It can be observed that each zonelD repeats periodically.

However, the approach of zone configuration proposed in specification 3GPP TS 36.331 has the following limitations: firstly, a resource pool is associated with a zonelD identifying a periodically repeating geographic region. This is beneficial in terms of control signaling overhead, as a single zonelD is enough to indicate multiple areas where a resource pool may be used. However, as a result of periodicity, the zonelD does not uniquely identify a specific geographic region. A method to uniquely identify a specific (non-periodic) geographic region would be beneficial, since traffic demand is generally not uniformly distributed, nor does it follow any periodic pattern in space. Some high-demand regions, such as a hotspot of high user density, may need more or larger radio resource pools than other regions with low user density.

Secondly, zones are uniformly sized and always rectangular. Having variable zone sizes and/or arbitrarily shaped zones would be beneficial in order to better adapt to the local road geometry and therefore to the spatial distribution of traffic demand. A way of implementing variable zone sizes and/or arbitrarily shaped zones in practice would be to provide not just one zonelD but a list of zonelDs for a given resource pool. However, this might incur significant control signaling overhead.

Finally, the concept of zone is limited to two-dimensional (2D) regions. However, some applications (e.g., drones) may benefit from considering the vertical dimension (i.e., elevation) as well, i.e., three-dimensional (3D) regions. In light of the above, there is a need for improved devices and methods for radio resource pool allocation for D2D communication allowing the assignment of a unique identifier to a spatial region and the selection of a radio resource pool on the basis of that identifier.

SUMMARY

It is an object of the invention to provide improved devices and methods for radio resource pool allocation for D2D communication allowing the assignment of a unique identifier to a spatial region and the selection of a radio resource pool on the basis of that identifier. The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

Generally, embodiments of the present invention can efficiently and uniquely identify a region of variable size in n-dimensional space on the basis of its location within an n- dimensional box, with respect to an orthant-based partitioning of the box at multiple hierarchical levels. The unique identity of the region comprises a sequence, and each element of the sequence identifies the orthant within which the region is located at each hierarchical level. Furthermore, according to embodiments of the invention, a D2D communication device can be provided with the following information, either via pre-configuration or from a network management entity, in particular a base station: the reference point (0, 0) (2D) or (0, 0, 0) (3D), and the dimensions of the box in latitude and longitude (and elevation, in 3D); and mapping of radio resource pools to specific (non-periodic) regions within the box, which may have different sizes. Based on its current location, the D2D communication device can determine the region(s) in which it is located and can select an appropriate radio resource pool for V2X sidelink communication.

The embodiments of the invention provide a key advantage of identifying regions of variable size by simply adjusting the length of the identification sequence, i.e., by choosing the appropriate hierarchical level.

More specifically, according to a first aspect, the invention relates to a D2D

communication device. The D2D communication device comprises: a communication interface configured to communicate with another D2D communication device using one or more radio resources of at least one radio resource pool of a plurality of radio resource pools; and a processing unit configured to determine an identifier on the basis of a spatial position of the D2D communication device within a predefined spatial region and to select the at least one radio resource pool on the basis of the identifier; wherein the identifier comprises a sequence of symbols, each symbol identifying the quadrant (2D) or octant (3D) within which the D2D communication device is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region. For the 2D case, each symbol can consist of two bits. For the 3D case, each symbol can consist of three bits. Thus, an improved D2D communication device is provided, allowing the assignment of a unique identifier to a spatial region and the selection of a radio resource pool on the basis of that identifier.

In a further possible implementation form of the first aspect, the processing unit is configured to determine the identifier on the basis of the spatial position of the D2D communication device and on the basis of region configuration information provided by a network management entity or preconfigured in the D2D communication device, wherein the region configuration information comprises information about respective dimensions of the predefined spatial region and/or a spatial position of a reference point of the predefined spatial region.

In a further possible implementation form of the first aspect, the processing unit is configured to select the at least one radio resource pool of the plurality of radio resource pools on the basis of the identifier and on the basis of the region configuration information, wherein the region configuration information comprises information about the respective radio resource pools of the plurality of radio resource pools allocated to each sub-region of a plurality of sub-regions of the predefined spatial region.

In a further possible implementation form of the first aspect, the spatial position is a two- dimensional spatial position and the predefined spatial region, and spatial subdivisions thereof, have the shape of a rectangle, in particular a square.

In a further possible implementation form of the first aspect, the spatial position is a three- dimensional spatial position and the predefined spatial region, and spatial subdivisions thereof, have the shape of a cuboid, in particular a cube.

According to a second aspect, the invention relates to a method of operating a D2D communication device, wherein the method comprises: determining an identifier on the basis of a spatial position of the D2D communication device within a predefined spatial region; selecting at least one radio resource pool of a plurality of radio resource pools on the basis of the identifier; and communicating with another D2D communication device using one or more radio resources of the at least one selected radio resource pool;

wherein the identifier comprises a sequence of symbols, each symbol identifying the quadrant (2D) or octant (3D) within which the D2D communication device is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region.

Thus, an improved method is provided, allowing the assignment of a unique identifier to a spatial region and the selection of a radio resource pool on the basis of that identifier.

According to a third aspect, the invention relates to a network management entity, wherein the network management entity comprises: a processing unit configured to generate region configuration information, wherein the region configuration information defines a plurality of sub-regions of a predefined spatial region and a respective allocation of one or more radio resource pools to each of the plurality of sub-regions; and a communication interface configured to provide the region configuration information to the D2D

communication device; wherein each of the plurality of sub-regions is identified by an identifier, wherein the identifier comprises a sequence of symbols, each symbol identifying the quadrant (2D) or octant (3D) within which the sub-region is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region.

Thus, an improved network management entity for allocating radio resources to a D2D communication device is provided.

In a further possible implementation form of the third aspect, the network management entity is a base station or a cloud server. According to a fourth aspect, the invention relates to a method of allocating radio resources to a D2D communication device. The method comprises: generating region configuration information, wherein the region configuration information defines a plurality of sub-regions of a predefined spatial region and a respective allocation of one or more radio resource pools to each of the plurality of sub-regions; and providing the region configuration information to the D2D communication device; wherein each of the plurality of sub-regions is identified by an identifier, wherein the identifier comprises a sequence of symbols, each symbol identifying the quadrant (2D) or octant (3D) within which the sub- region is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region.

Thus, an improved method for allocating radio resources to a D2D communication device is provided.

According to a fifth aspect, the invention relates to a computer program comprising program code for performing the method of the second or fourth aspect when executed on a computer.

The invention can be implemented in hardware and/or software. BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, wherein:

Figure 1 shows a schematic diagram illustrating an exemplary zone configuration according to the prior art;

Figure 2 shows a schematic diagram illustrating a D2D communication device according to an embodiment and a network management entity according to an embodiment;

Figure 3A shows a schematic diagram illustrating hierarchical levels of subdivision of a two-dimensional predefined spatial region determined by a D2D communication device according to an embodiment;

Figure 3B shows a schematic diagram illustrating hierarchical levels of subdivision of a three-dimensional predefined spatial region determined by a D2D communication device according to an embodiment; Figure 4 shows a diagram illustrating a method of operating a D2D communication device according to an embodiment; and

Figure 5 shows a diagram illustrating a method of allocating radio resources to a D2D communication device according to an embodiment.

In the various figures, identical reference signs will be used for identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, reference is made to the accompanying drawings, which form part of the disclosure, and in which are shown, by way of illustration, specific aspects in which the present invention may be placed. It will be appreciated that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, as the scope of the present invention is defined by the appended claims.

For instance, it will be appreciated that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a

corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Moreover, in the following detailed description as well as in the claims, embodiments with different functional blocks or processing units are described, which are connected with each other or exchange signals. It will be appreciated that the present invention covers embodiments as well, which include additional functional blocks or processing units that are arranged between the functional blocks or processing units of the embodiments described below.

Finally, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise. As will be described in more detail in the following, embodiments of the invention relate to a communication network comprising a D2D communication device and a network management entity, which allow uniquely identifying a spatial region and efficiently selecting a radio resource pool therein. Figure 2 shows a schematic diagram illustrating a communication network 200 comprising a D2D communication device 201 according to an embodiment and a network

management entity 231 according to an embodiment. The D2D communication device 201 is configured to communicate with another D2D communication device (not shown in figure 2) via a sidelink (or D2D) communication channel and communicate with the network management entity 231 via an uplink/downlink communication channel.

In the embodiment shown in figure 2, the D2D communication device 201 could be implemented in the form of a vehicle or a communication module of a vehicle. However, it will be appreciated that embodiments of the invention apply to D2D communication devices other than vehicles as well. In an exemplary embodiment, the network

management entity 231 can be a base station or a cloud server. As illustrated in figure 2, the D2D communication device 201 comprises a communication interface 203 configured to communicate with another D2D communication device using one or more radio resources of at least one radio resource pool of a plurality of radio resource pools.

Furthermore, the D2D communication device 201 comprises a processing unit 205. As will be described in more detail in the context of figures 3A and 3B, the processing unit 205 is configured to determine an identifier on the basis of a spatial position of the D2D communication device 201 within a predefined spatial region and to select the at least one radio resource pool on the basis of the identifier, wherein the identifier comprises a sequence of symbols and each symbol identifies the quadrant (2D) or octant (3D) within which the D2D communication device 201 is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region. As can be taken from figure 2, the network management entity 231 comprises a processing unit 235 configured to generate region configuration information, wherein the region configuration information defines a plurality of sub-regions of a predefined spatial region and a respective allocation of one or more radio resource pools to each of the plurality of sub-regions.

The network management entity 231 further comprises a communication interface 233 configured to provide the region configuration information to the D2D communication device 201 via the downlink channel. Moreover, each of the plurality of sub-regions is identified by an identifier and the identifier comprises a sequence of symbols, wherein each symbol identifies the quadrant (2D) or octant (3D) within which the sub-region is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region.

The processing unit 205 of the D2D communication device 201 can be further configured to determine the identifier on the basis of the spatial position of the D2D communication device 201 and on the basis of region configuration information provided by the network management entity 231 or preconfigured in the D2D communication device 201 , wherein the region configuration information comprises information about respective dimensions of the predefined spatial region and/or a spatial position of a reference point of the predefined spatial region. For instance, the region configuration information could comprise information about the length and/or width of the predefined spatial region. Moreover, the processing unit 205 is further configured to select the at least one radio resource pool of the plurality of radio resource pools on the basis of the identifier and on the basis of the region configuration information, wherein the region configuration information comprises information about the respective radio resource pools of the plurality of radio resource pools allocated to each sub-region of a plurality of sub-regions of the predefined spatial region. For instance, the region configuration information could comprise information about different frequency bands assigned to different radio resource pools. In geometry, an orthant (or hyperoctant) is the analogue in n-dimensional Euclidean space of a quadrant in the plane or an octant in three dimensions. In general, an orthant in n dimensions can be considered as the intersection of n mutually orthogonal half-spaces. By independent selections of half-space signs, there are 2 ⁿ orthants in n-dimensional space.

According to an embodiment of the invention, a region within an n-dimensional box (also known as n-orthotope), such as a rectangle or a cuboid, can be uniquely identified based on a hierarchy of n-dimensional orthants. Figures 3A and 3B show schematic diagrams illustrating two- and three-dimensional spatial regions determined by the D2D communication device 201 respectively according to embodiments of the invention, wherein a bit string can be used to identify each region within the n-dimensional box. Within this bit string, each consecutive n-bit substring corresponds to a consecutive hierarchical level and selects 1 out of 2 ⁿ orthants (e.g., 1 out of 4 quadrants in 2 dimensions, 1 out of 8 octants in 3 dimensions, etc.) at its hierarchical level. As the bit string gets longer, the region gets smaller. The scattered dots in figures 3A and 3B represent the locations of D2D communication devices. As can be observed, the spatial distribution of D2D communication devices can be highly nonuniform. This serves to illustrate a scenario where the ability to allocate radio resource pools to unique (non-periodic) sub-regions of variable size might be beneficial.

More specifically, each orthotope o _m (m = 1, ... , 2 ^2K ) at hierarchical level K is identified by a bit string, wherein the bit string comprises K substrings s ^(fe) as follows: s(l) _s (2) _ _S (K) Each n-bit substring s ^(fc) identifies the /c-level orthotope at hierarchical level k.

According to an embodiment, given the origin (0,0, ... ,0) and parameters L _lt L ₂ , - , L _n defining the dimensions of the n-dimensional box, an object such as the D2D

communication device 201 located at an arbitrary point x = (x ₁ , x ₂ , ... , ½) within the box can determine the identity of the /c-level rectangle (two dimensions) or cuboid (three dimensions) in which it is located according to the following formula:

(fe) _{= b} w _b m

' "n ^υ η- 1

wherein

b ^ik) = 2L ₂ ^h mod 2, j = 1, ... , n, k = 1,2,3

and then use this identity to perform an appropriate action for that region, namely selecting a radio resource pool assigned to that region. Thus, in an embodiment, the spatial position of the D2D communication device 201 can be a two-dimensional spatial position (as in the example shown in figure 3A), and the predefined spatial region as well as spatial subdivisions thereof can have the shape of a rectangle, in particular a square. Alternatively, the spatial position of the D2D communication device 201 can be a three- dimensional spatial position (as in the example shown in figure 3B), and the predefined spatial region as well as spatial subdivisions thereof can have the shape of a cuboid, in particular a cube. Figure 4 shows a diagram illustrating a corresponding method 400 of operating the D2D communication device 201 according to an embodiment. The method 400 comprises the steps of: determining 401 an identifier on the basis of a spatial position of the D2D communication device 201 within a predefined spatial region, wherein the identifier comprises a sequence of symbols, each symbol identifying the quadrant (2D) or octant (3D) within which the D2D communication device 201 is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region; selecting 403 at least one radio resource pool of a plurality of radio resource pools on the basis of the identifier; and communicating 405 with another D2D communication device using one or more radio resources of the at least one selected radio resource pool. Figure 5 shows a diagram illustrating a corresponding method 500 of allocating radio resources to the D2D communication device 201 according to an embodiment. The method 500 comprises the steps of: generating 501 region configuration information, wherein the region configuration information defines a plurality of sub-regions of a predefined spatial region and/or a respective allocation of one or more radio resource pools to each of the plurality of sub-regions, wherein each of the plurality of sub-regions is identified by an identifier, wherein the identifier comprises a sequence of symbols, each symbol identifying the quadrant (2D) or octant (3D) within which the sub-region is located at each one of a plurality of hierarchical levels of subdivision of the predefined spatial region; and providing 503 the region configuration information to the D2D communication device 201 . The method 500 can be performed by the network management entity 231 .

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations or embodiments, such feature or aspect may be combined with one or more other features or aspects of the other implementations or embodiments as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be

appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence. Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.