Precoding-based multi-transmitter transmission

Abstract

The embodiment of the invention relates to a multi-transmitter transmission method based on precoding, equipment, a device and a computer readable storage medium. In one method, an apparatus determines respective precoding for a plurality of antenna groups based on a total number of layers and a number of antennas per antenna group. The apparatus performs transmission of a total number of layers via the plurality of antenna groups by respective precoding of the plurality of antenna groups. In this manner, the total number of precodes for transmitting the total number of layers via the antenna group may be reduced.

Description

Technical Field

[0001] Various exemplary embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to methods, devices, apparatuses, and computer-readable storage media for precoding-based multi-transmitter transmission. Background Art

[0002] In some communication systems such as the fifth generation (5G) new radio (NR) system, multiple input multiple output (MIMO) is supported. Multiple transmitter (Tx) transmission can provide enhancements for MIMO systems. For example, several uplink (UL) MIMO can support 4 UL Tx antennas. For coherent Tx, partially coherent Tx, and non-coherent Tx, codebook-based and non-codebook-based transmission schemes are supported. It has been proposed to design UL MIMO using multiple transmitters such as 8Tx UL transmission. Summary of the invention

[0003] In a first aspect of the present disclosure, a device is provided. The device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the device to at least: determine corresponding precoding of multiple antenna groups based on the total number of layers and the number of antennas per antenna group; and perform transmission of layers of the total number of layers via the multiple antenna groups using the corresponding precoding of the multiple antenna groups.

[0004] In a second aspect of the present disclosure, a method is provided. The method includes: determining, at a device, corresponding precoding of multiple antenna groups based on the total number of layers and the number of antennas per antenna group; and performing transmission of layers of the total number of layers via the multiple antenna groups using the corresponding precoding of the multiple antenna groups.

[0005] In a third aspect of the present disclosure, a device is provided. The device includes a component for determining corresponding precoding of multiple antenna groups based on the total number of layers and the number of antennas per antenna group; and a component for performing transmission of layers of the total number of layers via the multiple antenna groups using the corresponding precoding of the multiple antenna groups.

[0006] In a fourth aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon for causing a device to execute the method according to the second aspect.

[0007] It should be understood that the invention summary is not intended to identify the key features or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0009] Figure 1 illustrates an example communication environment in which example embodiments of the present disclosure may be implemented;

[0010] Figure 2 illustrates an example block diagram of a cross-polarized antenna configuration;

[0011] Figure 3 A flowchart illustrating a method implemented at a device according to some example embodiments of the present disclosure is shown;

[0012] Figure 4 illustrates a simplified block diagram of a device suitable for implementing an example embodiment of the present disclosure; and

[0013] Figure 5 A block diagram illustrating an example computer-readable medium according to some example embodiments of the present disclosure; and

[0014] Figure 6 The figure shows N in the outdoor fixed wireless access (FWA) scenario. g =2 codebook performance.

[0015] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0016] The principles of the present disclosure will now be described with reference to some example implementations. It should be understood that these embodiments are described only for illustrative purposes and to help those skilled in the art understand and implement the present disclosure without implying any limitation on the scope of the present disclosure. The embodiments described herein can be implemented in various ways except for the way described below.

[0017] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0018] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is considered within the knowledge of those skilled in the art that other embodiments may be combined to affect such feature, structure, or characteristic, whether or not explicitly described.

[0019] It should be understood that although the terms "first", "second", etc. may be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0020] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is combined 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 of the elements.

[0021] As used herein, unless explicitly stated, performing a step "in response to A" does not indicate that the step is performed immediately after "A" occurs, and may include one or more intermediate steps.

[0022] The terms used herein are used only to describe specific embodiments and are not intended to limit the example embodiments. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "including", "having", "having", "including", and / or "comprising", when used herein, specify the presence of the features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0023] The term "circuitry" as used in this application may refer to one or more or all of the following:

[0024] (a) hardware circuit implementation only (such as implementation in analog and / or digital circuits only) and

[0025] (b) a combination of hardware circuitry and software such as (where applicable):

[0026] (i) a combination of analog and / or digital hardware circuits and software / firmware and

[0027] (ii) any portion of a hardware processor(s) with software (including digital signal processor(s), software and memory(s) that work together to enable a device (such as a mobile phone or server) to perform various functions) and

[0028] (c) Hardware circuits and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate, but which may not be present when the software is not required to operate.

[0029] The definition of circuitry applies to all uses of the term in this application, including any claims. As yet another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a 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 a particular claim element), a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0030] As used herein, the term "communication network" refers to a network that complies with any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), Advanced LTE (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. In addition, the communication between the terminal equipment and the network equipment in the communication network can be performed according to any suitable generation communication protocol, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocol and / or any other protocol currently known or developed in the future. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communication, there will certainly be future types of communication technologies and systems that can implement the present disclosure. The scope of the present disclosure should not be limited to the above-mentioned system.

[0031] As used herein, the term "network device" or "network access device" refers to a node in a communication network, via which a terminal device accesses the network and receives services from it. A network device may refer to a base station (BS) or an access point (AP), such as a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), a NR NB (also referred to as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an integrated access and backhaul (IAB) node, a low-power node (such as a femto, a micro, a non-terrestrial network (NTN)) or a non-terrestrial network device (such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous orbit (GEO) satellite, an aircraft network device), etc., depending on the terminology and technology applied. In some example embodiments, a radio access network (RAN) split architecture includes a centralized unit (CU) and a distributed unit (DU) located at an IAB donor node. The IAB node includes a mobile terminal (IAB-MT) part, which behaves like a UE towards a parent node, and the DU part of the IAB node is similar to a base station towards a next-hop IAB node.

[0032] The term "terminal device" refers to any terminal device that may be capable of wireless communication. As an example and not limitation, a terminal device may also be referred to as a communication device, a user equipment (UE), a user station (SS), a portable user station, a mobile station (MS), or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless regional loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device (such as a digital camera), a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded device (LEE), a laptop device (LME), a USB dongle, a smart device, a wireless client device (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated processing chain), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. The terminal device may also correspond to the mobile terminal (MT) part of an IAB node (eg, a relay node).In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

[0033] As used herein, the term "resource", "transmission resource", "resource block", "physical resource block" (PRB), "uplink resource" or "downlink resource" may refer to any resource used to perform communication, for example, communication between a terminal device and a network device, such as time domain resources, frequency domain resources, spatial domain resources, code domain resources, or any other resource capable of communication. In the following, unless explicitly stated, resources in both the frequency domain and the time domain will be used as examples of transmission resources to describe some example embodiments of the present disclosure. Note that the example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0034] As briefly mentioned above, multi-Tx transmission such as 8Tx UL transmission is proposed. For example, 8Tx UL transmission can be applied to support customer premises equipment (CPE), fixed wireless access (FWA), vehicles, industrial equipment, etc. As an example, UL demodulation reference signal (DMRS), sounding reference signal (SRS), SRS resource indicator (SRI) and transmitted precoding matrix indicator (TPMI) (including codebook) enhancements can be specified to enable 8Tx UL operation to support four and more layers per user equipment (UE) in the UL targeting CPE or FWA or vehicles or industrial equipment. It should be noted that potential limitations on the scope of this target (including coherence assumptions, full / non-full power modes) will be identified as part of this study.

[0035] Radio Access Network (RAN) 1 is studying 8Tx UL transmission, following Release 18 (Rel-18) Work Item Description (WID). RAN1 has reached several agreements for UL 8Tx transmission with partially coherent UEs. One agreement for codebook-based UL transmission for 8Tx UEs is to support NR Rel-15 UL 2TX / 4TX codebook and / or (multiple) 8x1 antenna selection vectors as a starting point for codebook design for partial or non-coherent precoding.

[0036] Another protocol is for partially coherent uplink precoding with 8TX UE codebook, when the number of antenna groups N g =2, the precoding design is based on the Rel-15 UL 4TX codebook and uses full phase interference coding. g =4, it can be selected from the following alternatives. One alternative (referred to as Alternative 1) can be a precoding design based on the Rel-15 UL 2TX codebook, and use full phase precoding. Another alternative (referred to as Alternative 2) can be a precoding design based on the Rel-15 UL 4TX codebook, and use partial phase precoding.

[0037] A further agreement is that for N g=4. Partially coherent uplink precoding by 8TX UE codebook, supporting alternatives (eg, alternative 1), where the precoding design is based on Rel-15 UL 2TX codebook, using full phase precoding, and further study of codebook size reduction may be considered.

[0038] Several mechanisms for 8Tx operation have been proposed. In some mechanisms, based on the protocol, the 8TX codebook design can be based on previously defined (Rel-15) 2Tx and 4Tx codebooks with multiple antenna groups (such as two or four). A combination of these 2Tx and / or 4Tx Rel-15 precodings may be used to define an 8Tx codebook for partially coherent uplink transmissions.

[0039] In some mechanisms, for the partially coherent 8TX codebook, a key design issue is how to manage the transmission of multiple layers from multiple antenna groups forming a partially coherent UE. RAN1 has agreed that for partially coherent UEs, a given layer can only be transmitted by one antenna group (i.e., a layer cannot be transmitted by two or more antenna groups). For multi-rank transmission, the size of the entire partially coherent codebook may be affected by the different combinations of transmitting multiple layers through multiple antenna groups.

[0040] However, in RAN1, for a device having a number of antenna groups N g = 2, results in a rather large number of precodings, which translates into a large number of bits in the TPMI feedback from the gNB to the UE. Therefore, how to reduce the number of precodings while avoiding a significant degradation in overall performance has become a matter of concern.

[0041] In order to solve at least part of the above problems or other potential problems, a solution of multi-Tx transmission based on precoding is proposed. According to an example embodiment, an apparatus (e.g., a terminal device) determines the corresponding precoding of multiple antenna groups based on the total number of layers and the number of antennas per antenna group. The apparatus performs transmission of layers of the total number of layers via multiple antenna groups using the corresponding precoding of the multiple antenna groups.

[0042] In this way, the precoding for transmitting all layers via multiple antenna groups can be easily determined. Compared with other mechanisms for determining precoding, the total number of precodings determined by this scheme can be reduced. On the other hand, the overall performance will not be reduced.

[0043] The following will refer to Figures 1 to 5 The principles and implementations of the present disclosure are described in detail. Figure 1 An example communication environment 100 is illustrated in which example embodiments of the present disclosure may be implemented. In the communication environment 100, a plurality of communication devices including a device 110 and a device 120 may communicate with each other.

[0044] In some example embodiments, apparatus 110 and apparatus 120 support MIMO. For example, for coherent Tx, partially coherent Tx, and non-coherent Tx, codebook-based and non-codebook-based transmissions are supported. As an example, apparatus 110 may perform transmissions such as 2Tx, 4Tx, or 8Tx.

[0045] In some example embodiments, if apparatus 110 is a terminal device and apparatus 120 is a network device serving the terminal device, the link from apparatus 120 to apparatus 110 is referred to as a downlink (DL), and the link from apparatus 110 to apparatus 120 is referred to as an uplink (UL). In DL, apparatus 120 is a transmitting (TX) device (or transmitter), and apparatus 110 is a receiving (RX) device (or receiver). In UL, apparatus 110 is a TX device (or transmitter), and apparatus 120 is an RX device (or receiver).

[0046] It should be understood that Figure 1 The number of devices and their connections shown in FIG. 1 are for illustration purposes only and do not imply any limitation. Communication environment 100 may include any suitable number of devices configured to implement example embodiments of the present disclosure.

[0047] In the following, for the purpose of illustration, some example embodiments will be described in the case where the apparatus 110 operates as a terminal device and the apparatus 120 operates as a network device. However, in some example embodiments, the operations described in conjunction with the terminal device may be implemented at a network device or other device, and the operations described in conjunction with the network device may be implemented at a terminal device or other device.

[0048] The communication in the communication environment 100 can be implemented according to any suitable (multiple) communication protocols, including but not limited to cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), etc., wireless local area network communication protocols such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol currently known or developed in the future. In addition, the communication can utilize any suitable wireless communication technology, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiple access (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM) and / or any other technology currently known or developed in the future.

[0049] As briefly mentioned, codebook designs such as the 8TX codebook design can be based on previously defined (Rel-15) 2Tx and 4Tx codebooks with multiple antenna groups (such as two or four). In some mechanisms, for the case of two antenna groups (i.e., N g =2), each antenna group may have 4 coherent Tx ports, where the precoding is based on the Rel-15 4Tx UL codebook.

[0050] Figure 2 An example typical cross-polarized antenna configuration 200 is illustrated. As shown, the antenna can be divided into two groups 210 and 250. Antenna group 210 includes antenna 215, antenna 220, antenna 225, and antenna 230, which are four coherent Tx ports. Antenna group 250 includes antenna 255, antenna 260, antenna 265, and antenna 270, which are another four coherent Tx ports. With antenna configuration 200, 8Tx can be configured.

[0051] In some mechanisms, multiple layers may be divided or split into different layer groups or layer sets. Table 1 below shows the number of layer split combinations and precodings for the case of two antenna groups.

[0052] Table 1

[0053]

[0054]

[0055] After RAN1#113 meeting, layer splits (2,3) / (3,2) and (3,4) / (4,3) are still under consideration. If the layer split (3,2) and (4,3) combinations are removed, the updated precoding numbers are shown in the table.

[0056] In Table 1, for N g =2, there are 696 8Tx precodings in total. The inventors recognize that most precodings are determined by combinations of lower rank precodings. For example, for rank-2 with a (1,1) antenna group combination, the total number of precodings is 256, because each 4Tx group can support 16 precodings from the precoding set defined in Rel-15. If all combinations of these 16 precodings are supported for two antenna groups, there will be 256 precodings.

[0057] The inventors also observed that removing certain layer splits, such as (3,2), will not significantly affect the total number of precoders. The layer split (3,2) has 32 precoders; similarly, the layer split (4,3) for rank-7 Tx has only 8 precoders.

[0058] Even if some layer splits are removed, such as (3,2), the total maximum number of 696 precodings is still greater than 128 or 256. This requires about 10 bits of TPMI to support all possible combinations.

[0059] Taking the rank 2 case as an example, three precoding sets are supported. The first set (labeled as (2,0) for layer splitting) has two layers transmitted by the first antenna group, and no layer is transmitted by the second antenna group. The second set (labeled as (0,2) for layer splitting) has two layers transmitted by the second antenna group, and no layer is transmitted by the first antenna group. The third set (labeled as (1,1) for layer splitting) has one layer transmitted by the first antenna group, and the second layer is transmitted by the second antenna group. The precoding assumed in the first set and the second set is the rank 2 precoding matrix from the legacy (Rel-15) UL codebook design. The precoding in the third set is the rank 1 precoding matrix from the legacy (Rel-15) UL codebook design. Therefore, the considered precoding matrix for N g = 2 The complete set of rank 2 precodings for the partially coherent design consists of all possible combinations of three precoding sets (272 as shown in Table 1). According to this design, the vast majority of precodings in the complete set for rank 2 are in the third set ((1,1) set: 256 out of 272 precodings).

[0060] As shown in Table 1, in RAN1, for a user having N g = 2, results in a rather large number of precoders, which translates into a large number of bits in the TPMI feedback from the gNB to the UE. The problem to be solved is how to reduce the number of precoders while avoiding a significant degradation in the overall performance.

[0061] In order to solve at least part of the above problems or other potential problems, a multi-Tx transmission scheme based on precoding is proposed. Figure 3 Describe the precoding-based multi-Tx transmission scheme. Figure 3 FIG. 3 is a flow chart showing an example method 300 implemented at a device according to some example embodiments of the present disclosure. For discussion purposes, Figure 1 The perspective description method 300 of the device 110 in FIG.

[0062] Method 300 may be applicable to any suitable multi-Tx transmission, such as 8Tx transmission or any other suitable multi-Tx transmission. For example, the multiple transmission may be performed by multiple antenna groups, such as two antenna groups or any other suitable number of antenna groups. Each antenna group may include multiple antennas, such as four antennas or any other suitable number of antennas. The multiple transmission may be associated with a total number of layers, such as two layers, three layers, four layers, or any other suitable total number of layers.

[0063] In the following, an exemplary embodiment is described by taking 8Tx transmission with two antenna groups and four antennas per antenna group as an example. However, it should be understood that this is only an example and not any limitation, and the concept described with respect to 8Tx transmission with two antenna groups and four antennas per antenna group can be applied to any other multiple transmission with any appropriate number of antenna groups, each group including any appropriate number of antennas.

[0064] At block 310, the apparatus 110 determines corresponding precoding for the plurality of antenna groups based on the total number of layers and the number of antennas per antenna group. As used herein, the total number of layers may also be referred to as a rank of transmission. The antennas of each antenna group may be referred to as antenna ports of each antenna group. The total number of antennas in the plurality of antennas may be the number of the plurality of transmitters.

[0065] At block 320, the apparatus 110 performs transmission of the total number of layers via the plurality of antenna groups using the corresponding precoding of the plurality of antenna groups. Figure 1 The transmission is performed by the device 120 in or any other suitable device. As used herein, the term "transmission of a total number of layers" may be referred to as "total number of layers transmission". For example, for a total of four layers, the transmission of four layers may be referred to as "four-layer transmission". The transmission is transmitted via multiple antenna groups, and therefore may also be referred to as "multi-Tx transmission".

[0066] In this way, the precoding of the transmission of the total number of layers via multiple antenna groups can be easily determined based on the total number of layers across multiple antenna groups. Compared with other mechanisms that determine precoding based on the number of layers via a single antenna group, the total number of precodings determined by the present solution can be reduced. On the other hand, the overall performance is not degraded.

[0067] In some example embodiments, the corresponding precoding of multiple antenna groups may constitute a codebook for multi-Tx transmission. That is, the codebook for multi-Tx transmission may be designed as the corresponding precoding of multiple antenna groups. As used herein, the determination of the precoding of the antenna group may also be referred to as a codebook design. This codebook design is an alternative to the design currently being considered in RAN1 and is intended to provide much lower overhead. This codebook design may be used for partially coherent multi-Tx, such as partially coherent 8Tx. For example, such a codebook may be a UL 8Tx partially coherent codebook.

[0068] In some example embodiments, the total number of layers includes a first set of layers and a second set of layers. The set of layers may include one or more layers. Alternatively or additionally, the set of layers may include zero layers, or include the total number of layers. For example, if the total number of layers is two, the first set of layers may include one layer, and the second set of layers may include the other of the two layers. Alternatively, the first set of layers may include zero layers, and the second set of layers may include a total of two layers, or vice versa.

[0069] In another example, if the total number of layers is three, the first set of layers may include one layer, and the second set of layers may include the other two of the three layers. Alternatively, the first set of layers may include two layers, and the second set of layers may include the other of the three layers. Alternatively, the first set of layers and the second set of layers may include zero layers and three layers, respectively.

[0070] In yet another example, if the total number of layers is four, the first set of layers may include two layers, and the second set of layers may include the other two of the four layers. Alternatively, the first set of layers and the second set of layers may include zero layers and four layers, respectively.

[0071] It should be understood that the splitting or partitioning of different layer sets for different total numbers of layers is for illustrative purposes only and does not imply any limitation. In some example embodiments, the total number of layers may include any number of layer sets, with any suitable number of layers in each set. The scope of the present disclosure is not limited herein.

[0072] Taking multiple antenna groups including two antenna groups as an example, the total number of layers may include a first set of layers and a second set of layers. The first set of layers may be transmitted via a first antenna group of the two antenna groups, and the second set of layers may be transmitted via a second antenna group of the two antenna groups. Alternatively, the first set of layers may be transmitted via the second antenna group of the two antenna groups, and the second set of layers may be transmitted via the first antenna group of the two antenna groups.

[0073] As briefly mentioned, at block 310, the apparatus 110 determines the respective precodings for the antenna groups. In the example of two antenna groups, at block 320, the apparatus 110 may perform transmission of a first set of layers via the first antenna group using a first precoding for the first antenna group, and perform transmission of a second set of layers via the second antenna group using a second precoding for the second antenna group.

[0074] In some example embodiments, if the number of layers in a certain layer set is one, then the corresponding precoding for the associated antenna group of the layer set may refer to a precoding vector. Alternatively or additionally, in some example embodiments, if the number of layers in a certain layer set is greater than one, then the corresponding precoding for the associated antenna group of the layer set may refer to a precoding matrix including more than one precoding vector. The number of elements or entries in the precoding vector may be equal to the number of antennas per antenna group.

[0075] In some example embodiments, apparatus 110 may determine a plurality of candidate precoding matrices from a codebook corresponding to the total number of layers and the number of antennas per antenna group. The codebook may be predefined or specified.

[0076] As an example, multiple candidate codebooks may be predefined or specified for multiple transmissions such as 4Tx UL transmission.As used herein, a candidate codebook for 4Tx UL transmission may be referred to as a 4Tx UL codebook.

[0077] An example candidate codebook for single-layer transmission using four antenna ports with transform precoding disabled is shown as Table 2 below. An example candidate codebook for two-layer transmission using four antenna ports with transform precoding disabled (also known as Rel-15 UL 4TX rank 2 codebook) is shown as Table 3 below. An example candidate codebook for three-layer transmission using four antenna ports with transform precoding disabled (also known as Rel-15 UL 4TX rank 3 codebook) is shown as Table 4 below. An example candidate codebook for four-layer transmission using four antenna ports with transform precoding disabled (also known as Rel-15 UL 4TX rank 4 codebook) is shown as Table 5 below. These example tables show precoding matrix designs for Release 15 (Rel-15) 4TX UL codebooks. In Tables 2 to 5, multiple precoding matrices W are specified or configured. These precoding matrices can be identified by TPMI indexes.

[0078] Table 2

[0079]

[0080] Table 3

[0081]

[0082] Table 4

[0083]

[0084] Table 5

[0085]

[0086] Several examples of candidate codebooks are described with reference to Tables 2 to 5. It should be understood that these example codebooks are only for illustrative purposes and do not imply any limitation. Any other suitable codebooks may be applied. The scope of the present disclosure is not limited in this respect.

[0087] In some example embodiments, the device 110 may select a codebook corresponding to the total number of layers and the number of antennas per antenna group from a plurality of candidate codebooks. For example, for a total of two layers (i.e., rank 2) and a case where each antenna group has four antennas, Table 3 may be selected. For another example, for a total of three layers (i.e., rank 3) and a case where each antenna group has four antennas, Table 4 may be selected. For example, for a total of four layers (i.e., rank 4) and a case where each antenna group has four antennas, Table 5 may be selected.

[0088] The apparatus 110 may determine a plurality of candidate precoding matrices from a codebook corresponding to the total number of layers and the number of antennas per antenna group. In some example embodiments, each candidate precoding matrix of the plurality of selected candidate precoding matrices has only non-zero entries.

[0089] In one example, if the total number of layers is two and the number of antennas per antenna group is four, the plurality of candidate precoding matrices in the codebook may be matrices with non-zero entries from Table 3. That is, the plurality of candidate precoding matrices may include

[0090] In another example, if the total number of layers is three and the number of antennas per antenna group is four, the plurality of candidate precoding matrices in the codebook may be matrices having only non-zero entries from Table 4. That is, the plurality of candidate precoding matrices may include and

[0091] In a further example, if the total number of layers is four and the number of antennas per antenna group is four, the plurality of candidate precoding matrices in the codebook may be matrices with non-zero entries from Table 5. That is, the plurality of candidate precoding matrices may include and

[0092] In some example embodiments, apparatus 110 may select a precoding matrix from a plurality of candidate precoding matrices. At block 320, apparatus 110 may determine the first precoding and the second precoding based on the selected precoding matrix.

[0093] As an example, if the first set of layers includes a first number of layers, the device 110 may determine the first precoding based on a first number of precoding vectors in the selected precoding matrix. The precoding vectors in the first number of precoding vectors may be associated with layers in the first set of layers. For example, for a total of three layers, if the first set of layers includes a single layer, the device 110 may determine the first precoding based on a single precoding vector in the selected precoding matrix.

[0094] For a total of three layers, for the layers of the second set, the apparatus 110 may determine the second precoding based on at least one remaining precoding vector in the selected precoding matrix. The remaining precoding vectors in the at least one remaining precoding vector may be associated with a layer in the layers of the second set. For example, if the layers of the second set include two layers, the apparatus 110 may determine the second precoding based on the two remaining precoding vectors in the selected precoding matrix.

[0095] Taking three-layer transmission as an example, assuming that the selected precoding matrix is Then the first precoding can be determined as And the second precoding can be determined as It should be understood that the first precoding may also be alternatively determined as different precoding vectors in the selected precoding matrix, and the second precoding may also be determined as two different remaining precoding vectors. The scope of the present disclosure is not limited in this regard.

[0096] Alternatively or additionally, in some example embodiments, the apparatus 110 may rearrange the precoding vectors in the selected precoding matrix to generate a precoding matrix (referred to as another precoding matrix). At block 320, the apparatus 110 may determine the first precoding and the second precoding based on the generated precoding matrix.

[0097] Still taking three-layer transmission as an example, assuming that the selected precoding matrix is Then another precoding matrix can be rearranged as or or Assume that another precoding matrix is Then the first precoding can be determined as And the second precoding can be determined as It should be understood that the first precoding may alternatively be determined as a different precoding vector in another precoding matrix, and the second precoding may also be determined as two different remaining precoding vectors. The scope of the present disclosure is not limited in this regard.

[0098] In this way, the total number of precodings for multi-layer transmission cases can be reduced by utilizing precoding matrices in a predefined or specified codebook. With this precoding design, overhead can be reduced.

[0099] Several example embodiments of precoding based on multi-Tx transmission have been described. It should be understood that for each antenna group, the corresponding precoding may include one or more precodings. For example, the first precoding for the first antenna group may include one precoding set or multiple precoding sets. An example embodiment for determining the precoding set (s) for each antenna group will now be described.

[0100] Now we describe two antenna groups (N g =2) and a total of two layers (rank 2) for N g The precoding design for the case of =2 and rank 2 can consist of the following three precoding sets.

[0101] The first precoding set corresponds to the case where 2 layers are transmitted by the first antenna group and no layers are transmitted by the second antenna group. That is, the layers of the first set include zero layers, and the layers of the second set include two layers. The first precoding set may consist of Rel-15 rank 2 precodings that do not contain any zero entries in the precoding vector. For example, the first precoding set may include 8 precodings with TPMI indexes 14 to 21 as shown in Table 3.

[0102] It should be noted that the design for the first precoding set is unchanged from the current design proposal in RAN1, indicated as layer combination (2,0) in the second column of Table 1. It should also be noted that the precodings shown in Table 3 are only for illustrative purposes and do not imply any limitation. Any other suitable precoding or precoding matrix with non-zero entries may be applied.

[0103] Similarly, the second precoding set corresponds to the case where 2 layers are transmitted by the second antenna group and no layers are transmitted by the first antenna group. That is, the layers of the first set include two layers, and the layers of the second set include zero layers. The second precoding set may consist of Rel-15 UL rank 2 precodings that do not contain any zero entries in the precoding vector. For example, the second precoding set may include 8 precodings with TPMI indices 14 to 21 as shown in Table 3. It should be noted that the design for the second precoding set is unchanged from the current design proposal in RAN1, indicated as layer combination (0,2) in the second column of Table 1.

[0104] Unlike the first precoding set and the second precoding set, the third precoding set is different from the current design proposal in RAN1. The third precoding set corresponds to a case where one layer is transmitted by the first antenna group and the second layer is transmitted by the second antenna group. That is, the layers of the first set include one layer and the layers of the second set include another layer.

[0105] In some example embodiments, the third precoding set may be formed from the Rel-15 UL rank 2 precoding matrix with non-zero entries in the precoding vector as shown in Table 3. The third precoding set may have two subsets of precodings which will be described below.

[0106] The first subset of precodings may contain eight precoding matrices formed based on eight precodings with only non-zero entries in the Rel-15 UL4 TX rank 2 codebook, for example, eight precodings of TPMI indexes 14 to 21 as shown in Table 3.

[0107] For each precoding matrix in the Rel-15 UL 4TX rank 2 precoding matrix, a precoding matrix for rank 2 transmission is formed such that the first layer is transmitted by the first antenna group using the first precoding vector of the Rel-15 4TX rank 2 precoding matrix, and the second layer is transmitted by the second antenna group using the second precoding vector of the Rel-15 4TX rank 2 precoding matrix. The result is that the first subset of precoding for N g =2 / eight precodings of rank 2.

[0108] The second subset of precoding contains eight precoding matrices, and these precoding matrices are also formed based on the eight precoding matrices with only non-zero entries in the Rel-15 UL4TX rank 2 codebook. However (unlike the first subset), for each of the eight Rel-15 4Tx rank 2 precoding matrices, a precoding matrix for rank 2 transmission is formed such that the first layer is transmitted by the first antenna group using the second precoding vector of the Rel-15 4TX rank 2 precoding matrix, and the second layer is transmitted by the second antenna group using the first precoding vector of the Rel-15 4TX rank 2 precoding matrix. The result is that the second subset of precoding for N g =2 / eight precodings of rank 2.

[0109] The third precoding set includes the first subset and the second subset of the above precodings, and consists of a total of 16 precodings.

[0110] It should be noted that for N g =2 / rank 2, the current design in RAN1 for the third precoding set starts from a rank 1 precoding vector in the Rel-15 UL codebook and has 256 precodings. The present design for the third precoding set starts from a rank 2 precoding matrix in the Rel-15 UL codebook and has 16 precodings (a significant reduction from 256).

[0111] In this way, for the (1,1) case (one layer is transmitted by one antenna group), the number of precodings is greatly reduced. The overhead can also be reduced.

[0112] Now, we describe the case where two antenna groups (N g =2) and a total of three layers (rank 3) case. g The precoding design for the cases of rank = 2 and rank 3 can consist of the following three precoding sets.

[0113] The first precoding set corresponds to the case where 3 layers are transmitted by the first antenna group and no layers are transmitted by the second antenna group. That is, the layers of the first set include three layers and the layers of the second set do not include layers. The first precoding set consists of Rel-15 UL rank 3 precodings that do not contain any zero entries in the precoding vector. For example, the first precoding set includes 4 precodings with TPMI indices 3 to 6 in Table 4. It should be noted that the design for the first precoding set is unchanged from the current design proposal in RAN1, indicated as layer combination (3,0) in the second column of Table 1.

[0114] The second precoding set corresponds to the case where 3 layers are transmitted by the second antenna group and no layers are transmitted by the first antenna group. That is, the first set of layers does not include layers, and the second set of layers includes three layers. The second precoding set consists of Rel-15 UL rank 3 precodings that do not contain any zero entries in the precoding vector: such as the 4 precodings with TPMI indices 3 to 6 in Table 4. It should be noted that the design for the second precoding set is unchanged from the current design proposal in RAN1, indicated as layer combination (0,3) in the second column of Table 1.

[0115] The third precoding set corresponds to the case where the first layer is transmitted by the first antenna group and the second two layers are transmitted by the second antenna group. That is, the layers of the first set include one layer and the layers of the second set include two layers. The third precoding set is formed by Rel-15 UL rank 3 precoding without any zero entries in the precoding vector, such as the precoding matrix with TPMI indexes 3 to 6 in Table 4. The third precoding set has a subset of precodings that can be designed as follows.

[0116] The first subset of precodings may include four precoding matrices formed based on four precodings with only non-zero entries in the Rel-15 UL 4TX rank 3 codebook, such as the precoding matrices with TPMI indices 3 to 6 in Table 4. For each precoding matrix in the Rel-15 UL 4TX rank 4 precoding matrix, a precoding matrix for rank 3 transmission is formed such that the first layer is transmitted by the first antenna group using the first precoding vector of the Rel-15 4TX rank 3 precoding matrix, and the second and third layers are transmitted by the second antenna group using the second and third precoding vectors of the Rel-15 4TX rank 3 precoding matrix. The result is that the first subset of precodings for N precodings is formed. g =2 / four precodings of rank 4.

[0117] The second subset of precoding may contain four precoding matrices, and these precoding matrices are formed based on the four precoding matrices with only non-zero entries in the Rel-15UL 4TX rank 3 codebook, such as the precoding matrices with TPMI indices 3 to 6 in Table 4. However (unlike the first subset), for each of the two Rel-15 4Tx rank 3 precoding matrices, a precoding matrix for rank 3 transmission is formed such that the first two layers are transmitted by the first antenna group using the first two precoding vectors of the Rel-15 4TX rank 3 precoding matrix, and the third layer is transmitted by the second antenna group using the third precoding vector of the Rel-154TX rank 3 precoding matrix. The result is that for N in the second subset of precoding g =2 / four precodings of rank 4.

[0118] The third subset of precoding may include four precoding matrices formed based on the four precoding matrices with only non-zero entries in the Rel-15 UL4TX rank 3 codebook, such as the precoding matrices with TPMI indices 3 to 6 in Table 4. However (unlike the first and second subsets), for each of the two Rel-15 4Tx rank 3 precoding matrices, a precoding matrix for rank 3 transmission is formed such that the first two layers are transmitted by the first antenna group using the first and third precoding vectors of the Rel-154TX rank 3 precoding matrix, while the third layer is transmitted by the second antenna group using the second precoding vector of the Rel-154TX rank 3 precoding matrix. The result is that the second subset of precoding for N g =2 / four precodings of rank 4.

[0119] The third precoding set includes the first subset, the second subset and the third subset of the above precodings, and consists of a total of 12 precodings.

[0120] It should be noted that additional subsets may be included in this third precoding set using the same type of approach used to form the three subsets listed above, for example, by taking different pairs of precoding vectors from the Rel-15 UL 4TX rank 3 precoding matrix for one antenna group, and using the remaining precoding vectors in the Rel-15 UL 4TX rank 3 precoding matrix for another antenna group. These different possibilities can be directly enumerated and are not listed here.

[0121] In this way, by utilizing Rel-15 UL 4TX precoding, the total number of precodings can be reduced by forming partial coherent precodings based on 4TX precoding. In addition, this precoding design is a lower overhead design.

[0122] Now, we describe the case where two antenna groups (N g =2) and a total of four layers (rank 4). g The precoding design for the cases of rank = 2 and rank 4 can consist of three precoding sets.

[0123] The first precoding set corresponds to the case where 4 layers are transmitted by the first antenna group and no layers are transmitted by the second antenna group. That is, the layers of the first set include four layers and the layers of the second set do not include layers. The first precoding set consists of Rel-15 UL rank 4 precodings that do not contain any zero entries in the precoding vector. For example, the first precoding set may include 2 precodings with TPMI indexes 3 to 4 in Table 5. It should be noted that the design for the first precoding set is unchanged from the current design proposal in RAN1, indicated as layer combination (4,0) in the second column of Table 1.

[0124] The second precoding set corresponds to the case where 4 layers are transmitted by the second antenna group and no layers are transmitted by the first antenna group. That is, the first set of layers does not include layers and the second set of layers includes four layers. The second precoding set consists of Rel-15 UL rank-4 precodings that do not contain any zero entries in the precoding vector, such as the 2 precodings with TPMI indexes 3 to 4 in Table 5. It should be noted that the design for the second precoding set is unchanged from the current design proposal in RAN1, indicated as layer combination (0,4) in the second column of Table 1.

[0125] The third precoding set corresponds to the case where the first two layers are transmitted by the first antenna group and the second two layers are transmitted by the second antenna group. That is, the layers of the first set include two layers and the layers of the second set include two layers. The third precoding set is formed by Rel-15 UL rank 4 precoding without any zero entries in the precoding vector, such as the precoding matrix with TPMI indexes 3 to 4 in Table 5. The third precoding set has a subset of two precodings designed as follows.

[0126] The first subset of precodings may include two precoding matrices formed based on two precodings with only non-zero entries in the Rel-15 UL 4TX rank 4 codebook, such as the precoding matrices with TPMI indexes 3 to 4 in Table 5. For each precoding matrix in the Rel-15 UL 4TX rank 4 precoding matrix, a precoding matrix for rank 4 transmission is formed such that the first two layers are transmitted by the first antenna group using the first two precoding vectors of the Rel-15 4TX rank 4 precoding matrix, and the second two layers are transmitted by the second antenna group using the second two precoding vectors of the Rel-15 4TX rank 4 precoding matrix. The result is that the first subset of precodings for N g =2 / two precodings of rank 4.

[0127] The second subset of precoding may include two precoding matrices formed based on two precodings with only non-zero entries in the Rel-15 UL4TX rank 4 codebook, such as the precoding matrices with TPMI indexes 3 to 4 in Table 5. However (unlike the first subset), for each of the two Rel-15 4Tx rank 4 precoding matrices, a precoding matrix for rank 4 transmission is formed such that the first two layers are transmitted by the first antenna group using the second two precoding vectors of the Rel-15 4TX rank 4 precoding matrix, while the second two layers are transmitted by the second antenna group using the first two precoding vectors of the Rel-15 4TX rank 4 precoding matrix. The result is that the first two layers in the second subset of precoding for N g =2 / two precodings of rank 4.

[0128] The third precoding set includes the first precoding subset and the second precoding subset, and consists of a total of 4 precodings.

[0129] It should be noted that additional subsets may be included in this third precoding set using the same type of approach used to form the three subsets listed above, for example, by taking different pairs of precoding vectors from the Rel-15 UL 4TX rank 4 precoding matrix for the first antenna group, while using the remaining precoding vectors in the Rel-15 UL 4TX rank 4 precoding matrix for the second antenna group. These different possibilities are straightforward to enumerate and are not listed here.

[0130] In this way, by utilizing Rel-15 UL 4TX precoding, the total number of precodings can be reduced by forming partial coherent precodings based on 4TX precoding. In addition, this precoding design is a lower overhead design.

[0131] Several exemplary embodiments of precoding determination or codebook design for rank 2, rank 3, and rank 4 have been described. With such a codebook design, the total number of precodings can be reduced. In addition, the overhead can be reduced without affecting the overall performance.

[0132] It should be understood that although some example embodiments are described by taking 8Tx transmission with two antenna groups and four antennas per antenna group as an example, this is only an example and not any limitation. The concept described with respect to 8Tx transmission with two antenna groups and four antennas per antenna group can be applied to any other multiple transmission with any appropriate number of antenna groups and each group including any appropriate number of antennas. It should also be understood that these example codebooks, example tables, example precoding matrices, and example precoding vectors are only for illustrative purposes and do not imply any limitation.

[0133] In some example embodiments, an apparatus capable of performing any of the methods 300 (e.g., Figure 1 The device 110 in the method 300 may include a component for performing the corresponding operation of the method 300. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The third device may be implemented as or included in Figure 1 In the device 110.

[0134] In some example embodiments, the apparatus includes: means for determining corresponding precodings for a plurality of antenna groups based on a total number of layers and a number of antennas per antenna group; and means for performing transmission of layers of the total number of layers via the plurality of antenna groups using the corresponding precodings for the plurality of antenna groups.

[0135] In some example embodiments, the total number of layers includes a first set of layers and a second set of layers, and the means for performing transmission of the total number of layers includes: means for performing transmission of the layers of the first set via the first antenna group using a first precoding of a first antenna group among the multiple antenna groups, and performing the transmission of the layers of the second set via the second antenna group using a second precoding of a second antenna group among the multiple antenna groups.

[0136] In some example embodiments, the apparatus further comprises: means for determining a plurality of candidate precoding matrices from a codebook corresponding to a total number of layers and a number of antennas per antenna group; means for selecting a precoding matrix from the plurality of candidate precoding matrices; and means for determining the first precoding and the second precoding based on the selected precoding matrix.

[0137] In some example embodiments, each candidate precoding matrix of the plurality of candidate precoding matrices has non-zero entries.

[0138] In some example embodiments, the first set of layers includes a first number of layers, and the means for determining the first precoding includes: means for determining the first precoding based on a first number of precoding vectors in a selected precoding matrix, the precoding vectors in the first number of precoding vectors being associated with layers in the first set of layers.

[0139] In some example embodiments, the means for determining the second precoding comprises means for determining the second precoding based on at least one remaining precoding vector in the selected precoding matrix, a remaining precoding vector of the at least one remaining precoding vector being associated with a layer of the second set of layers.

[0140] In some example embodiments, the apparatus further comprises: means for rearranging precoding vectors in the selected precoding matrix to generate a precoding matrix; and means for determining the first precoding and the second precoding based on the generated precoding matrix.

[0141] In some example embodiments, the total number of layers is two, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0142] In some example embodiments, the total number of layers is three, the number of antennas in each antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0143] In some example embodiments, the total number of layers is four, the number of antennas in each antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0144] In some example embodiments, the apparatus further comprises means for performing the method 300 or other operations of some example embodiments of the apparatus 110. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to perform the operations.

[0145] Figure 4 4 is a simplified block diagram of a device 400 suitable for implementing an example embodiment of the present disclosure. The device 400 may be provided to implement a communication device, such as Figure 1 The device 110 or the device 120 shown. As shown in the figure, the device 400 includes one or more processors 410, one or more memories 420 coupled to the processor 410, and one or more communication modules 440 coupled to the processor 410.

[0146] The communication module 440 is used for two-way communication. The communication module 440 has one or more communication interfaces to support communication with one or more other modules or devices. The communication interface may represent any interface necessary for communication with other network elements. In some example embodiments, the communication module 440 may include at least one antenna.

[0147] Processor 410 may be of any type suitable for the local technology network, and may include one or more of the following: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture, as non-limiting examples. Device 400 may have multiple processors, such as application specific integrated circuit chips, which are time-slaved to the clock of a synchronized master processor.

[0148] The memory 420 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 424, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), optical disk, laser disk, and other magnetic storage and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 422 and other volatile memories that do not persist over the duration of a power outage.

[0149] The computer program 430 includes computer executable instructions executed by the associated processor 410. The instructions of the program 430 may include instructions for performing the operations / actions of some example embodiments of the present disclosure. The program 430 may be stored in a memory, such as ROM 424. The processor 410 may perform any appropriate actions and processes by loading the program 430 into the RAM 422.

[0150] The exemplary embodiments of the present disclosure may be implemented by means of a program 430, so that the device 400 may execute the Figure 3 Any process of the present disclosure discussed. The exemplary embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0151] In some example embodiments, program 430 may be tangibly embodied in a computer-readable medium that may be included in device 400 (such as in memory 420) or other storage device accessible by device 400. Device 400 may load program 430 from the computer-readable medium to RAM 422 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. As used herein, the term "non-transitory" is a limitation of the medium itself (i.e., tangible, not a signal), not a limitation on data storage persistence (e.g., RAM vs. ROM).

[0152] Figure 5 An example of a computer readable medium 500 is shown which may be in the form of a CD, DVD or other optical storage disk. Computer readable medium 500 has program 430 stored thereon.

[0153] Generally, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other graphical representations, it should be understood that the boxes, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof, as non-limiting examples.

[0154] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium (such as a non-transitory computer-readable medium). The computer program product includes computer executable instructions, such as instructions included in a program module, which are executed in a device on a target physical or virtual processor to perform any method as described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The functions of the program modules can be combined or split between program modules as needed in various embodiments. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0155] The program code for executing the method of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0156] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0157] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing. More specific examples of computer readable storage media would include an electrical connection with one or more wires, a portable computer floppy disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0158] In addition, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown or in sequence, or to perform all of the operations shown, to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of the present disclosure, but as descriptions of features that may be specific to a particular embodiment. Unless explicitly stated, certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, unless explicitly stated, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0159] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

[0160] According to one aspect of the present disclosure, a device includes at least one processor; and at least one memory, wherein the at least one memory stores instructions, which, when executed by the at least one processor, cause the device to: determine corresponding precoding for multiple antenna groups based on a total number of layers and a number of antennas per antenna group; and perform transmission of layers of the total number of layers via the multiple antenna groups using the corresponding precoding for the multiple antenna groups.

[0161] In some example embodiments, the total number of layers includes a first set of layers and a second set of layers, and the apparatus is caused to: perform transmission of the first set of layers via the first antenna group using a first precoding for a first antenna group among the plurality of antenna groups, and perform transmission of the second set of layers via the second antenna group using a second precoding for a second antenna group among the plurality of antenna groups.

[0162] In some example embodiments, the apparatus is further caused to: determine a plurality of candidate precoding matrices from a codebook corresponding to a total number of layers and a number of antennas per antenna group; select a precoding matrix from the plurality of candidate precoding matrices; and determine a first precoding and a second precoding based on the selected precoding matrix.

[0163] In some example embodiments, each candidate precoding matrix of the plurality of candidate precoding matrices has non-zero entries.

[0164] In some example embodiments, the first set of layers includes a first number of layers, and the apparatus is further caused to determine a first precoding based on a first number of precoding vectors in a selected precoding matrix, the precoding vectors in the first number of precoding vectors being associated with layers in the first set of layers.

[0165] In some example embodiments, the apparatus is further caused to determine a second precoding based on at least one remaining precoding vector in the selected precoding matrix, a remaining precoding vector of the at least one remaining precoding vector being associated with a layer of the second set of layers.

[0166] In some example embodiments, the apparatus is further caused to: rearrange the precoding vectors in the selected precoding matrix to generate a precoding matrix; and determine the first precoding and the second precoding based on the generated precoding matrix.

[0167] In some example embodiments, the total number of layers is two, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0168] In some example embodiments, the total number of layers is three, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0169] In some example embodiments, the total number of layers is four, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0170] According to one aspect of the present disclosure, a method includes: determining, at a device, corresponding precoding of multiple antenna groups based on a total number of layers and a number of antennas per antenna group; and performing transmission of layers of the total number of layers via the multiple antenna groups using the corresponding precoding of the multiple antenna groups.

[0171] In some example embodiments, the total number of layers includes a first set of layers and a second set of layers, and wherein performing transmission of the total number of layers includes: performing transmission of the first set of layers via the first antenna group using a first precoding of a first antenna group among the plurality of antenna groups, and performing transmission of the second set of layers via the second antenna group using a second precoding of a second antenna group among the plurality of antenna groups.

[0172] In some example embodiments, the method further includes determining a plurality of candidate precoding matrices from a codebook corresponding to the total number of layers and the number of antennas per antenna group; selecting a precoding matrix from the plurality of candidate precoding matrices; and determining the first precoding and the second precoding based on the selected precoding matrix.

[0173] In some example embodiments, each candidate precoding matrix of the plurality of candidate precoding matrices has non-zero entries.

[0174] In some example embodiments, the first set of layers includes a first number of layers, and wherein determining the first precoding includes: determining the first precoding based on a first number of precoding vectors in a selected precoding matrix, the precoding vectors in the first number of precoding vectors being associated with the layers in the first set of layers.

[0175] In some example embodiments, determining the second precoding comprises determining the second precoding based on at least one remaining precoding vector in the selected precoding matrix, a remaining precoding vector of the at least one remaining precoding vector being associated with a layer of the second set of layers.

[0176] In some example embodiments, the method further comprises: rearranging the precoding vectors in the selected precoding matrix to generate a precoding matrix; and determining the first precoding and the second precoding based on the generated precoding matrix.

[0177] In some example embodiments, the total number of layers is two, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0178] In some example embodiments, the total number of layers is three, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0179] In some example embodiments, the total number of layers is four, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook include: and

[0180] According to one aspect of the present disclosure, an apparatus includes: a component for determining corresponding precoding of multiple antenna groups based on a total number of layers and a number of antennas per antenna group; and a component for performing transmission of layers of the total number of layers via the multiple antenna groups using the corresponding precoding of the multiple antenna groups.

[0181] According to one aspect of the present disclosure, a computer-readable medium includes instructions stored thereon, the instructions being used to cause an apparatus to at least perform a method according to any example embodiment of the present disclosure.

[0182] Implementations of the present disclosure may be described according to the following description, features of which may be combined in any reasonable manner.

[0183] Antenna Group N g =2

[0184] In antenna group N g = 2, each antenna group should have 4 coherent Tx ports with Rel-15 4TxUL codebook. A typical cross-polarization antenna configuration can be as follows Figure 2 shown.

[0185] After the RAN1#113 meeting, g = 2 are listed in Table 1, where layer splitting (2,3) / (3,2) and (3,4) / (4,3) are still under discussion. If the layer splitting (3,2) and (4,3) combinations are removed, the updated precoding numbers are shown in the table.

[0186] Table 1 for N g =2 layer division and precoding number

[0187]

[0188]

[0189] Using this list, for N g= 2There are 696 8Tx precodings in total. We have two observations:

[0190] Most of the precoding is determined by the combination of lower rank precodings. For example, for rank-2 with (1,1) antenna group combination, the total number of precodings is 256, because each 4Tx group can support 16 precodings, as defined in Rel-15. If all combinations of these 16 precodings are supported, there will be 256 precodings.

[0191] Removing certain layer splits, such as (3,2), will not affect the total number of precoders. Layer split (3,2) has 32 precoders; layer split (4,3) for rank-7 Tx has only 8 precoders.

[0192] The total maximum number of 696 precodings is still greater than 128 or 256. It requires about 10 bits of TPMI to support all possible combinations.

[0193] Observation 1: For N g =2, the total number of 8Tx precoding based on the current RAN1 protocol may require 10-bit TPMI.

[0194] During the last RAN1 meeting, there was a discussion on the choice between (2,3) and / or (3,2) layer splits and between (3,4) and (4,3) layer splits. From the TPMI overhead point of view, as shown in the table, a layer split of (2,3) will contribute 32 precoders, while a layer split of (3,4) will have 8 precoders. Considering the total number of 696 precoders, these two layer splits will not have a large impact on the total TPMI overhead.

[0195] Observation 2: Layer split (2,3) and layer split (3,4) have 32 precodings and 8 precodings respectively.

[0196] Based on this table, the three layer splits (1,1), (1,2), and (2,1) will have 256, 128, and 128 precodings, respectively. The total number of these precodings will be 512, with 256 rank-1 and 256 rank-2 precodings. If we need the total number of precodings limited for TPMI overhead, some combination of these three layer splits needs to be reduced.

[0197] For rank-1 precoding with layer split (1,1), the 256 precodings come from all combinations of 4Tx rank-1 precodings (16 in total), as specified in 38.211, for TPMI indices from 12 to 27:

[0198] Table 2 Rel-15 4Tx rank-1 codebook: TPMI=12-27

[0199]

[0200] To reduce the number of precoders, we do not need to use all combinations of precoders. Instead, we can restrict certain combinations. A simple approach is to restrict the two antenna groups from 16×16 to 16×4. This can reduce the number of precoders for layer split (1,1) from 256 to 64.

[0201] Proposal 1: Consider limiting the total number of precodings for rank-2 layer split (1,1) to 64.

[0202] For rank-3 layer splits (1,2) and (2,1), we can use a similar approach to restrict the two antenna group combinations from 16×8 to 8×4 for layer split (1,2), and from 8×16 to 4×8 for layer split (2,1). This approach will reduce the total number of rank-2 precoders to 64.

[0203] Table 1 Rel-15 4Tx rank-2 codebook: TPMI 14-21

[0204]

[0205] Proposal 2: Consider limiting the total number of precodings for rank-3 layer splitting (1,2) and layer splitting (2,1) to 64.

[0206] RAN1 agrees to support fully coherent codebooks with up to 7-bit TPMI (128 precoders), and non-coherent CBs with 256 precoders. Partially coherent codebooks should have similar ranges. Based on RAN1's ​​decision on fully coherent CB designs and non-coherent CB designs, we support:

[0207] Proposal 3: Targeting N g =2, the maximum number of inter-precodings for the 8Tx part should reach 256 (8-bit TPMI).

[0208] In order to consider how to reduce N g =2, assuming the rank 2 case in Table 1, where there are three precoding sets. The first and second sets are for (2,0) and (0,2), respectively, with eight precodings in each set. The third set is for (1,1) and has 256 precodings. The third set is designed so that each antenna group transmits one layer using one of the Rel-15 4TX rank 1 precodings (limited to a set of 16 precodings with only non-zero entries). The result is a first set of 16 possible precodings, a second set of 16 possible precodings, and a total of 256 precodings for the (1,1) case.

[0209] For N g=2, with a rank 2 of (1,1) An alternative strategy to consider is to utilize Rel-15 4TX rank 2 precoding instead of Rel-15 4TX rank 1 precoding. For each of the eight Rel-15 4TX rank 2 precodings that have only non-zero entries, we will have two corresponding precodings for (1,1) transmissions for the UE. For the first precoding, the first antenna group transmits using the first column of the Rel-15 4TX rank 2 precoding, and the second antenna group transmits using the second column of the Rel-15 4TX rank 2 precoding. For the second precoding, the first antenna group transmits using the second column of the Rel-15 4TX rank 2 precoding, and the second antenna group transmits using the first column of the Rel-15 4TX rank 2 precoding. The result is that for N g =2, with rank 2 of (1,1), we only have 16 precodings instead of 256 as captured by the original design in Table 1.

[0210] Figure 6 The figure shows the outdoor FWA scenario for N g = 2 codebook performance: burst services (target RU is 20%, 60%, 80%) and full buffer services. Figure 6 As shown, compared with the N captured in the previous RAN1 protocol g =2 compared to the original design for N g =2, with the rank 2 case of (1,1), this alternative design provides slightly improved performance. Figure 6 The performance of the alternative design and the original Table 1 design for the outdoor FWA scenario is shown under full buffering and three bursty traffic conditions (target RU is 20%, 60% and 80%). Figure 6 In Table 1, "CB-all" represents the original precoding design captured in Table 1, where all entries are consistent with the previous RAN1 agreement. "CB-proposed" represents the original precoding design, but with 16 precodings based on the Rel-15 rank 2 4TX codebook in the rank 2, (2,2) case, instead of 256 precodings based on the Rel-15 rank 1 4TX codebook. Note that the proposed alternative design for rank 2, (1,1) provides improved performance, but with substantially fewer rank 2 precodings.

[0211] Observation 3: For N g =2(1,1) case, utilizing Rel-15 4TX rank 2 precoding (with only non-zero entries) can significantly reduce the overall number of rank 2 precodings, while providing similar or slightly improved performance compared to utilizing Rel-15 4TX rank 1 precoding for (1,1).

[0212] Proposal 4: For N g= 2 and with (1,1) rank 2 transmission, consider g =2 rank 2 precoding uses Rel-15 4TX rank 2 precoding instead of Rel-15 4TX rank 1 precoding.

[0213] In order to further reduce the g =2, we can observe that similar constructions can be made for the rank 3 and rank 4 cases. For the rank 3 (2,1) and (1,2) cases: Instead of utilizing 4TX rank 2 and rank 1 precoding, we can simply utilize the 4TX rank 3 precoding matrix (with non-zero entries) and appropriately assign the three columns of the 4TX rank 3 precoding to the two antenna groups. For the rank 4 (2,2) case, instead of utilizing 4TX rank 2 precoding, we can utilize 4TX rank 4 precoding (with only non-zero entries) and assign two of the columns to transmit two layers from one antenna group, and the other two columns to transmit the other two layers from the second antenna group. The result will be a substantial reduction in the size of the overall codebook, and based on Figure 6 We would expect comparable overall performance given the results in

[0214] Proposal 5: For N g = 2 and with rank 3 transmissions of (2,1) and (1,2), consider g =2 rank 3 precoding uses Rel-15 4TX rank 3 precoding instead of Rel-15 4TX rank 1 and rank 2 precoding.

[0215] Proposal 6: For N g = 2 and with a rank 4 transmission of (2,2), consider g =2 rank 3 precoding uses Rel-15 4TX rank 4 precoding instead of Rel-154TX rank 2 precoding.

Claims

1. A device for communication, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to: Determining corresponding precoding for the plurality of antenna groups based on the total number of layers and the number of antennas in each antenna group; as well as Transmission of the total number of layers is performed via the multiple antenna groups using the corresponding precoding of the multiple antenna groups.

2. The apparatus of claim 1 , wherein the total number of layers comprises a first set of layers and a second set of layers, and the apparatus is caused to: The transmission of the first set of layers is performed via a first antenna group among the multiple antenna groups using a first precoding of the first antenna group, and the transmission of the second set of layers is performed via a second antenna group among the multiple antenna groups using a second precoding of a second antenna group.

3. The apparatus of claim 2, wherein the apparatus is further caused to: Determine a plurality of candidate precoding matrices from a codebook corresponding to the total number of layers and the number of antennas per antenna group; Selecting a precoding matrix from the plurality of candidate precoding matrices; as well as The first precoding and the second precoding are determined based on the selected precoding matrix. 4 . The apparatus of claim 3 , wherein each candidate precoding matrix of the plurality of candidate precoding matrices has non-zero entries.

5. An apparatus according to claim 3 or claim 4, wherein the first set of layers comprises a first number of layers, and the apparatus is further caused to: The first precoding is determined based on the first number of precoding vectors in the selected precoding matrix, the precoding vectors in the first number of precoding vectors being associated with layers in the first set of layers.

6. The apparatus of claim 5, wherein the apparatus is further caused to: The second precoding is determined based on at least one remaining precoding vector in the selected precoding matrix, remaining precoding vectors in the at least one remaining precoding vector being associated with layers in the second set of layers.

7. The apparatus of claim 3, wherein the apparatus is further caused to: Rearranging the precoding vectors in the selected precoding matrix to generate a precoding matrix; and The first precoding and the second precoding are determined based on the generated precoding matrix.

8. The apparatus according to claim 2 or claim 3, wherein the total number of layers is two, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook comprises: and 9. The apparatus according to claim 2 or claim 3, wherein the total number of layers is three, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook comprises: and 10. The apparatus according to claim 2 or claim 3, wherein the total number of layers is four, the number of antennas per antenna group is four, and the plurality of candidate precoding matrices in the codebook comprises: and

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