Network assisted antenna gain adaptation of user equipment for uplink multiple input multiple output precoding

Abstract

Example embodiments of the present disclosure are directed to network assisted antenna gain adaptation of user equipment (UE) for uplink (UL) multiple input multiple output (MIMO) precoding. A method comprises receiving, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus; and determining the matrix at least based on the information; and performing the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

Description

[0001] NETWORK ASSISTED ANTENNA GAIN ADAPTATION OF USER EQUIPMENT FOR UPLINK MULTIPLE INPUT MULTIPLE OUTPUT PRECODING

[0002] RELATED APPLICATION

[0003] [1] This application claims priority to IN provisional Application No. 202441074793 filed October 3, 2024, which is incorporated herein by reference in its entirety.

[0004] FIELD

[0005] [2] Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for network assisted antenna gain adaptation of user equipment (UE) for uplink (UL) multiple input multiple output (MIMO) precoding.

[0006] BACKGROUND

[0007] [3] When UEs are equipped with multiple antennas, the UL precoding structure can be designed to further improve the performance of UL MIMO systems. 3GPP codebook definition and precoding method are evaluated based on Isotropic antennas at the UE and Uniform Linear Array (ULA) structure (in particular for 8TX UEs).

[0008] SUMMARY

[0009] [4] In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus; and determine the matrix at least based on the information; and perform the uplink precoding procedure at least based on the matrix and the precoding matrix.

[0010] [5] In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: estimate respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; determine a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus at least based on the estimation; transmit, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

[0011] [6] In a third aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus; and determining the matrix at least based on the information; and performing the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

[0012] [7] In a fourth aspect of the present disclosure, there is provided a method. The method comprises: estimating respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; determining a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus at least based on the estimation; transmitting, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

[0013] [8] In a fifth aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for receiving, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus; and means for determining the matrix at least based on the information; and means for performing the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

[0014] [9] In a sixth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for estimating respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; means for determining a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus at least based on the estimation; means for transmitting, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

[0015]

[0010] In a seventh aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the third aspect.

[0016]

[0011] In an eighth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the fourth aspect.

[0017]

[0012] It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019]

[0013] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0020]

[0014] FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

[0021]

[0015] FIG. 2 illustrates an example of codebook-based UL MIMO procedure;

[0022]

[0016] FIG. 3 illustrates an example of a 4-antenna port (AP) UE with different radiation patterns per AP;

[0023]

[0017] FIG. 4 illustrates a signaling chart for a communication in accordance with some example embodiments of the present disclosure;

[0024]

[0018] FIG. 5 illustrates a flowchart of a method implemented at a first apparatus in accordance with some example embodiments of the present disclosure;

[0025]

[0019] FIG. 6 illustrates a flowchart of a method implemented at a second apparatus in accordance with some example embodiments of the present disclosure;

[0026]

[0020] FIG. 7 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0027]

[0021] FIG. 8 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0028]

[0022] Throughout the drawings, the same or similar reference numerals represent the same or similar element.

[0029] DETAILED DESCRIPTION

[0030]

[0023] Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

[0031]

[0024] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0032]

[0025] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0033]

[0026] It shall be understood that although the terms “first,” “second,” ..., etc. in front of noun(s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0034]

[0027] 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.

[0035]

[0028] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0036]

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0037]

[0030] As used in this application, the term “circuitry” may refer to one or more or all of the following:

[0038] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[0039] (b) combinations of hardware circuits and software, such as (as applicable):

[0040] (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and

[0041] (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause a first apparatus, such as a mobile phone or server, to perform various functions) and

[0042] (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.

[0043]

[0031] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, 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.

[0044]

[0032] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), 5.5G, the sixth generation (6G) communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0045]

[0033] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0046]

[0034] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0047]

[0035] As used herein, the term “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and / or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0048]

[0036] FIG. 1 illustrates an example communication environment 100 in which example embodiments of the present disclosure can be implemented. As shown in FIG. 1, the communication network 100 may comprise a first apparatus 110 which may be, for example, a terminal device. In some example embodiments, the terminal device may also be discussed as a UE.

[0049]

[0037] The communication network 100 may further comprise a second apparatus 120, which may be, for example, a network device. In some example embodiments, the network device may be discussed as a BS, a gNB, or an eNB.

[0050]

[0038] A serving area provided by the second apparatus 120 is called a cell 102. The first apparatus 110 may communicate with the second apparatus 120 within the cell 102. The cell currently serving the first apparatus 110 may be considered as a serving cell.

[0051]

[0039] In some example embodiments, if the first apparatus 110 is a terminal device and second apparatus 120 is a network device, a link from the second apparatus 120 to first apparatus 110 is referred to as a downlink (DL), while a link from the first apparatus 110 to second apparatus 120 is referred to as an uplink (UL). In DL, the second apparatus 120 is a transmitting (TX) apparatus (or a transmitter) and the first apparatus 110 is a receiving (RX) apparatus (or a receiver). In UL, the first apparatus 110 is a TX apparatus (or a transmitter) and the second apparatus 120 is a RX apparatus (or a receiver).

[0052]

[0040] It is to be understood that the number of network devices and terminal devices shown in FIG. 1 is given for the purpose of illustration without suggesting any limitations. The communication environment 100 may include any suitable number of network devices and terminal devices.

[0053]

[0041] Communications in the communication environment 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0054]

[0042] As described above, 3GPP codebook definition and precoding method are evaluated based on Isotropic antennas at the UE and Uniform Linear Array (ULA) structure (in particular for 8TX UEs). However, direct consequence of such assumptions might indicate a sub-optimal codebook design that does not account for antenna link degradation.

[0055]

[0043] It has been shown that many real world UEs select lower rank transmission to avoid utilizing a sub -optimal codebook with higher rank.

[0056]

[0044] The current UL MIMO procedure deployed in the field for 5G NR networks is codebook based, that is, the gNB signals a Transmitted Precoding Matrix Indicator (TPMI) to the UE for selecting a precoding matrix to be used during physical uplink shared channel (PUSCH) procedures.

[0057]

[0045] FIG. 2 illustrates an example of codebook-based UL MIMO procedure 200. 4 antenna ports are arranged at both gNB 220 and UE 210. As shown in FIG. 2, after the gNB 220 requests the UE 210 to transmit a non-pre-coded SRS from each UL antenna port, the UE 210 transmit UL reference signals (e.g., sounding reference signals, SRSs) by using non-pre-coded SRS resources.

[0058]

[0046] The SRS can be configured to transmit sequentially or as shown simultaneously, depending on the capabilities of the UE 210. However, simultaneously transmitted SRS’s will reduce the power of each SRS to comply with the requirements for maximum combined Tx power at the UE and thus will reduce the coverage.

[0059]

[0047] Then the gNB 220 estimates the channel based on the received SRSs using precoded receive beams and determines the best TPMI from the appropriate pre-defined codebook.

[0060]

[0048] Then the gNB 220 transmits the Rank indicator (RI), SRS resource indicator (SRI) and TPMI to the UE 210. Then the UE 210 transmits the PUSCH with UL pre-coding obtained indication, i.e., the RI, the SRI and the TPMI.

[0049] That is, the UL pre-coding is based on the received TPMI and may result in a sub- optimal UE precoding, as the used codebook assumes a ULA antenna array made of isotropic cross-polarized antennas at the UE.

[0061]

[0050] One of the drawbacks of this procedure shown in FIG. 2 is that the UE relies on a low-resolution codebook. Some tables of precoding matrix for single layer transmission for PUSCH are listed below.

[0062] Table 1: Precoding matrix for single-layer transmission using two antenna ports

[0063] Table 2: Precoding matrix for single-layer transmission using 4 antenna ports with transform precoding enabled

[0064] Table 3: Precoding matrix for single-layer transmission using 4 antenna ports with transform precoding disabled

[0065]

[0066]

[0051] The precoding information and number of layers for UL is transmitted via the Downlink Control Information (DCI) as the combination of TPMI and UL-RI. The bit field mapped to index is shown in below:

[0067] Table 4: Precoding information and number of layers for 4 antenna ports, if transform precoder is disabled, maxRank =2 or 3 or 4, and ul-FullPowerTransmission is not configured or configured to fullpowerMode2 or configured to fullpower

[0068]

[0069]

[0052] Current codebook (CB) specification included only includes two possible amplitude levels, namely amplitude equal to 1 (antenna port activated) or amplitude 0 (antenna port deactivated). Such approach stems from the assumption of isotropic antennas where one or more of the antennas could be blocked significantly relative to the other antennas, in which case it is assumed that the blocked antenna(s) should be completely deactivated.

[0070]

[0053] However, as shown in FIG. 3, several realistic aspects suggest that precoding strategies that account for unbalanced amplitudes can yield substantial improvements to precoding efficiency. Among others, user hand grip which hinder signal transmission and directional antenna gain which may point in a direction different from the one of the gNB can result in largely unbalanced port to port path losses. With a “rough” approach such as the ON-OFF approach, it is not possible to correctly compensate or exploit such scenarios.

[0071]

[0054] For example, amplitude imbalance causes the different antenna ports to have uneven link budgets with the gNB.

[0072]

[0055] Amplitude imbalance could be tackled at the TPMI level, however the dimension of a CB which needs to include the amplitude would largely increase, therefore increase the amount of signaling overhead. With a rough calculation, let us assume a Ar-antenna port fully coherent CB composed of M vectors each with unit amplitude. Such codebook would need [log2M] bits to select one vector. If we assume to extend it with N different amplitudes, the CB would have MNNTentries, hence needing [log2MNNT] = [log2M + lVrlog2TV] bits to select one vector. For example, assume a 4-antenna port CB with 20 precoding vectors (M = 20) each having unit amplitude. The TPMI field to select a vector would be made of 5 bits. If we assume to extend the amplitude to 8 different values (8 amplitude levels, N = 8), the total number of bits required to select a vector from this CB would increase to 17 ( [log220 + 41og28]), with a 340% increase in overhead.

[0073]

[0056] The problem is how to extend the current codebook-based approach to include an amplitude compensation step which is required to compensate for realistic UE antenna patterns and potential blockage by the user hand grip.

[0074]

[0057] In accordance with some example embodiments of the present disclosure, there is provided a solution for network assisted UE antenna gain adaptation for CB UL MIMO precoding. In this solution, the gNB estimates respective antenna gains or relative antenna gains or imbalance in respective amplitude gains and determine a matrix for an amplitude balancing of transmit antenna ports of the UE during an uplink precoding of the UE at least based on the estimation. The gNB transmits, to the UE, an indication of a precoding matrix and information associated with determining a matrix. The UE determines the matrix at least based on the information and performs the uplink precoding procedure at least based on the matrix and the precoding matrix.

[0075]

[0058] The solution of the present disclosure may improve the system by extending the cases in which the signals transmitted from two or more UE’s antennas will be effectively received at the gNB, even when the UE antenna patterns have very uneven gain in that given direction, therefore increasing the cases in which using multiple layers is possible. The solution of the present disclosure may also improve the system by extending the case in which activating multiple antennas becomes beneficial, thus improving the overall link budget by exploiting array gain.

[0076]

[0059] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0077]

[0060] Reference is now made to FIG. 4, which shows a signaling chart 400 for communication according to some example embodiments of the present disclosure. As shown in FIG. 4, the signaling chart 400 involves a first apparatus 110 and a second apparatus 120. For the purpose of discussion, reference is made to FIG. 1 to describe the

[0078] 1-1signali Png chart 400. It is noted that the order of acts / steps shown in FIG. 4 is only an example not limitation.

[0079]

[0061] As shown in FIG. 4, the first apparatus 110 may transmit (402) the capability information (which may be called as an amplitude codebook (ACB) capability information) to the second apparatus 120. For example, the first apparatus 110 may transmit a report of a capability of supporting a multi-stage uplink precoding, e.g., a 2- stage uplink precoding. For example, the capability information may be transmitted from the first apparatus 110 to the second apparatus 120 via a Radio Resource Control (RRC). That is, the capability information exchange field may be placed in the RRC signaling.

[0080]

[0062] In some embodiments, the first apparatus 110 may indicate, in the report, a set of amplitude balancing values supported by the first apparatus 110. The set of amplitude balancing values may be selected from a pre-defined CB. The pre-defined CB may be known by both first and second apparatus.

[0081]

[0063] The pre-defined CB may comprise a plurality of antenna amplitude index (AAI) matrices. The AAI matrix is diagonal, and it can be defined by a vector of dimension N_T, where N_T represents the number of transmit antenna ports at the first apparatus 110, which contains the diagonal elements of the AAI matrix. The AAI mentioned herein may be referred to as indices corresponding to the amplitude balancing values defined in the pre-defined CB.

[0082]

[0064] As an example, a possible codebook definition for 2 and 3 antenna ports where ACB(n) denotes the Amplitude Codebook for ‘n’ antenna port which contain the vectors of diagonal elements of the AAI matrix.

[0083]

[0065] For example, a codebook for “n” antenna ports may be denoted as ACB(n) which means the Amplitude Codebook for “n” antenna port. For example,

[0084] 1 0 0 1 1 0 1 1 0 1 5i -1. 5' 0

[0085] B (3 0 f 1 f 0 f 1 f 0 f 1 f l.E f 0 f 1 f L f c f 1.. f ■ ■

[0086] 0- oJ 1J 0- 1J 1J 0 1.5 -1 .5 1 1 1

[0087] 1 0 r2■2 0 rl 1 0 [3] 3 0 1 -1 0- r4 -4 0 f 0 f 1 f 1 f 0 f 2 f 3 f 0 f 1 f 1 f 0 f 3 f 4 f 0 f 1 f 1 f 0 f 4 L2J L2J 0 Li Li 0 L3 L3 .0. Li 1J Led .4J L4- 0 LiJ LiJ

[0088]

[0066] The diagonal elements of the AAI matrix shall be normalized so that Zilail2 =1, where ctj is one element of the vector of dimension N_T that defines the AAI matrix.

[0089]

[0067] It is possible to generalize the entries of such codebook as: following these rules, i.e., each vector of the above CB must be normalized to preserve total transmit power where cmG {0, 1, 1.5, 2, 3, 4} (or any other set of numbers) subject to:

[0090] -At least one cm#= 0 (i.e., the AAI matrix is not a zero matrix).

[0091]

[0068] The {c1, used herein may be referred to as a set of amplitude balancing values

[0092]

[0069] It is to be understood that other possible Amplitude Codebook may also be used for the solution of the present disclosure.

[0093]

[0070] In some embodiments, based on the pre-defined CB, the ACB capability may further comprise a capability of the first apparatus 110 of implementing the novel antenna amplitude tuning and it can include possible amplitude boosting / attenuating values that the first apparatus 110 is able to implement. This will limit the ACB that can be used by the second apparatus 120. For example, the first apparatus 110 may communicate a set of values {0, 1, 1.5}, or {0, 1, 2}, {0, 1, 2, 3}. The resulting ACBs will therefore be built solely based on these possible values.

[0094]

[0071] As shown in FIG. 4, the second apparatus 120 may configure (404) the first apparatus 110 for an uplink reference signal transmission, e.g., SRS transmission. Then the first apparatus 110 may transmit (406) the uplink reference signal transmission to the second apparatus 120.

[0095]

[0072] Based on the received uplink reference signal transmission, the second apparatus 120 may perform (408) channel estimation for the uplink channel between the first apparatus 110 and the second apparatus 120. In this process, the second apparatus 120 may estimate respective antenna gains or relative antenna gains or imbalance in respective amplitude gains and determine (410) a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus 110.

[0096]

[0073] As an option, if there is a pre-defined CB comprising a plurality of matrices, the second apparatus 120 may select one of the matrix from the codebook of matrices, whose elements belong to a set of amplitude balancing values supported and indicated by the first apparatus 110, and the selected matrix is closest to the derived optimal diagonal matrix.

[0097]

[0074] That is, in this case, the second apparatus 120 may transmit (412), to the first apparatus 110, in addition to an indication of a precoding matrix which is associated with a precoding matrix indicator (TPMI), information associated with determining a matrix for amplitude balancing including an indication of the matrix selected from the predefined CB, e.g., an amplitude codebook.

[0098]

[0075] As another option, if there is no pre-defined CB, the second apparatus 120 may derive the ‘optimal’ amplitude balancing values and map / quantize the derived optimal values to the values in a set of amplitude balancing values supported and indicated by the first apparatus 110. In this case, the second apparatus 120 may transmit (412), to the first apparatus 110, in addition to an indication of a precoding matrix which is associated with a precoding matrix indicator (TPMI), information associated with determining a matrix for amplitude balancing including values of diagonal elements of the matrix. The matrix may be a diagonal matrix of a dimension equal to the number of transmit antenna ports.

[0099]

[0076] In this case, the values of diagonal elements of the matrix may be received by the first apparatus 110 in a physical uplink shared channel (PUSCH) configuration information element (IE), the IE may indicate a set of indices corresponding to the values of diagonal elements of the matrix, which may be considered as AAI coefficients as described above. Furthermore, as an example, the PUSCH configuration may also comprise an IE indicating enabling the multi-stage uplink precoding, e.g., two-stage uplink precoding.

[0100]

[0077] As an example, for selecting the AAI, the second apparatus 120 may receive the SRS transmitted from each UE antenna port and may estimate the amplitude of the channel gain per UE antenna port which is denoted by G(ri) (with n = 1, ..., NT~). The AAI matrix is selected to match as close as possible with the vector G defined as G = [6(1), 6(2), ..., G(NTf]TThis can be done, e. g., as: a) minimize \\diag MA) — G\\2. b) maximize \diag(MA)HG|

[0101]

[0078] An example of PUSCH configuration is shown below where the new fields and information elements are added for the matrix and multi-stage uplink precoding capability.

[0102] Table 5 where the field “twoStageACBPrecoding” indicates the UE to enable two-stage ACB precoding and the field “coefficientsAAI” indicates the AAI coefficients to the UE for performing 2-stage ACB precoding. The field “AAl-coefficient” in the above example is shown be an integer between 1 to 16 where the meaning of the indicated integer can be, for example,

[0103] Integer where I G {1, ... 16} may denote the amplitude level of:

[0104] Example 1: I dB (supporting 1 dB to 16 dB amplitude pre-conditioning with 1 dB step size),

[0105] Example 2: 2(Z — 1) dB (supporting 0 dB to 30 dB amplitude pre-conditioning with 2 dB step size),

[0106] Example 3: — 15 + 2(Z — 1) (supporting -15 to 15 amplitude pre-conditioning levels with a step size of 2),

[0107] The field “maxUEantennaPorts” denotes the maximum number of UE antenna ports which for our case is 4 but can be more (e.g., 8, 16). These configurations such as maxUEantennaPorts and AAl-coefficient shall be subject to UE capability reporting.

[0108]

[0079] In some example embodiments, the information may also be transmitted from the second apparatus 120 to the first apparatus 110 via an RRC signaling or a medium access control-control element (MAC-CE).

[0080] In some example embodiments, the matrix may comprise elements chosen from a set of amplitude balancing values

[0109] {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm. The diagonal elements of the matrix may satisfy at least one diagonal element of the matrix is not equal to zero.

[0110]

[0081] In some example embodiments, the matrix may comprise elements chosen from a set of amplitude balancing values

[0111] {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

[0112]

[0082] In addition to the information associated with determining a matrix for amplitude balancing, the second apparatus 120 may also transmit, to the first apparatus, an indication of a precoding matrix such as SRI, RI and TPMI. As an example, the information associated with determining a matrix may be received via longer periodicity than the TPMI.

[0113]

[0083] The first apparatus 110 may determine (414), based on the information, the matrix either from the pre-defined codebook or values of diagonal elements of the matrix corresponding to a set of indices. For example, the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports.

[0114]

[0084] Then the first apparatus 110 may calculate (416) the UL precoder based on the precoding matrix and information associated with the matrix, e.g., from AAI and TPMI by performing the product of the precoder matrices indicated by AAI and TPMI. For example, the first apparatus 110 may calculate an uplink precoder by pre-multiplying the precoding matrix chosen through the TPMI by the determined matrix. Then the first apparatus 110 may perform the uplink pre-coding procedure by using the calculated uplink precoder.

[0115]

[0085] For example, the UL precoder represents as: x = MAPS where

[0116] • s = is a column vector of dimension ‘L’ which contains the information bearing symbols, where L is the number of transmit layers, and snrepresents the symbol for the nthlayer.

[0117] • P G CWTXLjs aprecoding matrix, indicated by the gNB to the UE by means of the

[0118] TPMI. The dimension of P is NTX L (i.e., Number of transmit antennas times Number of layers).

[0119] • x G CNTX1is the complex baseband transmit signal vector of dimension equal to the number of transmit antennas.

[0120] • MAG CNTXNTis a diagonal matrix of dimension equal to the number of transmit antennas.

[0121]

[0086] It is to be understood that this matrix MAmay or may not signaled together with the TPMI and may be selected based on statistics build by the gNB and they are signaled at much slower rate.

[0122]

[0087] It is possible that the antenna-port amplitude balancing can be executed for each layer independently. In other words, the matrix refers to a diagonal matrix of a dimension equal to the number of transmit antenna ports relative to a single layer. where:

[0123] - MA(l) is a diagonal matrix of dimension equal to the number of transmit antennas relative to the 1thlayer. The proposed AAI matrix MA(T) balances the amplitude among the different antenna ports of the UE for the layer T. This matrix is chosen (and signaled) by the gNB among inside the codebook of dimension NT.

[0124] - P(Z) is the 1-th column vector of the matrix P.

[0125] - s(Z) represents the 1-th layer.

[0126]

[0088] After determining the UL precoder, the first apparatus 110 may generate the precoded PUSCH data by multiplying the non-precoded PUSCH data by the precoding matrix derived. Then the first apparatus 110 may transmit (418) precoded PUSCH data on the ports corresponding to the SRS resource. If multiple SRS resources was used to transmit SRS, then the PUSCH data will be transmitted on the ports corresponding to the SRS resource indicated by SRI.

[0127]

[0089] In some other examples, the information associated with determining a matrix comprises an indication of a reference antenna port and amplitude balancing values of transmit antenna ports relative to the amplitude of the reference antenna port.

[0128]

[0090] Then the first apparatus 110 may determine the matrix based on an amplitude value of the reference antenna port and the amplitude values of transmit antenna ports relative to the amplitude of the reference antenna port.

[0129]

[0091] Specifically, the second apparatus 120 selects one antenna port as a “reference”. The amplitudes are then signaled as relative to the amplitude of the reference antenna (whose amplitude is automatically set to 1).

[0130]

[0092] In order to adapt this method of signaling a field named REF_ANTENNA (an integer from 0 to N_T-1) needs to be signaled by the second apparatus 120 to the first apparatus 110. The amplitude of this antenna will be set equal to 1. The remaining N_T- 1 antennas amplitude will be signaled through any of the aforementioned methods, with the only difference that they will be referring to N_T-1 antenna ports, and the values will have to be interpreted as factors of the reference antenna.

[0131]

[0093] As an example, Consider a UE with 4 antenna ports. The reference antenna is REF_ANTENNA = 2. Using the first method, the gNB selects the following 3 antenna ports precoding amplitude matrix (PAM):

[0132]

[0094] The resulting amplitude multiplying matrix is therefore:

[0133] 0.25 0 0 0- where the element in the third row, third column of the matrix MAis set equal to 1 as it is relative to the reference antenna.

[0134]

[0095] In some other examples, the ACB is composed of scalars, the gNB will signal one scalar per antenna port. In the case in which the ACB dimensions (i.e., the number of possible selectable scalars) is not a power of 2, the scalars chosen are compressed in the same field, in order to reduce the signaling overhead.

[0135] ACB = {0,0.25,0.5,1,2,4}

[0136]

[0096] In this case ACB has dimension D=6. which means minimum amount of bit to signal a port is b=3. Let us assume the UE has NT= 4 antenna ports. Signaling the values separately would include a total of b X Nt= 3x4 = 12 bits. However, it is possible to compress the feedback by “stacking” the feedback.

[0137]

[0097] In this way the AAI for all the ports can be in [log2(DNT) ] = [Arlog2D] = 11.

[0138]

[0098] Based on this solution, the array gain activating all the available APs can be maximized and the amplitude to match the channel strength can be correctly allocated.

[0139]

[0099] FIG. 5 shows a flowchart of an example method 500 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0140]

[0100] At block 510, the first apparatus 110 receives, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus, and

[0141]

[0101] At block 520, the first apparatus 110 determines the matrix at least based on the information.

[0142]

[0102] At block 530, the first apparatus 110 performs the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

[0103] In some example embodiments, the information comprises an indication of the matrix from an amplitude codebook.

[0143]

[0104] In some example embodiments, the information comprises values of diagonal elements of the matrix.

[0144]

[0105] In some example embodiments, the information is indicated in a physical uplink shared channel, PUSCH, configuration by one or more information elements, IES, and wherein the one or more IEs comprises at least one of: a set of indices corresponding to the values of diagonal elements of the matrix; or an indication of enabling the multi-stage uplink precoding.

[0145]

[0106] In some example embodiments, the method 500 further comprises: transmitting, to the second apparatus via a radio resource control, RRC, signaling, a report of a capability of supporting a multi-stage uplink precoding.

[0146]

[0107] In some example embodiments, the report comprises a set of amplitude balancing values supported by the first apparatus.

[0147]

[0108] In some example embodiments, the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports.

[0148]

[0109] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm.

[0149]

[0110] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

[0150]

[0111] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values with a normalization having unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0151]

[0112] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values without a normalization with non-unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0113] In some example embodiments, the method 500 further comprises: receiving, from the second apparatus, the information via downlink control information, DCI, or an RRC signaling or a medium access control-control element, MAC-CE.

[0152]

[0114] In some example embodiments, the method 500 further comprises: calculating an uplink precoder by pre-multiplying the precoding matrix chosen through the TPMI by the matrix; and performing the uplink pre-coding procedure by using the calculated uplink precoder.

[0153]

[0115] In some example embodiments, the information is received via longer periodicity than the TPMI.

[0154]

[0116] In some example embodiments, the matrix is per all spatial layers or per a single spatial layer associated with transmit antenna ports of the first apparatus.

[0155]

[0117] In some example embodiments, the information comprises: an indication of a reference antenna port; and amplitude balancing values of transmit antenna ports relative to an amplitude of the reference antenna port; wherein determining the matrix based on the information comprises determining the matrix based on the amplitude value of the reference antenna port and the amplitude values of transmit antenna ports relative to the amplitude of the reference antenna port.

[0156]

[0118] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0157]

[0119] FIG. 6 shows a flowchart of an example method 600 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0158]

[0120] At block 610, the second apparatus 120 estimates respective antenna gains or relative antenna gains or imbalance in respective amplitude gains.

[0159]

[0121] At block 620, the second apparatus 120 determines a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus at least based on the estimation.

[0160]

[0122] At block 630, the second apparatus 120 transmits, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

[0123] In some example embodiments, the information comprises an indication of the matrix selected from an amplitude codebook.

[0161]

[0124] In some example embodiments, the information comprises values of diagonal elements of the matrix.

[0162]

[0125] In some example embodiments, the information is indicated in a physical uplink shared channel, PUSCH, configuration by one or more information elements, IES, and wherein the one or more IEs comprises at least one of: a set of indices corresponding to the values of diagonal elements of the matrix; or an indication of enabling the multi-stage uplink precoding.

[0163]

[0126] In some example embodiments, the method 600 further comprises: receiving, from the first apparatus via a radio resource control, RRC, signaling, a report of a capability of supporting a multi-stage uplink precoding.

[0164]

[0127] In some example embodiments, the report comprises a set of amplitude balancing values supported by the first apparatus.

[0165]

[0128] In some example embodiments, the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports of the first apparatus.

[0166]

[0129] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values

[0167] {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm.

[0168]

[0130] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

[0169]

[0131] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values with a normalization having unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0170]

[0132] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values without a normalization with non-unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0171]

[0133] In some example embodiments, the method 600 further comprises: transmitting, to the first apparatus, the information via downlink control information, DCI, or an RRC signaling or a medium access control-control element, MAC-CE.

[0172]

[0134] In some example embodiments, the indication of a precoding matrix comprises a precoding matrix indicator, TPMI, configured for the first apparatus,

[0173]

[0135] In some example embodiments, the information is transmitted via longer periodicity than the TPMI.

[0174]

[0136] In some example embodiments, the matrix is per all spatial layers or per a single spatial layer associated with transmit antenna ports of the first apparatus.

[0175]

[0137] In some example embodiments, the information comprises an indication of reference antenna port and amplitude balancing values of transmit antenna ports relative to an amplitude value of the reference antenna port.

[0176]

[0138] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0177]

[0139] In some example embodiments, a first apparatus capable of performing any of the method 500 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1.

[0178]

[0140] In some example embodiments, the first apparatus comprises means for receiving, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus; and means for determining the matrix at least based on the information; and means for performing the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

[0179]

[0141] In some example embodiments, the information comprises an indication of the matrix from an amplitude codebook.

[0142] In some example embodiments, the information comprises values of diagonal elements of the matrix.

[0180]

[0143] In some example embodiments, the information is indicated in a physical uplink shared channel, PUSCH, configuration by one or more information elements, IES, and wherein the one or more IEs comprises at least one of: a set of indices corresponding to the values of diagonal elements of the matrix; or an indication of enabling the multi-stage uplink precoding.

[0181]

[0144] In some example embodiments, the first apparatus further comprises: means for transmitting, to the second apparatus via a radio resource control, RRC, signaling, a report of a capability of supporting a multi-stage uplink precoding.

[0182]

[0145] In some example embodiments, the report comprises a set of amplitude balancing values supported by the first apparatus.

[0183]

[0146] In some example embodiments, the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports.

[0184]

[0147] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values

[0185] {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm.

[0186]

[0148] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

[0187]

[0149] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values with a normalization having unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0188]

[0150] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values without a normalization with non-unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0189]

[0151] In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, the information via downlink control information, DCI, or an RRC signaling or a medium access control-control element, MAC-CE.

[0190]

[0152] In some example embodiments, the first apparatus further comprises: means for calculating an uplink precoder by pre-multiplying the precoding matrix chosen through the TPMI by the matrix; and means for performing the uplink pre-coding procedure by using the calculated uplink precoder.

[0191]

[0153] In some example embodiments, the information is received via longer periodicity than the TPMI.

[0192]

[0154] In some example embodiments, the matrix is per all spatial layers or per a single spatial layer associated with transmit antenna ports of the first apparatus.

[0193]

[0155] In some example embodiments, the information comprises: an indication of a reference antenna port; and amplitude balancing values of transmit antenna ports relative to an amplitude of the reference antenna port; wherein determining the matrix based on the information comprises determining the matrix based on the amplitude value of the reference antenna port and the amplitude values of transmit antenna ports relative to the amplitude of the reference antenna port.

[0194]

[0156] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0195]

[0157] In some example embodiments, a second apparatus capable of performing any of the method 600 (for example, the second apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1.

[0196]

[0158] In some example embodiments, the second apparatus comprises means for estimating respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; means for determining a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus at least based on the estimation; means for transmitting, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

[0197]

[0159] In some example embodiments, the information comprises an indication of the matrix selected from an amplitude codebook.

[0198]

[0160] In some example embodiments, the information comprises values of diagonal elements of the matrix.

[0199]

[0161] In some example embodiments, the information is indicated in a physical uplink shared channel, PUSCH, configuration by one or more information elements, IES, and wherein the one or more IEs comprises at least one of: a set of indices corresponding to the values of diagonal elements of the matrix; or an indication of enabling the multi-stage uplink precoding.

[0200]

[0162] In some example embodiments, the second apparatus further comprises: means for receiving, from the first apparatus via a radio resource control, RRC, signaling, a report of a capability of supporting a multi-stage uplink precoding.

[0201]

[0163] In some example embodiments, the report comprises a set of amplitude balancing values supported by the first apparatus.

[0202]

[0164] In some example embodiments, the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports of the first apparatus.

[0203]

[0165] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values

[0204] {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm.

[0205]

[0166] In some example embodiments, the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

[0206]

[0167] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values with a normalization having unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0207]

[0168] In some example embodiments, the matrix comprises elements chosen from the set of amplitude balancing values without a normalization with non-unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

[0169] In some example embodiments, the second apparatus further comprises: means for transmitting, to the first apparatus, the information via downlink control information, DCI, or an RRC signaling or a medium access control-control element, MAC-CE.

[0208]

[0170] In some example embodiments, the indication of a precoding matrix comprises a precoding matrix indicator, TPMI, configured for the first apparatus,

[0209]

[0171] In some example embodiments, the information is transmitted via longer periodicity than the TPMI.

[0210]

[0172] In some example embodiments, the matrix is per all spatial layers or per a single spatial layer associated with transmit antenna ports of the first apparatus.

[0211]

[0173] In some example embodiments, the information comprises an indication of reference antenna port and amplitude balancing values of transmit antenna ports relative to an amplitude value of the reference antenna port

[0212]

[0174] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0213]

[0175] FIG. 7 is a simplified block diagram of a device 700 that is suitable for implementing example embodiments of the present disclosure. The device 700 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 as shown in FIG. 1. As shown, the device 700 includes one or more processors 710, one or more memories 720 coupled to the processor 710, and one or more communication modules 740 coupled to the processor 710.

[0214]

[0176] The communication module 740 is for bidirectional communications. The communication module 740 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 740 may include at least one antenna.

[0215]

[0177] The processor 710 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0216]

[0178] The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 724, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), an optical disk, a laser disk, and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 722 and other volatile memories that will not last in the power-down duration.

[0217]

[0179] A computer program 730 includes computer executable instructions that are executed by the associated processor 710. The instructions of the program 730 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 730 may be stored in the memory, e.g., the ROM 724. The processor 710 may perform any suitable actions and processing by loading the program 730 into the RAM 722.

[0218]

[0180] The example embodiments of the present disclosure may be implemented by means of the program 730 so that the device 700 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 6. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0219]

[0181] In some example embodiments, the program 730 may be tangibly contained in a computer readable medium which may be included in the device 700 (such as in the memory 720) or other storage devices that are accessible by the device 700. The device 700 may load the program 730 from the computer readable medium to the RAM 722 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0220]

[0182] FIG. 8 shows an example of the computer readable medium 800 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 800 has the program 730 stored thereon.

[0183] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0221]

[0184] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0222]

[0185] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0223]

[0186] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0224]

[0187] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmable readonly memory (EPROM or Flash memory), an optical fiber, a portable compact disc readonly memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0225]

[0188] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

[0226]

[0189] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding procedure of the first apparatus; and determine the matrix at least based on the information; and perform the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

2. The first apparatus of claim 1, wherein the information comprises an indication of the matrix from an amplitude codebook.

3. The first apparatus of claim 1, wherein the information comprises values of diagonal elements of the matrix.

4. The first apparatus of claim 3, wherein the information is indicated in a physical uplink shared channel, PUSCH, configuration by one or more information elements, IES, and wherein the one or more IEs comprises at least one of: a set of indices corresponding to the values of diagonal elements of the matrix; or an indication of enabling the multi-stage uplink precoding.

5. The first apparatus of any of claims 1-4, wherein the first apparatus is caused to: transmit, to the second apparatus via a radio resource control, RRC, signaling, a report of a capability of supporting a multi-stage uplink precoding.

6. The first apparatus of claim 5, wherein the report comprises a set of amplitudebalancing values supported by the first apparatus.

7. The first apparatus of claim 1, wherein the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports.

8. The first apparatus of claim 6, wherein the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm.

9. The first apparatus of claim 6, wherein the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

10. The first apparatus of claim 6, wherein the matrix comprises elements chosen from the set of amplitude balancing values with a normalization having unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

11. The first apparatus of claim 6, wherein the matrix comprises elements chosen from the set of amplitude balancing values without a normalization with non-unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

12. The first apparatus of any of claims 1-11, wherein the first apparatus is caused to: receive, from the second apparatus, the information via downlink control information, DCI, or an RRC signaling or a medium access control-control element, MAC-CE.

13. The first apparatus of any of claims 1-12, wherein the indication of the precoding matrix comprises a precoding matrix indicator, TPMI, configured for the first apparatus, and wherein the first apparatus is caused to:calculate an uplink precoder by pre-multiplying the precoding matrix chosen through the TPMI by the matrix; and perform the uplink pre-coding procedure by using the calculated uplink precoder.

14. The first apparatus of claim 13, wherein the information is received via longer periodicity than the TPMI.

15. The first apparatus of any of claims 1-14, wherein the matrix is per all spatial layers or per a single spatial layer associated with transmit antenna ports of the first apparatus.

16. The first apparatus of claim 1, wherein the information comprises: an indication of a reference antenna port; and amplitude balancing values of transmit antenna ports relative to an amplitude value of the reference antenna port; wherein determining the matrix based on the information comprises determining the matrix based on the amplitude value of the reference antenna port and the amplitude values of transmit antenna ports relative to the amplitude of the reference antenna port.

17. The first apparatus of any of claim 1-16, wherein the first apparatus comprises a terminal device and the second apparatus comprises a network device.

18. A second apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: estimate respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; determine a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus at least based on the estimation; transmit, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

19. The second apparatus of claim 18, wherein the information comprises an indication of the matrix selected from an amplitude codebook.

20. The second apparatus of claim 18, wherein the information comprises values of diagonal elements of the matrix.

21. The second apparatus of claim 20, wherein the information is indicated in a physical uplink shared channel, PUSCH, configuration by one or more information elements, IES, and wherein the one or more IES comprises at least one of: a set of indices corresponding to the values of diagonal elements of the matrix; or an indication of enabling the multi-stage uplink precoding.

22. The second apparatus of claim 18, wherein the second apparatus is caused to: receive, from the first apparatus via a radio resource control, RRC, signaling, a report of a capability of supporting a multi-stage uplink precoding.

23. The second apparatus of claim 22, wherein the report comprises a set of amplitude balancing values supported by the first apparatus.

24. The second apparatus of claim 18, wherein the matrix is a diagonal matrix of a dimension equal to the number of transmit antenna ports of the first apparatus.

25. The second apparatus of claim 24, wherein the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} with a normalization having unit Frobenius norm.

26. The second apparatus of claim 24, wherein the matrix comprises elements chosen from a set of amplitude balancing values {0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10} without a normalization with non-unit Frobenius norm.

27. The second apparatus of claim 24, wherein the matrix comprises elements chosen from the set of amplitude balancing values with a normalization having unitFrobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

28. The second apparatus of claim 24, wherein the matrix comprises elements chosen from the set of amplitude balancing values without a normalization with non-unit Frobenius norm, and wherein diagonal elements of the matrix satisfies at least one diagonal element of the matrix is not equal to zero.

29. The second apparatus of any of claims 18-28, wherein the second apparatus is caused to: transmit, to the first apparatus, the information via downlink control information, DCI, or an RRC signaling or a medium access control-control element, MAC-CE.

30. The second apparatus of any of claims 18-29, wherein the indication of a precoding matrix comprises a precoding matrix indicator, TPMI, configured for the first apparatus.

31. The second apparatus of claim 30, wherein the information is transmitted via longer periodicity than the TPMI.

32. The second apparatus of any of claims 18-31, wherein the matrix is per all spatial layers or per a single spatial layer associated with transmit antenna ports of the first apparatus.

33. The second apparatus of claim 18, wherein the information comprises an indication of reference antenna port and amplitude balancing values of transmit antenna ports of the first apparatus relative to an amplitude value of the reference antenna port.

34. The second apparatus of any of claim 18-33, wherein the first apparatus comprises a terminal device and the second apparatus comprises a network device.

35. A method comprising: receiving, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitudebalancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus; determining the matrix at least based on the information; and performing the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

36. A method comprising: estimating respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; determining a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus at least based on the estimation; and transmitting, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

37. A first apparatus comprising: means for receiving, from a second apparatus, an indication of a precoding matrix and information associated with determining a matrix, wherein the matrix is for amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus; and means for determining the matrix at least based on the information; and means for performing the uplink pre-coding procedure at least based on the matrix and the precoding matrix.

38. A second apparatus comprising: means for estimating respective antenna gains or relative antenna gains or imbalance in respective amplitude gains; means for determining a matrix for an amplitude balancing of transmit antenna ports of the first apparatus during an uplink precoding of the first apparatus at least based on the estimation; and means for transmitting, to the first apparatus, an indication of a precoding matrix and information associated with determining the matrix.

39. A computer readable medium comprising instructions stored thereon forcausing an apparatus at least to perform the method of claim 35 or the method of claim

Images