Multi-transmitting antenna codebook enhancement method and system for wireless communication

Abstract

A new air interface (NR) technique for a 5th-Generation (5G) wireless communication system is configured to use multiple transmit / receive antennas to provide higher throughput and lower error rates. Embodiments of the disclosed technology are directed to configuring an uplink 8Tx candidate codebook. In an example, the bit size and mapping of the precoding indication are based on one or more parameters associated with a capability or configuration of a wireless user equipment (UE). An example method of wireless communication includes receiving, by a wireless device, a precoding indication from a network node; and determining a precoding for transmission based on the precoding indication, where the precoding indication is used for indicating at least one of the following: a number of port groups, one or more ranks, or one or more pieces of precoding information, each piece of precoding information being associated with a rank of the one or more ranks.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to digital wireless communications. BACKGROUND

[0002] Mobile telecommunication technology is pushing the world towards an increasingly interconnected and networked society. Next generation systems and wireless communication technologies will need to support a wider range of use case characteristics and provide a more complex and fine-grained range of access requirements and flexibility compared to existing wireless networks.

[0003] Long-Term Evolution (LTE) is a standard for wireless communication for mobile devices and data terminals developed by the 3rd Generation Partnership Project (3GPP). LTE Advanced (LTE-A) is a wireless communication standard that enhances the LTE standard. The 5th generation wireless system, referred to as 5G, advances the LTE and LTE-A wireless standards and is committed to supporting higher data rates, massive connectivity, ultra-low latency, high reliability, and other emerging service requirements. SUMMARY

[0004] Techniques for reducing the number of candidate codebooks in a system with multiple transmit / receive (TX / RX) antennas and determining a bit size of a precoding indication to improve the performance of a wireless communication system are disclosed.

[0005] In an aspect, a method of wireless communication includes receiving, by a wireless device, a precoding indication from a network node, and determining, based on the precoding indication, a precoding for a transmission, wherein the precoding indication is to indicate at least one of a number of port groups, one or more ranks, or one or more precoding information each associated with a rank of the one or more ranks.

[0006] In another aspect, a method of wireless communication includes transmitting, by a network node, a precoding indication to a wireless device, wherein the wireless device is configured to determine, based on the precoding indication, a precoding for a transmission, and wherein the precoding indication is to indicate at least one of a number of port groups, one or more ranks, or one or more precoding information each associated with a corresponding rank of the one or more ranks.

[0007] In yet another exemplary aspect, the above method is embodied in the form of processor-executable code and stored in a non-transitory computer-readable storage medium. The code included in the computer-readable storage medium, when executed by a processor, causes the processor to implement the method described in this patent document.

[0008] In yet another exemplary embodiment, an apparatus configured or operable to perform the above method is disclosed.

[0009] The above and other aspects and implementations thereof are more fully described in the following detailed description along with the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 A flowchart of an example method for wireless communication is shown.

[0011] Figure 2 A flowchart of another example method for wireless communication is shown.

[0012] Figure 3 A block diagram of an example hardware platform, which can be part of a network device or a communication device, is shown.

[0013] Figure 4 Examples of wireless communication including base stations (BSs) and user equipments (UEs) based on some implementations of the disclosed technology are shown. DETAILED DESCRIPTION

[0014] Example titles for the following sections are used to facilitate understanding of the disclosed subject matter and do not limit the scope of the claimed subject matter in any way. Thus, one or more features of one example section can be combined with one or more features of another example section. Still further, 5G terminology is used for explanatory purposes, but the disclosed technology is not limited to 5G technology and can be used to implement wireless systems of other protocols as well.

[0015] New Radio (NR) technology for the fifth generation (5G) mobile communication system is continuously improving to provide higher quality wireless communication. One key feature is to support high capability wireless devices (or user equipments (UEs)), such as customer premise equipment (CPE) and fixed wireless access (FWA), to improve uplink (UL) quality. One of the supported features is to use up to 8 Tx (antenna ports) for UL transmission, as legacy UEs can support up to 4 Tx.

[0016] The described embodiments address at least the following technical problems in existing and emerging systems:

[0017] The number of candidate codebooks for UL 8Tx is large, which can cause large overhead, and should be reduced based on some rules.

[0018] - For joint indication of precoding, how to map the value of indication to precoding and the bit size of precoding indication is not clear.

[0019] 1 Overview of Precoding Information and Coherence Level

[0020] In some embodiments, a wireless device (e.g., a UE) reports a capability of a coherence level or a number of port group(s), and a network node (e.g., a base station, a gNB, etc.) configures or indicates the coherence level or the number of port group(s) (set).

[0021] As used herein, a coherence level reflects the coherence capability among port groups. If 2 ports are coherent, the phase between the 2 ports can be controlled by a transmitter, e.g., by a UE when the two ports are transmit ports of the UE. If 2 ports are non-coherent, the phase cannot be assumed to be controlled by a transmitter. For a UE supporting more than 2 ports, some ports can be coherent and some ports are non-coherent, thus from the perspective of the UE, it has partially coherent ports. For 8Tx, i.e., 8 ports, the coherence level can be full coherence, i.e., all 8 ports are coherent; partial coherence 1 indicates there are 2 (4Tx or 4 ports) groups; partial coherence 2 indicates there are 4 (2Tx or 2 ports) groups; non-coherent indicates no port is coherent. The ports can be coherent within a group and non-coherent across groups. In some cases, the coherence level corresponds to the number of port groups. The full coherence level corresponds to 1 group, i.e., Ng=1, the first type of partial coherence level corresponds to 2 groups, i.e., Ng=2, the second type of partial coherence corresponds to 4 groups, i.e., Ng=4, and non-coherent corresponds to 8 groups, i.e., Ng=8.

[0022] In some embodiments, a network node indicates a precoding for transmission by a joint encoding indication in a DCI (Downlink Control Information). The joint encoding indication can indicate rank information and precoding information to form the precoding. A wireless device receives the coherence or the number of port group(s) (set) and the DCI, and determines the precoding for transmission.

[0023] In some embodiments, the precoding information can be a set of parameter values, a transmit precoding matrix indicator (TPMI) indicating the set of parameter values, or one or more TPMIs. In this context, each TPMI corresponds to a non-zero rank. This is summarized in Table 1.

[0024] Table 1: Summary of Number of Groups Indication and TPMI

[0025]

[0026]

[0027] As used herein, the term rank split or layer number split corresponds to a split of the layer number or the sum of one or more ranks (each rank corresponds to a port group) with reference to 8 Tx ports (all port groups).

[0028] 2. Embodiment 1: Restriction on rank combination

[0029] In some embodiments, and for a codebook that is partially coherent or non-coherent, the baseline scheme uses full flexibility of rank combination and TPMI. However, in practice, full flexibility can result in too many candidates of precoding and too much overhead of precoding indication. The described embodiments describe restrictions that can be applied to rank combination, as follows.

[0030] Group balancing rule : When using the group balancing (or group equalization) rule, almost even split of layers among port groups can be achieved. For example, 4 ports can be split into 2 for 2-port groups and 2; 5 ports can be split into 2 for 2-port groups and 3.

[0031] In some embodiments, if rank permutation of rank split and rank indication is supported, for 2-port groups, 5 can be split into 3 and 2, i.e., 3+2, or split into 2 and 3, i.e., 2+3. This means that port group index is sensitive to layer split. 2+3 results in port group index 0 having 2 layers, while port group index 1 has 3 layers; while 3+2 results in port group index 0 having 3 layers, while port group index 1 has 2 layers.

[0032] Whether rank permutation is supported can be based on a predetermined rule or configured by a parameter from a network node. In one example, the predetermined rule can be that, when rank / layer is split, a lower port group index has the same or fewer number of layers than a higher port group index. For example, 5 is split into 2+3.

[0033] Group selection rule : When using the group selection rule, layers are distributed in as few groups as possible. For example, 4 ports can be split into 4+0, and 5 ports can be split into 4+1. If 2 groups of 8 ports are supported, one group of 4 ports can support at most 4 layers. If 4 groups are supported, one group can support at most 2 layers.

[0034] In some embodiments, whether 4 ports can also be split into 0+4, or whether 5 ports can also be split into 1+4, depends on the rank permutation rule. If the rank permutation rule is supported, 4 can also be split into 0+4 or 4+0, and 5 can also be split into 1+4 or 4+1.

[0035] In addition, the group selection rule can be only for each 4-port group (e.g., can correspond to 2 panels in the UE, with 2 back-to-back directions) or only for each 2-port group (e.g., can correspond to 4 panels in the UE, with 4 different directions).

[0036] - For 4-port group selection, 2-port group selection is not recommended. This results in 1 pair of 2-port groups within one 4-port group still using the group balancing rule, unless additionally configured to enable group selection.

[0037] - This also results in for 1-port group, 4-port group selection and 2-port group selection group selection rules are not recommended, unless additionally configured.

[0038] In some embodiments, a show indication can be used. Alternatively, an implicit approach can be taken, where the highest coherence level can be used to determine which level group selection should be applied to. For example:

[0039] - If the highest coherence level is full coherence, there is no need to support group selection rules for any one port group.

[0040] - If the highest coherence level is partial 1 coherence, group selection rules are supported for 4-port groups, but there is no need to support group selection rules for 2-port groups.

[0041] - If the highest coherence level is partial 2 coherence, group selection rules are supported for 2-port groups.

[0042] In this document, it is assumed that full coherence level is greater than partial 1 coherence level, partial 1 coherence level is greater than partial 2 coherence level, and partial 2 coherence level is greater than non-coherent level.

[0043] In some embodiments, both group selection rules and group balancing rules can be implemented based on the provided configuration.

[0044] Option 1: Only one rule is configured, and the candidate codebook is selected based on the enabled rule only.

[0045] Group selection ...

[0046] or

[0047] Group balancing ...

[0048] Option 2: The group balancing rule is always enabled, and the configuration specifies whether to support the group selection rule on top of the group balancing rule.

[0049] Group selection + group balancing ...

[0050] or

[0051] Group balancing ...

[0052] The specified number (N g ) of port groups can have different sets for different configurations.

[0053] For Option 1, there are two sets for two rules.

[0054] For Option 2, the set of two balancing rules and balancing+selection rules

[0055] For 4-port group: group selection + group balancing ...

[0056] or

[0057] For 2-port group: group balancing ...

[0058] 3 Embodiment 2: Restriction on nested codebook structure

[0059] In some embodiments, whether to use the nested codebook structure is also related to the number of candidate codebooks. A UE with stronger coherence capability can support not only the codebooks of higher coherence levels, but also the codebooks of lower coherence levels. For example, for a 4-port UE, the codebooks can be identified as having a full-coherence part, a partial-coherence part, and a non-coherence part. For a UE supporting full-coherence level, the codebooks of full-coherence, partial-coherence, and non-coherence can be used, and the coherence levels configured by the gNB (and transmitted to the UE) are full-coherence, partial-coherence, and non-coherence. For a UE supporting partial-coherence level, the codebooks of partial-coherence and non-coherence can be used, and the coherence levels configured by the gNB are partial-coherence and non-coherence. For a UE supporting non-coherence level, the available codebooks can only include the non-coherence part. The nested codebook structure means that the available codebooks for a UE with a certain coherence level include the codebooks of its highest coherence level, as well as the codebooks of the coherence levels lower than its highest coherence level.

[0060] However, for an 8Tx UE, there are four coherence levels, and for each coherence level, there can be hundreds of codebooks. If the nested structure is adopted, there will usually be many available (or candidate) codebooks, which can cause unnecessary huge overhead. Some described embodiments aim to reduce the number of candidate codebooks and are configured to support the following schemes:

[0061] Scheme 1: Configure one or more Ng values based on UE capability, and determine the candidate codebooks based on the configured Ng value(s). Alternatively, configure one or more coherence levels based on UE capability, and determine the candidate codebooks based on the configured coherence level(s). Note that it is not necessary to support all codebooks with Ng values greater than the configured Ng, nor to support all codebooks with coherence levels lower than the configured coherence level.

[0062] Scheme 2: Utilizing the relationship of the group balancing rule and the group selection rule, determine the candidate codebook based on UE capability.

[0063] - For full-coherent as the highest level, codebooks of Ng = 1, 2, 4 and 8 are allowed, only group balancing rule is employed.

[0064] - For partial 1-coherent as the highest level, codebooks of Ng = 2, 4 and 8 are allowed, where only group selection rule is employed for 4-port group only, and group balancing rule is employed for other types of port groups.

[0065] - For partial 2-coherent as the highest level, codebooks of Ng = 4 and 8 are available, where only group selection rule is employed for 2-port group only, and group balancing rule is employed for other types of port groups.

[0066] - For non-coherent as the highest level, codebook of Ng = 8 is allowed, and group balancing rule and group selection rule are the same.

[0067] 4 Embodiment 3: Codebook definition and signaling

[0068] 4.1 Indication of number of port groups, TPMI and rank

[0069] In some embodiments, an indication scheme of joint encoding is implemented. In this context, the gNB indicates to the UE an indication of joint encoding of number of port groups, TPMI and rank for each port group to indicate the precoding for transmission, e.g., via DCI. The UE receives the indication of joint encoding to determine the precoding for transmission.

[0070] In some embodiments, the indication of joint encoding is used to indicate one entry in one table or a combination of entries of more than one table. For example:

[0071] - For one table, the single table includes at least one of the following parts: full-coherent part (i.e., Ng = 1), partial 1-coherent part (i.e., Ng = 2), partial 2-coherent part (i.e., Ng = 4) or non-coherent part (i.e., Ng = 8).

[0072] - For multiple tables, each table corresponds to at least one of the following parts: full-coherent part (i.e., Ng = 1), partial 1-coherent part (i.e., Ng = 2), partial 2-coherent part (i.e., Ng = 4) or non-coherent part (i.e., Ng = 8). In one example, four tables can be used, each table for Ng = 1, 2, 4 and 8. In another example, two tables can be used, the first table for Ng = 1 and the second table for Ng = 2, 4 and 8.

[0073] In some embodiments, the bit size of the indication of the joint coding depends on the number of entries of one or more tables available to the UE. The number of entries can be the sum of the number of available entries in the one or more tables. This results in the indication of the joint coding being based on the available entries indicating a codebook from one table or a combination of several tables. The combination can simply be a logical combination of entries determined from several parts. The available entries can be determined according to one or more of the following aspects:

[0074] - maxRANK, combinations / lists of maxRANK,

[0075] - port group index sensitive (rank restriction / indication permutation) rules,

[0076] - group selection rules and / or group balancing rules,

[0077] - nested construction rules,

[0078] - TPMI reduction rules, or

[0079] - a configured pattern from a predefined set of patterns to determine at least one of the following aspects: port group index sensitive (rank restriction / indication permutation) rules, group selection rules and / or group balancing rules, nested construction rules, or TPMI reduction rules. Alternatively, or in addition, the pattern can be related to the UE antenna layout (e.g., Ng, same or different directions) and can be reported by the UE to the gNB.

[0080] In the above embodiments and examples, the codebook refers to a precoding or precoding matrix.

[0081] 4.2 Codebook definition

[0082] In some embodiments, multiple tables or hybrid (or nested) tables are used to define the entries corresponding to the selectable codebooks.

[0083] Option 1: A single hybrid table is defined corresponding to all coherence levels, and rules to select part or all of the entries in the table are defined for different nested schemes. For example, the following table shown can be used for conventional nested construction, flexible partial set (e.g., part 3 + part 4), etc.

[0084] Part 4 Non-coherent Part 3, Ng = 4 Part 2 coherent Part 2, Ng = 2 Part 1 coherent Part 1, Ng = 1 Full-coherent

[0085] Option 2: Several tables are defined separately, each table for one of multiple Ng values (e.g., non-coherent, part 2 coherent, part 1 coherent, and full coherent), and the number of entries of the indication signaling is based on the Ng configuration and the nested scheme. One or more of the following options can be implemented.

[0086] - Each part can have a complete codebook set based on one or more parameters including maxRANK, combination / list of maxRANK, port group index sensitive (rank restriction / indication permutation) rules, group selection rules and / or group balancing rules, nested construction rules or TPMI reduction rules. The UE can determine the available codebooks (entries) based on its own capability or configuration.

[0087] - For each part, there are different settings of the number of entries for different cases of UEs. For example, for each mode value, a set of entries is provided, and the UE determines the available codebook based on its own mode.

[0088] - For the candidate codebook set, the full-coherent part has a variable size depending on N1 / N2 / O1 / O2, where N1 and N2 correspond to the number of rows and columns of antenna elements in a panel (antenna panel), respectively, and O1 and O2 correspond to the respective oversampling.

[0089] Part 4 Non-coherent

[0090] Part 3, Ng = 4 Part 2 coherent

[0091] Part 2, Ng = 2 Part 1 coherent

[0092] Part 1, Ng = 1 Full-coherent

[0093] Option 3: A number of tables (or different columns in one table, as in the traditional case) are defined, each for different combinations of non-coherent, partial 2-coherent, partial 1-coherent and full-coherent. Based on the Ng configuration and the nested scheme, one table is determined for indication. An example is shown below.

[0094]

[0095]

[0096] Full-coherent or Ng = 1 The precoding information can be a parameter value set including at least one of i 1,1 , i 1,2 , i 1,3 , or i2. The value range of i 1,1 , i 1,2 can be determined according to N1, N2 and the corresponding oversampling O1, O2. N1 / N2 can be configured. N1 and N2 are the number of rows and columns of antenna elements in a panel (antenna panel), respectively. O1 / O2 can be configured or determined according to N1 / N2 or the number of layers. i 1,3 and i2 for phase are determined for the DL codebook.

[0097] The following is an example of a fully coherent table.

[0098] TPMI rank field Number of layers (rank) Precoding information (i 1,1 , 1,2 , 1,3 , or a combination of values of i1 and i2 0-3 1 i 1,1 = 0, i 1,2 = 0, i 1,3 = 0, or i2= 0-3]]> 4-7 1 i 1,1 = 1, i 1,2 = 0, i 1,3 = 0, or i2= 0-3]]> ... 16-17 2 i 1,1 = 0, i 1,2 = 0, i 1,3 = 0, or i2= 0-1]]> 18-19 2 i 1,1 = 0, i 1,2 = 0, i 1,3 = 1, or i2= 0-1]]> ...

[0099] Wherein, UE determines i for each rank. 1,1 i 1,2 i 1,3 The range of values ​​for each parameter of i2 can be the same or different for parameters of different ranks. TPMI and rank are indexed together in the following order:

[0100] – From rank 1 to the highest rank, for example, rank 8

[0101] For each rank, the combinations of the four parameter values ​​are ordered according to predefined rules. For example, first i2 increases, then i... 1,3 Then i 1,2 Finally, i 1,1 Alternatively, the predefined rule can also be another order, such as first i 1,3 Increase, then i2, then i 1,2 Finally, i 1,1 .

[0102] Part 1 coherent or Ng = 2 :

[0103] In one example, rank 1 and rank 8 can have the following rank partitioning scheme, also known as level partitioning.

[0104] Rank All layers in one antenna group Layers split across 2 antenna groups 1 (1,0),(0,1) - 8 - (4,4)

[0105] Ranks 2 to 7 can have the following rank partitioning schemes, also known as level partitioning.

[0106]

[0107] In the table above, the entries within single hash symbols #·# correspond to group balancing rule partitioning, the entries within double brackets [[·]] correspond to a group rule, the entries within double curly braces {{·}} correspond to group selection, and the entries within forward slashes / / · / / correspond to group index sensitivity for each rule.

[0108] In another example, the indication of the joint encoding can be partially rank-limited as shown in the following example, which follows the notation in the previous table.

[0109]

[0110]

[0111] Part 2 coherent or Ng = 4 :

[0112] For Ng=2, some rules can be reused, e.g., for layer partitioning, whether balanced way or converging way or both can be supported; for TPMI candidate reduction, whether some reduction can happen for some higher rank.

[0113]

[0114]

[0115] In one example, the following shows a table of two 4Tx partial coherent TPMIs to indicate the codebook for Ng=4, which follows the notation in the previous table.

[0116] For the following cases:

[0117] Issue 1: If 2 groups are used to support Ng=4, does the rank combination set need to be the same as Ng=2, or more?

[0118] Issue 2: If 2 groups are used to support Ng=8, i.e., non-coherent, does it need less rank combination.

[0119] Use the following solutions:

[0120] Solution 1: Same rank combination with same restriction, or no restriction for Ng=2, 4 and 8, or no restriction for full coherent, partial 1 coherent, partial 2 coherent or non-coherent.

[0121] Solution 2: Different rank restriction for Ng=2, 4, 8 respectively

[0122] - Ng=2 or partial 1 coherent can only support part of the set

[0123] - Ng=4 or partial 2 coherent can need more than one rank partition for Ng=2, or various rank split schemes

[0124] - Ng=8 or non-coherent can need part of the set for typical use case of port selection. In this document, the highest level of coherence or the lowest Ng can be used to determine to use 2 group rank split candidates for Ng=8 or non-coherent. In one example, for the highest level of full coherent, all layers in one antenna group can be used, or layers split across 2 antenna groups with group selection rule; for the highest level of partial 1 coherent, partial 2 coherent or non-coherent, layers split across 2 antenna groups can be used.

[0125] Whether to use solution 1 or solution 2 can depend on pre-defined rule, or explicit configuration, or implicit parameter (e.g., nesting parameter).

[0126] The following shows different options of indication of joint coding for Ng=4, following the notation in the previous tables.

[0127] Option 1 with 4 groups:

[0128]

[0129] Option 2 with 2 groups (2 4Tx TPMI):

[0130]

[0131]

[0132] Non-coherent or Ng = 8 :

[0133] The following examples are for 2 groups (2 4Tx TPMI)

[0134]

[0135] In some embodiments, the predefined set of precodings for UL 4Tx and UL 2Tx for rank 1-4 and rank 1-2, respectively, are as shown in the following tables.

[0136]

[0137]

[0138]

[0139] Example implementations and embodiments of the disclosed technology

[0140] Figure 1 A flow diagram illustrating an example method for wireless communication is shown. The method 100 includes receiving (110), by a wireless device, a precoding indication from a network node, and determining (120), based on the precoding indication, a precoding for a transmission, wherein the precoding indication is to indicate at least one of: a number of port groups, one or more ranks, or one or more precoding information, each precoding information being associated with one of the one or more ranks.

[0141] Figure 2 A flow diagram illustrating another example method for wireless communication is shown. The method 200 includes transmitting (210), by a network node, a precoding indication to a wireless device, wherein the wireless device is configured to determine, based on the precoding indication, a precoding for a transmission, and wherein the precoding indication is to indicate at least one of: a number of port groups, one or more ranks, or one or more precoding information, each precoding information being associated with a corresponding rank of the one or more ranks.

[0142] The embodiments provide in particular the following technical solutions:

[0143] 1.A method of wireless communication, comprising: receiving, by a wireless device, a precoding indication from a network node; and determining, based on the precoding indication, a precoding for transmission, wherein the precoding indication is used to indicate at least one of: a number of port groups, one or more ranks, or one or more precoding information, each precoding information being associated with a rank of the one or more ranks.

[0144] 2.A method of wireless communication, comprising: transmitting, by a network node, a precoding indication to a wireless device, wherein the wireless device is configured to determine, based on the precoding indication, a precoding for transmission, and wherein the precoding indication is used to indicate at least one of: a number of port groups, one or more ranks, or one or more precoding information, each precoding information being associated with a corresponding rank of the one or more ranks.

[0145] 3.The method of solution 1 or 2, wherein each of the port groups corresponds to a respective rank equal to or greater than zero.

[0146] 4.The method of solution 1 or 2, wherein each of the one or more precoding information comprises a transmission precoding matrix indicator (TPMI) or a set of parameter values.

[0147] 5.The method of solution 1 or 2, wherein the precoding information is associated with the corresponding rank greater than zero.

[0148] 6.The method of solution 1 or 2, wherein the precoding indication comprises precoding information and associated ranks jointly encoded in downlink control information (DCI).

[0149] 7.The method of solution 1 or 2, wherein the one or more ranks are based on a predetermined rule or based on a parameter signaled by the network node.

[0150] 8.The method of solution 1 or 2, wherein the number of port groups is associated with a coherence level comprising full coherence, first type of partial coherence, second type of partial coherence, or non-coherent.

[0151] 9. The method of solution 1 or 2, wherein the one or more ranks are based on a group balancing rule, wherein (a) a first rank exceeds a second rank by no more than one, or (b) the first rank is less than the second rank by no more than one, and wherein the first rank corresponds to a first port group having a smaller index than a second port group corresponding to the second rank.

[0152] 10. The method of solution 1 or 2, wherein the one or more ranks are based on a group selection rule, wherein (a) one of the one or more ranks is greater than one, or (b) at most one of the one or more ranks is greater than one and less than K / Ng, and the other ranks are zero or K / Ng, wherein the number of port groups (Ng) is one, two, four, or eight, and wherein K is the number of transmit antenna ports used for transmission.

[0153] 11. The method of solution 1 or 2, wherein the number of port groups (Ng) is a configured value or is based on a configured coherence level, and wherein the coherence level comprises at least one of: full coherence, a first type of partial coherence, a second type of partial coherence, or non-coherent. In some examples, the coherence level can comprise one or more of four coherence levels, namely, full coherence, a first type of partial coherence (also referred to as partial 1 coherence), a second type of partial coherence (also referred to as partial 2 coherence), or non-coherent.

[0154] 12. The method of solution 1 or 2, wherein the one or more ranks are based on a group selection rule or a group balancing rule according to a highest level of coherence level configured for the wireless device or a smallest number of Ng configured for the wireless device, wherein Ng is the number of port groups, and wherein the coherence level comprises at least one of: full coherence, a first type of partial coherence, a second type of partial coherence, or non-coherent.

[0155] 13. The method of solution 12, wherein, in response to the highest level of coherence level being the full coherence, the wireless device is configured to determine the one or more ranks corresponding to Ng = 1, 2, 4, or 8 with the group balancing rule.

[0156] 14. The method of solution 12, wherein, in response to the highest level of coherence level being the first type of partial coherence, the wireless device is configured to determine the one or more ranks corresponding to Ng = 2, 4, or 8, wherein the group selection rule is implemented for Ng = 2, and wherein the group balancing rule is implemented for other Ng.

[0157] 15. The method of solution 12, wherein, in response to a highest level of the coherence levels being partial coherence of the first type, the wireless device is configured to determine the one or more ranks corresponding to Ng = 2, 4, or 8, wherein the group selection rule is implemented for Ng = 2, and wherein the group balancing rule is implemented for Ng = 2, 4, or 8.

[0158] 16. The method of solution 12, wherein, in response to a highest level of the coherence levels being partial coherence of the second type, the wireless device is configured to determine the one or more ranks corresponding to Ng = 4 or 8, wherein the group selection rule is implemented for Ng = 4, and wherein the group balancing rule is implemented for other Ng.

[0159] 17. The method of solution 12, wherein, in response to a highest level of the coherence levels being partial coherence of the second type, the wireless device is configured to determine the one or more ranks corresponding to Ng = 4 or 8, wherein the group selection rule is implemented for Ng = 4, and wherein the group balancing rule is implemented for Ng = 4 or 8.

[0160] 18. The method of solution 1 or 2, wherein the precoding indication is indicated by a field in downlink control information (DCI), and the precoding indication is for the field to indicate a number of the port groups, the one or more ranks, or the one or more precoding information, and each precoding information is associated with a rank of the one or more ranks.

[0161] 19. The method of solution 18, wherein a bit length of the precoding indication field is based on a number of entries of one or more tables determined by the wireless device.

[0162] 20. The method of solution 19, wherein the number of entries is based on at least one of: a maximum rank for the transmission, or a maximum rank for one port group, each rule in a rule set, or a mode configured to use one or more rules in the rule set, and wherein the rule set comprises a port group index rule, a group balancing rule, a group selection rule, a nested construction rule, or a TPMI reduction rule.

[0163] 21. The method of solution 20, wherein in response to a port group index rule being enabled, rank X and rank Y are associated with a particular index order of port groups. In some examples, if the port group index rule is enabled, then if there is an entry indicating a first rank of a first port group is a rank value X and a second rank of a second port group is a rank value Y (Y not equal to X), then there is no entry indicating a first rank of the first port group is a rank value Y and a second rank of the second port group is a rank value X.

[0164] Alternatively, if the port group index rule is not enabled, then there is at least one entry indicating a first rank of a first port group is a rank value Y and a second rank of a second port group is a rank value X.

[0165] 22. The method of solution 20, wherein in response to the nested configuration rule being implemented, the number of port groups (Ng) is a configured value or is based on a configured level of coherence, wherein the level of coherence includes at least one of: full coherence, a first type of partial coherence, a second type of partial coherence, or non-coherent, or the one or more ranks are based on a highest level of coherence configured for the wireless device or a minimum number of Ng configured for the wireless device according to a group selection rule or a group balancing rule.

[0166] 23. The method of solution 20, wherein the mode is related to an antenna layout of the wireless device.

[0167] 24. The method of solution 19, wherein the precoding indication field corresponds to an entry of one table or an entry of a combination of multiple tables.

[0168] 25. The method of solution 19, wherein the number of port groups is associated with a level of coherence including at least one of: full coherence, a first type of partial coherence, a second type of partial coherence, or non-coherent.

[0169] 26. The method of solution 25, wherein the one table includes an entry associated with each of the configured levels of coherence or each of the configured Ngs.

[0170] 27. The method of solution 25, wherein each of the multiple tables includes an entry associated with one of the configured levels of coherence or one of the configured Ngs.

[0171] 28. The method of solution 25, wherein each of the multiple tables includes an entry associated with a combination of different levels of coherence from the configured levels of coherence.

[0172] 29. An apparatus for wireless communication, comprising a processor configured to implement a method recited in one or more of solutions 1 to 28.

[0173] 30. A non-transitory computer readable program storage medium having code stored thereon, the code, when executed by a processor, causing the processor to implement a method recited in one or more of solutions 1 to 28.

[0174] Figure 3 A block diagram of an example hardware platform 300, which can be part of a network device (e.g., a base station) or a communication device (e.g., a user equipment (UE)), is shown. The hardware platform 300 includes at least one processor 310 and a memory 305 having instructions stored thereon. The instructions executed by the processor 310 configure the hardware platform 300 to perform the operations described in the various embodiments discussed in this patent document. A transmitter 315 transmits or sends information or data to another device. For example, a network device transmitter can send a message to a user equipment. A receiver 320 receives information or data transmitted or sent by another device. For example, a user equipment can receive a message from a network device. Figures 1-2

[0175] Embodiments as discussed above will be applicable to wireless communication. Figure 4 An example of a wireless communication system (e.g., a 5G or NR cellular network) is shown, including a base station 420 and one or more user equipments (UEs) 411, 412, and 413. In some embodiments, a UE uses a communication link to a network (sometimes referred to as an uplink direction, as depicted by dashed arrows 431, 432, 433) to access a BS (e.g., a network), which in turn enables subsequent communication from the BS to the UE (e.g., shown in a direction from the network to the UE, sometimes referred to as a downlink direction, as depicted by arrows 441, 442, 443). In some embodiments, a BS sends information to a UE (sometimes referred to as a downlink direction, as depicted by arrows 441, 442, 443), which in turn enables subsequent communication from the UE to the BS (e.g., shown in a direction from the UE to the BS, sometimes referred to as an uplink direction, as depicted by dashed arrows 431, 432, 433). A UE can be, for example, a smartphone, a tablet, a mobile computer, a machine to machine (M2M) device, and an Internet of Things (IoT) device, etc.

[0176] ​Some of the embodiments described herein are described in the general context of methods or processes, which can be implemented in one embodiment by a computer program product, executable program code including computer executable instructions, such as program code, embodied in a computer readable medium executed by computers in networked environments. A computer readable medium can include removable storage devices and non-removable storage devices, including but not limited to Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVDs), etc. Accordingly, a computer readable medium can include non-transitory storage media. Generally, program modules can include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer executable instructions, or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

[0177] Some of the disclosed embodiments can be implemented as devices or modules using hardware circuitry, software, or a combination thereof. For example, hardware circuitry implementations can include discrete analog and / or digital circuitry, such as that integrated as part of a printed circuit board. Alternatively, or additionally, the disclosed components or modules can be implemented as an Application Specific Integrated Circuit (ASIC) and / or a Field Programmable Gate Array (FPGA) device. Some implementations can additionally or alternatively include a Digital Signal Processor (DSP), which is a specialized microprocessor optimized for the needs of digital signal processing, having an architecture optimized for the manipulation of digital signals associated with the disclosed functionality of the present application. Similarly, the various components or sub-components within each module can be implemented in software, hardware, or firmware. Connections between the modules and / or components within the modules can be provided using any of the connection methods and media known in the art, including but not limited to communication over the Internet, wired or wireless networks using appropriate protocols.

[0178] While this document contains many specifics, these should not be construed as limitations on the scope of the invention claimed or that which might be protected by its letters patent. It is also contemplated that the features described in this document could be implemented in a combination of embodiments other than the specific ones described. In addition, although features might be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be deleted and the claimed combination can also concern several separate items. Similarly, devices or processes described above can not be required to be implemented in the order described, or in sequential order, or in any order, to achieve desirable results. All such modifications are considered to be within the scope of the present invention.

[0179] Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this disclosure.

Claims

1. A method for wireless communication, comprising: The wireless device receives precoded instructions from the network node; as well as The precoding for transmission is determined based on the precoding indication. The precoding indication is used to indicate at least one of the following: the number of port groups, one or more ranks, or one or more precoding information, each precoding information being associated with a rank among the one or more ranks.

2. A method for wireless communication, comprising: The network node transmits the precoding instruction to the wireless device. The wireless device is configured to determine precoding for transmission based on the precoding indication, and The precoding indication is used to indicate at least one of the following: the number of port groups, one or more ranks, or one or more precoding information, each precoding information being associated with a corresponding rank among the one or more ranks.

3. The method according to claim 1 or 2, wherein, Each port group in the port group corresponds to a rank that is equal to or greater than zero.

4. The method according to claim 1 or 2, wherein, Each of the one or more precoding messages includes a Transport Precoding Matrix Indicator (TPMI) or a set of parameter values.

5. The method according to claim 1 or 2, wherein, The precoded information is associated with the corresponding rank, which is greater than zero.

6. The method according to claim 1 or 2, wherein, The precoding indication includes precoding information jointly encoded in the downlink control information (DCI) and the associated rank.

7. The method according to claim 1 or 2, wherein, The one or more ranks are based on predetermined rules or on parameters notified by the network nodes via signals.

8. The method according to claim 1 or 2, wherein, The number of port groups is associated with a coherence level that includes fully coherent, partially coherent of the first type, partially coherent of the second type, or incoherent.

9. The method according to claim 1 or 2, wherein, The one or more ranks are based on group balancing rules, wherein (a) the first rank exceeds the second rank by no more than one, or (b) the first rank is less than the second rank by no more than one, and wherein the first rank corresponds to a first port group having an index smaller than that of a second port group corresponding to the second rank.

10. The method according to claim 1 or 2, wherein, The one or more ranks are based on a group selection rule, wherein (a) one of the one or more ranks is greater than 1, or (b) at most one of the one or more ranks is greater than 1 and less than K / N. g And the other ranks are 0 or K / N g The number of port groups (N) g ) can be 1, 2, 4 or 8, where K is the number of transmit antenna ports used for transmission.

11. The method according to claim 1 or 2, wherein, The number of port groups (N) g ) is a configured value or a coherence level based on the configuration, wherein the coherence level includes at least one of the following: fully coherent, partially coherent of a first type, partially coherent of a second type, or incoherent.

12. The method according to claim 1 or 2, wherein, The one or more ranks are based on the highest level configured for the coherence level of the wireless device or N configured for the wireless device. g The minimum number of group selection rules or group balancing rules, where N g The number of port groups is denoted as , and the coherence level includes at least one of the following: fully coherent, partially coherent of a first type, partially coherent of a second type, or incoherent.

13. The method according to claim 12, wherein, In response to the highest level of coherence being fully coherent, the wireless device is configured to determine with N using the group balancing rule. g =1, 2, 4 or 8, corresponding to one or more ranks.

14. The method according to claim 12, wherein, In response to the highest level of coherence being partial coherence of the first type, the wireless device is configured to determine with N g = 2, 4 or 8 corresponding to one or more ranks, wherein the group selection rule is implemented for N g =2, and wherein the group balancing rule is implemented for the other N g .

15. The method according to claim 12, wherein, In response to the highest level of coherence being partial coherence of the first type, the wireless device is configured to determine with N g = 2, 4 or 8 corresponding to one or more ranks, wherein the group selection rule is implemented for N g =2, and wherein the group balancing rule is implemented for N g =2, 4 or 8.

16. The method according to claim 12, wherein, In response to the highest level of coherence being the second type of partial coherence, the wireless device is configured to determine with N g = 4 or 8 corresponding to the one or more ranks, wherein the group selection rule is implemented for N g =4, and wherein the group balancing rule is implemented for the other N g .

17. The method according to claim 12, wherein, In response to the highest level of coherence being the second type of partial coherence, the wireless device is configured to determine with N g = 4 or 8 corresponding to the one or more ranks, wherein the group selection rule is implemented for N g =4, and wherein the group balancing rule is implemented for N g =4 or 8.

18. The method according to claim 1 or 2, wherein, The precoding indication is indicated by a field in the downlink control information (DCI), and the precoding indication is used to indicate the number of port groups, the one or more ranks, or the one or more precoding information, and each precoding information is associated with a rank in the one or more ranks.

19. The method according to claim 18, wherein, The bit length of the precoding indication field is based on the number of entries in one or more tables determined by the wireless device.

20. The method according to claim 19, wherein, The number of entries is based on at least one of the following: The maximum rank used for the transmission, or Maximum rank for a port group Each rule in the rule set, or A pattern configured to use one or more rules from the rule set, and The rule set includes port group index rules, group balancing rules, group selection rules, nested construction rules, or TPMI reduction rules.

21. The method according to claim 20, wherein, In response to the port group indexing rule being enabled, rank X and rank Y are associated with a specific indexing order of the port group.

22. The method according to claim 20, wherein, In response to the nested construction rule being implemented, The number of port groups (N) g The value is a configured value or a coherence level based on the configuration, wherein the coherence level includes at least one of the following: fully coherent, partially coherent of a first type, partially coherent or incoherent of a second type, or... The one or more ranks are based on the highest level configured for the coherence level of the wireless device or N configured for the wireless device. g The minimum number of group selection rules or group balancing rules.

23. The method of claim 20, wherein, The pattern is related to the antenna layout of the wireless device.

24. The method according to claim 19, wherein, The pre-encoding indicator field corresponds to an entry from one table or an entry from a combination of multiple tables.

25. The method according to claim 19, wherein, The number of port groups is associated with a coherence level including at least one of fully coherent, partially coherent of the first type, partially coherent of the second type, or incoherent.

26. The method of claim 25, wherein, The table includes a coherence level associated with each of the coherence levels in the configuration or with the N of the configuration. g N for each configuration g Related entries.

27. The method according to claim 25, wherein, Each of the multiple tables includes a coherence level of one of the coherence levels of the configuration or a configuration of N. g One of the configurations of N g Related entries.

28. The method according to claim 25, wherein, Each of the multiple tables includes entries associated with combinations of different coherence levels from the coherence levels in the configuration.

29. An apparatus for wireless communication, comprising a processor configured to implement the method according to one or more of claims 1 to 28.

30. A non-transitory computer-readable program storage medium having code stored thereon, the code, when executed by a processor, causing the processor to perform the method according to one or more of claims 1 to 28.

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