UL MIMO codebook procedure

Abstract

A UE receives a first index for TPMI and a second index for an AP vector for an uplink transmission by the UE, and determines a TPMI to use by searching for the first index from TPMIs having phase settings for 1, 2, or 4 antenna ports. The UE determines an AP vector to use by searching for the second index, and determines an AP configuration based on the determined AP vector and the determined TPMI. The UE transmits an uplink transmission by applying the determined TPMI and the AP configuration. The network element determines the first index and the second index, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports. The network element transmits the first index for the TPMI and the second index for the AP vector, and receives the uplink transmission.

Description

UL MIMO Codebook ProcedureTECHNICAL FIELD

[0001] Examples of embodiments herein relate generally to wireless communications and, more specifically, relate to codebook use in the wireless communications.BACKGROUND

[0002] Uplink Multiple Input Multiple Output (MIMO) using a codebook in 3GPP (3rd Generation Partnership Project) standards refers to a technique where multiple antennas at the transmitter (e.g., a user equipment, e.g., a mobile device) and receiver (e.g., a base station) are used to improve the communication performance.

[0003] In uplink (UL) MIMO, the communication occurs from the mobile device (User Equipment, UE) to the base station (e.g., eNodeB or gNodeB, depending on the generation). Uplink MIMO enhances data rates, coverage, and reliability by exploiting spatial diversity and spatial multiplexing gains. Spatial diversity uses multiple antennas to combat fading, while spatial multiplexing allows the transmission of multiple data streams simultaneously to increase throughput.

[0004] The use of a codebook in MIMO systems refers to the selection of predefined precoding matrices. These matrices dictate how signals are combined across different antennas before transmission, enabling better signal quality and spatial separation. The codebook is a set of fixed precoder matrices known to both the transmitter and the receiver. The codebook-based approach reduces the amount of channel state information (CSI) needed for feedback, simplifying the system design.

[0005] Steps in Codebook-Based Precoding are as follows:

[0006] 1 . The receiver (a network element such as a base station) measures the channel characteristics based on reference signals sent by the transmitter.

[0007] 2. The base station determines the optimal precoding matrix from the predefined codebook based on channel measurements.

[0008] 3. The base station sends feedback to the UE, indicating the selected codebook entry or index.

[0009] 4. The UE uses the specified precoding matrix from the codebook to pre-process the transmitted signal across its antennas.

[0010] In 4G LTE (fourth generation, long term evolution), LTE initially supported Single-User MIMO (SU-MIMO), with enhancements for Multi-User MIMO (MU-MIMO) in later releases. LTE used relatively simple codebooks for two-antenna and four-antenna configurations, primarily supporting openloop and closed-loop MIMO modes. Open-loop does not require feedback, while closed-loop relies oncodebook feedback from the base station. The rank, e.g., the number of independent data streams, is dynamically adapted based on the channel conditions.

[0011] 5G NR (fifth generation, new radio) improved upon this using more advanced MIMO. In particular, 5G NR significantly expands the MIMO capabilities with higher-order MIMO (up to 8 layers for UL), flexible numerology, and support for Massive MIMO. 5G employs a two-stage codebook approach, providing more refined beamforming and spatial domain optimization. The codebook includes the following: 1) a Type I codebook, which supports single-layer or multi-layer transmission with different levels of quantization for precoding matrices; and a type II codebook, which is used for advanced scenarios like higher-layer MIMO or Massive MIMO, where finer granularity in beam selection is needed. 5G also includes more sophisticated feedback mechanisms, which allow better adaptation of the transmission parameters based on the channel's spatial characteristics.

[0012] In summary, uplink MIMO with a codebook in 3GPP standards provides a structured approach to using multiple antennas for performance gains, enabling adaptive spatial processing to optimize transmission.BRIEF SUMMARY

[0013] This section is intended to include examples and is not intended to be limiting.

[0014] In an exemplary embodiment, a method is disclosed that includes A method, comprising: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0015] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0016] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least toperform: A method, comprising: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPM I ) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0017] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: A method, comprising: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0018] In another exemplary embodiment, an apparatus comprises means for: A method, comprising: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0019] In an exemplary embodiment, a method is disclosed that includes determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1 , 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

[0020] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0021] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

[0022] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1 , 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

[0023] In another exemplary embodiment, an apparatus comprises means for: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1 , 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings use reference numerals, where the same reference numerals may be used to refer to like parts throughout, but parts having the same reference numeral can differ in operation and components. In the attached drawings:

[0025] FIG. 1 is a table illustrating a preceding matrix W for single-layer transmission using 2 antenna ports;

[0026] FIG. 2 is a table illustrating a preceding matrix W for single-layer transmission using 4 antenna ports;

[0027] FIG. 3 illustrates a realistic UE antenna model for smartphone;

[0028] FIG. 4 is a graph of a set of curves illustrating envelope coverage (CCDF,Complementary Cumulative Distribution Function) at 2.6 GHz for a reference smartphone with 4 APs using the current 3GPP UL MIMO CB for different AP configurations;

[0029] FIG. 5 illustrates Table 1, which is a table of TPMI spherical coverage of 3GPP codebook entries for a UE with 4 APs;

[0030] FIG. 6 illustrates Table 2, which illustrates a number of combinations and required bits for a fully expanded UL MIMO codebook;

[0031] FIG. 7A is a flow diagram of a method for an UL MIMO codebook procedure performed by a UE that performs Method #1 in an example;

[0032] FIG. 7B is a flow diagram of a method for an UL MIMO codebook procedure performed by a network element that performs Method #1 in an example;

[0033] FIG. 7C is a flow diagram of a method for an UL MIMO codebook procedure performed by a UE that performs Method #2 in an example;

[0034] FIG. 7D is a flow diagram of a method for an UL MIMO codebook procedure performed by a network element that performs Method #2 in an example;

[0035] FIG. 7E is a flow diagram of a method for an UL MIMO codebook procedure performed by a UE that performs Method #3 in an example;

[0036] FIG. 7F is a flow diagram of a method for an UL MIMO codebook procedure performed by a network element that performs Method #3 in an example;

[0037] FIG. 8 illustrates Table 3, which illustrates a generalized TPMI index table for smartphone UE with non-uniform antenna implementation;

[0038] FIG. 9 illustrates Table 4, which illustrates an antenna port vector (APvec) index table for smartphone UE with non-uniform antenna implementation;

[0039] FIG. 10 is a graph of a set of curves of envelope coverage (CCDF) at 2.6 GHz for a reference smartphone using the current 3GPP UL MIMO CB for different AP configurations;

[0040] FIG. 11 illustrates Table 5, which illustrates a generalized TPMI index table for smartphone UE with non-uniform antenna implementation including an entry for single AP configuration;

[0041] FIG. 12 illustrates a signaling chart of examples;

[0042] FIGS. 13A, 13B, 13C, and 13D represent UE radiation patterns at 2.6 GHz for the top left, top right, bottom left, and bottom right, respectively, of a smartphone;

[0043] FIG. 14 is a graph of a set of curves illustrating MIMO codebook as described herein versus a Full UL MIMO codebook;

[0044] FIG. 15 is a graph of a set of curves illustrating a minimum envelope coverage at 2.6 GHz for reference smartphone using the current 3GPP UL MIMO OB for different AP configurations;

[0045] FIG. 16, which is split into FIGS. 16A, 16B, and 16C, illustrates Table 6, which is a full codebook for 4 APs and with a 90° phase granularity, expressed in absolute phase values;

[0046] FIG. 17, which is split into FIGS. 17A and 17B, illustrates Table 7, which is full codebook for 4 APs; and

[0047] FIG. 18 is a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced.DETAILED DESCRIPTION OF THE DRAWINGS

[0048] Abbreviations that may be found in the specification and / or the drawing figures are defined below, at the end of the detailed description section.

[0049] The word "exemplary” is used herein to mean "serving as an example, instance, or illustration.” Any embodiment described herein as "exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the examples.

[0050] When more than one drawing reference numeral, word, or acronym is used within this description withand in general as used within this description, the 7” may be interpreted as "or”, "and”, or "both”. 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.

[0051] 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.

[0052] It is noted that capital and lowercase words or phrases are considered to be the same herein. For instance, the words Slice, slice, and SLICE are the same, as are the phrases Network Repository Function, network repository function, and NETWORK REPOSITORY FUNCTION.

[0053] Any flow diagram or signaling diagram herein is considered to be a logic flow diagram, and illustrates the operation of an exemplary method, results of execution of computer program instructions embodied on a computer readable memory, and / or functions performed by logic implemented in circuitry. For methods, flow diagrams, and signaling diagrams, the orders of method steps, blocks in the flow, or signaling are not critical and instead are examples.

[0054] Technical context is now provided for technical areas related to the understanding of the examples. This document uses the term "antenna port” (AP). It is helpful to provide an introduction to this term and its use. A UE interacts with its antenna array using RF (radio frequency) receive chains, and these antennas are also referred to as physical antennas. Antenna Ports (APs) are defined by their logical characteristics such as the reference signal they carry. Different types of reference signals are transmitted on different antenna ports, such as DMRS (Demodulation reference signal) for demodulation and CSI-RS (channel state information-reference signal) for channel state information reporting. The number of logical APs should not exceed the number of physical antennas, and the number of logical APs can be different for DL (downlink) and UL (uplink), and are often related to the number of supported MIMO (multiple input, multiple output) layers in DL and UL.

[0055] The 5G (fifth generation) standard focuses on three type of device categories:

[0056] 1) eMBB (Enhanced mobile broadband) 5G devices, mainly smartphones, tablets and mobile hotspot routers.

[0057] 2) Outdoor and indoor CPE (Customer premises equipment) for 5G fixed wireless access.

[0058] 3) Different types of 5G S-modules (5G Superior Universal Modules) for industrial applications.

[0059] These devices vary significantly in size (e.g., form factor) with very different antenna design from amount to frequency coverage, antenna placement relative to the device chassis (e.g., and its ground plane) and antenna characteristics, like radiation patterns. Devices like FWAs (Fixed wireless accesses) and CPEs are designed with antennas having well defined and uniform characteristics, which fit well the current 3GPP (third generation partnership project) 5G UL MIMO (Uplink multiple input, multiple output) codebooks, as that is derived and optimized for linear antennas with uniform characteristics.

[0060] 5G UL MIMO capable devices mainly rely on Codebook-based UL MIMO that utilizes the codebooks specified in 3GPP TS 38.211 for different layer and antenna port combinations and examples of these 3GPP defined codebooks are shown in FIG. 1 and FIG. 2. FIG. 1 is a table illustrating aprecoding matrix W (where W is used to refer to weights) for single-layer transmission using 1 or 2 antenna ports, and FIG. 2 is a table illustrating a precoding matrix W for single-layer transmission using 1, 2, or 4 antenna ports.

[0061] Smartphones, which are by far the most dominant device type in terms of market share and traffic, are not implemented with antennas having uniform characteristics. However, UE (user equipment, which include smartphones) antennas within 3GPP have and are simulated as having uniform characteristics, whereby the 3GPP defined UL Ml MO codebooks result in good performance.

[0062] A model for 4-port realistic UE having 4 antennas, one at each corner, has been proposed in the contribution R1 -2403997 "Discussion on Channel model adaptation / extension of TR38.901 for 7-24GHz”, 3GPP TSG RAN WG1 #117, Fukuoka, Japan, 20 - 24 May, 2024. This updated model is based on electromagnetic simulations on a reference smartphone. FIG. 3 illustrates a realistic UE antenna model for a smartphone. This figure shows a user equipment 10, as a smartphone, having a front side 320. Four antenna ports 310-1 (top left side), 310-2 (top right side), 310-3 (bottom left side), and 310- 4 (bottom right side) are shown, and each of these produces a corresponding radiation pattern 330-1, 330- 2, 330-3, and 330-4. Distance between the antenna ports 1 and 2 and 3 and 4 is dy=150mm, and distance between the antenna ports 1 / 3 and 2 / 4 is dx=70mm.

[0063] One of observations, such as by using FIG. 3, is that the smartphone antennas present directive properties that limit the directions in which more than two antennas have significant and equal gain, which is a prerequisite for optimal antenna combination with a precoding vector. In addition, such antennas will also have differences in phase and elliptical polarization for each angular direction (not linear polarization as assumed by the 3GPP-defined UL MIMO codebook). As such, this is far from uniform antenna characteristics, as assumed by the current 3GPP UL MIMO codebook.

[0064] The current codebooks defined in 5G pose some limitations and challenges for UE devices with antennas having non-uniform characteristics, which is the reality for handheld devices like smartphones with 4 APs for most of the system band. The main challenge for the current defined 3GPP UL MIMO Codebook is as follows.

[0065] Not all Antenna Port (AP) combinations are supported. Only 2 combinations out of 6 unique antenna combinations for 2 AP are included (AP 1 & 3 and AP 2 & 4) and no entries for 3 APs. As such, the performance of the 3GPP UL MIMO OB is dependent on the used UE AP to physical antenna mapping, when such a device has non-uniform antennas, i.e. , which physical antenna will be mapped as AP1 , and the like. This mapping is dependent on the order of the UE transmitted SRSs (Sounding reference signals) (which SRS is transmitted from which physical antenna), as these SRSs are used by the gNB (a base station for 5G / NR, new radio) to derive the best codebook for the given channel conditions.

[0066] Refer to FIG. 4, which is a graph of a set of curves illustrating envelope coverage (CCDF, Complementary Cumulative Distribution Function) at 2.6 GHz for a reference smartphone with 4 APs using the current 3GPP UL Ml MO CB for different AP configurations. Curve 440: Single (Best) antenna selection for all angular directions. Curve 430: 3GPP UL Ml MO CB for AP configuration of 1, 2, 3, 4. Curve 420: 3GPP UL MIMO CB for AP configuration of 1, 3, 2, 4. Curve 410: 3GPP UL MIMO CB for AP configuration of 1, 2, 4, 3.

[0067] Given FIG. 4, consider the 3GPP codebook for three different AP configurations using four antennas (top right, top left, bottom right, and bottom left) simulated with a reference smartphone at 2.6 GHz and where:

[0068] 1) AP configuration (1, 2, 3, 4) will allow the gNB to combine AP 1 & 3 and AP 2 & 4 for the 2 APs codebook entries (TPMI, Transmit Precoding Matrix Identity, 4 to 11), which in this example is, respectively, the top right antenna with the bottom right antenna and the top left antenna with the bottom left antenna.

[0069] 2) AP configuration (1 , 3, 2, 4) will allow the gNB to combine AP 1 & 2 and AP 3 & 4 for the 2 APs codebook entries, which in this example is the top right antenna with the top left antenna and the bottom right antenna with the bottom left antenna.

[0070] 3) AP configuration (1 , 2, 4, 3) will allow the gNB to combine AP 1 & 4 and AP 2 & 3 for the 2 APs codebook entries, which in this example is the top right antenna with the bottom left antenna and the top left antenna with the bottom right antenna.

[0071] Only 3 out of the 6 possible unique antenna combination of 2 APs for precoding have been evaluated for this example, as the used antenna radiation patterns are mirrored versions of each other, which is a result of the geometrical symmetry of the reference smartphone. That will of course not be the case for a realistic smartphone where such a symmetrical relationship is unlikely.

[0072] The Complementary Cumulative Distribution Functions (CCDFs) were obtained from evaluating all 283GPP codebook entries for 2500 uniformly distributed points on the full angular sphere and the maximum obtainable combined antenna gain value was found for each uniform point. These values were then sorted in a descending order and plotted in FIG. 4. The curves in FIG. 4 are one example of the effect antennas with non-uniform characteristics have on the currently defined codebook for UL MIMO within 3GPP. Other antenna configurations, or the same antenna at other frequencies, will display a different behavior (CCDF distribution). Antennas with different characteristics will show more or less variance to the order of the APs when utilizing the 3GPP defined UL MIMO precoding codebook. As such, antennas with similar characteristics will have less variance, while antenna with different characteristics will have more variance.

[0073] It's clear that differences of up to 2 dB may be observed (maximum antenna gain values) depending on the configured AP configuration at the UE, where two of the three AP configurations are not much better than selecting one of the four possible antennas (e.g., Best Antenna Selection) for the 40% of the sphere representing the high gain regions.

[0074] The reason for this diversity relates to the effectiveness of the used codebook on the antennas. This is illustrated in Table 1 of FIG. 5, which is a table of TPMI spherical coverage of 3GPP codebook entries for a UE with 4 APs, where the 3GPP codebook entry resulting in the highest antenna gain value have been found for each angular uniform direction, whereafter the angular coverage of each codebook entry have been calculated. The codebook entries have then been sorted into single active AP codebook entries (TPMI 0-3), two active AP codebook entries (TPMI 4-11) or 4 active AP codebook entries (TPM1 12-27). More antenna gain may be realized by combining more antennas. However, when the two or more antennas have different antenna characteristics, combining two or more antennas may only result in an increase in antenna gain for limited angular directions. This is especially the case when its only possible to select 2 out of 6 possible pairs, whereby selecting in the wrong order may result in selecting antennas having maximum gain (directivity) in different angular directions, reducing the angular directions with increased antenna gain. This is seen in FIG. 5 for AP combination where the coverage values for two AP combining (TPMI 0-3) are lower. Selecting a better order of the APs will result in higher values of the combined antenna gain. Consider the following.

[0075] UE AP configuration (1, 2, 3,4) will have the best antenna gain by only selecting a single AP (no antenna combining) for 33% of the uniform angular directions, combining 2 APs will result in the highest antenna gain for 7 % of the uniform angular directions, while combining 4 APs will result in the highest antenna gain for 60 % of the uniform angular directions.

[0076] It's evident from Table 1 that AP configuration (1, 3, 2, 4) has much more successful precoding (antenna combining) gains, as only 12 % of the uniform angular directions will result in the highest antenna with only a single AP codebook entry (TPMI 0-3). This is not the case for AP configuration (1, 2, 3, 4,) and (1, 2, 4, 3) where around 30 % of the uniform angular directions will result in the highest antenna with only a single AP codebook entry (selecting a single antenna).

[0077] One way to articulate this problem is the following. How is it possible to design codebooks and enhance the current 3GPP defined UL Ml MO codebook to be independent of the UE AP configurations? That is, an update to the current UL MIMO codebooks is needed to better support UE models with more realistic non-uniform antenna characteristics, as UE AP-port-to-physical-antennas- configuration is unknown to the network. As such, the target for the description herein is UEs utilizing codebook-based precoding for UL MIMO.

[0078] The examples below address at least this problem. Different embodiments of possible updated UL MIMO codebooks that are independent on the UE AP configuration are provided below. Examples provide one or more of the following:

[0079] 1) Splitting the UL MIMO codebook into a TPMI and an APvec (antenna port vector) portion;

[0080] 2) Allows UE interpretation of the 3 TPMI and APvec combinations; and / or

[0081] 3) UE signaling of a "preferred” UL MIMO codebook, e.g., based on uniform or non- uniform antenna characteristics.

[0082] The following uses a nested topical structure for ease of reference. This nested topical structure has the following categories and subcategories: I, II, III ... are main categories; a, b, c... are subcategories; 1, 2, 3... are further subcategories; and i, ii, ill... are even further subcategories.

[0083] For illustration purposes, the examples below discuss UE supporting 4 antennas. Please note that the examples are not limited to 4x4 UL MIMO. The methods apply to other cases as well, for example, 6x6 UL MIMO, 8x8 UL MIMO, or NxN UL MIMO, where N is an integer, representing a maximum number of supported antenna ports.

[0084] I. Method #1

[0085] A simple approach could be to expand to current UL MIMO codebook to include all viable precoding combinations for a UE supporting 4 antennas (AP) (including 3 APs, as only 1, 2, or 4 APs are supported). However, that will result in 156 unique combinations for antenna combining utilizing 90° phase shifts (PSs) and might not scale well for a UE supporting more than 4 antennas (AP) or for a higher granularity of the phase. This is illustrated in Table 2 of FIG. 6, which illustrates a number of combinations and required bits for a fully expanded UL MIMO codebook.

[0086] The total number of mathematical combinations when combining four antennas is equal to TotAnt comb= (Phcomb)( AnLs>= 44= 256, where Phcomb is the number of phase combinations and #Ants is the number of antennas. That is, this describes the combinations when using all four antennas. Additional combinations exist for three antennas out of four, two antennas of out four, and one antenna out of four, which may be similarly handled but are not described. For the combinations when using all four antennas, since antenna combining is relying on the relative phase difference between the APs, the number of unique combinations for antenna combining can as derived as follows:

[0091] The total number of unique codebook combinations are the 4+24+64+64=156. In comparison, the current 3GPP UL Ml MO codebook contains 28 combinations, which requires 5 bits to signal. The full codebook can be found described below, together with an definition of unique combinations for antenna combining.

[0092] FIG. 7A is a flow diagram of a method for performing Method #1 in an example. This is assumed to be performed by a UE. The flow includes in, block 710, receiving, from a network element (such as a gNB or other base station), an index for transmit precoding matrix identity (TPMI) for an uplink transmission by the user equipment. In block 720, the UE determines a TPMI to use for the uplink transmission by searching for the index from a table of TPMIs covering all viable precoding combinations on different phase and antenna port settings from one antenna port to a maximum number of supported antenna ports. In block 730, the UE transmits an uplink transmission at least by applying the determined TPMI.

[0093] Referring to FIG. 7B, this figure is a flow diagram of a method for an UL MIMO codebook procedure performed by a network element that performs Method #1 in an example. The network element may be a base station such as a gNB, RAN, or other access network, or part of some split functionality such as a central unit. The network element determines a transmit precoding matrix identity (TPMI) to use for an uplink transmission by a user equipment, wherein the determining comprises determining an index for the TPMI from a table of TPMIs covering all viable precoding combinations on different phase and antenna port settings from one antenna port to a maximum number of supported antenna ports. See block 711. In block 721, the network element transmits, to the user equipment, the index for the TPMI. In block 731, the network element receives, from the user equipment, the uplink transmission.

[0094] II. Method #2

[0095] In this method, the existing UL MIMO codebook is kept as shown in FIG. 1 and FIG. 2, but the gNB is enabled to reconfigure the APs at the UE. This can be achieved be defining a 2-bit AP vector, referred to as APvec, which defines multiple APvecs as illustrated below:

[0096] a) APvec = 00, which corresponds to AP configuration [1, 2, 3, 4] ;

[0097] b) APvec = 01 , which corresponds to AP configuration [1 , 3, 2, 4] ;

[0098] c) APvec = 10, which corresponds to AP configuration [1 , 2, 4, 3] ; and

[0099] d) APvec = 11, which corresponds to AP configuration [2, 4, 3, 1],

[0100] The individual APvecs (antenna port vectors) have a same number of elements as do the TPMIs, and individual elements in the APvecs refer to positions of individual phase settings in the TPMIs. Furthermore, the order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should be reordered. For instance, applying the APvec of [2, 4, 3, 1] to the TPMI with W = [1 j -j 0] results in an antenna port configuration of [j 0 -j 1], This example results in a reordering of the phase settings, and this type of reordering is also referred to as permuting. It is noted that the APvec of 00 does not result in reordering of the phase settings, but the other APvecs do result in reordering of the phase settings.

[0101] The phase shifts applied to individual antenna ports of 90 degrees would be 0, 90, 180, 270, which corresponds to phase settings (e.g., in the TPMIs) of 1, j, -1, -j, respectively. A 45-degree version will include [0, 45, 90, 135, 180, 225, 270, 315] degree settings. The corresponding complex mapping (in the TPMIs) would be [1, (1+j), j, (-1 +j), -1, (-1-j), -j, (1-j)].

[0102] It is assumed that the UE will know the AP configuration when transmitting the SRS signals and can thereby use the information in the APvec to reconfigure the AP, with the phase setting indicated by the legacy UL MIMO codebook signaling (e.g., as in FIGS. 1 and 2).

[0103] This requires a total of 5 + 2 = 7 bits for both the CB and APvec signaling, which is still one bit less than a full codebook implementation, however not including 3 AP configurations (i.e., no configurations using 3 APs are included). As the full codebook uses 8 bits (Method #1), only 2 bits are used for the APvec in this embodiment. The first three entries ensure that the first selected antenna can be combined with any of the remaining three antennas for TPMI entries 4 to 11 representing two AP combining. The fourth entry is for free, and the selected AP combination will add 8 more combination of two AP combining and 16 more combination for four AP combining.

[0104] In addition, both vectors will not always have to be signaled for each codebook change. A pre-coding update without AP re-configurations will still only require a 5-bit signaling. More details of the dynamic behavior of DCI with both the TPMI and the APvec or only the TPMI is described below.

[0105] This implementation will result in 45 unique codebook entries, where the unique 2 AP combinations are increased from 8 to 24, but the unique 4 AP combinations are limited in increases. The limited increase in unique 4 AP combinations is due to the nature of the 3GPP defined codebook that only include 5 phase combinations, that are then AP-interchanged to create the remaining 11 phase combinations. This is exactly what the APvec is aiming to achieve, whereby the APvec almost only adds additional combinations to the 2 AP combinations for this case.

[0106] FIG. 7C is a flow diagram of a method for an UL Ml MO codebook procedure that performs Method #2 in an example. The flow in FIG. 7C is performed by a UE. In block 735, the UE receives, from a network element such as a gNB or other base station, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment. In block 740, the UE determines a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports. The UE, in block 745, determines an antenna port vector to use by searching for the second index from multiple antenna port vectors. In block 750, the UE determines an antenna port configuration based on the determined antenna port vector and the determined TPMI. Using the previous example of applying the APvec of [2, 4, 3, 1] to the TPMI with W = [1 j -j 0], this results in an antenna port configuration of [j 0 — j 1]. The UE in block 755 transmits an uplink transmission at least by applying the determined TPMI and the antenna port configuration. Concerning blocks 750 and 755, it is noted that the APvec and the TPMI can be interpreted in at least the following two ways:

[0107] a) The APvec determines the order of the antenna ports and the TPMI determines the relative phase difference between the antenna ports:

[0108] 1) Apply the correct antenna port order (e.g., as per the APvec); and

[0109] 2) Apply the TP M I .

[0110] b) The APvec is used the reorder the TPMI:

[0111] 1) Reorder the TPMI; and

[0112] 2) Apply the reordered TPMI.

[0113] Turning to FIG. 7D, this figure is a flow diagram of a method for an UL MIMO codebook procedure performed by a network element that performs Method #2 in an example. The network element may be a base station such as a gNB, RAN, or other access network, or part of some split functionality such as a central unit. In block 736, the network element determines a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1 , 2, or 4 antenna ports. In block 741, the network element transmits, to the userequipment, the first index for the TPMI and the second index for the antenna port vector. The network element, in block 746, receives, from the user equipment, the uplink transmission.

[0114] III. Method #3

[0115] This method is divided into two possible implementations: Method #3a; and Method #3b. A general method for both is described in FIG. 7E, which is a flow diagram of a method for an UL Ml MO codebook procedure that performs Method #3 in an example. The flow in FIG. 7E is performed by a UE. In block 765, the UE receives, from a network element such as a gNB or other base station, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment. In block 770, the UE determines a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings from one antenna port to a maximum number of supported antenna ports, for example, phase settings for one of 1, 2, 3, or 4 antenna ports or 2, 3, or 4 antenna ports. The UE, in block 775, determines an antenna port vector to use by searching for the second index from multiple antenna port vectors. In block 777, the UE determines which elements in the determined antenna port vector to use based on a number of phase settings in the determined TPMI. In block 780, the UE determines an antenna port configuration based at least on the determined elements for the determined antenna port vector and the determined TPMI. The UE in block 785 transmits an uplink transmission at least by applying the TPMI and the antenna port configuration. Concerning blocks 780 and 785, it is noted that the APvec and the TPMI can be interpreted in at least the following two ways:

[0116] a) The APvec determines the order of the antenna ports and the TPMI determines the relative phase difference between the antenna ports:

[0117] 1) Apply the correct antenna port order (e.g., as per the APvec); and

[0118] 2) Apply the TPMI.

[0119] b) The APvec is used the reorder the TPMI:

[0120] 1) Reorder the TPMI; and

[0121] 2) Apply the reordered TPMI.

[0122] FIG. 7F is a flow diagram of a method for an UL Ml MO codebook procedure performed by a network element that performs Method #3 in an example. The network element may be a base station such as a gNB, RAN, or other access network, or part of some split functionality such as a central unit. In block 766, the network element determines a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings from one antenna port to a maximum number of supported antenna ports, for example, phase settings for one of 1, 2, 3, or 4 antenna ports or 2, 3, or 4 antenna ports antenna ports. The network element in block 771 transmits, to the userequipment, the first index for the TPMI and the second index for the antenna port vector. In block 776, the network element receives, from the user equipment, the uplink transmission.

[0123] a. Method #3a

[0124] A third implementation, is based on implementation 2, but with a different split between bits used for the pre-coding indexes and bits for the APvec and with codebook entries optimized for the use of an APvec.

[0125] The precoding matrix is reduced to 4 bits, resulting in 16 indexes (see Table 3 of FIG. 8, which illustrates a generalized TPMI index table for a smartphone UE with non-uniform antenna implementation) and the APvec is expanded to 3-bits resulting in 8 configurations (see Table 4 in FIG. 9, which illustrates an antenna port vector (APvec) index table for a smartphone UE with a non-uniform antenna implementation).

[0126] The APvec always contains 4 ports, whereas the TPMI contains 2, 3 or 4 phase settings (and the other entries are zero). As such, a UE receiving a TPMI of two phase settings will only use the first two APs in the APvec and a UE receiving a TPMI of three phase settings will only use the first three APs in the APvec.

[0127] The TPMI and the APvec will not both have to be transmitted for each codebook update at the UE, as mentioned previously. The interpretation of the three combinations may be as follows:

[0128] 1) Use or receive both a TPMI and an APvec: Apply the AP configuration as defined by the APvec, with the phase settings defined by TPMI.

[0129] 2) Use or receive only a TPMI: Update the current configured AP with the phase settings defined by TPMI.

[0130] 3) Use or receive only an APvec: This scenario indicated a single AP configuration, using the first defined AP in the APvec.

[0131] The advantage of this approach is that the codebook does not have to include an entry for a single AP configuration, which can be a suitable approach, as the codebook only consists of 16 entries.

[0132] This implementation will result in 111 unique codebook entries, with the TPMI and APvec entries shown in Table 3 (FIG. 8) and Table 4 (FIG. 9), which is a significant increase compared to the 45 combinations obtained for Method #2, reusing the current 3GPP UL MIMO codebook.

[0133] The difference in envelope coverage between the current 3GPP AP UE configuration dependent UL MIMO codebook and the updated UL MIMO OB disclosed in this example provides benefits. Refer to FIG. 10, which is a graph of a set of curves of envelope coverage (CCDF) at 2.6 GHz for a reference smartphone using the current 3GPP UL MIMO OB for different AP configurations. Curve 910: UL MIMO OB (of the third method). Curve 940: 3GPP UL MIMO OB for AP configuration of 1, 2 ,3 ,4. Curve930: 3GPP UL MIMO CB for AP configuration of 1, 3 ,2 ,4. Curve 920: 3GPP UL MIMO CB for AP configuration of 1, 2 ,4 ,3. With reference to FIG. 10, the updated UL MIMO codebook results in a general improved performance (up to 2 dB for the high antenna gain angular regions), while being independent on the UE AP configuration.

[0134] b. Method #3b

[0135] A second implementation of Method #3 is described now, where the TPMI table includes an entry for a single AP configuration, as shown in Table 5 of FIG. 11, which illustrates a generalized TPMI index table for a smartphone UE with non-uniform antenna implementation including an entry for single AP configuration.

[0136] The APvec is the same as shown in Table 4 (FIG. 9), but with a different interpretation when the APvec is sent (e.g., and received) alone: Use or receive only an APvec: Update the currently used TPMI with the AP order defined be APvec.

[0137] This reduces signaling overhead. Another advantage of this approach is that the order of the APs can be changed alone, while keeping the already configured TPMI. However, one of the 4 AP TPMI (15 in Table 3, see FIG. 8) is substituted with the single AP entry (now the first entry).

[0138] IV. Fifth Example

[0139] In this example, the UE can signal uniform or non-uniform antenna implementation, for the gNB to select the correct codebook:

[0140] a) Legacy codebook for UEs with uniform antenna implementation; or

[0141] b) A codebook as described herein for UEs with non-uniform antenna implementation.

[0142] V. Signaling Chart Example

[0143] Referring to FIG. 12, this figure illustrates a signaling chart of examples.

[0144] Step #1 : The UE 10 is assumed to be RRC connected with a gNB 70.

[0145] Step #2: The UE 10 sends a UE capability report to the gNB 70 that may include an indication for uniform or non-uniform UL MIMO CB for the static case. That is, the UE is either implemented with either uniform or non-uniform AP, but not with both in an example for a static case. This may be indicated via RRC signaling.

[0146] Step #3: The gNB initiates Codebook-Based UL MIMO.

[0147] Step #4: The gNB allocates resources for the UE for a number of SRS transmissions equal to the number of supported APs at the UE.

[0148] Step #5: The UE transmits (using at least part of the allocated resources) SRSs for the gNB an unknown AP to physical antenna mapping.

[0149] Step #6: The UE may include an indication for uniform or non-uniform UL MIMO CB for the dynamic case via UCI. With respect to this step, most UEs will likely be implemented with antennashaving either static uniform or non-uniform characteristics, where the indication for uniform or non-uniform UL MIMO CB could be included in the UE capability report (Step #2). For example, the antennas for FR1 (frequency range 1) could be non-uniform and for FR2 (frequency range 2) uniform. However, other UEs could have a combination of antennas having both uniform and non-uniform characteristics, especially for the 15 GHz 6G system band. This band could be implemented with four antennas with non-uniform characteristics (shared with other sub 10 GHz system bands) and maybe a single dual polarized antenna array (uniform antenna characteristics), but only supporting four-layer DL MIMO. As such, the UE might have to select four out of 6 antennas for SRS transmission. Thus, the indication for uniform or non-uniform UL MIMO CB might be sent dynamically (e.g., every time the signaling in step #6 is performed).

[0150] Step #7: The gNB derives the best AP configuration and TPMI. As background, the gNB knows the ordering of the logical APs, but not how those logical APs are mapped to the physical antennas. As such, the UE performs SRS switching according to 3GPP TS 38.214, each SRS resource in a ResourceSet consists of N SRS ports and the UE knows the association between SRS ports and UE physical antenna ports. The gNB derives the best APs based on SRS ports and then the UE knows how to map that onto the physical APs.

[0151] Step #8: The gNB informs the UE of the selected AP configuration (APvec) and / or TPMI via DOI. In example, the gNB calculates the H-Matrix of the current channel conditions and derives the best TPMI for the UE. As the gNB knows the last selected TPMI, the gNB also knows if only an updated TPMI and / or APvec are / is needed.

[0152] Step #9: The UE applies the informed AP configuration (APvec) and precoding (TPMI) to data, for the UL MIMO layers, for subsequent transmission.

[0153] Step #10: The UE transmits the pre-coded UL MIMO layers.

[0154] VI. Dynamic DOI signaling of precoding index and APvec:

[0155] DOI format 0_1 is typically used in 5G NR to schedule uplink data with PUSCH (physical uplink shared channel). It is carried by the PDCCH (physical downlink control channel), providing the UE with the necessary information to perform uplink transmission. This information includes fields such as time and frequency resource assignment, modulation and coding scheme and, among others, precoding index / number of layers (e.g., TPMI) and antenna ports. Examples herein also recommend the addition of the APvec information to the DCI signaled to the UE. This could either be:

[0156] a) An APvec field in this DCI format that would occupy between 2-3 bits (depending on the method employed); or

[0157] b) A modified version of the existing TPMI field, which would now also include the APvec information. If the latter is considered, then this field, as other fields in this DCI format, could have adynamic bit length, dependent on whether the gNodeB wants to update TPMI information (4 to 5 bits), APvec information (2 to 3 bits) or both.

[0158] VII. Smartphone Radiation Patterns at 2.6 GHz:

[0159] The following is a description of simulations in CST for all typical supported 5G system bands and the envisioned 6G system bands. This model and those simulation results are used as a reference smartphone and the radiation patterns at 2.6 GHz are shown in FIGS. 13A, 13B, 13C, and 13D, which represent UE radiation patterns at 2.6 GHz for the top left, top right, bottom left, and bottom right, respectively, of a smartphone. These radiation patterns have a directivity around 6.0 d Bi with the maximum gain for each radiation pattern in different angular directions.

[0160] VIII. Example Results

[0161] The envelope coverage performance of the disclosed UL MIMO codebook of Method #3 versus the full UL MIMO codebook Method #1 (Method #3 is shown in FIG. 14, where it is clear to see that the envelope coverage performance is almost similar. The two worst performing AP configurations using the original 3GPP codebook are included as references. Curve 1320: UL MIMO OB from Method #1 . Curve 1310: Full UL MIMO OB, Method #3. Curve 1340: 3GPP UL MIMO OB for AP configuration of 1, 2 ,3 ,4. Curve 1330: 3GPP UL MIMO OB for AP configuration of 1, 2 ,4 ,3.

[0162] Improved envelope coverage performance and independence towards UE AP configuration include some of the benefits highlighted herein for the UL MIMO codebook herein. However, the UL MIMO codebook herein is also superior when looking at the minimum configurable antenna gains, which can be used to increase the SI NR (signal-to-interference-plus-noise ratio) between different MIMO layers departing / arriving at different angular directions. An improvement of around 3 dB is observed.

[0163] The dotted CCDF curves for the combined minimum antenna gain values are obtained from evaluating all 283GPP codebook entries for 2500 uniformly distributed points on the full angular sphere and finding the minimum obtainable combined antenna gain value for each point. These values are then sorted in a descending order and plotted in FIG. 15 as dotted curves 1410. The solid curves 1420 are plotted as the maximum gain values from FIG. 4.

[0164] IX. Codebook for Method #1

[0165] As antenna combining is dependent on the relative phase difference between the antennas, many of the mathematically unique combinations will be non-unique for the antenna combining. This is illustrated below for 3GPP TPMI index 18 [1, j, -1, -j], which represents the following absolute phase values: (0°, 90°, 180°, 270°). This will result in in the following relative phase values between AP1&AP2, AP2&AP3 and AP3&AP4 = (90°, 90°, 90°). As such:

[0166] a) Absolute phase values (0°, 90°, 180°, 270°), and relative phase values (90°, 90°,90°);

[0167] b) Absolute phase values (270°, 0°, 90°, 180°), and relative phase values (90°, 90°, 90°);

[0168] c) Absolute phase values (180°, 270°, 0°, 90°), and relative phase values (90°, 90°, 90°)

[0169] d) Absolute phase values (90°, 180°, 270°, 0°), and relative phase values (90°, 90°, 90°).

[0170] Conclusion: these four non-identical mathematical combinations only result in one unique antenna pattern as an outcome of any of the combinations.

[0171] The full 156 entry codebook in absolute phase values is shown in Table 6, where the first AP is used as reference with a 0° absolute phase value. Refer to FIG. 16, which is split into FIGS. 16A, 16B, and 16C, illustrates Table 6, which is a full codebook for 4 APs and with a 90° phase granularity, expressed in absolute phase values. This is one example of a way of covering with all combinations for beam steering.

[0172] The codebook shown in Table 6 can be converted to the format used within 3GPP as shown in Table 7. Refer to FIG. 17, which is split into FIGS. 17A and 17B, illustrates Table 7, which is full codebook for 4 APs.

[0173] X. Other examples

[0174] Turning to FIG. 18, this figure shows a block diagram of one possible and non-limiting example of a cellular network 1 that is connected to a user equipment (UE) 10. A number of elements are shown in the cellular network of FIG. 18: a base station 70; and a core network 90.

[0175] In FIG. 18, a user equipment (UE) 10 is in wireless communication via radio link 11 with the base station 70 of the cellular network 1 . A UE 10 is a wireless communication device, such as a mobile device, that is configured to access a cellular network. The UE 10 is illustrated with one or more antennas 28. The ellipses 2 indicate there could be multiple UEs 10 in wireless communication via radio links with the base station 70. The UE 10 includes one or more processors 13, one or more memories 15, and other circuitry 16. The other circuitry 16 includes one or more receivers (Rx(s)) 17 and one or more transmitters (Tx(s)) 18. A program 12 is used to cause the UE 10 to perform the operations described herein. For a UE 10, the other circuitry 16 could include circuitry such as for user interface elements (not shown) like a display. The program 12 may be implemented via instructions stored in memory / memories 15 and executed by processor(s) 13, or by circuitry such being implemented as part of the processor(s) or other circuitry elements, or both.

[0176] The base station 70, as a network element of the cellular network 1 , provides the UE 10 access to cellular network 1 and to the data network 91 via the core network 90 (e.g., via a user plane function (UPF) of the core network 90). As such, the base station 70 may be considered to be an accessnode, which provides access by UE(s) 10 to the cellular network 1. The base station 70 is illustrated as having one or more antennas 58. In general, the base station 70 may be referred to as RAN node 70, although many will make reference to this as a gNB (gNode B, a base station for NR, new radio) instead. There are, however, many other examples of RAN nodes including an eNB (evolved Node B) or TRP (Transmission-Reception Point). The base station 70 includes one or more processors 73, one or more memories 75, and other circuitry 76. The other circuitry 76 includes one or more receivers (Rx(s)) 77 and one or more transmitters (Tx(s)) 78. A program 72 is used to cause the base station 70 to perform the operations described herein. The program 72 may be implemented via instructions stored in memory / memories 75 and executed by processor(s) 73, or by circuitry such being implemented as part of the processor(s) or other circuitry elements, or both.

[0177] It is noted that the base station 70 may instead be implemented via other wireless technologies, such as Wi-Fi (a wireless networking protocol that devices use to communicate without direct cable connections). In the case of Wi-Fi, the link 11 could be characterized as a wireless link.

[0178] Two or more base stations 70 communicate using, e.g., link(s) 79. The link(s) 79 may be wired or wireless or both and may implement, e.g., an Xn interface for 5G (fifth generation), an X2 interface for LTE (Long Term Evolution), or other suitable interface for other standards.

[0179] The cellular network 1 may include a core network 90 that may include core network functionality, and which provide connectivity via a link or links 81 with a data network 91, such as a telephone network and / or a data communications network (e.g., the Internet). The core network 90 includes one or more processors 93, one or more memories 95, and other circuitry 96. The other circuitry 96 includes one or more receivers (Rx(s)) 97 and one or more transmitters (Tx(s)) 98. A program 92 is used to cause the core network 90 to perform the operations described herein. The program 92 may be implemented via instructions stored in memory / memories 95 and executed by processor(s) 93, or by circuitry such being implemented as part of the processor(s) or other circuitry elements, or both.

[0180] The core network 90 could be a 5GC (5G core network). The core network 90 can implement or comprise multiple network functions (NF(s)) 99, and the program 92 may comprise one or more of the NFs 99. A 5G core network may use circuitry such as memory and processors, which may implement a virtualization layer. It could be a single standalone computing system, a distributed computing system, or a cloud computing system. The NFs 99 of the core network could be containers or virtual machines running on the circuitry of the computing system(s) making up the core network 90.

[0181] Core network functionality for 5G may include access and mobility management functionality that is provided by a network function 99 such as an access and mobility management function (AMF), session management functionality that is provided by a network function such as a session management function (SMF). Core network functionality for access and mobility management in an LTE(Long Term Evolution) network may be provided by an MME (Mobility Management Entity) and / or SGW (Serving Gateway) functionality, which routes data to the data network. Many others are possible, as illustrated by the examples in FIG. 18: AMF; SMF; MME; SGW; GMLC (Gateway Mobile Location Center); LMF (Location Management Function); UDM (Unified Data Management) / UDR (Unified Data Repository); NRF (Network Repository Function); and / or E-SMLC (Evolved Serving Mobile Location Center). These are merely exemplary core network functionality that may be provided by the core network 90, and note that both 5G and LTE core network functionality might be provided by the core network 90. The base station 70 is coupled via a backhaul link 31 to the core network 90. The base station 70 and the core network 90 may include an NG (Next Generation) interface for 5G, or an S1 interface for LTE, or other suitable interface for other radio access technologies for communicating via the backhaul link 31 .

[0182] In the data network 91 , there are instructions 94 stored in a computer-readable storage medium 4-1, which could be circuitry such as long-term memory such as a hard drive or a solid- state drive, a short-term memory such as dynamic random-access memory, or a combination of both (e.g., reading from long-term memory for temporary placement into short-term memory and subsequent downloading). The computer-readable medium 4-1 contains instructions 94 that, when downloaded and installed into the programs 12, 72, and 92 and / or memories 15, 75, or 95 of the corresponding UE 10, base station 70, and / or core element(s) 90, and executed by processor(s) 13, 73, or 93, cause the respective device to perform corresponding actions described herein. The computer-readable storage medium 4 may be implemented in other forms, such as via instructions 94 on a compact disc (as a computer-readable storage medium 4-2) or a memory stick.

[0183] The programs 12, 72, and 92 contain instructions (as part of a corresponding program 12, 72, and 92) stored by corresponding one or more memories 15, 75, or 95. These instructions, when executed by the corresponding one or more processors 13, 73, or 93, cause the corresponding apparatus 10, 70, or 90, to perform the operations described herein. The computer readable memories 15, 75, or 95 are circuitry and may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, firmware, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The processors 13, 73, and 93, are circuitry and may be of any type suitable to the local technical environment. For example, these processors may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), processors based on a multi-core processor architecture, and may also include specialized circuits such as field- programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices and other devices, or combinations of these devices, as non-limiting examples. The processors 13, 73, and 93are circuitry that can be programmed to perform functions via software, firmware or the like (including microcode), but are not solely software.

[0184] The receivers 17, 77, and 97, and the transmitters 18, 78, and 98 may implement wired or wireless interfaces. The receivers and transmitters may be grouped together as transceivers.

[0185] The cellular network 1 may implement network virtualization, which is the process of combining circuitry and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities (such as network functions 99) that result from the network virtualization are still implemented, at some level, using circuitry such as processors 73 and / or 93 and memories 75 and / or 95, and also such virtualized entities create technical effects.

[0186] In general, the various embodiments of the user equipment 10 can include, but are not limited to, devices implementing cellular technologies (such as smart phones, mobile phones, cellular phones, voice over Internet Protocol (IP) (VoIP) phones, and / or wireless local loop phones), tablets, portable computers, vehicles or vehicle-mounted devices for, e.g., wireless V2X (vehicle-to-everything) communication, image capture devices such as digital cameras, gaming devices, music storage and playback appliances, Internet appliances (including Internet of Things, loT, devices), loT devices with sensors and / or actuators for, e.g., automation applications, as well as portable units or terminals that incorporate combinations of such functions, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), Universal Serial Bus (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. That is, the UE 10 could be any end device that may be capable of wireless communication. By way of example rather than limitation, the UE may also be referred to as a communication device, terminal device (MT), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT).

[0187] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect and / or advantage of one or more of the example embodiments disclosed herein is providing and using an updated UL Ml MO codebook that is independent of AP configuration of UEs with antenna having non-uniform characteristics.. Another technical effect and / oradvantage of one or more of the example embodiments disclosed herein is overall reduced overhead signaling for UL MIMO codebook update, e.g., in DCI (Downlink control information). Another technical effect and / or advantage of one or more of the example embodiments disclosed herein is more UL MIMO codebook entries for overall less bit usage.

[0188] The following are additional examples.

[0189] Example 1 . A method, comprising: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1 , 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0190] Example 2. The method according to example 1, wherein: individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered; and transmitting by the user equipment the uplink transmission at least by applying the determined TPMI and the antenna port configuration comprises applying ordering of the individual elements in the determined antenna port vector to the individual phase settings in the determined TPMI to form the antenna port configuration and applying the phase settings in the antenna port configuration to corresponding antenna ports.

[0191] Example 3. The method according to example 2, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the determined TPMI for the applying but the others of the multiple antenna port vectors reorder the individual phase settings in the determined TPMI for the applying.

[0192] Example 4. The method according to any of examples 1 to 3, wherein the multiple TPMIs comprise elements from the following table: for 1, 2, or 4 antenna ports.

[0193] Example 5. The method according to any of examples 1 to 4, wherein the multiple TPMIs are indicated via 5 bits and the multiple antenna port vectors are indicated via 2 bits.

[0194] Example 6. The method according to example 5, wherein the multiple TPMIs are selected from a table with 28 indexes for 1, 2, or 4 antenna ports.

[0195] Example 7. The method according to example 5, wherein the antenna port vector is determined from the multiple antenna port vectors using one of four possible values.

[0196] Example 8. The method according to any of examples 1 to 7, wherein: the first index for the TPMI is received as a current first index for a current reception; the second index for the antenna port vector is received as a previous second index for a previous reception of the second index, but a second index for the current reception is not received; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the current first index and the antenna port configuration based on the previous second index.

[0197] Example 9. The method according to any of examples 1 to 7, wherein: the first index for the TPMI is received as a previous first index for a previous reception, but a first index for a current reception is not received; the second index for the antenna port vector is received as a current second index for a current reception of the second index; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the previous first index and the antenna port configuration based on the current second index.

[0198] Example 10. The method according to any of examples 1 to 9, wherein: the method further comprises indicating, by the user equipment to the network element, a capability to support uniform or non-uniform antenna array characteristics, the indicating performed prior to the receiving; and the determining the TPMI, determining the antenna port vector, determining, by the user equipment, determining the antenna port configuration, and the transmitting are performed based on the capability to support non-uniform antenna array characteristics.

[0199] Example 11. The method according to example 10, wherein the capability is indicated via radio resource control signaling.

[0200] Example 12. The method according to any of examples 1 to 9, wherein the second index for the antenna port vector is indicated via a field in downlink control information (DCI) from the network element to the user equipment.

[0201] Example 13. The method according to example 12, wherein the downlink control information (DCI) is DCI format 0_1.

[0202] Example 14. A method comprising: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

[0203] Example 15. The method according to example 14, wherein: individual antenna port vectors have a same number of elements as do the TPMIs, and individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elementsin the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered.

[0204] Example 16. The method according to example 15, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the TPMI but the others of the multiple antenna port vectors reorder the individual phase settings in the TPMI.

[0205] Example 17. An apparatus, comprising means for: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0206] Example 18. The apparatus according to example 17, wherein: individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered; and transmitting by the user equipment the uplink transmission at least by applying the determined TPMI and the antenna port configuration comprises applying ordering of the individual elements in the determined antenna port vector to the individual phase settings in the determined TPMI to form the antenna port configuration and applying the phase settings in the antenna port configuration to corresponding antenna ports.

[0207] Example 19. The apparatus according to example 18, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the determined TPMI for the applying but the others of the multiple antenna port vectors reorder the individual phase settings in the determined TPMI for the applying.

[0208] Example 20. The apparatus according to any of examples 17 to 19, wherein the multiple TPMIs comprise elements from the following table: for 1, 2, or 4 antenna ports.

[0209] Example 21 . The apparatus according to any of examples 17 to 20, wherein the multiple TPMIs are indicated via 5 bits and the multiple antenna port vectors are indicated via 2 bits.

[0210] Example 22. The apparatus according to example 21, wherein the multiple TPMIs are selected from a table with 28 indexes for 1, 2, or 4 antenna ports.

[0211] Example 23. The apparatus according to example 21, wherein the antenna port vector is determined from the multiple antenna port vectors using one of four possible values.

[0212] Example 24. The apparatus according to any of examples 17 to 23, wherein: the first index for the TPMI is received as a current first index for a current reception; the second index for the antenna port vector is received as a previous second index for a previous reception of the second index, but a second index for the current reception is not received; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the current first index and the antenna port configuration based on the previous second index.

[0213] Example 25. The apparatus according to any of examples 17 to 23, wherein: the first index for the TPMI is received as a previous first index for a previous reception, but a first index for a current reception is not received; the second index for the antenna port vector is received as a current second index for a current reception of the second index; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the previous first index and the antenna port configuration based on the current second index.

[0214] Example 26. The apparatus according to any of examples 17 to 25, wherein: the means are further configured for indicating, by the user equipment to the network element, a capability to support uniform or non-uniform antenna array characteristics, the indicating performed prior to the receiving; and the determining the TPMI, determining the antenna port vector, determining, by the user equipment, determining the antenna port configuration, and the transmitting are performed based on the capability to support non-uniform antenna array characteristics.

[0215] Example 27. The apparatus according to example 26, wherein the capability is indicated via radio resource control signaling.

[0216] Example 28. The apparatus according to any of examples 17 to 25, wherein the second index for the antenna port vector is indicated via a field in downlink control information (DCI) from the network element to the user equipment.

[0217] Example 29. The apparatus according to example 28, wherein the downlink control information (DCI) is DCI format 0_1.

[0218] Example 30. An apparatus comprising means for: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

[0219] Example 31. The apparatus according to example 30, wherein: individual antenna port vectors have a same number of elements as do the TPMIs, and individual elements in the antennaport vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered.

[0220] Example 32. The apparatus according to example 31, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the TPMI but the others of the multiple antenna port vectors reorder the individual phase settings in the TPMI.

[0221] Example 33. An apparatus, comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

[0222] Example 34. The apparatus according to example 33, wherein: individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered; and transmitting by the user equipment the uplink transmission at least by applying the determined TPMI and the antenna port configuration comprises applying ordering of the individual elements in the determined antenna port vector to the individual phase settings in the determined TPMI to form the antenna port configuration and applying the phase settings in the antenna port configuration to corresponding antenna ports.

[0223] Example 35. The apparatus according to example 34, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the determined TPMI for the applying but the others of the multiple antenna port vectors reorder the individual phase settings in the determined TPMI for the applying.

[0224] Example 36. The apparatus according to any of examples 33 to 35, wherein the multiple TPMIs comprise elements from the following table: for 1, 2, or 4 antenna ports.

[0225] Example 37. The apparatus according to any of examples 33 to 36, wherein the multiple TPMIs are indicated via 5 bits and the multiple antenna port vectors are indicated via 2 bits.

[0226] Example 38. The apparatus according to example 37, wherein the multiple TPMIs are selected from a table with 28 indexes for 1, 2, or 4 antenna ports.

[0227] Example 39. The apparatus according to example 37, wherein the antenna port vector is determined from the multiple antenna port vectors using one of four possible values.

[0228] Example 40. The apparatus according to any of examples 33 to 39, wherein: the first index for the TPMI is received as a current first index for a current reception; the second index for the antenna port vector is received as a previous second index for a previous reception of the second index, but a second index for the current reception is not received; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the current first index and the antenna port configuration based on the previous second index.

[0229] Example 41 . The apparatus according to any of examples 33 to 39, wherein: the first index for the TPMI is received as a previous first index for a previous reception, but a first index for a current reception is not received; the second index for the antenna port vector is received as a current second index for a current reception of the second index; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the previous first index and the antenna port configuration based on the current second index.

[0230] Example 42. The apparatus according to any of examples 33 to 41 , wherein: the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform indicating, by the user equipment to the network element, a capability to support uniform or non-uniform antenna array characteristics, the indicating performed prior to the receiving; and the determining the TPMI, determining the antenna port vector, determining, by the user equipment, determining the antenna port configuration, and the transmitting are performed based on the capability to support non-uniform antenna array characteristics.

[0231] Example 43. The apparatus according to example 42, wherein the capability is indicated via radio resource control signaling.

[0232] Example 44. The apparatus according to any of examples 33 to 41 , wherein the second index for the antenna port vector is indicated via a field in downlink control information (DCI) from the network element to the user equipment.

[0233] Example 45. The apparatus according to example 44, wherein the downlink control information (DCI) is DCI format 0_1.

[0234] Example 46. An apparatus comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; transmitting, by the network element to the userequipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

[0235] Example 47. The apparatus according to example 46, wherein: individual antenna port vectors have a same number of elements as do the TPMIs, and individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered.

[0236] Example 48. The apparatus according to example 47, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the TPMI but the others of the multiple antenna port vectors reorder the individual phase settings in the TPMI.

[0237] Example 49. A computer program, comprising instructions which, when the program is executed by an apparatus, cause the apparatus to carry out the methods of any of examples 1 to 16.

[0238] Example 50. The computer program according to example 49, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus.

[0239] Example 51 . The computer program according to example 49, wherein the computer program is directly loadable into an internal memory of the apparatus.

[0240] As used in this application, the term "circuitry” may refer to one or more or all of the following:

[0241] (a) hardware-only circuit implementations (such as implementations in analog, digital, and / or quantum circuitry) and

[0242] (b) combinations of hardware circuits and software such as (as applicable): (I) a combination of analog, digital, and / or quantum hardware circuit(s) with software / firmware and (ii) any or all portions of hardware processor(s) (including digital and / or quantum processor(s)) with software, and memory(ies) that work together to cause an apparatus, such as a mobile device, computing device, or server, to perform various functions) and

[0243] (c) any or all portions of hardware circuit , such as microprocessor(s), processor(s) and / or quantum processors, that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0244] 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 orprocessor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0245] In an example embodiment, software (e.g., application logic, an instruction set) as used herein is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in FIG. 18. A computer-readable medium may comprise a computer-readable storage medium (e.g., memories 15, 75, and 95 or other device) that may be any media or means that can contain, store, and / or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals, and therefore may be considered to be non-transitory. 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, random access memory, versus ROM, read-only memory).

[0246] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

[0247] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[0248] It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

[0249] The following abbreviations that may be found in the specification and / or the drawing figures are defined as follows:

[0250] 3GPP third generation partnership project

[0251] 5G fifth generation

[0252] 5G S-module 5G Superior Universal Module

[0253] AMF access and mobility management function

[0254] AP antenna port

[0255] APvec antenna port vector

[0256] CB codebook

[0257] CCDF Complementary Cumulative Distribution Function

[0258] CPE Customer premises equipment

[0259] CSI-RS channel state information-reference signal

[0260] DRMS Demodulation reference signal

[0261] eMBB Enhanced mobile broadband

[0262] E-SMLC evolved serving mobile location center

[0263] eNB (or eNodeB) evolved Node B (e.g., an LTE base station)

[0264] FWA Fixed wireless access

[0265] GMLC Gateway Mobile Location Center

[0266] gNB (or gNodeB) base station for 5G / NR

[0267] l / F interface

[0268] LMF Location Management Function

[0269] LTE long term evolution

[0270] MIMO multiple input, multiple output

[0271] MME mobility management entity

[0272] NF network function

[0273] ng or NG next generation

[0274] NR new radio

[0275] NRF Network Repository Function

[0276] N / W or NW network

[0277] PDCCH physical downlink control channel

[0278] PUSCH physical uplink shared channel

[0279] RAN radio access network

[0280] Rx receiver

[0281] SGW serving gateway

[0282] SI NR signal-to-interference-plus-noise ratio

[0283] SMF session management function

[0284] SRS Sounding reference signal

[0285] TPMI Transmit Precoding Matrix Identity

[0286] TRP transmission-reception point

[0287] Tx transmitter

[0288] UCI uplink control information

[0289] UDM unified data management

[0290] UDR unified data repository

[0291] UE user equipment (e.g., a wireless, typically mobile device)

[0292] UL uplink (from UE to network)

[0293] UPF user plane function

Claims

What is claimed is:

1. A method, comprising: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPM I) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

2. The method according to claim 1, wherein: individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered; and transmitting by the user equipment the uplink transmission at least by applying the determined TPMI and the antenna port configuration comprises applying ordering of the individual elements in the determined antenna port vector to the individual phase settings in the determined TPMI to form the antenna port configuration and applying the phase settings in the antenna port configuration to corresponding antenna ports.

3. The method according to claim 2, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the determined TPMI for the applying but the others of the multiple antenna port vectors reorder the individual phase settings in the determined TPMI for the applying.The method according to any of claims 1 to 3, wherein the multiple TPMIs comprise elements from the following table:for 1 , 2, or 4 antenna ports.An apparatus, comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: receiving, by a user equipment from a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector for an uplink transmission by the user equipment; determining, by the user equipment, a TPMI to use by searching for the first index from multiple TPMIs comprising phase settings for 1, 2, or 4 antenna ports; determining, by the user equipment, an antenna port vector to use by searching for the second index from multiple antenna port vectors; determining, by the user equipment, an antenna port configuration based on the determined antenna port vector and the determined TPMI; and transmitting, by the user equipment, an uplink transmission at least by applying the determined TPMI and the antenna port configuration.

6. The apparatus according to claim 5, wherein: individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered; and transmitting by the user equipment the uplink transmission at least by applying the determined TPMI and the antenna port configuration comprises applying ordering of the individual elements in the determined antenna port vector to the individual phase settings in the determined TPMI to form the antenna port configuration and applying the phase settings in the antenna port configuration to corresponding antenna ports.

7. The apparatus according to claim 6, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the determined TPMI for the applying but the others of the multiple antenna port vectors reorder the individual phase settings in the determined TPMI for the applying.The apparatus according to any of claims 5 to 7, wherein the multiple TPMIs comprise elements from the following table:for 1 , 2, or 4 antenna ports.

9. The apparatus according to any of claims 5 to 8, wherein the multiple TPMIs are indicated via 5 bits and the multiple antenna port vectors are indicated via 2 bits.

10. The apparatus according to claim 9, wherein the multiple TPMIs are selected from a table with 28 indexes for 1, 2, or 4 antenna ports.11 . The apparatus according to claim 9, wherein the antenna port vector is determined from the multiple antenna port vectors using one of four possible values.

12. The apparatus according to any of claims 5 to 11, wherein: the first index for the TPMI is received as a current first index for a current reception; the second index for the antenna port vector is received as a previous second index for a previous reception of the second index, but a second index for the current reception is not received; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the current first index and the antenna port configuration based on the previous second index.

13. The apparatus according to any of claims 5 to 11, wherein: the first index for the TPMI is received as a previous first index for a previous reception, but a first index for a current reception is not received; the second index for the antenna port vector is received as a current second index for a current reception of the second index; and the transmitting comprises transmitting an uplink transmission at least by applying the determined TPMI based on the previous first index and the antenna port configuration based on the current second index.

14. The apparatus according to any of claims 5 to 13, wherein: the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform indicating, by the user equipment to the network element, a capability to support uniform or non-uniform antenna array characteristics, the indicating performed prior to the receiving; andthe determining the TPMI, determining the antenna port vector, determining, by the user equipment, determining the antenna port configuration, and the transmitting are performed based on the capability to support non-uniform antenna array characteristics.

15. The apparatus according to claim 14, wherein the capability is indicated via radio resource control signaling.

16. The apparatus according to any of claims 5 to 13, wherein the second index for the antenna port vector is indicated via a field in downlink control information (DCI) from the network element to the user equipment.

17. The apparatus according to claim 16, wherein the downlink control information (DCI) is DCI format 0_1.

18. An apparatus comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: determining, by a network element, a first index for transmit precoding matrix identity (TPMI) and a second index for an antenna port vector of multiple antenna port vectors for an uplink transmission by a user equipment, wherein the first index for the TPMI is determined from multiple TPMIs comprising phase settings for 1 , 2, or 4 antenna ports; transmitting, by the network element to the user equipment, the first index for the TPMI and the second index for the antenna port vector; and receiving, by the network element from the user equipment, the uplink transmission.

19. The apparatus according to claim 18, wherein: individual antenna port vectors have a same number of elements as do the TPMIs, and individual elements in the antenna port vectors refer to positions of individual phase settings in the TPMIs, and an order of the individual elements in the antenna port vectors describe how the phase settings in the TPMIs should or should not be reordered.

0. The apparatus according to claim 19, wherein one of the antenna port vectors in the multiple antenna port vectors does not reorder the individual phase settings in the TPM I but the others of the multiple antenna port vectors reorder the individual phase settings in the TPMI.

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