Improved precoding-based multi-antenna uplink transmission

Abstract

The disclosure inter alia relates to an apparatus. The apparatus may comprise at least one processor. The apparatus may further comprise at least one memory storing instructions. The instructions, when executed by the at least one processor, may cause the apparatus to perform transmitting, to a network node, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus. The instructions, when executed by the at least one processor, may further cause the apparatus to perform receiving, from the network node, precoding control information determined at least in part based on the antenna element distance information. The instructions, when executed by the at least one processor, may further cause the apparatus to perform performing an uplink transmission based on the precoding control information. Alternatively or in addition to the antenna element distance information, antenna element grouping information may be transmitted.

Description

[0001] Improved precoding-based multi-antenna uplink transmission

[0002] TECHNOLOGICAL FIELD

[0003] Various example embodiments relate to wireless communication networks, in particular to performing an uplink transmission in such networks with multiple antennas and using precoding.

[0004] BACKGROUND

[0005] Precoding is a technique used in wireless communication networks in particular to enable Multiple Input Multiple Output (MIMO) uplink transmissions. For example, precoding may be used to optimize throughput of an uplink transmission with multiple data streams (or layers) transmitted via multiple antenna elements using so-called codebooks. Examples of wireless communication networks comprise cellular networks such as networks operating according to Long Term Evolution (LTE), 5G or 6G radio access technology. 5G radio access technology may also be referred to as New Radio (NR) access technology. The 3rd Generation Partnership Project, 3GPP, develops standards for LTE, 5G / NR and 6G. One of the topics discussed within 3GPP is how to further improve precoding-based uplink transmissions.

[0006] SUMMARY OF SOME EXAMPLE EMBODIMENTS

[0007] Cellular network standards generally support different types of user equipment (UE) such as, e.g., Customer Premise Equipment (CPE), devices for industrial applications, or consumer devices like smartphones, tablets etc. In order to enable multi-antenna uplink transmissions, so-called codebooks (e.g., sets of matrices) may be used, wherein a precoding matrix to be used by a UE in a particular situation may be selected by a respective network node (e.g., a gNB) communicating with the UE. The various precoding matrices included in such codebooks may be derived under certain assumptions, for example that the individual antenna elements used for a multi-antenna element uplink transmission have same antenna characteristics, are spaced uniformly, and / or are spaced from each other at distances between about 0.5A and OJA, with the wavelength A corresponding to a respective carrier frequency f according to A = c / f, with the phase velocity c.

[0008] Certain UEs, however, in particular consumer devices like smartphones, tablets etc., may comprise multiple antenna elements not having same antenna characteristics, being spaced non-uniformly, and / or not being spaced from each other at distances between 0.5A and 0.7A. In particular the impact of a non-uniform spacing and / or the antenna elements not being spaced at said distances on a combined radiation pattern of the antenna elements may not be accounted for by said codebooks. As a result, a particular precodingmatrix selected to be used for an uplink transmission may not lead to a desired and / or required combined radiation pattern.

[0009] For example, combining two antenna elements that are spaced at a distance larger than about 0.7A (e.g., being spaced at a distance of A, 2A, or more) may result in a ripple (i.e., a variation over the angular domain) with respect to a combined antenna gain causing the combined antenna gain to be sensitive to movement and / or rotation of the UE. If movement and / or rotation of the UE is likely in a certain situation, it may in that case be appropriate to select a precoding matrix combining antenna elements that are spaced relatively close to each other. If, in another scenario, movement and / or rotation of the UE is less likely, on the other hand, it may in that case be appropriate to select a precoding matrix combining antenna elements that are spaced relatively far apart from each other, for example because doing so may offer an enhanced performance (e.g., throughput) while an increased sensitivity to movement and / or rotation of the UE may be tolerable in this scenario.

[0010] In view of the above, certain embodiments of the disclosure may have the effect of improving precodingbased multi-antenna element uplink transmissions, in particular when being performed by consumer devices. In particular, certain embodiments of the disclosure may enable to account for the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances on a combined radiation pattern of the antenna elements in order to effectively control a tradeoff between performance and robustness of multi-antenna element uplink transmissions performed by such devices.

[0011] According to a first example aspect, there is disclosed an apparatus. The apparatus may comprise at least one processor. The apparatus may further comprise at least one memory storing instructions. The instructions, when executed by the at least one processor, may cause the apparatus to perform transmitting, to a network node, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus. The instructions, when executed by the at least one processor, may further cause the apparatus to perform receiving, from the network node, precoding control information determined at least in part based on the antenna element distance information. The instructions, when executed by the at least one processor, may further cause the apparatus to perform performing an uplink transmission based on the precoding control information.

[0012] The apparatus according to the first example aspect may be or may comprise a user equipment (UE).

[0013] According to a second example aspect, there is disclosed an apparatus. The apparatus may comprise at least one processor. The apparatus may further comprise at least one memory storing instructions. Theinstructions, when executed by the at least one processor, may cause the apparatus to perform receiving, from a user equipment, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the user equipment. The instructions, when executed by the at least one processor, may further cause the apparatus to perform determining, at least in part based on the antenna element distance information, precoding control information. The instructions, when executed by the at least one processor, may further cause the apparatus to perform transmitting the precoding control information to the user equipment.

[0014] The apparatus according to the second example aspect may be or may comprise a network node such as, e.g., a Radio Access Network (RAN) node.

[0015] According to a third example aspect, there is disclosed an apparatus. The apparatus may comprise at least one processor. The apparatus may further comprise at least one memory storing instructions. The instructions, when executed by the at least one processor, may cause the apparatus to perform transmitting, to a network node, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the apparatus into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements. The instructions, when executed by the at least one processor, may further cause the apparatus to perform receiving, from the network node, precoding control information determined at least in part based on the antenna element grouping information. The instructions, when executed by the at least one processor, may further cause the apparatus to perform performing an uplink transmission based on the precoding control information.

[0016] The apparatus according to the third example aspect may be or may comprise a user equipment (UE).

[0017] According to a fourth example aspect, there is disclosed an apparatus. The apparatus may comprise at least one processor. The apparatus may further comprise at least one memory storing instructions. The instructions, when executed by the at least one processor, may cause the apparatus to perform receiving, from a user equipment, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the user equipment into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements. The instructions, when executed by the at least one processor, may further cause the apparatus to perform determining, at least in part based on the antenna element grouping information, precoding control information. The instructions, when executed by the at least one processor, may further cause the apparatus to perform transmitting the precoding control information to the user equipment.The apparatus according to the fourth example aspect may be or may comprise a network node such as, e.g., a RAN node.

[0018] According to each of the example aspects, a respective method is also disclosed.

[0019] Thus, according to the first example aspect, there is disclosed a method performed by an apparatus. The method may comprise transmitting, to a network node, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus. The method may further comprise receiving, from the network node, precoding control information determined at least in part based on the antenna element distance information. The method may further comprise performing an uplink transmission based on the precoding control information.

[0020] The apparatus by which the method according to the first example aspect is performed may be or may comprise a user equipment (UE).

[0021] According to the second example aspect, there is disclosed a method performed by an apparatus. The method may comprise receiving, from a user equipment, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the user equipment. The method may further comprise determining, at least in part based on the antenna element distance information, precoding control information. The method may further comprise transmitting the precoding control information to the user equipment.

[0022] The apparatus by which the method according to the second example aspect is performed may be or may comprise a network node such as, e.g., a RAN node.

[0023] According to the third example aspect, there is disclosed a method performed by an apparatus. The method may comprise transmitting, to a network node, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the apparatus into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements. The method may further comprise receiving, from the network node, precoding control information determined at least in part based on the antenna element grouping information. The method may further comprise performing an uplink transmission based on the precoding control information.

[0024] The apparatus by which the method according to the third example aspect is performed may be or may comprise a user equipment (UE).According to the fourth example aspect, there is disclosed a method performed by an apparatus. The method may comprise receiving, from a user equipment, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the user equipment into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements. The method may further comprise determining, at least in part based on the antenna element grouping information, precoding control information. The method may further comprise transmitting the precoding control information to the user equipment.

[0025] The apparatus by which the method according to the fourth example aspect is performed may be or may comprise a network node such as, e.g., a RAN node.

[0026] Any of the disclosed devices (e.g., the apparatus according to any of the described example aspects) may be a stationary device or a mobile device. A user equipment may in particular be a terminal device, e.g. a mobile device such as a smartphone, a tablet, a wearable, a smartwatch, a low power device, an loT device, an I loT device, a vehicle, a truck, a drone, an airplane, or the like. A user equipment may in particular be capable of communicating with (transmitting and / or receiving signals and / or data to / from) one or more other user equipments and / or with one or more network nodes, such as a base station of a wireless communication network. Generally, a user equipment may be any device enabled for communication with a wireless communication network and / or with another user equipment.

[0027] A network node may be understood as a wireless communication station installed at a fixed or mobile location and may in particular be or comprise an entity of a radio access network of a wireless communication system. For instance, a network node may be, comprise, or be part of a base station of a wireless communication network of any generation (e.g. a gNB, eNodeB, NodeB, BTS or the like) of a 3GPP standard. Generally, a network node may be or comprise a hardware or software component implementing a certain functionality. In an example, a network node may be an entity as defined by 3GPP 5G or NR standard (also referred to as gNB). Accordingly, while a network node may be understood to be implemented in or be a single device or module, a network node may also be implemented across or comprise multiple devices or modules. As such, a network node may in particular be implemented in or be a stationary device. Multiple network nodes may in particular establish a wireless communication system or network, which may in particular be an NR or 5G system (5GS) or any other wireless communications system defined by a past or future standard, in particular successors of the present 3GPP standards. Network nodes may be capable of being in direct and / or indirect communication with user equipment.According to the example aspects of the present disclosure, there is in each case also disclosed a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus to perform the method of the respective aspect. The computer program may in each case be stored on a computer-readable storage medium, in particular a tangible and / or non-transitory medium. The computer readable storage medium could for example be a disk or a memory or the like. The computer program could be stored in the computer readable storage medium in the form of instructions encoding the computer-readable storage medium. The computer readable storage medium may be intended for taking part in the operation of a device, like an internal or external memory, for instance a Read-Only Memory (ROM) or hard disk of a computer, or be intended for distribution of the program, like an optical disc.

[0028] Thus, according to the example aspects of the present disclosure, there is in each case also disclosed a computer-readable storage medium having stored thereon the computer program of the respective aspect.

[0029] Any disclosure herein relating to any example aspect is to be understood to be equally disclosed with respect to any subject-matter according to the respective example aspect, e.g. relating to an apparatus, a method, a computer program, and a computer-readable storage medium. For example, any passage describing at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform a step is to be understood as disclosing the step as a method step itself. The same holds the other way around, i.e., any passage describing a method or method step is to be understood as disclosing at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform the method or method step. The disclosure of a method or a method step shall also be considered as a disclosure of means for performing and / or causing to perform the respective method or method step. Likewise, the disclosure of means for performing and / or causing to perform a method or method step shall also be considered as a disclosure of the method or method step itself.

[0030] Specifically, an apparatus (e.g., the apparatus according to any of the described example aspects) is disclosed, configured to carry out, perform and / or control or comprising respective means for performing and / or controlling the method according to any of the above-mentioned example aspects. Further, an apparatus (e.g., the apparatus according to any of the described example aspects) is disclosed comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform the method according to any aspect.

[0031] The apparatus according to any aspect may comprise means for performing the specified method or steps.In general, the means or functionality of any of the disclosed devices or apparatuses (e.g., the apparatus according to any of the described example aspects) may be implemented in hardware and / or software. They may comprise one or multiple modules or units providing the respective functionality. They may for instance comprise at least one processor for executing computer program code for performing the required functions, at least one memory storing the program code, or both. They could comprise for instance circuitry that is designed to implement the required functions, for instance implemented in a chipset or a chip, like an integrated circuit. In general, the means may comprise for instance one or more processing means or processors.

[0032] Specific means may be used to implement specific functions / functionalities / features, e.g. transmitting means for transmitting, to a network node, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus, receiving means for receiving, from the network node, precoding control information determined at least in part based on the antenna element distance information, and / or means for performing an uplink transmission based on the precoding control information (said means may for example be comprised by the apparatus according to the first example aspect).

[0033] Further examples of specific means may comprise, e.g., receiving means for receiving, from a user equipment, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the user equipment, determining means for determining, at least in part based on the antenna element distance information, precoding control information, and / or transmitting means for transmitting the precoding control information to the user equipment (said means may for example be comprised by the apparatus according to the second example aspect).

[0034] Further examples of specific means may comprise, e.g., transmitting means for transmitting, to a network node, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the apparatus into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements, receiving means for receiving, from the network node, precoding control information determined at least in part based on the antenna element grouping information, and / or means for performing an uplink transmission based on the precoding control information (said means may for example be comprised by the apparatus according to the third example aspect).

[0035] Further examples of specific means may comprise, e.g., receiving means for receiving, from a user equipment, antenna element grouping information grouping at least part of a plurality of antenna elementsassociated with the user equipment into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements, determining means for determining, at least in part based on the antenna element grouping information, precoding control information, and / or transmitting means for transmitting the precoding control information to the user equipment (said means may for example be comprised by the apparatus according to the fourth example aspect).

[0036] Thus, according to the respective example aspects of the present disclosure, there is in each case also disclosed a respective apparatus comprising means for performing a method according to the respective aspect of the present disclosure.

[0037] Any of the above-disclosed example aspects may, however, in general be performed by an apparatus, which may be a module or a component for a device, for example a chip.

[0038] The apparatus according to any aspect may comprise only (i.e., consist of) the disclosed components, for instance means, processor, memory, circuitry, or may further comprise one or more additional components.

[0039] The described aspects may be advantageous in terms of a performance (e.g., throughput) and / or a robustness, and thus reliability, of precoding-based multi-antenna element uplink transmissions. More specifically, in accordance with the described aspects, by determining precoding control information at least in part based on information about distances in between and / or a spatial arrangement of a plurality of antenna elements with which an uplink transmission is to be performed, the impact of a non-uniform spacing of the antenna elements and / or of antenna elements being spaced at relatively large distances (e.g., larger than 1A) on a resulting combined radiation pattern of the antenna elements may be advantageously taken into account. In particular, depending on said distances in between and / or the spatial arrangement of the antenna elements, the precoding may be controlled such as to optimize a tradeoff between a performance (e.g., throughput) and a robustness of the uplink (e.g., to movement and / or rotation of a UE).

[0040] The aforementioned advantages may in particular be achieved by transmitting (e.g., by a UE) antenna element distance information and / or antenna element grouping information to a network node, and by determining the precoding control information to be used for an uplink transmission at least in part based on the antenna element distance information and / or based on the antenna element grouping information.In the following, various example embodiments of the various example aspects of the present disclosure are described in detail. It will be understood that any disclosure herein relating to any example aspect is to be understood to be disclosed in a corresponding manner with respect to any other example aspect.

[0041] The apparatuses, methods, computer programs and / or storage media in accordance with the described aspects may for instance correspond to apparatuses, methods, computer programs and / or storage media for 6G (e.g. standardized in 3GPP Rel-20 or beyond), in particular for enhanced Mobile Broadband (eMBB) devices.

[0042] The plurality of antenna elements may for instance comprise at least two antenna elements. In example embodiments, the plurality of antenna elements comprises (e.g., exactly) two, three or four antenna elements. An antenna element may for example comprise or correspond to an antenna port (AP) or to an (e.g., physical) antenna. An antenna port may for instance be understood as a logical entity for transmitting and / or receiving radio signals. Alternatively or in addition, an antenna port may be defined such that a channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. Correspondingly, an (e.g., physical) antenna may for instance be understood as a physical entity for transmitting and / or receiving radio signals. In example embodiments, the plurality of antenna elements comprises or corresponds to a plurality of antenna ports and / or of (e.g., physical) antennas.

[0043] The plurality of antenna elements being associated with the apparatus may for instance mean that the plurality of antenna elements is comprised by the apparatus (e.g., forms part of the apparatus). In other words, in example embodiments, the antenna elements are antenna elements of the apparatus.

[0044] Alternatively or in addition, the plurality of antenna elements being associated with the apparatus may mean that the plurality of antenna elements is (e.g. directly or indirectly) coupled to the apparatus and / or that the plurality of antenna elements is usable for the apparatus for transmitting and / or receiving radio signals. In example embodiments, the plurality of antenna elements is thus comprised and / or usable by the apparatus.

[0045] As mentioned, according to some of the described aspects, antenna element distance information indicative of at least one distance in between a plurality of antenna elements may be transmitted to and / or received by, e.g., a network node. The at least one distance in between the plurality of antenna elements may comprise or may correspond to a plurality of distances in between the plurality of antenna elements. Said plurality of distances may be understood as part of an antenna design of the apparatus. In example embodiments, each of the at least one distance comprises or corresponds to a respective distance inbetween a respective pair of antenna elements among the plurality of antenna elements. In particular, there may be (e.g. exactly) one respective distance between a respective pair of antenna elements among the plurality of antenna elements.

[0046] Alternatively or in addition, (e.g., each of) the at least one distance may correspond to a distance between a respective first antenna element among the plurality of antenna elements and one or more respective second antenna elements among the plurality of antenna elements being spaced from the first antenna element at least or exactly at the respective distance.

[0047] A respective distance may comprise or may correspond to a distance in (e.g., exactly) one, two or three spatial dimensions. For example, a distance may comprise or may correspond to a distance in a first direction (e.g., an x-axis), in a second direction (e.g., a y-axis), and / or in a third direction (e.g., a z-axis).

[0048] A distance in between a respective pair of antenna elements may indicate a spacing or a separation in between the pair of antenna elements. Therefore, a distance in between a pair of antenna elements may also be referred to as an antenna separation. In other words, in example embodiments, the distance in between a respective pair of antenna elements corresponds to a distance from a first antenna element of the pair of antenna elements to a second antenna element of the pair of antenna elements, or vice versa. The formulations “distance in between” and “distance between” antenna elements are used interchangeably herein.

[0049] In example embodiments, (e.g., each of) the at least one distance corresponds to an electrical distance or a physical distance. A physical distance may for instance correspond to an absolute measure of a distance, for example provided in units of length such as millimeter (mm), centimeter (cm), meter (m), or the like. The physical distance between antenna elements may be fixed, e.g. constant in time. An electrical distance may for instance correspond to an electrical length corresponding to the physical distance, for example provided in multiples of a respective wavelength A corresponding to a respective carrier frequency f (e.g. to be used by the apparatus for the uplink transmission) according to A = c / f, with the phase velocity c.

[0050] In example embodiments, the physical distance p and the electrical distance d are thus related as follows:

[0051] d = p / A .

[0052] The electrical distance between antenna elements may depend on a respective wavelength and thus on a respective carrier frequency, which may in turn be variable in time, and may thus not be fixed. The at leastone distance may thus represent an absolute measure, or a frequency-dependent and / or wavelengthdependent measure, of a respective spacing in between (e.g., respective pairs of) the plurality of antenna elements.

[0053] It has been found that in particular the electrical distance is suitable to account for the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances and, as a result, to control the precoding in an advantageous manner, as further described herein. Further, the physical distance has been found to allow for a reduced complexity of determining and / or communicating distances between antenna elements in particular due to being time-independent.

[0054] As mentioned, the antenna element distance information is indicative of the at least one distance. For example, the antenna element distance information may comprise information (e.g., values) representing (e.g., each of) the at least one distance. In example embodiments, the antenna element distance information thus comprises distance values, e.g. provided in units of length and / or in multiples of a respective wavelength.

[0055] Alternatively or in addition, the antenna element distance information may comprise information (e.g., values) indicating respective distance ranges associated with (e.g., each of) the at least one distance. A respective distance range being associated with a respective distance may in particular mean that the distance falls into the distance range. For example, a first distance range division value may indicate that a distance falls into a first distance range, a second distance range division value may indicate that a distance falls into a second distance range, and so forth. A distance range may for example correspond to a set of distances lying (e.g., numerically) above a predefined minimum distance and / or below a predefined maximum distance such that said predefined minimum distance and / or said predefined maximum distance define the distance range. Respective distance ranges may for instance be indicated as respective binary numbers or binary digits. Said distance range division values may thus comprise or correspond to binary numbers (e.g., bit sequences) or binary digits indicating said distance ranges. In example embodiments, the antenna element distance information thus comprises binary numbers or digits. In particular binary numbers or digits allow for reduced complexity and bandwidth requirements when transmitting the antenna element distance information.

[0056] In example embodiments, the antenna element distance information comprises distance information indicating the at least one distance and antenna element identification information identifying at least one of the plurality of antenna elements associated with the at least one distance. In other words, in example embodiments, the distance information and the antenna element identification information together form theantenna element distance information. The distance information may in particular correspond to the information representing (e.g., each of) the at least one distance and / or the information indicating respective distance ranges, as further described herein.

[0057] The antenna element identification information may comprise or may correspond to information for respectively identifying at least one of the plurality of antenna elements associated with a respective one of the at least one distance (e.g., the two antenna elements being spaced at the respective distance). To this end, in example embodiments, the antenna element identification information comprises or corresponds to at least one antenna element identifier for respectively identifying the at least one of the plurality of antenna elements.

[0058] In example embodiments, the antenna element identification information comprises or corresponds to information for identifying respective pairs of antenna elements among the plurality of antenna elements, wherein said pairs of antenna elements are respectively spaced from each other at a corresponding one of the at least one distance. In other words, respective pairs of antenna elements among the plurality of antenna elements may be associated with respective distances among the at least one distance. Antenna elements being associated with a distance may mean that said distance represents a distance in between the antenna elements.

[0059] Alternatively or in addition, in example embodiments, the antenna element identification information comprises or corresponds to information for identifying a single antenna element among the plurality of antenna elements, wherein said antenna element is spaced from some or all other antenna elements among the plurality of antenna elements at least or exactly at a corresponding one of the at least one distance.

[0060] In example embodiments, the antenna element identification information comprises or corresponds to binary numbers (e.g., bit sequences) or binary digits. For example, a first binary number or a first binary digit may identify a first pair of antenna elements among the plurality of antenna elements, a second binary number or a second binary digit may identify a second pair of antenna elements among the plurality of antenna elements, and so forth. In particular binary numbers or binary digits allow for reduced complexity and bandwidth requirements when identifying the antenna element(s).

[0061] The antenna element distance information may thus comprise two information blocks, the distance information as a first information block and the antenna element identification information as a second information block. Thereby, a respective (e.g., each) value comprised by one of the two information blocksmay be implicitly or explicitly associated with at least one corresponding value comprised by the respective other information block. For example, a respective (e.g., each) distance value comprised by the distance information may be associated with a respective antenna element identification value comprised by the antenna element identification information, and vice versa.

[0062] The distance information and the antenna element identification information may be comprised by the antenna element distance information in a manner such as to ensure an association in between respective values comprised by the distance information and respective values comprised by the antenna element identification information. In other words, the distance information and the antenna element identification information may be stored in association within the antenna element distance information. In this way, e.g. respective distances may be associated with respective subsets of antenna elements among the plurality of antenna elements.

[0063] In example embodiments, the antenna element distance information relates to only part of the plurality of antenna elements. In other words, in example embodiments, the antenna element distance information does not comprise antenna element distance information (e.g., distance information and / or antenna element identification information) for part of the plurality of antenna elements. Yet put differently, in example embodiments, no distance is indicated for part of the plurality of antenna elements.

[0064] For example, the distances between respective pairs of antenna elements may be indicated except for one, two, or more distances. It has been found that indicating some but not all distances associated with the plurality of antenna elements may at least in some scenarios suffice to account for the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances, while advantageously saving bandwidth by dispensing with transmitting the omitted distance information.

[0065] In example embodiments, the antenna element distance information is obtained by the apparatus. For example, the antenna element distance information may be retrieved from an internal memory of the apparatus and / or may be determined by the apparatus. For instance, the antenna element distance information may be determined by the apparatus based on one or more physical distance values, e.g. stored in and / or retrieved from an internal memory of the apparatus, and further based on one or more carrier frequencies to be used for the uplink transmission. To this end, first, respective wavelengths may be computed based on respective carrier frequencies (e.g., forming a frequency band) to be used for the uplink transmission. Then, respective electrical distance values may be computed based on the physical distance values and based on the wavelengths.Thus, in example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform:

[0066] - determining (e.g., computing) the antenna element distance information (e.g., one or more electrical distance values) at least in part based on one or more carrier frequencies to be used for the uplink transmission.

[0067] The one or more carrier frequencies to be used for the uplink transmission may correspond to one or more radio frequencies to be used by the respective apparatus (e.g., a UE) for performing the uplink transmission. As mentioned, respective wavelengths may be determined based on the one or more carrier frequencies. In other words, the one or more carrier frequencies may be associated with the one or more wavelengths. The determined distance information (e.g., electrical distance values) may then be associated with corresponding antenna element identification information in order to provide the antenna element distance information.

[0068] In example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform:

[0069] - indicating, to the network node, a capability of the apparatus to provide antenna element distance information.

[0070] In other words, the apparatus may indicate to the network node that it is capable of and / or configured for determining and / or transmitting antenna element distance information, as further described herein. To this end, the apparatus may transmit an indication of the capability to provide antenna element distance information to the network node (e.g., as part of a capability report of the apparatus). In this way, the network node may advantageously be informed that precoding control information to be provided to the apparatus may be determined (also) based on antenna element distance information.

[0071] As mentioned, the antenna element distance information may be transmitted (e.g., communicated) by the apparatus to the network node. In example embodiments, the antenna element distance information is transmitted by the apparatus to the network node as part of at least one of:

[0072] o Uplink Control Information, UCI; or

[0073] o a Medium Access Control, MAC, control element.

[0074] The antenna element distance information may thus for instance be transmitted to the network node by the apparatus via the Physical Uplink Control Channel (PUCCH) and / or via a MAC-CE (Control Element). Theantenna element distance information may be transmitted as part of an existing UCI and / or MAC-CE (e.g., serving also a different purpose) and / or as part of a dedicated UCI and / or MAC-CE (e.g., serving only the purpose of indicating distances between antenna elements).

[0075] As mentioned, the precoding control information may be determined at least in part based on the antenna element distance information. In other words, in example embodiments, the antenna element distance information is used for determining the precoding control information, e.g. by selecting appropriate antenna elements (e.g., antennas or antenna ports) to use for precoding the uplink transmission and / or by excluding specific antenna elements (e.g., antennas or antenna ports) from being used for precoding the uplink transmission. For example, the precoding control information may be determined such that a desired and / or required combined radiation pattern and a desired antenna gain is achieved when performing the uplink transmission based on the determined precoding control information and using the plurality of antenna elements associated with the apparatus, with the antenna elements being spaced at distances indicated by the antenna element distance information. In particular in this way, the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances on a combined radiation pattern may advantageously be accounted for, as further described herein.

[0076] In example embodiments, at least part of the plurality of antenna elements are spaced non-uniformly and / or at distances of more than 0.5A, in particular of more than OVA, in particular of more than A, with the wavelength A corresponding to a carrier frequency to be used for the uplink transmission (e.g., according to A = c / ). Thus, in example embodiments, some or all of the plurality of antenna elements are spaced non-uniformly and / or at distances of more than 0.5A, 0.7A, or A. For example, at least part of the plurality of antenna elements may be spaced from further antenna elements at distances of more than 2A, 4A or 7A, as described below.

[0077] Some antenna elements being spaced non-uniformly may for example mean that at least one first spacing in between at least one first pair of antenna elements is different from at least one second spacing in between at least one second pair of antenna elements. Some antenna elements being spaced at a certain distance may for instance mean that at least some of the antenna elements are exactly or approximately spaced at said distance.

[0078] As one specific, non-limiting example, in an example smartphone (an example of a user equipment), the electrical distance d in between at least some of the antenna elements may, e.g., range from approximately 0.35A to 7.5A, depending on the selected physical antennas and a selected carrier frequency.It has been found that in particular relatively large distances in between antenna elements may influence the antenna Array Factor (AF) of an array of antenna elements. In other words, the antenna Array Factor may depend (e.g., directly) on respective (e.g., electrical) distances in between the antenna elements of the antenna array. Mathematically, this may be expressed as AF = AF(d). In view of this, the described aspects are particularly advantageous for apparatuses comprising antenna elements being spaced at relatively large distances such as more than 0.5A, 0.7A, or more than A (e.g., smartphones).

[0079] In example embodiments, the precoding control information are determined further based on a mobility of the user equipment (an example of the apparatus according to the first example aspect). In other words, in example embodiments, the precoding control information are determined based on the antenna element distance information and based on the mobility of the apparatus according to the first example aspect. The mobility of the apparatus may for instance correspond to and / or indicate (e.g., quantify) a degree of movement and / or of rotation of the apparatus.

[0080] For example, if it is determined that the apparatus moves and / or rotates (examples of a mobility of the apparatus) relatively fast, precoding control information may be determined that accounts for the relatively high degree of mobility of the apparatus, e.g. by indicating a precoding matrix that combines antenna elements that are spaced relatively close to each other. It has been found that antenna elements that are spaced closer to each other may yield a combined radiation pattern with a broader beamwidth, leading to an enhanced robustness of the combined radiation pattern to mobility of the apparatus. Thus, advantageously, the resulting combined radiation pattern may in this case be less sensitive to movement and / or rotation of the apparatus.

[0081] If it is on the other hand determined that the apparatus moves and / or rotates relatively slow, precoding control information may be determined that accounts for the relatively low degree of mobility of the apparatus, e.g. by indicating a precoding matrix that combines antenna elements that are spaced relatively far apart from each other. It has been found that antenna elements that are spaced relatively far apart from each other may in certain scenarios yield a combined radiation pattern with a narrower beamwidth but offering an enhanced antenna gain. Thus, a performance of the uplink transmission may advantageously be enhanced while an increased sensitivity to a mobility of the apparatus due to the narrower beamwidth may be tolerable.

[0082] The precoding control information may indicate one or more precoding matrices, e.g. from among a plurality of precoding matrices comprised by a precoding codebook, to be used for the uplink transmission. To this end, a Transmit Precoding Matrix Indicator (TPMI) may be used.Thus, in example embodiments, the precoding control information comprises at least one Transmit Precoding Matrix Indicator, TPMI. In example embodiments, the at least one TPMI indicates one or more precoding matrices. A TPMI may allow for selecting a precoding matrix from a precoding codebook.

[0083] Alternatively or in addition, the precoding control information may comprise further information for controlling the precoding.

[0084] As mentioned, based on the precoding control information, an uplink transmission may be performed. In other words, the precoding control information may be used for performing the uplink transmission, e.g. by first precoding the uplink data based on the precoding control information and by then transmitting the precoded uplink data. In example embodiments, performing the uplink transmission based on the precoding control information thus comprises a) precoding data to be included in the uplink transmission based on the precoding control information and b) transmitting the precoded data. Performing an uplink transmission to a network node may comprise transmitting uplink data to the network node. The uplink transmission may in particular comprise or correspond to a Physical Uplink Shared Channel (PUSCH) transmission. Performing the uplink transmission may thus comprise or correspond to performing a PUSCH transmission.

[0085] The antenna element distance information that may be transmitted by the apparatus according to the first example aspect may in particular correspond to the antenna element distance information that may be received by the apparatus according to the second example aspect. Further, the precoding control information that may be received by the apparatus according to the first example aspect may in particular correspond to the precoding control information that may be determined and / or transmitted by the apparatus according to the second example aspect. Further, the uplink transmission performed by the apparatus according to the first example aspect may in particular correspond to the uplink transmission received by the apparatus according to the second example aspect. As a result, the apparatus according to the second example aspect may advantageously be able to effectively control a tradeoff between performance and robustness of a multi-antenna element uplink transmission performed by the apparatus according to the first example aspect.

[0086] Thus, in example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus according to the second example aspect to perform:

[0087] - receiving, from the user equipment, an uplink transmission performed based on the precoding control information.The uplink transmission performed by the apparatus according to the first example aspect may thus in particular correspond to an uplink transmission to the network node.

[0088] As mentioned, according to some of the described aspects, antenna element grouping information grouping at least part of the plurality of antenna elements into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements may be transmitted to and / or received by, e.g., a network node. The spatial arrangement of the plurality of antenna elements may comprise or may correspond to a spatial arrangement (e.g., respective spatial positions) of the plurality of antenna elements with respect (e.g., relative) to each other and / or with respect (e.g., relative) to a predetermined reference position. In other words, the spatial arrangement of the plurality of antenna elements may correspond to an absolute and / or relative positioning of (e.g., each of) the plurality of antenna elements. Said spatial arrangement of the antenna elements may be understood as part of an antenna design of the apparatus.

[0089] The spatial arrangement of the plurality of antenna elements may in particular comprise or correspond to a respective spatial arrangement of each of the plurality of antenna elements. In other words, (e.g., the entirety of) the individual spatial arrangements of the respective antenna elements may form the (e.g., overall) spatial arrangement of the plurality of antenna elements.

[0090] The one or more antenna element groups may for instance comprise at least two antenna element groups. In example embodiments, the one or more antenna element groups comprise (e.g., exactly) two, three or four antenna element groups. An antenna element group may for instance be understood as a group of one or more antenna elements. In other words, one or more antenna elements from among the plurality of antenna elements (e.g., a subset of the plurality of antenna elements) may together form an antenna element group.

[0091] As mentioned, at least part of the plurality of antenna elements associated with the apparatus may be grouped into the one or more antenna element groups. Thus, either part of or all of the plurality of antenna elements may be grouped into the one or more antenna element groups. Grouping antenna elements into antenna element groups may for instance comprise or correspond to collating and / or pooling the antenna elements in respective subsets, said subsets respectively forming the antenna element groups. In other words, (e.g., each of) the at least part of the plurality of antenna elements may be grouped into the one or more antenna element groups by indicating, for a respective antenna element, to which antenna element group it belongs.Grouping the at least part of the plurality of antenna elements into the one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements may for instance comprise or correspond to spatially grouping the at least part of the plurality of antenna elements. Correspondingly, in example embodiments, the one or more antenna element groups correspond to one or more spatial antenna element groups spatially grouping the at least part of the plurality of antenna elements.

[0092] For example, antenna elements arranged in spatial proximity with respect (e.g., relative) to each other, e.g. adjacent antenna elements, may be grouped into a same antenna element group. Further, antenna elements arranged remotely with respect (e.g., relative) to each other (e.g., not arranged in spatial proximity) may for instance be grouped into different antenna element groups.

[0093] In example embodiments, the at least part of the plurality of antenna elements is grouped into the one or more antenna element groups based on one or more threshold values relating to the spatial arrangement of the plurality of antenna elements. The one or more threshold values relating to the spatial arrangement of the plurality of antenna elements may for instance indicate and / or define whether or not two antenna elements are arranged in spatial proximity or not. To this end, the one or more threshold values may comprise or may correspond to one or more distance thresholds respectively representing a respective threshold distance in between respective pairs of antenna elements. A respective threshold distance may correspond to a physical distance or to an electrical distance, as further described herein.

[0094] For example, it may be determined based on the one or more threshold values if one or more first antenna elements are arranged in spatial proximity (e.g., relative) to a second antenna element, e.g. are spaced from the second antenna element within one or more distance thresholds. Based on a result of said determination, the one or more first antenna elements may be grouped into a same antenna element group as the second antenna element (e.g., if the one or more first antenna elements are determined to be arranged in spatial proximity to the second antenna element) or into an antenna element group different from an antenna element group of the second antenna element (e.g., if the one or more first antenna elements are determined to be not arranged in spatial proximity to the second antenna element).

[0095] Thus, in example embodiments, grouping the at least part of the plurality of antenna elements into the one or more antenna element groups based on the one or more threshold values (e.g., one or more distance thresholds) comprises

[0096] - determining, based on the one or more threshold values, that one or more first antenna elements from among the at least part of the plurality of antenna elements are arranged in spatial proximity to a second antenna element from among the at least part of the plurality of antenna elements; andbased thereon, grouping the one or more first antenna elements into a same antenna element group as the second antenna element.

[0097] In example embodiments, at least one of the one or more threshold values is predetermined. Thus, either part of or all of the one of the one or more threshold values may be predetermined. One or more threshold values being predetermined may for example mean that the one or more threshold values are determined (e.g., computed) before a method according to one of the described aspects is performed and / or that the one or more threshold values are (e.g., already) stored in a memory, e.g. of the apparatus and / or of the network node, at the time when a method according to one of the described aspects is performed. The (e.g., stored) threshold values may then be retrieved from said memory and provided (e.g., transmitted) to the apparatus (e.g., a UE).

[0098] Thus, in example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform at least one of:

[0099] - retrieving the one or more threshold values from an internal memory of the apparatus; or

[0100] - receiving the one or more threshold values from the network node.

[0101] Alternatively or in addition to being predetermined, the one or more threshold values may be determined (e.g., dynamically) when performing a method according to one of the described aspects, e.g. by the apparatus or by the network node, and may be retrieved by and / or provided (e.g., transmitted) to the apparatus.

[0102] As mentioned, the antenna element grouping information groups the at least part of the plurality of antenna elements into one or more antenna element groups. For example, the antenna element grouping information may comprise information (e.g., values) indicating at least one respective antenna element group of a respective one of the at least part of the plurality of antenna elements.

[0103] To this end, the antenna element grouping information may for instance comprise or correspond to one or more antenna element group indices, (e.g., each of) the one or more antenna element group indices respectively indicating a respective antenna element group. For example, a first antenna element group index may indicate a first antenna element group, a second antenna element group index may indicate a second antenna element group, and so forth. A respective antenna element group may for instance be indicated as a binary number or binary digit. In example embodiments, the antenna element grouping information thus comprises binary numbers (e.g., bit sequences) or binary digits. In particular binarynumbers or digits allow for reduced complexity and bandwidth requirements when transmitting the antenna element grouping information.

[0104] A respective one (e.g., each) of the plurality of antenna elements may be associated with a Sounding Reference Signal (SRS). Thus, in example embodiments, by grouping a respective one (e.g., each) of the plurality of antenna elements into a respective antenna element group, also the respective SRS associated with the respective antenna element will be associated with the respective antenna element group, for instance by using a single multi-port SRS resource for a respective antenna element group.

[0105] In example embodiments, the antenna element grouping information comprises antenna element identification information identifying a respective antenna element of the at least part of the plurality of antenna elements, and grouping information indicating a respective antenna element group of the one or more antenna element groups into which the respective antenna element is grouped. In other words, the grouping information and the antenna element identification information may together form the antenna element grouping information.

[0106] The grouping information may in particular comprise information (e.g., values) indicating at least one respective antenna element group of a respective antenna element, as further described herein. The antenna element identification information may comprise or correspond to information for identifying a respective antenna element grouped into a respective antenna element group. To this end, in example embodiments, the antenna element identification information comprises or corresponds to at least one antenna element identifier for respectively identifying the respective antenna elements grouped into respective antenna element groups.

[0107] In example embodiments, the antenna element identification information comprises or corresponds to binary numbers (e.g., bit sequences) or binary digits. For example, a first binary number or a first binary digit may identify a first antenna element (e.g. being grouped into a first antenna element group), a second binary number or a second binary digit may identify a second antenna element (e.g. also being grouped into the first antenna element group or being grouped into a second antenna element group), and so forth. In particular binary numbers or digits allow for reduced complexity and bandwidth requirements when identifying the antenna element(s).

[0108] The antenna element grouping information may thus comprise two information blocks, the grouping information as a first information block and the antenna element identification information as a second information block. Thereby, a respective (e.g., each) value comprised by one of the two information blocksmay be implicitly or explicitly associated with at least one corresponding value comprised by the respective other information block. For example, a respective (e.g., each) each antenna element identification value comprised by the antenna element identification information may be associated with a respective value indicating at least one respective antenna element group, and vice versa.

[0109] The grouping information and the antenna element identification information may be comprised by the antenna element grouping information in a manner such as to ensure an association in between respective values comprised by the grouping information and respective values comprised by the antenna element identification information. In other words, the grouping information and the antenna element identification information may be stored in association within the antenna element grouping information. In this way, respective antenna element groups may be indicated for the at least part of the plurality of antenna elements.

[0110] In example embodiments, the antenna element grouping information is obtained by the apparatus according to the third example aspect. For example, the antenna element grouping information may be retrieved from an internal memory of the apparatus and / or may be determined by the apparatus. For instance, the antenna element grouping information may be determined by the apparatus based on one or more physical distance values, e.g. stored in and / or retrieved from an internal memory of the apparatus, and further based on one or more carrier frequencies to be used for the uplink transmission.

[0111] Thus, in example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus according to the third example aspect to perform:

[0112] - determining (e.g., computing) the antenna element grouping information at least in part based on one or more carrier frequencies to be used for the uplink transmission.

[0113] To this end, first, respective wavelengths may be determined (e.g., computed) based on respective carrier frequencies (e.g., forming a frequency band) to be used for the uplink transmission. Then, respective electrical distance values may be determined (e.g., computed) based on the physical distance values and based on the wavelengths. Based on the electrical distance values, the at least part of the plurality of antenna elements may then for example be grouped into the one or more antenna element groups based on one or more electrical distance thresholds (e.g., threshold values with respect to an electrical distance).

[0114] As mentioned, the one or more carrier frequencies to be used for the uplink transmission may correspond to one or more radio frequencies to be used by the respective apparatus (e.g., a UE) for performing theuplink transmission. Further, as mentioned, respective wavelengths may be determined based on the one or more carrier frequencies.

[0115] Alternatively or in addition to grouping antenna elements into antenna element groups based on electrical distance values, the at least part of the plurality of antenna elements may be grouped into the one or more antenna element groups (e.g., directly) based on the one or more physical distance values based on one or more physical distance thresholds (e.g., threshold values with respect to a physical distance).

[0116] It has been found that in particular grouping antenna elements based on electrical distances is suitable to account for the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances and, as a result, to control the precoding in an advantageous manner, as further described herein. Further, grouping antenna elements based on physical distances has been found to allow for a reduced complexity of determining and / or communicating a grouping reflecting a spatial arrangement of antenna elements in particular due to the physical distances being time-independent.

[0117] The determined grouping information (e.g., one or more values indicating respective antenna element groups) may then be associated with corresponding antenna element identification information in order to provide the antenna element grouping information.

[0118] In example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform:

[0119] - indicating, to the network node, a capability of the apparatus to provide antenna element grouping information.

[0120] In other words, the apparatus may indicate to the network node that it is capable of and / or configured for determining and / or transmitting antenna element grouping information, as further described herein. To this end, the apparatus may transmit an indication of the capability to provide antenna element grouping information to the network node (e.g., as part of a capability report of the apparatus). In this way, the network node may advantageously be informed that precoding control information to be provided to the apparatus may be determined (also) based on antenna element grouping information.

[0121] As mentioned, the antenna element grouping information may be transmitted (e.g., communicated) by the apparatus to the network node. In example embodiments, the antenna element grouping information is transmitted by the apparatus to the network node as part of at least one of:

[0122] o Uplink Control Information, UCI; oro a Medium Access Control, MAC, control element.

[0123] The antenna element grouping information may thus for instance be transmitted to the network node by the apparatus via the Physical Uplink Control Channel (PUCCH) and / or via a MAC-CE (Control Element). The antenna element grouping information may be transmitted as part of an existing UCI and / or MAC-CE (e.g., serving also a different purpose) and / or as part of a dedicated UCI and / or MAC-CE (e.g., serving only the purpose of grouping antenna elements).

[0124] As mentioned, by grouping a respective one (e.g., each) of the plurality of antenna elements into a respective antenna element group, also a respective SRS associated with the respective antenna element may be associated with the respective antenna element group. Thus, in example embodiments, a respective antenna element group associated with a respective SRS associated with a respective antenna element grouped into the antenna element group is indicated to the network node by the SRS (e.g., by virtue of the respective SRS being associated with the respective antenna element which may be grouped into the antenna element group). The antenna element grouping information may thus be transmitted by the apparatus to the network node as part of a plurality of SRS being respectively associated with the plurality of antenna elements.

[0125] As mentioned, the precoding control information may be determined at least in part based on the antenna element grouping information. In other words, in example embodiments, the antenna element grouping information is used for determining the precoding control information, e.g. by selecting appropriate antenna elements (e.g., antennas or antenna ports) to use for precoding the uplink transmission and / or by excluding specific antenna elements (e.g., antennas or antenna ports) from being used for precoding the uplink transmission. For example, the precoding control information may be determined such that a desired and / or required combined radiation pattern and a desired antenna gain is achieved when performing the uplink transmission based on the determined precoding control information and using the plurality of antenna elements associated with the apparatus, with the antenna elements being spatially arranged as indicated by the antenna element grouping information. In particular in this way, the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances on a combined radiation pattern may advantageously be accounted for, as further described herein.

[0126] In example embodiments, the precoding control information are determined further based on a mobility of the user equipment (an example of the apparatus according to the third example aspect). In other words, in example embodiments, the precoding control information are determined based on the antenna element grouping information and based on the mobility of the apparatus according to the third example aspect. Themobility of the apparatus may for instance correspond to and / or indicate (e.g., quantify) a degree of movement and / or of rotation of the apparatus.

[0127] For example, if it is determined that the apparatus moves and / or rotates (examples of a mobility of the apparatus) relatively fast, precoding control information may be determined that accounts for the relatively high degree of mobility of the apparatus, e.g. by indicating a precoding matrix that combines antenna elements that are spaced relatively close to each other (e.g., antenna elements being grouped together). It has been found that antenna elements that are spaced closer to each other may yield a combined radiation pattern with a broader beamwidth, leading to an enhanced robustness of the combined radiation pattern to mobility of the apparatus. Thus, advantageously, the resulting combined radiation pattern may in this case be less sensitive to movement and / or rotation of the apparatus.

[0128] If it is on the other hand determined that the apparatus moves and / or rotates relatively slow, precoding control information may be determined that accounts for the relatively low degree of mobility of the apparatus, e.g. by indicating a precoding matrix that combines antenna elements that are spaced relatively far apart from each other (e.g., antenna elements not being grouped together). It has been found that antenna elements that are spaced relatively far apart from each other may in certain scenarios yield a combined radiation pattern with a narrower beamwidth but offering an enhanced performance. Thus, a performance of the uplink transmission may advantageously be enhanced while an increased sensitivity to a mobility of the apparatus due to the narrower beamwidth may be tolerable.

[0129] The antenna element grouping information that may be transmitted by the apparatus according to the third example aspect may in particular correspond to the antenna element grouping information that may be received by the apparatus according to the fourth example aspect. Further, the precoding control information that may be received by the apparatus according to the third example aspect may in particular correspond to the precoding control information that may be determined and transmitted by the apparatus according to the fourth example aspect. Further, the uplink transmission performed by the apparatus according to the third example aspect may in particular correspond to the uplink transmission received by the apparatus according to the fourth example aspect. As a result, the apparatus according to the fourth example aspect may advantageously be able to effectively control a tradeoff between performance and robustness of a multi-antenna element uplink transmission performed by the apparatus according to the third example aspect.

[0130] Thus, in example embodiments, the instructions, when executed by the at least one processor, further cause the apparatus according to the fourth example aspect to perform:receiving, from the user equipment, an uplink transmission performed based on the precoding control information.

[0131] The uplink transmission performed by the apparatus according to the third example aspect may thus in particular correspond to an uplink transmission to the network node.

[0132] As used herein, performing a second step based on a first step may for example mean that the second step may be performed, e.g. directly, in response to the first step, e.g. without any intermediate steps in between the first step and the second step. Alternatively, performing a second step based on a first step may mean that the second step may be performed (merely) after the first step, e.g. such that there may be at least one intermediate step in between the first step and the second step.

[0133] It is to be understood that the presentation of the embodiments disclosed herein is merely by way of examples and non-limiting.

[0134] Herein, the disclosure of a method step shall also be considered as a disclosure of means for performing the respective method step. Likewise, the disclosure of means for performing a method step shall also be considered as a disclosure of the method step itself.

[0135] Other features of the present disclosure will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the present disclosure, for which reference should be made to the appended claims. It should be further understood that the drawings are not drawn to scale and that they are merely intended to conceptually illustrate the structures and procedures described herein.

[0136] BRIEF DESCRIPTION OF THE FIGURES

[0137] Some example embodiments will now be described with reference to the accompanying drawings in which

[0138] FIG. 1 exemplarily illustrates a user equipment and a network node in wireless communication;

[0139] FIGS. 2A-2F exemplarily illustrate various combined radiation patterns;

[0140] FIGS. 3A, 3B exemplarily illustrate two of the radiation patterns of FIGS. 2A-2F in a one-dimensional cut;FIG. 4 shows an example embodiment of a method according to the first example aspect;

[0141] FIG. 5 shows an example embodiment of a method according to the second example aspect;

[0142] FIG. 6 shows an example embodiment of a method according to the third example aspect;

[0143] FIG. 7 shows an example embodiment of a method according to the fourth example aspect;

[0144] FIG. 8 shows an example of a signaling flow chart according to example embodiments of the described aspects;

[0145] FIG. 9 shows a block diagram of an example of an apparatus according to some of the described aspects;

[0146] FIG. 10 shows a block diagram of an example of an apparatus according to some of the described aspects;

[0147] FIG. 11 shows a schematic illustration of examples of tangible and non-transitory computer- readable storage media.

[0148] DETAILED DESCRIPTION OF THE FIGURES

[0149] The following description serves to deepen the understanding of the present disclosure and shall be understood to complement and be read together with the description of example embodiments of the present disclosure as provided in the above SUMMARY section of this specification.

[0150] In the following, an example wireless communication system, within which the present disclosure may be applied, is described. While the radio system in the examples below is a 5G / NR system, this is only to be considered a non-limiting example.

[0151] FIG. 1 exemplarily illustrates a UE 100 (an example of the apparatus according to the first example aspect and of the apparatus according to the third example aspect) in wireless communication with a gNB 110 (an example of the apparatus according to the second example aspect and of the apparatus according to the fourth example aspect) via a radio link 10. Radio link 10 may enable transmitting / receiving information and / or signals in between the UE 100 and the gNB 110.For example, UE 100 may transmit, to gNB 110 (an example of a network node), antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with UE 100. Further, UE 100 may receive, from gNB 110, precoding control information determined at least in part based on the transmitted antenna element distance information. Further, UE 100 may perform an uplink transmission to gNB 110 based on the received precoding control information.

[0152] Correspondingly, gNB 110 may receive, from UE 100, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with UE 100. Further, gNB 110 may determine, at least in part based on the received antenna element distance information, precoding control information. Further, gNB 110 may transmit the precoding control information to UE 100. Further, gNB 110 may receive, from UE 100, an uplink transmission performed based on the precoding control information.

[0153] Further, alternatively or in addition, UE 100 may transmit, to gNB 110, antenna element grouping information grouping at least part of a plurality of antenna elements associated with UE 100 into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements.

[0154] Further, UE 100 may receive, from gNB 110, precoding control information determined at least in part based on the transmitted antenna element grouping information. Further, UE 100 may perform an uplink transmission to gNB 110 based on the received precoding control information.

[0155] Correspondingly, gNB 110 may receive, from UE 100, antenna element grouping information grouping at least part of a plurality of antenna elements associated with UE 100 into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements. Further, gNB 110 may determine, at least in part based on the received antenna element grouping information, precoding control information. Further, gNB 110 may transmit the precoding control information to UE 100. Further, gNB 110 may receive, from UE 100, an uplink transmission performed based on the precoding control information.

[0156] As indicated in FIG. 1, example UE 100 comprises four antenna ports (AP) 104a, 104b, 104c, 104d.

[0157] Antenna ports 104a, 104b are located at the top of UE 100, antenna ports 104c, 104d are located at the bottom of UE 100. Antenna ports 104a, 104b may be grouped into a top antenna element group 40 (a first example of an antenna element group), antenna ports 104c, 104d may be grouped into a bottom antenna element group 50 (a second example of an antenna element group). A distance in between antenna ports 104a and 104b is smaller than a distance in between each of antenna ports 104a, 104b and each of antenna ports 104c, 104d. A radiation pattern of each of antenna ports 104a-104d may be essentially omnidirectional in the azimuthal direction (e.g., having only a slight directivity, for instance of about 5 d Bi) .A combined radiation pattern at UE 100 may result from a phase-shifted superposition of the (essentially omnidirectional) individual radiation patterns of the respective antenna ports 104a-104d (or a subset thereof), and may be used for performing a respective beamformed / precoded uplink transmission (an example of a multi-antenna uplink transmission).

[0158] Now, in accordance with example embodiments of the present disclosure, the impact of the spacing of antenna ports 104a-104d and / or of their spatial arrangement on a resulting combined radiation pattern of the antenna elements may be advantageously taken into account. To this end, UE 100 may transmit antenna element distance information (e.g., information about the spacing of antenna ports 104a-104d) and / or antenna element grouping information (e.g., information about a spatial grouping of antenna ports 104a-104d) to gNB 110. Based on the transmitted antenna element distance information and / or on the transmitted antenna element grouping information, gNB 110 may then determine precoding control information to be used for an uplink transmission to be performed by UE 100 to gNB 110. In particular, based on said distances in between antenna ports 104a-104d and / or the spatial arrangement of antenna ports 104a-104d, the precoding may be controlled by gNB 110 such as to optimize a tradeoff between an uplink performance (e.g., throughput) and a robustness of the uplink (e.g., with respect to a mobility of UE 100).

[0159] The following may be considered as important types of device categories in the 5G / NR standard:

[0160] a) eMBB (enhanced Mobile Broadband) 5G devices, in particular smartphones, tablets and / or mobile hotspot routers;

[0161] b) Outdoor and / or indoor Customer Premise Equipment (CPE) for 5G Fixed Wireless Access (FWA);

[0162] c) Different type of 5G S-modules, e.g. for industrial applications.

[0163] These devices may vary significantly in size (e.g., form factor), with highly different antenna design from a number of antennas to frequency coverage, antenna placement relative to the device chassis (e.g., ground plane) and antenna characteristics, like radiation patterns. Devices like FWAs and CPEs may be designed with antennas having well defined and uniform characteristics, which may fit well the current 3GPP 5G uplink (UL) MIMO codebooks, as said codebooks are derived and optimized for antennas with uniform characteristics.5G UL MIMO capable devices may in particular rely on Codebook based UL MIMO that utilizes the codebooks specified in 3GPP Technical Specification (TS) 38.211 for different layer and Antenna Port (AP) combinations (e.g., for 1 , 2 or 4 APs).

[0164] The precoding values in said codebooks may have been derived under the assumption that the individual antenna elements have same antenna characteristics and are spaced uniformly, typically between 0.5A to OJA, with the wavelength A corresponding to a respective carrier frequency according to A = c / , with the carrier frequency f and the phase velocity c. This approach may result in an overall good performance and coverage of the 3GPP defined UL MIMO codebook with well-defined combined radiation patterns having a single high gain main beam with high side lobe suppressions of, e.g., more than 13 dB for boresight beam configuration.

[0165] Smartphones, which may be considered as a dominant device type in terms of market share and traffic, may however not be implemented with antennas having uniform spacing between 0.5A to 0.7A, as exemplary illustrated for UE 100 in FIG. 1. As an example, a smartphone may have a physical size of 10 mm x 70 mm x 150 mm (thickness, width, length). Further, as an example, a smartphone may be implemented with 14 antennas to allow for 4x4 (four-antenna four-layer) MIMO and may support the following frequency ranges (e.g., including both 2G, LTE, 5G and various potential frequency ranges for 6G):

[0166] • 2 x LB (Low-Band) antennas = 699 MHz to 960 MHz

[0167] • 4 x MHB (Mid-High Band) antennas = 1710 MHz to 2690 MHz

[0168] • 4 x UHB (Ultra-High Band) antennas = 3300 MHz to 4800 MHz (including 6G-1 (4400 MHz to 4800 MHz))

[0169] • 4 x 6G-2 antennas = 7125 MHz to 8400 MHz

[0170] • 4 x 6G-3 antennas = 14800 MHz to 15350 MHz

[0171] The above represents one possible example antenna implementation. Other UEs may be implemented with a different number of physical antennas covering different combinations of frequency bands.

[0172] An important observation in accordance with the present disclosure is that smartphone antennas may be not positioned in a uniform grid of half a wavelength (i.e., A / 2), which may be the spacing of elements for a Uniform Linear Array (ULA). As a result, respective electrical distances (e.g., respective physical distances in units of wavelength) between the APs on a UE may depend on the selected physical antennas and / or ona current configured system frequency (an example of a carrier frequency), which translates into possible electrical distances between two APs ranging from approximately 0.35A to 7.5A, for the above example.

[0173] Such non-uniform and / or relatively large spacing, and / or spatial arrangement will have a large impact on the combined radiation patterns using the precoding entries of the codebooks specified in 3GPP TS 38.211. This is however not reflected by 3GPP evaluation models, where UE antennas for FR1 may, e.g., be modelled as sets of two orthogonal isotropic or dipole antennas, each set space with a distance of half a wavelength.

[0174] In view of this, certain embodiments of the present disclosure may have the effect of improving precodingbased multi-antenna element uplink transmissions, e.g. when being performed by consumer devices such as smartphones. In particular, certain embodiments of the present disclosure may enable to account for the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances on a combined radiation pattern of the antenna elements.

[0175] The combined radiation pattern of multiple antennas may in particular depend on the radiation patterns of the individual antennas and respective electrical distances between the antennas. Said electrical distances may, e.g., be derived from respective (e.g., temporally constant) physical distances and a respective (e.g., temporally variable) system frequency (e.g., carrier frequency). At least some of these properties may be unknown to the gNB. As a result, the gNB may not be able to derive which precoding value (e.g., TPMI) is best for the current channel conditions (considering that the electrical properties of the UE antennas may be seen as part of the channel estimation). In particular, the gNB may not be able to estimate an actual shape of the combined radiation pattern a specific TPMI will cause at the UE. The radiation patterns of the individual antennas at the UE may also be unknown to the UE itself, since the UE (e.g., a smartphone) may be affected by a user of the UE and / or by objects in its near-field environment.

[0176] However, in accordance with the example aspects of the present disclosure, respective electrical distances between multiple selected antennas and / or a spatial arrangement of multiple selected antennas may be known to the UE and may be directly related to the antenna Array Factor (AF), which can be expressed as follows:

[0177] > > <>

[0178]

[0179] where:

[0180] • k = 2n / (angular wavenumber).

[0181] • N = Number of antenna elements in the x-direction.

[0182] • M = Number of antenna elements in the y-direction.

[0183] • ) = Gain of the (nthmth) antenna element in the angular direction of (0, ).

[0184] • dxn= Distance in the x-direction from the nthelement to the first element.

[0185] • dyn= Distance in the y-direction from the nthelement to the first element.

[0186] • ft = Relative phase shift (precoding phase value).

[0187] FIGS. 2A-2F exemplarily illustrate various combined radiation patterns 20a-20f of two antennas being spaced from each other at various distances. In particular, FIGS. 2A-2F show the effect of the AF on the combined radiation patterns 20a-20f for distances between the two antennas provided in units of wavelength, namely as the electrical distance between the two antennas increases from 0.35A (FIG. 2A) over 0.5A (FIG. 2B), A (FIG. 20), 2A (FIG. 2D) and 4A (FIG. 2E) to 7.5A (FIG. 2F). A respective dot hatching in FIGS. 2A-2F indicates a respective radiated power in units of dBi. A maximum gain varies from 1.7 dBi (FIG. 2A) to 3.0 dBi (FIGS. 2B-2F). The effective gain amounts to 0.0 dBi in FIGS. 2A-2F.

[0188] As can be seen in particular in FIGS. 2C-2F, there is a ripple 21 for relatively large electrical distances (e.g., larger than 0.5A) in between the two antennas affecting the combined radiation patterns 20c-20f. The radiation patterns shown in FIGS. 2A-2F correspond to the radiation pattern of a UE comprising two antennas having isotropic characteristics. Further, it has been found in accordance with the present disclosure that the ripple of the combined radiation patterns of multiple antennas such as ripple 21 exemplarily illustrated in FIGS. 2C-2F is decisive also for directive UE antennas.

[0189] As a result, in accordance with the present disclosure, combining antennas with relatively large electrical distances between the antennas has been found to result in a relatively strong ripple over the angular domain of the radiation pattern as exemplarily shown in the 2D-cuts in FIGS. 3A, 3B.

[0190] FIGS. 3A, 3B exemplarily illustrate radiation patterns 20e (4A) and 20f (7.5A) in respective one-dimensional cuts. More specifically, FIGS. 3A, 3B show the impact of the angular ripple 31 caused by the array factor on the antenna gain 30a, 30b provided in units of dBi as a function of the azimuth provided in degrees (°). The 3 dB radiation bandwidth of the beams around an azimuth of zero amounts to only about 8.0° for an electrical distance of 4A (FIG. 3A) and amounts to only about 4.5° for an electrical distance of 7.5A (FIG.

[0191] 3B).As a result, it has been found that precoding an uplink signal to be transmitted via two antennas with such electrical distances in between them may be highly sensitive to changes in the uplink transmission channel, e.g. movement and / or rotation of the UE (examples of a mobility of the UE).

[0192] In accordance with examples of the present disclosure, it has been found to be beneficial for the gNB in such a scenario to select a precoding of antennas with smaller electrical spacing to configure the UE with a radiation pattern having a broader 3dB radiation beamwidth, thus reducing a risk of having a null towards a main signal path towards the gNB (an example of improving a robustness of an uplink transmission), even though one or more other precoding values for antennas with a larger electrical spacing may have a potentially better MIMO performance (e.g., throughput), e.g. may be better suited for the current channel condition in terms of performance.

[0193] In view of the above, certain embodiments of the present disclosure may enable to account for the impact of a non-uniform spacing of antenna elements and / or of antenna elements being spaced at relatively large distances on a combined radiation pattern of the antenna elements in order to enable a gNB to effectively control a tradeoff between a high performance narrow beam but mobility-sensitive UE pattern selection (e.g., TPMI), versus a broad beam UE pattern selection with less performance but higher robustness to rotation / mobility. To this end, example embodiments of the present disclosure enable the UE to communicate one or more current electrical distances between configured Antenna Ports and / or a spatial grouping of the configured Antenna Ports to the gNB.

[0194] An example smartphone may support up to four layers for various frequency bands, e.g. above 1 GHz, for example with two antenna ports in the top of the smartphone and two antenna ports in the bottom of the smartphone, as exemplarily illustrated in FIG. 1 for UE 100. In the following are disclosed four example embodiments enabling a UE to signal the corresponding distances and / or spatial arrangement of the antenna ports of said example smartphone to a gNB:

[0195] Example embodiment #1

[0196] The individual electrical distances between four AP can be expressed by a total of six combinations that may be represented by 3-Bits (an example of antenna element identification information that comprises or corresponds to binary numbers), for example as follows:

[0197] Bit #000 = AP#1 to AP#2

[0198] Bit#007 = AP#1 to AP#3Bit #010 = AP#1 to AP#4

[0199] Bit#011 = AP#2 to AP#3

[0200] Bit#700 = AP#2 to AP#4

[0201] Bit#7O7 = AP#3 to AP#4

[0202] The electrical distance (d) for each AP combination can be represented by, e.g., the following 2-Bit interval (an example of distance range division values that comprise or correspond to binary numbers indicating said distance ranges):

[0203] Bit #00 = d < 1A

[0204] Bit #01 = 1A < d < 2A

[0205] Bit #10 = 2A < d < 4A

[0206] Bit #11 = d > 4A

[0207] The numbering of the AP may be linked to the allocated SRS resources (an example of antenna elements being associated with Sounding Reference Signals), whereby the UE may have to update the electrical distance for the AP combinations if it changes its AP to physical antenna mapping. This may for instance be communicated via UCI or MAC-CE. The number of Bits used for the electrical distance may be expanded to more than 2 Bits, advantageously allowing for a higher granularity of the distance intervals.

[0208] Example embodiment #2

[0209] The individual electrical distances between four AP may be reduced to four combinations, where the two diagonal combinations may be removed, as said combinations may be estimated from the remaining four reported electrical antenna port distances (an example of antenna element distance information that relates to only part of the plurality of antenna elements). The resulting four combinations may then be represented by 2-Bits, i.e. one bit less than Example embodiment #1 :

[0210] Bit #00 = AP#1 to AP#2

[0211] Bit #01 = AP#1 to AP#3

[0212] Bit #10 = AP#2 to AP#4

[0213] Bit#ll = AP#3 to AP#4

[0214] The electrical distance for each AP combination may be represented by the same 2-Bit interval as for Example embodiment #1.Example embodiment #3

[0215] The UE may also signal the physical distance (p) between the APs, as the gNB may know the currently used system frequency, as shown below:

[0216] Bit #00 = p < 50 mm

[0217] Bit #01 = 50 mm < p < 100 mm

[0218] Bit #10 = 100 mm < p < 150 mm

[0219] Bit #11 = p > 150 mm

[0220] Such an implementation may require more than 2 Bits, as the accuracy of the interval may depend on the system frequency. For example, the above physical distance ranges may translate into the following electrical distance ranges for 2.0 GHz (left), 7.5 GHz (middle), and 15.0 GHz (right):

[0221] Bit #00 = d < 0.33A Bit #00 = d < 1.25A Bit #00 = d < 2.50A

[0222] Bit #01 = 0.33A < d < 0.67A Bit #01 = 1.25A < d < 2.50A Bit #01 = 2.50A < d < 5.00A Bit# 0 = 0.67 < d < 1.00A Bit #10 = 2.50A < d < 3.75A Bit #10 = 5.00A < d < 7.50A Bit #11 = d > 1.00A Bit #11 = d > 3.75 A Bit #11 = d > 7.50A

[0223] 2.0 GHz 7.5 GHz 15.0 GHz

[0224] Example embodiment #4

[0225] The fourth example embodiment categorizes each UE antenna into a Spatial Antenna Group (SAG) (an example of the at least one antenna element group). In this way, when the UE transmits SRS, the UE may inform the gNB about which SAG each SRS belongs to as the SRS may be transmitted on a per UE AP basis.

[0226] A new signaling may be defined to associate each (active) SRS port (i.e. 1001 to 1003) to a SAG. This may for example be done via a new uplink control information UCI or MAC-CE.

[0227] This association may be defined as fixed / constant in the UE capabilities. Alternatively or in addition, the SRS port may be remapped to a respective SAG via UCI in a dynamic fashion, e.g. by using a corresponding parameter, for instance a parameter dynamicSRSport2SAG. This parameter may for instance be dynamic in size of used bits. For example, 4 SRS port may give 4 bits payload, and 2 SRS port may give 2 bits payload.The UE may configure the different SAGs based on the physical or electrical distances in between the APs (an example of grouping antenna elements into antenna element groups based on their spatial arrangement). For example, a first SAG may be the two AP located at the top of the phone, while a second SAG may be the two AP located at the bottom of the phone. The number of spatial groups may be expanded to 4, 8 etc. if desired and / or required, and the UE may allocate more AP for some spatial AP groups than for other spatial AP groups.

[0228] Example embodiment #4 may only require one (e.g., single) bit for each AP, thereby saving bandwidth.

[0229] A distance value either electrical or physical may be defined that the UE may use for allocating APs to one or the other spatial group. That distance value may be a fixed predetermined value (an example of a predetermined threshold value) or may be dynamically communicated by the gNB to the UE (an example of a threshold value being determined dynamically). This approach may result in all APs belonging to a same AP group, where all SRSs transmitted with a SAG value of zero may be interpreted by the gNB to mean that the distances between all APs are less than the distance value for the AP groups. Spatial AP group values of one for all APs may be interpreted by the gNB that the distances between all APs are greater than the distance value for the AP groups.

[0230] The described aspects may be considered to offer in particular one or more of the following advantages:

[0231] • Enabling a gNB to estimate a shape of combined radiation pattern of a UE.

[0232] • Enabling a gNB to avoid precoding indexes (e.g., TPMI) that combine antenna ports with a large electrical distance, in particular for high-speed UE and / or rotating UEs (examples of UE mobility).

[0233] • Enable a gNB to fast and effectively switch between TPMI categories, thus controlling the robustness vs performance tradeoff as further described herein.

[0234] • Enabling a gNB to update a TPMI selection if a UE changes a mapping between physical antennas and antenna ports.

[0235] Said advantages may be considered to be in particular achieved by one or more of the following:

[0236] • Reporting of (e.g., all) AP pairs and the electrical distances between these AP pairs.

[0237] • Reporting of (e.g., only) a subset of AP pairs and the electrical distances between these AP pairs.

[0238] • Reporting of spatial AP groups, e.g. via SRS.

[0239] FIG. 4 shows an example embodiment 400 of a method according to the first example aspect. Method 400 may for example be performed by an apparatus according to the first example aspect (e.g., a UE). First,antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus may be transmitted to a network node (action 410). Further, precoding control information determined at least in part based on the antenna element distance information may be received from the network node (action 420). Further, an uplink transmission may be performed based on the precoding control information (action 430).

[0240] An example implementation of method 400 will be described in detail further below with respect to FIG. 8.

[0241] FIG. 5 shows an example embodiment 500 of a method according to the second example aspect. Method 500 may for example be performed by an apparatus according to the second example aspect (e.g., a network node). First, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the user equipment may be received from a user equipment (action 510). Further, precoding control information may be determined at least in part based on the antenna element distance information (action 520). Further, the precoding control information may be transmitted to the user equipment (action 530).

[0242] An example implementation of method 500 will be described in detail further below with respect to FIG. 8.

[0243] FIG. 6 shows an example embodiment 600 of a method according to the third example aspect. Method 600 may for example be performed by an apparatus according to the third example aspect (e.g., a UE). First, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the apparatus into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements may be transmitted to a network node (action 610). Further, precoding control information determined at least in part based on the antenna element grouping information may be received from the network node (action 620). Further, an uplink transmission may be performed based on the precoding control information (action 630).

[0244] FIG. 7 shows an example embodiment 700 of a method according to the fourth example aspect. Method 700 may for example be performed by an apparatus according to the fourth example aspect (e.g., a network node). First, antenna element grouping information grouping at least part of a plurality of antenna elements associated with the user equipment into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements may be received from a user equipment (action 710). Further, precoding control information may be determined at least in part based on the antenna element grouping information (action 720). Further, the precoding control information may be transmitted to the user equipment (action 730).In the following, an example implementation of methods 400, 500 is described.

[0245] FIG. 8 shows an example of a signaling flow chart 800 between UE 100 and gNB 110 according to example embodiments of the described aspects. Flow chart 800 comprises the following actions:

[0246] Action 801 : UE 100 is assumed to be RRC connected with gNB 110 (an example of radio link 10).

[0247] Action 802: UE 100 sends a UE capability report to gNB 110 that may include the capability to signal Antenna Port electrical spacing (an example of indicating a capability of the apparatus to provide antenna element distance information). Alternatively or in addition, the capability report may include the capability to signal a spatial grouping of the antenna ports (an example of indicating a capability of the apparatus to provide antenna element grouping information).

[0248] Action 803: gNB 110 initiates Codebook-Based UL MIMO.

[0249] Action 804: gNB 110 allocates resources for a number of SRS transmissions equal to the number of supported AP atthe UE.

[0250] Action 805: UE 100 transmits SRSs with for the gNB an unknown AP to physical antenna mapping for each SRS resource.

[0251] Action 806: UE 100 transmits the electrical AP distances for the current AP mapping, e.g. via UCI (an example of transmitting antenna element distance information indicative of at least one distance in between a plurality of antenna elements). Alternatively or in addition, UE 100 may transmit a spatial grouping of the antenna ports to gNB 110 (an example of transmitting antenna element grouping information grouping at least part of a plurality of antenna elements into one or more antenna element groups based on a spatial arrangement of the plurality of antenna elements).

[0252] Action 807: gNB 110 derives the best TPMI taking into account the electrical AP distances and UE mobility (an example of determining the precoding control information based on the antenna element distance information and further based on the mobility of the apparatus). Alternatively or in addition, gNB 110 may derive the bestTMPI taking into account UE mobility and the spatial grouping of the antenna ports (an example of determining the precoding control information based on the antenna element grouping information and further based on the mobility of the apparatus).Action 808: gNB 110 informs UE 100 of the selected TPMI, e.g. via DCI (an example of transmitting precoding control information to the user equipment).

[0253] Action 809: UE 100 applies the informed precoding (TPMI) (an example of precoding uplink data based on precoding control information).

[0254] Action 810: UE 100 transmits the pre-coded UL MIMO layers (an example of performing the uplink transmission based on the precoding control information).

[0255] In particular by UE 100 transmitting the electrical AP distances and / or the spatial grouping of the antenna ports to gNB 110 (action 806), by gNB 110 deriving the best TPMI taking into account UE mobility and the electrical AP distances and / or the spatial grouping (action 807) and informing UE 100 of the selected TPMI (action 808), and by UE 100 applying the precoding (action 809) and transmitting the pre-coded UL MIMO layers (action 810), the precoding may be controlled by gNB 110 such as to optimize a tradeoff between an uplink performance and a robustness of the uplink to a mobility of UE 100, as further described herein. In particular, the Array Factor may have a strong influence on a combined antenna radiation pattern and communicating electrical distances between APs to a gNB may enable to calculate the Array Factor for different precoding values and to thereby estimate an excited radiation pattern at a UE for different TPMIs.

[0256] FIG. 9 shows a block diagram of an example 100 of an apparatus according to the first example aspect and / or according to the third example aspect (e.g., a UE). For example, apparatus 100 may be one of a smartphone, a tablet computer, a notebook computer, a smart watch, a smart band, an loT device or a vehicle or a part thereof.

[0257] Apparatus 100 comprises a processor 101. Processor 101 may represent a single processor or two or more processors, which are for instance at least partially coupled, for instance via a bus. Processor 101 executes a program code stored in program memory 102 (for instance program code causing apparatus 100 in connection with an apparatus 110 according to the second example aspect and / or according to the fourth example aspect to perform one or more of the example embodiments of a method according to any of the described aspects or parts thereof, when executed on processor 101, and interfaces with a main memory 103. Program memory 102 may also contain an operating system for processor 101. Some or all of memories 102 and 103 may also be included into processor 101.One of or both of a main memory and a program memory of a processor (e.g. program memory 102 and main memory 103) could be fixedly connected to the processor (e.g. processor 101) or at least partially removable from the processor, for instance in the form of a memory card or stick.

[0258] A program memory (e.g. program memory 102) may for instance be a non-volatile memory. It may for instance be a FLASH memory (or a part thereof), any of a ROM, PROM, EPROM, MRAM or a FeRAM (or a part thereof) or a hard disc (or a part thereof), to name but a few examples. For example, a program memory may for instance comprise a first memory section that is fixedly installed, and a second memory section that is removable from, for instance in the form of a removable SD memory card.

[0259] A main memory (e.g. main memory 103) may for instance be a volatile memory. It may for instance be a DRAM memory, to give non-limiting example. It may for instance be used as a working memory for processor 101 when executing an operating system, an application, a program, and / or the like.

[0260] Processor 101 further controls a communication interface 104 (e.g. radio interface) configured to receive and / or transmit data and / or information. For instance, communication interface 104 may be configured to transmit and / or receive radio signals from a network node, in particular as described herein. It is to be understood that any computer program code based processing required for receiving and / or evaluating radio signals may be stored in an own memory of communication interface 104 and executed by an own processor of communication interface 104 and / or it may be stored for example in memory 103 and executed for example by processor 101.

[0261] Communication interface 104 may in particular be configured to communicate according to a cellular communication system like a 2G / 3G / 4G / 5G or future generation cellular communication system, e.g. 6G. Apparatus 100 may use radio interface 104 to communicate with a network node.

[0262] For example, the communication interface 104 may further comprise a BLE and / or Bluetooth radio interface including a BLE transmitter, receiver or transceiver. For example, radio interface 104 may additionally or alternatively comprise a WLAN radio interface including at least a WLAN transmitter, receiver or transceiver.

[0263] The components 102 to 104 of apparatus 100 may for instance be connected with processor 101 by means of one or more serial and / or parallel busses.It is to be understood that apparatus 100 may comprise various other components. For example, apparatus 100 may optionally comprise a user interface (e.g. a touch-sensitive display, a keyboard, a touchpad, a display, etc.).

[0264] FIG. 10 shows a block diagram of an example 110 of an apparatus according to the second example aspect and / or according to the fourth example aspect (e.g., a network node, for instance a base station or a gNB). For instance, apparatus 110 may be configured for scheduling and / or transmitting signals to the apparatus 100, as described above.

[0265] Apparatus 110 comprises a processor 111. Processor 111 may represent a single processor or two or more processors, which are for instance at least partially coupled, for instance via a bus. Processor 111 executes a program code stored in program memory 112 (for instance program code causing apparatus 110 to perform alone or together with apparatus 100 example embodiments according to the described aspects or parts thereof), and interfaces with a main memory 113.

[0266] Program memory 112 may also comprise an operating system for processor 111. Some or all of memories 112 and 113 may also be included into processor 111.

[0267] Moreover, processor 111 controls a communication interface 114 which is for example configured to communicate according to a cellular communication system like a 2G / 3G / 4G / 5G or future generation cellular communication system, e.g. 6G. Communication interface 114 of apparatus 110 may be realized by radio heads for instance and may be provided for communication between a network node and a user equipment.

[0268] The components 112 to 114 of apparatus 110 may for instance be connected with processor 111 by means of one or more serial and / or parallel busses.

[0269] It is to be understood that apparatuses 100, 110 may comprise various other components.

[0270] FIG. 11 shows a schematic illustration of examples of tangible and non-transitory computer-readable storage media according to the present disclosure that may for instance be used to implement memory 102 of FIG. 9 or memory 112 of FIG. 10. To this end, FIG. 11 displays a flash memory 1000, which may for instance be soldered or bonded to a printed circuit board, a solid-state drive 1001 comprising a plurality of memory chips (e.g. Flash memory chips), a magnetic hard drive 1002, a Secure Digital (SD) card 1003, aUniversal Serial Bus (USB) memory stick 1004, an optical storage medium 1005 (such as for instance a CD-ROM or DVD) and a magnetic storage medium 1006.

[0271] Any presented connection in the described embodiments is to be understood in a way that the involved components are operationally coupled. Thus, the connections can be direct or indirect with any number or combination of intervening elements, and there may be merely a functional relationship between the components.

[0272] As used in this text, the term ‘circuitry’ may refer to one or more or all of the following:

[0273] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[0274] (b) combinations of hardware circuits and software (and / or firmware), such as (as applicable):

[0275] (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[0276] (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0277] This definition of ‘circuitry’ applies to all uses of this term in this text, including in any claims. As a further example, as used in this text, the term ‘circuitry’ also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term ‘circuitry’ also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0278] Any of the processors mentioned in this text, in particular but not limited to processors 101 and 111 of FIGS. 9 and 10, could be a processor of any suitable type. Any processor may comprise but is not limited to one or more microprocessors, one or more processor(s) with accompanying digital signal processor(s), one or more processor(s) without accompanying digital signal processor(s), one or more special-purpose computer chips, one or more field-programmable gate arrays (FPGAS), one or more controllers, one or more application-specific integrated circuits (ASICS), or one or more computer(s). The relevant structure / hardware has been programmed in such a way to carry out the described function.Moreover, any of the actions or steps described or illustrated herein may be implemented using executable instructions in a general-purpose or special-purpose processor and stored on a computer-readable storage medium (e.g., disk, memory, or the like) to be executed by such a processor. References to ‘computer-readable storage medium’ should be understood to encompass specialized circuits such as FPGAs, ASICs, signal processing devices, and other devices.

[0279] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0280] The wording “A, or B, or C, or a combination thereof’ or “at least one of A, B and C” or “at least one of A, B or C” or “A, B, and / or C” may be understood to be not exhaustive and to include at least the following: (i) A, or (ii) B, or (iii) C, or (iv) A and B, or (v) A and C, or (vi) B and C, or (vii) A and B and C.

[0281] It will be understood that the embodiments disclosed herein are only example, and that any feature presented for a particular example embodiment may be used with any aspect of the present disclosure on its own or in combination with any feature presented for the same or another particular example embodiment and / or in combination with any other feature not mentioned. It will further be understood that any feature presented for an example embodiment in a particular category may also be used in a corresponding manner in an example embodiment of any other category.

[0282] List of abbreviations

[0283] FWA Fixed Wireless Access

[0284] CPE Customer Premise Equipment

[0285] UL Uplink

[0286] MIMO Multiple Input Multiple Output

[0287] UE User Equipment

[0288] gNB next Generation Node B

[0289] AP Antenna Port

[0290] TPMI Transmit Precoding Matrix Indicator

[0291] DCI Downlink control information (PDCCH)

[0292] UCI Uplink Control Information (PUCCH)

[0293] RRC Radio Resource Control (3x.331)SRS Sounding Reference Signal (UL)

[0294] SAG a Spatial Antenna Group

[0295] ULA Uniform Linear Array

[0296] MAC-CE Medium Access Control - Control Element

Claims

C l a i m s1. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:- transmitting, to a network node, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus; - receiving, from the network node, precoding control information determined at least in part based on the antenna element distance information; and- performing an uplink transmission based on the precoding control information.

2. The apparatus of claim 1 , wherein the at least one distance corresponds to an electrical distance or a physical distance.

3. The apparatus of any of claims 1 or 2, wherein the antenna element distance information comprises distance information indicating the at least one distance and antenna element identification information identifying at least one of the plurality of antenna elements associated with the at least one distance.

4. The apparatus of any of claims 1 to 3, wherein the antenna element distance information relates to only part of the plurality of antenna elements.

5. The apparatus of any of claims 1 to 4, wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:- determining the antenna element distance information at least in part based on one or more carrier frequencies to be used for the uplink transmission.

6. The apparatus of any of claims 1 to 5, wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:- indicating, to the network node, a capability of the apparatus to provide antenna element distance information.

7. The apparatus of any of claims 1 to 6, wherein the antenna element distance information is transmitted by the apparatus to the network node as part of at least one of:o Uplink Control Information, UCI; oro a Medium Access Control, MAC, control element.

8. The apparatus of any of claims 1 to 7, wherein at least part of the plurality of antenna elements are spaced non-uniformly and / or at distances of more than 0.5A, in particular of more than OJA, in particular of more than A, with the wavelength A corresponding to a carrier frequency to be used for the uplink transmission.

9. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:- receiving, from a user equipment, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the user equipment; - determining, at least in part based on the antenna element distance information, precoding control information; and- transmitting the precoding control information to the user equipment.

10. The apparatus of claim 9, wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:- receiving, from the user equipment, an uplink transmission performed based on the precoding control information.

11. The apparatus of any of claims 9 or 10, wherein the precoding control information are determined further based on a mobility of the user equipment.

12. The apparatus of any of claims 9 to 11 , wherein the precoding control information comprises at least one Transmit Precoding Matrix Indicator, TPMI.

13. A method, performed by an apparatus, the method comprising:- transmitting, to a network node, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the apparatus;- receiving, from the network node, precoding control information determined at least in part based on the antenna element distance information; and- performing an uplink transmission based on the precoding control information.

14. A method, performed by an apparatus, the method comprising:- receiving, from a user equipment, antenna element distance information indicative of at least one distance in between a plurality of antenna elements associated with the user equipment; - determining, at least in part based on the antenna element distance information, precoding control information; and- transmitting the precoding control information to the user equipment.

15. A computer program comprising instructions, which, when executed by an apparatus, cause the apparatus to perform the method of any of claims 13 or 14.

16. A computer-readable storage medium having stored thereon the computer program of claim 15.

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