COMMUNICATIONS METHOD AND APPARATUS, AND DEVICE

[0001] This application is a continuation of International Application No. PCT/CN2020/108995, filed on Aug. 13, 2020, which claims priority to Chinese Patent Application No. 201910760894.7, filed on Aug. 16, 2019. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties.

[0002] Embodiments of this application relate to the field of communications technologies, and in particular, to a communications method and apparatus, and a device.

[0003] In a wireless communications system, when sending an uplink signal, a terminal device generates a baseband signal on a baseband. A radio frequency signal is obtained after the baseband signal passes through a radio frequency transmit link of the terminal device, and then the radio frequency signal is sent through an antenna of the terminal device. The radio frequency link includes a radio frequency integrated circuit, a power amplifier (power amplifier, PA), and a duplexer/filter.

[0004] Currently, coherent capabilities of a terminal device may include a fully-coherent capability, a partially-coherent capability, and a non-coherent capability. Different coherent capabilities represent phase calibration between different antenna ports. Terminal devices that simultaneously support a plurality of transmit antenna ports may have different coherent capabilities. When supporting only the non-coherent capability, the terminal device can support only a non-coherent codeword. When supporting only the partially-coherent capability, the terminal device can support only a partially-coherent codeword or a non-coherent codeword. When supporting the fully-coherent capability, the terminal device can support a fully-coherent codeword, a partially-coherent codeword, and a non-coherent codeword.

[0005] In an existing power control mechanism, rank (rank)-1 uplink transmission is used as an example. Only a fully-coherent codeword can support a physical uplink shared channel (physical uplink shared channel, PUSCH) in using rated maximum transmit power for sending. Maximum PUSCH transmit power that can be supported by a partially-coherent codeword is 1/2 of the rated maximum transmit power, and maximum PUSCH transmit power that can be supported by a non-coherent codeword is 1/4 of the rated maximum transmit power. For rank-2 and rank-3 uplink transmission, the non-coherent codeword cannot support the PUSCH in using the rated maximum transmit power. It can be learned that neither the terminal device supporting the partially-coherent capability nor the terminal device supporting the non-coherent capability can send the PUSCH at the rated maximum transmit power, and consequently PUSCH sending quality is poor.

[0006] Embodiments of this application provide a communications method and apparatus, and a device, to improve PUSCH sending quality.

[0007] According to a first aspect, a first communications method is provided. The method includes: A terminal device determines a first codeword set, where the first codeword set includes a first codeword, the first codeword is a 4×1 matrix, and each element in the matrix is a non-zero element; and

[0008] the first codeword is one of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ -j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ 1\\ -j\end{array}\right],\mathrm{or}\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ -1\\ j\end{array}\right].$

[0009] The method may be performed by a first communications apparatus. The first communications apparatus may be a communications device or a communications apparatus, for example, a chip system, that can support the communications device in implementing a function required in the method. For example, the first communications apparatus is a terminal apparatus. For example, the terminal apparatus is the terminal device, a chip system that is disposed in the terminal device and that is configured to implement functions of the terminal device, or another component configured to implement functions of the terminal device.

[0010] In this embodiment of this application, for example, the first codeword set determined by the terminal device may include at least one first codeword, and a quantity of at least one first codeword may be greater than or equal to 1. The first codeword may be a 4×1 fully-coherent codeword. The terminal device sends uplink data to a network device by using the fully-coherent codeword, so that power for sending the uplink data can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device.

[0011] For example, the first codeword set may include the at least one first codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword. Alternatively, the first codeword set may further include another codeword in addition to the at least one first codeword.

[0012] With reference to the first aspect, in a possible implementation of the first aspect, the method further includes:

[0013] The terminal device sends coherent capability indication information, where the coherent capability indication information is used to indicate that the terminal device has a non-coherent capability.

[0014] The terminal device having the non-coherent capability supports a non-coherent codeword set, the non-coherent codeword set includes only at least one fourth codeword, and each column of the fourth codeword includes only one non-zero element.

[0015] The terminal device may send the coherent capability indication information of the terminal device to the network device, so that the network device can determine whether the terminal device is a terminal device having a fully-coherent capability, a terminal device having a partially-coherent capability, or a terminal device having a non-coherent capability. In this embodiment of this application, for example, the terminal device is the terminal device having the non-coherent capability. Based on the coherent capability indication information, the network device may determine that the terminal device has the non-coherent capability, or may determine that the terminal device supports the non-coherent codeword set. It can be learned that in this embodiment of this application, even the terminal device having the non-coherent capability can send uplink data by using a fully-coherent codeword, so that power for sending the uplink data can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device.

[0016] With reference to the first aspect, in a possible implementation of the first aspect,

[0017] the first codeword set further includes a second codeword, the second codeword is a 4×2 matrix, and each element in the second codeword is a non-zero element; and

[0018] the second codeword is one of the following codewords:

$\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ 1& -1\\ 1& -1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ j& -j\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ 1& -1\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ j& -j\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ 1& -1\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ j& -j\\ -j& j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ 1& -1\\ -j& j\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ j& -j\\ 1& -1\end{array}\right].$

[0019] For example, the first codeword set may include at least one second codeword, and a quantity of at least one second codeword may be greater than or equal to 1. The first codeword is a 4×1 fully-coherent codeword, and the second codeword is a 4×2 fully-coherent codeword. That is, the first codeword set may include different types of fully-coherent codewords, so that the codeword included in the first codeword set can support transmission at more layers.

[0020] For example, the first codeword set may include the at least one first codeword and the at least one second codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword and the at least one second codeword. Alternatively, the first codeword set may further include another codeword in addition to the at least one first codeword and the at least one second codeword.

[0021] With reference to the first aspect, in a possible implementation of the first aspect,

[0022] the first codeword set further includes a third codeword, the third codeword is a 4×3 matrix, and each element in the third codeword is a non-zero element; and

[0023] the third codeword is one of the following codewords:

$\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ 1& 1& -1\\ 1& -1& -1\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ j& j& -j\\ j& -j& -j\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ 1& 1& -1\\ -1& 1& -1\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ j& j& -j\\ -j& j& j\end{array}\right].$

[0024] For example, the first codeword set may include at least one third codeword, and a quantity of at least one third codeword may be greater than or equal to 1. The first codeword is a 4×1 fully-coherent codeword, and the third codeword is a 4×3 fully-coherent codeword. That is, the first codeword set may include different types of fully-coherent codewords, so that the codeword included in the first codeword set can support transmission at more layers.

[0025] For example, the first codeword set may include the at least one first codeword and the at least one third codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword and the at least one third codeword. Alternatively, the first codeword set may further include another codeword, for example, the at least one second codeword, in addition to the at least one first codeword and the at least one third codeword.

[0026] With reference to the first aspect, in a possible implementation of the first aspect,

[0027] the first codeword set further includes at least one fourth codeword, and a quantity of columns of the fourth codeword included in the first codeword set is not greater than 3; and

[0028] a value of a power scaling factor corresponding to the fourth codeword included in the first codeword set is 1.

[0029] The fourth codeword may be a non-coherent codeword. In addition to the fully-coherent codeword, the first codeword set may further include the non-coherent codeword, provided that the value of the power scaling factor corresponding to the fourth codeword included in the first codeword set is 1. Therefore, when the terminal device sends uplink data by using the fourth codeword included in the first codeword set, transmit power can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device. It should be noted that, if the fourth codeword is included in the non-coherent codeword set but is not included in the first codeword set, a value of a power scaling factor corresponding to the fourth codeword may be 1/4. Alternatively, if the fourth codeword is included in both the non-coherent codeword set and the first codeword set, or is not included in the non-coherent codeword set but is included in the first codeword set, a value of a power scaling factor corresponding to the fourth codeword may be 1.

[0030] For example, the first codeword set may include the at least one first codeword and the at least one fourth codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword and the at least one fourth codeword. Alternatively, the first codeword set may further include another codeword, for example, the at least one second codeword or the at least one third codeword, in addition to the at least one first codeword and the at least one fourth codeword.

[0031] With reference to the first aspect, in a possible implementation of the first aspect, the first codeword set further includes at least one fifth codeword, the fifth codeword is a 4×1 matrix, and each column of the matrix includes only two non-zero elements; and the at least one fifth codeword includes one or more of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right]\mathrm{or}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right],$

and a value of a power scaling factor corresponding to the fifth codeword included in the first codeword set is 1.

[0032] The fifth codeword may be a partially-coherent codeword. In addition to the fully-coherent codeword, the first codeword set may further include the partially-coherent codeword, provided that the value of the power scaling factor corresponding to the fifth codeword included in the first codeword set is 1/2 or 1. Therefore, when the terminal device sends uplink data by using the fifth codeword included in the first codeword set, transmit power can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device. It should be noted that, if the fifth codeword is included in the partially-coherent codeword set but is not included in the first codeword set, a value of a power scaling factor corresponding to the fifth codeword may be 1/2. Alternatively, if the fifth codeword is included in both the partially-coherent codeword set and the first codeword set, or is not included in the partially-coherent codeword set but is included in the first codeword set, a value of a power scaling factor corresponding to the fifth codeword may be 1/2 or 1.

[0033] For example, the first codeword set may include the at least one first codeword and the at least one fifth codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword and the at least one fifth codeword. Alternatively, the first codeword set may further include another codeword, for example, the at least one second codeword, the at least one third codeword, or the at least one fourth codeword, in addition to the at least one first codeword and the at least one fifth codeword.

[0034] With reference to the first aspect, in a possible implementation of the first aspect, the method further includes:

[0035] The terminal device sends first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1 or a codebook subset 2, where

[0036] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword; and

[0037] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0038] With reference to the first aspect, in a possible implementation of the first aspect, the method further includes:

[0039] The terminal device sends first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0040] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword;

[0041] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right];$

[0042] the codebook subset 3 includes the first codeword, the second codeword, the third codeword, and

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right];$

and

[0043] the codebook subset 4 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0044] The first codeword set may include one or more codebook subsets, and the terminal device may determine, from the first codeword set, a codebook subset applicable to the terminal device. After selection, the terminal device may notify the network device of information about the selected codebook subset. Therefore, when selecting a codeword for the terminal device, the network device may select the codeword from the codebook subset, so that the codeword selected by the network device meets an actual capability of the terminal device as much as possible.

[0045] With reference to the first aspect, in a possible implementation of the first aspect,

[0046] the codebook subset 2 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right];$

and/or

[0047] the codebook subset 4 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right],$

and the fourth codeword is a codeword whose dimension is 4×2 in the first codeword set.

[0048] The codebook subset 2 may further include a non-coherent codeword, so that the codebook subset 2 can include a fully-coherent codeword, a partially-coherent codeword, and the non-coherent codeword. Types of the included codewords are comprehensive. The same is true for the codebook subset 4.

[0049] With reference to the first aspect, in a possible implementation of the first aspect, the method further includes:

[0050] The terminal device receives first DCI, where the first DCI is used to indicate to select a seventh codeword from the first codebook subset.

[0051] The terminal device sends, based on the seventh codeword, uplink data scheduled by using the first DCI.

[0052] For example, if the network device determines that the terminal device supports the first codebook subset, the network device may select a codeword from the first codebook subset as a codeword for sending the uplink data by the terminal device. For example, the network device selects the seventh codeword. The network device may indicate, by using the first DCI, the terminal device to select the seventh codeword. After receiving the first DCI, the terminal device may select the seventh codeword from the first codebook subset. The network device selects the seventh codeword based on the codebook subset supported by the terminal device, so that the selected seventh codeword can meet an actual capability of the terminal device.

[0053] Alternatively, the terminal device may not need to send the first capability indication information to the network device. In this case, the network device may send the first DCI to the terminal device, to indicate to select the seventh codeword from the first codebook subset. In this case, the network device may not know a capability of the terminal device, that is, does not know the codebook subset supported by the terminal device. Therefore, the network device may independently select a corresponding codebook subset as the first codebook subset, and select the seventh codeword from the codebook subset. For example, the network device may determine the first codebook subset based on empirical information (for example, the network device knows capabilities of a plurality of terminal devices covered by the network device. This may be used as empirical information). Alternatively, even in this case, the network device may select the first codebook subset based on a capability of the terminal device. For example, the codebook subset supported by the terminal device is known to the network device in advance. For example, the terminal device reports the codebook subset to the network device in another manner, or the network device learns of the codebook subset by using a core network device. In this case, the network device may select the first codebook subset based on the capability of the terminal device, to select the seventh codeword.

[0054] Alternatively, even if the terminal device sends the first capability indication information to the network device, the network device may not select the codebook subset based on a capability of the terminal device. In this case, the first codebook subset is not selected based on the capability of the terminal device.

[0055] In this manner, regardless of whether the network device knows the codebook subset supported by the terminal device, the network device may select a corresponding codeword for the terminal device, so that the terminal device can complete sending of the uplink data.

[0056] According to a second aspect, a second communications method is provided. The method includes: A network device determines a first codeword set, where the first codeword set includes a first codeword, the first codeword is a 4×1 matrix, and each element in the matrix is a non-zero element; and

[0057] the first codeword is one of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ -j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ 1\\ -j\end{array}\right],\mathrm{or}\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ -1\\ j\end{array}\right].$

[0058] The method may be performed by a second communications apparatus. The second communications apparatus may be a communications device or a communications apparatus, for example, a chip system, that can support the communications device in implementing a function required in the method. For example, the second communications apparatus is a network device, a chip system that is disposed in the network device and that is configured to implement functions of the network device, or another component configured to implement functions of the network device.

[0059] With reference to the second aspect, in a possible implementation of the second aspect, the method further includes:

[0060] The network device receives coherent capability indication information, where the coherent capability indication information is used to indicate that a terminal device has a non-coherent capability.

[0061] The terminal device having the non-coherent capability supports a non-coherent codeword set, the non-coherent codeword set includes only at least one fourth codeword, and each column of the fourth codeword includes only one non-zero element.

[0062] With reference to the second aspect, in a possible implementation of the second aspect,

[0063] the first codeword set further includes a second codeword, the second codeword is a 4×2 matrix, and each element in the second codeword is a non-zero element; and

[0064] the second codeword is one of the following codewords:

$\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ 1& -1\\ 1& -1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ j& -j\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ 1& -1\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ j& -j\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ 1& -1\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ j& -j\\ -j& j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ 1& -1\\ -j& j\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ j& -j\\ 1& -1\end{array}\right].$

[0065] With reference to the second aspect, in a possible implementation of the second aspect,

[0066] the first codeword set further includes a third codeword, the third codeword is a 4×3 matrix, and each element in the third codeword is a non-zero element; and

[0067] the third codeword is one of the following codewords:

$\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ 1& 1& -1\\ 1& -1& -1\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ j& j& -j\\ j& -j& -j\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ 1& 1& -1\\ -1& 1& -1\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ j& j& -j\\ -j& j& j\end{array}\right].$

[0068] With reference to the second aspect, in a possible implementation of the second aspect,

[0069] the first codeword set further includes at least one fourth codeword, and a quantity of columns of the fourth codeword included in the first codeword set is not greater than 3; and

[0070] a value of a power scaling factor corresponding to the fourth codeword included in the first codeword set is 1.

[0071] With reference to the second aspect, in a possible implementation of the second aspect,

[0072] the first codeword set further includes at least one fifth codeword, the fifth codeword is a 4×1 matrix, and each column of the matrix includes only two non-zero elements; and the at least one fifth codeword includes one or more of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right]\mathrm{or}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right],$

and a value of a power scaling factor corresponding to the fifth codeword included in the first codeword set is 1.

[0073] With reference to the second aspect, in a possible implementation of the second aspect, the method further includes:

[0074] The network device receives first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1 or a codebook subset 2, where

[0075] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword; and

[0076] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0077] With reference to the second aspect, in a possible implementation of the second aspect, the method further includes:

[0078] The network device receives first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0079] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword;

[0080] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right];$

[0081] the codebook subset 3 includes the first codeword, the second codeword, the third codeword, and

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right];$

and

[0082] the codebook subset 4 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0083] With reference to the second aspect, in a possible implementation of the second aspect,

[0084] the codebook subset 2 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right];$

and/or

[0085] the codebook subset 4 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right],$

and the fourth codeword is a codeword whose dimension is 4×2 in the first codeword set.

[0086] With reference to the second aspect, in a possible implementation of the second aspect, the method further includes:

[0087] The network device sends first DCI, where the first DCI is used to indicate the terminal device to select a seventh codeword from the first codebook subset, and the seventh codeword is used to send uplink data scheduled by using the first DCI.

[0088] The network device receives, based on the seventh codeword, the uplink data scheduled by using the first DCI.

[0089] For technical effects achieved by the second aspect or the possible implementations of the second aspect, refer to the descriptions of the technical effects achieved by the first aspect or the possible implementations of the first aspect.

[0090] According to a third aspect, a third communications method is provided. The method includes: A terminal device determines a first codeword set, where the first codeword set includes at least one first codeword, and the at least one first codeword includes

$\left\{\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right]\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ -1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right]\right\}\mathrm{or}\left\{,\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ -1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ j\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -j\\ -1\end{array}\right]\right\}.$

[0091] The method may be performed by a third communications apparatus. The third communications apparatus may be a communications device or a communications apparatus, for example, a chip system, that can support the communications device in implementing a function required in the method. For example, the third communications apparatus is a terminal apparatus. For example, the terminal apparatus is a terminal device, a chip system that is disposed in the terminal device and that is configured to implement functions of the terminal device, or another component configured to implement functions of the terminal device.

[0092] In this embodiment of this application, for example, the first codeword set determined by the terminal device may include at least one first codeword. The first codeword may be a 4×1 fully-coherent codeword. The terminal device sends uplink data to a network device by using the fully-coherent codeword, so that power for sending the uplink data can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device.

[0093] With reference to the third aspect, in a possible implementation of the third aspect, the method further includes:

[0094] The terminal device sends coherent capability indication information, where the coherent capability indication information is used to indicate that the terminal device has a partially-coherent capability.

[0095] The terminal device having the partially-coherent capability supports a partially-coherent codeword set and a non-coherent codeword set; the non-coherent codeword set includes only at least one second codeword, and each column of the second codeword includes only one non-zero element; and the partially-coherent codeword set includes only at least one third codeword, and each column of the third codeword includes only two non-zero elements.

[0096] The terminal device may send the coherent capability indication information of the terminal device to the network device, so that the network device can determine whether the terminal device is a terminal device having a fully-coherent capability, a terminal device having a partially-coherent capability, or a terminal device having a non-coherent capability. In this embodiment of this application, for example, the terminal device is the terminal device having the partially-coherent capability. Based on the coherent capability indication information, the network device may determine that the terminal device has the partially-coherent capability, or may determine that the terminal device supports the partially-coherent codeword set and the non-coherent codeword set. It can be learned that in this embodiment of this application, even the terminal device having the partially-coherent capability can send uplink data by using a fully-coherent codeword, so that power for sending the uplink data can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device.

[0097] With reference to the third aspect, in a possible implementation of the third aspect,

[0098] the first codeword set further includes at least one second codeword, and a value of a power scaling factor corresponding to the second codeword is 1; and/or

[0099] the first codeword set further includes at least one third codeword, and a value of a power scaling factor corresponding to the third codeword is 1/2 or 1.

[0100] The second codeword is a non-coherent codeword. In addition to the fully-coherent codeword, the first codeword set may further include the non-coherent codeword, provided that the value of the power scaling factor corresponding to the second codeword included in the first codeword set is 1. Therefore, codewords included in the first codeword set are more abundant, and when the terminal device sends uplink data by using the second codeword included in the first codeword set, transmit power can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device. It should be noted that, if the second codeword is included in the non-coherent codeword set but is not included in the first codeword set, a value of a power scaling factor corresponding to the second codeword may be 1/4. Alternatively, if the second codeword is included in both the non-coherent codeword set and the first codeword set, or is not included in the non-coherent codeword set but is included in the first codeword set, a value of a power scaling factor corresponding to the second codeword may be 1.

[0101] The third codeword is a partially-coherent codeword. In addition to the fully-coherent codeword, the first codeword set may further include the partially-coherent codeword, provided that the value of the power scaling factor corresponding to the third codeword included in the first codeword set is 1/2 or 1. Therefore, codewords included in the first codeword set are more abundant, and when the terminal device sends uplink data by using the third codeword included in the first codeword set, transmit power can reach rated maximum transmit power, to improve sending quality of the uplink data, and also improve transmit power utilization of the terminal device. It should be noted that, if the third codeword is included in the non-coherent codeword set but is not included in the first codeword set, a value of a power scaling factor corresponding to the third codeword may be 1/2. Alternatively, if the third codeword is included in both the non-coherent codeword set and the first codeword set, or is not included in the non-coherent codeword set but is included in the first codeword set, a value of a power scaling factor corresponding to the third codeword may be 1/2 or 1.

[0102] For example, the first codeword set may include the at least one first codeword and the at least one second codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword and the at least one second codeword. Alternatively, the first codeword set may further include another codeword, for example, the at least one third codeword, in addition to the at least one first codeword and the at least one second codeword.

[0103] For example, the first codeword set may include the at least one first codeword and the at least one third codeword, but does not include another codeword, that is, the first codeword set includes only the at least one first codeword and the at least one third codeword. Alternatively, the first codeword set may further include another codeword, for example, the at least one second codeword, in addition to the at least one first codeword and the at least one third codeword.

[0104] With reference to the third aspect, in a possible implementation of the third aspect, the method further includes:

[0105] The terminal device sends first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1 or a codebook subset 2, where

[0106] the codebook subset 1 includes the first codeword; and

[0107] the codebook subset 2 includes the first codeword and the at least one third codeword.

[0108] With reference to the third aspect, in a possible implementation of the third aspect, the method further includes:

[0109] The terminal device sends first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0110] the codebook subset 1 includes the first codeword;

[0111] the codebook subset 2 includes the first codeword and the at least one third codeword;

[0112] the codebook subset 3 includes the first codeword and the at least one second codeword; and

[0113] the codebook subset 4 includes the first codeword, the at least one second codeword, and the at least one third codeword.

[0114] The first codeword set may include one or more codebook subsets, and the terminal device may determine, from the first codeword set, a codebook subset applicable to the terminal device. After selection, the terminal device may notify the network device of information about the selected codebook subset. Therefore, when selecting a codeword for the terminal device, the network device may select the codeword from the codebook subset, so that the codeword selected by the network device meets an actual capability of the terminal device as much as possible.

[0115] With reference to the third aspect, in a possible implementation of the third aspect, the method further includes:

[0116] The terminal device receives first DCI, where the first DCI is used to indicate to select a fourth codeword from the first codebook subset.

[0117] The terminal device sends, based on the fourth codeword, uplink data scheduled by using the first DCI.

[0118] For example, if the network device determines that the terminal device supports the first codebook subset, the network device may select a codeword from the first codebook subset as a codeword for sending the uplink data by the terminal device. For example, the network device selects the fourth codeword. The network device may indicate, by using the first DCI, the terminal device to select the fourth codeword. After receiving the first DCI, the terminal device may select the fourth codeword from the first codebook subset. The network device selects a fourth codeword based on the codebook subset supported by the terminal device, so that the selected fourth codeword can meet an actual capability of the terminal device.

[0119] Alternatively, the terminal device may not need to send the first capability indication information to the network device. In this case, the network device may send the first DCI to the terminal device, to indicate to select the fourth codeword from the first codebook subset. In this case, the network device may not know a capability of the terminal device, that is, does not know the codebook subset supported by the terminal device. Therefore, the network device may independently select a corresponding codebook subset as the first codebook subset, and select the fourth codeword from the codebook subset. For example, the network device may determine the first codebook subset based on empirical information (for example, the network device knows capabilities of a plurality of terminal devices covered by the network device. This may be used as empirical information). Alternatively, even in this case, the network device may select the first codebook subset based on a capability of the terminal device. For example, the codebook subset supported by the terminal device is known to the network device in advance. For example, the terminal device reports the codebook subset to the network device in another manner, or the network device learns of the codebook subset by using a core network device. In this case, the network device may select the first codebook subset based on the capability of the terminal device, to select the fourth codeword.

[0120] Alternatively, even if the terminal device sends the first capability indication information to the network device, the network device may not select the codebook subset based on a capability of the terminal device. In this case, the first codebook subset is not selected based on the capability of the terminal device.

[0121] In this manner, regardless of whether the network device knows the codebook subset supported by the terminal device, the network device may select a corresponding codeword for the terminal device, so that the terminal device can complete sending of the uplink data.

[0122] According to a fourth aspect, a fourth communications method is provided. The method includes: A network device determines a first codeword set, where the first codeword set includes at least one first codeword, and the at least one first codeword includes

$\left\{\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right]\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ -1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right]\right\}\mathrm{or}\left\{,\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ -1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ j\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -j\\ -1\end{array}\right]\right\}.$

[0123] The method may be performed by a fourth communications apparatus. The fourth communications apparatus may be a communications device or a communications apparatus that can support the communications device in implementing a function required in the method, for example, a chip system. For example, the fourth communications apparatus is the network device, a chip system that is disposed in the network device and that is configured to implement functions of the network device, or another component configured to implement functions of the network device.

[0124] With reference to the fourth aspect, in a possible implementation of the fourth aspect, the method further includes:

[0125] The network device receives coherent capability indication information, where the coherent capability indication information is used to indicate that a terminal device has a partially-coherent capability.

[0126] The terminal device having the partially-coherent capability supports a partially-coherent codeword set and a non-coherent codeword set; the non-coherent codeword set includes only at least one second codeword, and each column of the second codeword includes only one non-zero element; and the partially-coherent codeword set includes only at least one third codeword, and each column of the third codeword includes only two non-zero elements.

[0127] With reference to the fourth aspect, in a possible implementation of the fourth aspect,

[0128] the first codeword set further includes at least one second codeword, and a value of a power scaling factor corresponding to the second codeword is 1; and/or

[0129] the first codeword set further includes at least one third codeword, and a value of a power scaling factor corresponding to the third codeword is 1.

[0130] With reference to the fourth aspect, in a possible implementation of the fourth aspect, the method further includes:

[0131] The network device receives first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset includes a codebook subset 1 or a codebook subset 2, where

[0132] the codebook subset 1 includes the first codeword; and

[0133] the codebook subset 2 includes the first codeword and the at least one third codeword.

[0134] With reference to the fourth aspect, in a possible implementation of the fourth aspect, the method further includes:

[0135] The network device receives first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where the codebook subset 1 includes the first codeword;

[0136] the codebook subset 2 includes the first codeword and the at least one third codeword;

[0137] the codebook subset 3 includes the first codeword and the at least one second codeword; and

[0138] the codebook subset 4 includes the first codeword, the at least one second codeword, and the at least one third codeword.

[0139] With reference to the fourth aspect, in a possible implementation of the fourth aspect, the method further includes:

[0140] The network device sends first DCI, where the first DCI is used to indicate the terminal device to select a fourth codeword from the first codebook subset, and the fourth codeword is used to send uplink data scheduled by using the first DCI.

[0141] The network device receives, based on the fourth codeword, the uplink data scheduled by using the first DCI.

[0142] For technical effects achieved by the fourth aspect or the possible implementations of the fourth aspect, refer to the descriptions of the technical effects achieved by the third aspect or the possible implementations of the third aspect.

[0143] According to a fifth aspect, a communications apparatus is provided. For example, the communications apparatus is a communications device. The communications device is configured to perform the method according to any one of the first aspect or the possible implementations of the first aspect. Specifically, the communications device may include a module configured to perform the method according to any one of the first aspect or the possible implementations of the first aspect, for example, include a processing module. Optionally, the communications device may further include a transceiver module. For example, the communications device is the terminal device described above.

[0144] The processing module is configured to determine a first codeword set, where the first codeword set includes a first codeword, the first codeword is a 4×1 matrix, and each element in the matrix is a non-zero element; and

[0145] the first codeword is one of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ -j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ 1\\ -j\end{array}\right],\mathrm{or}\left[\begin{array}{c}1\\ -j\\ -1\\ j\end{array}\right].$

[0146] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0147] the transceiver module is configured to send coherent capability indication information, where the coherent capability indication information is used to indicate that the terminal device has a non-coherent capability.

[0148] The terminal device having the non-coherent capability supports a non-coherent codeword set, the non-coherent codeword set includes only at least one fourth codeword, and each column of the fourth codeword includes only one non-zero element.

[0149] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0150] the first codeword set further includes a second codeword, the second codeword is a 4×2 matrix, and each element in the second codeword is a non-zero element; and

[0151] the second codeword is one of the following codewords:

$\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ 1& -1\\ 1& -1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ j& -j\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ 1& -1\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ j& -j\\ -1& 1\end{array}\right]\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ 1& -1\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ j& -j\\ -j& j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ 1& -1\\ -j& j\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ j& -j\\ 1& -1\end{array}\right].$

[0152] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0153] the first codeword set further includes a third codeword, the third codeword is a 4×3 matrix, and each element in the third codeword is a non-zero element; and

[0154] the third codeword is one of the following codewords:

$\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ 1& 1& -1\\ 1& -1& -1\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ j& j& -j\\ j& -j& -j\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ 1& 1& -1\\ -1& 1& 1\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ j& j& -j\\ -j& j& j\end{array}\right].$

[0155] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0156] the first codeword set further includes at least one fourth codeword, and a quantity of columns of the fourth codeword included in the first codeword set is not greater than 3; and

[0157] a value of a power scaling factor corresponding to the fourth codeword included in the first codeword set is 1.

[0158] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0159] the first codeword set further includes at least one fifth codeword, the fifth codeword is a 4×1 matrix, and each column of the matrix includes only two non-zero elements; and the at least one fifth codeword includes one or more of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right]\mathrm{or}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right],$

and a value of a power scaling factor corresponding to the fifth codeword included in the first codeword set is 1.

[0160] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0161] the transceiver module is further configured to send first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset includes a codebook subset 1 or a codebook subset 2, where

[0162] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword; and

[0163] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0164] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0165] the transceiver module is further configured to send first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0166] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword;

[0167] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right];$

[0168] the codebook subset 3 includes the first codeword, the second codeword, the third codeword, and

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right];$

and

[0169] the codebook subset 4 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0170] With reference to the fifth aspect, in a possible implementation of the fifth aspect,

[0171] the codebook subset 2 further includes the at least one fourth codeword and/or a codeword,

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right];$

and/or

[0172] the codebook subset 4 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right],$

and the fourth codeword is a codeword whose dimension is 4×2 in the first codeword set.

[0173] With reference to the fifth aspect, in a possible implementation of the fifth aspect, the transceiver module is further configured to:

[0174] receive first DCI, where the first DCI is used to indicate to select a seventh codeword from the first codebook subset; and

[0175] send, based on the seventh codeword, uplink data scheduled by using the first DCI.

[0176] For technical effects achieved by the fifth aspect or the possible implementations of the fifth aspect, refer to the descriptions of the technical effects achieved by the first aspect or the possible implementations of the first aspect.

[0177] According to a sixth aspect, a communications apparatus is provided. For example, the communications apparatus is a communications device. The communications device is configured to perform the method according to any one of the second aspect or the possible implementations of the second aspect. Specifically, the communications device may include a module configured to perform the method according to any one of the second aspect or the possible implementations of the second aspect, for example, include a processing module. Optionally, the communications device may further include a transceiver module. For example, the communications device is the network device described above.

[0178] The processing module is configured to determine a first codeword set, where the first codeword set includes a first codeword, the first codeword is a 4×1 matrix, and each element in the matrix is a non-zero element; and

[0179] the first codeword is one of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ -j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ 1\\ -j\end{array}\right],\mathrm{or}\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ -1\\ j\end{array}\right].$

[0180] With reference to the sixth aspect, in a possible implementation of the sixth aspect, the transceiver module is configured to receive coherent capability indication information, where the coherent capability indication information is used to indicate that a terminal device has a non-coherent capability.

[0181] The terminal device having the non-coherent capability supports a non-coherent codeword set, the non-coherent codeword set includes only at least one fourth codeword, and each column of the fourth codeword includes only one non-zero element.

[0182] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0183] the first codeword set further includes a second codeword, the second codeword is a 4×2 matrix, and each element in the second codeword is a non-zero element; and

[0184] the second codeword is one of the following codewords:

$\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ 1& -1\\ 1& -1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ j& -j\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ 1& -1\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ j& -j\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ 1& -1\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ j& -j\\ -j& j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ 1& -1\\ -j& j\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ j& -j\\ 1& -1\end{array}\right].$

[0185] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0186] the first codeword set further includes a third codeword, the third codeword is a 4×3 matrix, and each element in the third codeword is a non-zero element; and

[0187] the third codeword is one of the following codewords:

$\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ 1& 1& -1\\ 1& -1& -1\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ j& j& -j\\ j& -j& -j\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ 1& 1& -1\\ -1& 1& 1\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ j& j& -j\\ -j& j& j\end{array}\right].$

[0188] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0189] the first codeword set further includes at least one fourth codeword, and a quantity of columns of the fourth codeword included in the first codeword set is not greater than 3; and

[0190] a value of a power scaling factor corresponding to the fourth codeword included in the first codeword set is 1.

[0191] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0192] the first codeword set further includes at least one fifth codeword, the fifth codeword is a 4×1 matrix, and each column of the matrix includes only two non-zero elements; and the at least one fifth codeword includes one or more of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right]\mathrm{or}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right],$

and a value of a power scaling factor corresponding to the fifth codeword included in the first codeword set is 1.

[0193] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0194] the transceiver module is further configured to receive first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset includes a codebook subset 1 or a codebook subset 2, where

[0195] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword; and

[0196] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0197] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0198] the transceiver module is further configured to receive first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0199] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword;

[0200] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right];$

[0201] the codebook subset 3 includes the first codeword, the second codeword, the third codeword, and

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right];$

and

[0202] the codebook subset 4 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0203] With reference to the sixth aspect, in a possible implementation of the sixth aspect,

[0204] the codebook subset 2 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right];$

and/or

[0205] the codebook subset 4 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right],$

and the fourth codeword is a codeword whose dimension is 4×2 in the first codeword set.

[0206] With reference to the sixth aspect, in a possible implementation of the sixth aspect, the transceiver module is further configured to:

[0207] send first DCI, where the first DCI is used to indicate the terminal device to select a seventh codeword from the first codebook subset, and the seventh codeword is used to send uplink data scheduled by using the first DCI; and

[0208] receive, based on the seventh codeword, the uplink data scheduled by using the first DCI.

[0209] For technical effects achieved by the sixth aspect or the possible implementations of the sixth aspect, refer to the descriptions of the technical effects achieved by the second aspect or the possible implementations of the second aspect.

[0210] According to a seventh aspect, a communications apparatus is provided. For example, the communications apparatus is a communications device. The communications device is configured to perform the method according to any one of the third aspect or the possible implementations of the third aspect. Specifically, the communications device may include a module configured to perform the method according to any one of the third aspect or the possible implementations of the third aspect, for example, include a processing module. Optionally, the communications device may further include a transceiver module. For example, the communications device is the terminal device described above.

[0211] The processing module is configured to determine a first codeword set, where the first codeword set includes at least one first codeword, and the at least one first codeword includes

$\left\{\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ -1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ ­j\\ ­j\end{array}\right]\right\}\hspace{1em}\mathrm{or}\left\{\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ ­1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ ­j\\ ­j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ j\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -j\\ -1\end{array}\right]\right\}.$

[0212] With reference to the seventh aspect, in a possible implementation of the seventh aspect,

[0213] the transceiver module is configured to send coherent capability indication information, where the coherent capability indication information is used to indicate that the terminal device has a partially-coherent capability.

[0214] The terminal device having the partially-coherent capability supports a partially-coherent codeword set and a non-coherent codeword set; the non-coherent codeword set includes only at least one second codeword, and each column of the second codeword includes only one non-zero element; and the partially-coherent codeword set includes only at least one third codeword, and each column of the third codeword includes only two non-zero elements.

[0215] With reference to the seventh aspect, in a possible implementation of the seventh aspect,

[0216] the first codeword set further includes at least one second codeword, and a value of a power scaling factor corresponding to the second codeword is 1; and/or

[0217] the first codeword set further includes at least one third codeword, and a value of a power scaling factor corresponding to the third codeword is 1.

[0218] With reference to the seventh aspect, in a possible implementation of the seventh aspect,

[0219] the transceiver module is further configured to send first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset includes a codebook subset 1 or a codebook subset 2, where

[0220] the codebook subset 1 includes the first codeword; and

[0221] the codebook subset 2 includes the first codeword and the at least one third codeword.

[0222] With reference to the seventh aspect, in a possible implementation of the seventh aspect,

[0223] the transceiver module is further configured to send first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0224] the codebook subset 1 includes the first codeword;

[0225] the codebook subset 2 includes the first codeword and the at least one third codeword;

[0226] the codebook subset 3 includes the first codeword and the at least one second codeword; and

[0227] the codebook subset 4 includes the first codeword, the at least one second codeword, and the at least one third codeword.

[0228] With reference to the seventh aspect, in a possible implementation of the seventh aspect, the transceiver module is further configured to:

[0229] receive first DCI, where the first DCI is used to indicate to select a fourth codeword from the first codebook subset; and

[0230] send, based on the fourth codeword, uplink data scheduled by using the first DCI.

[0231] For technical effects achieved by the seventh aspect or the possible implementations of the seventh aspect, refer to the descriptions of the technical effects achieved by the third aspect or the possible implementations of the third aspect.

[0232] According to an eighth aspect, a communications apparatus is provided. For example, the communications apparatus is a communications device. The communications device is configured to perform the method according to any one of the fourth aspect or the possible implementations of the fourth aspect. Specifically, the communications device may include a module configured to perform the method according to any one of the fourth aspect or the possible implementations of the fourth aspect, for example, include a processing module. Optionally, the communications device may further include a transceiver module. For example, the communications device is the network device described above.

[0233] The processing module is configured to determine a first codeword set, where the first codeword set includes at least one first codeword, and the at least one first codeword includes

$\left\{\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ -1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ ­j\\ ­j\end{array}\right]\right\}\hspace{1em}\mathrm{or}\left\{\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ 1\\ ­1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -1\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ ­j\\ ­j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ j\\ 1\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -1\end{array}\right]\right\}.$

[0234] With reference to the eighth aspect, in a possible implementation of the eighth aspect,

[0235] the transceiver module is configured to receive coherent capability indication information, where the coherent capability indication information is used to indicate that a terminal device has a partially-coherent capability.

[0236] The terminal device having the partially-coherent capability supports a partially-coherent codeword set and a non-coherent codeword set; the non-coherent codeword set includes only at least one second codeword, and each column of the second codeword includes only one non-zero element; and the partially-coherent codeword set includes only at least one third codeword, and each column of the third codeword includes only two non-zero elements.

[0237] With reference to the eighth aspect, in a possible implementation of the eighth aspect, the first codeword set further includes at least one second codeword, and a value of a power scaling factor corresponding to the second codeword is 1; and/or the first codeword set further includes at least one third codeword, and a value of a power scaling factor corresponding to the third codeword is 1.

[0238] With reference to the eighth aspect, in a possible implementation of the eighth aspect,

[0239] the transceiver module is further configured to receive first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset includes a codebook subset 1 or a codebook subset 2, where

[0240] the codebook subset 1 includes the first codeword; and

[0241] the codebook subset 2 includes the first codeword and the at least one third codeword.

[0242] With reference to the eighth aspect, in a possible implementation of the eighth aspect,

[0243] the transceiver module is further configured to receive first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0244] the codebook subset 1 includes the first codeword;

[0245] the codebook subset 2 includes the first codeword and the at least one third codeword;

[0246] the codebook subset 3 includes the first codeword and the at least one second codeword; and

[0247] the codebook subset 4 includes the first codeword, the at least one second codeword, and the at least one third codeword.

[0248] With reference to the eighth aspect, in a possible implementation of the eighth aspect, the transceiver module is further configured to:

[0249] send first DCI, where the first DCI is used to indicate the terminal device to select a fourth codeword from the first codebook subset, and the fourth codeword is used to send uplink data scheduled by using the first DCI; and

[0250] receive, based on the fourth codeword, the uplink data scheduled by using the first DCI.

[0251] For technical effects achieved by the eighth aspect or the possible implementations of the eighth aspect, refer to the descriptions of the technical effects achieved by the fourth aspect or the possible implementations of the fourth aspect.

[0252] According to a ninth aspect, a communications apparatus is provided. The communications apparatus includes a processor, and optionally, may further include a transceiver. The processor and the transceiver are coupled to each other, and are configured to implement the method according to the first aspect or the possible implementations of the first aspect. For example, the communications apparatus is a communications device. Alternatively, for example, the communications apparatus is a chip disposed in a communications device. For example, the communications device is a terminal device. For example, the transceiver is implemented by using an antenna, a feeder, a codec, and the like in the communications device. Alternatively, if the communications apparatus is the chip disposed in the communications device, the transceiver is, for example, a communications interface in the chip. The communications interface is connected to a radio frequency transceiver component in the communications device, to receive and send information by using the radio frequency transceiver component.

[0253] The processor is configured to determine a first codeword set, where the first codeword set includes a first codeword, the first codeword is a 4×1 matrix, and each element in the matrix is a non-zero element; and

[0254] the first codeword is one of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ -j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ 1\\ -j\end{array}\right],\mathrm{or}\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ -1\\ j\end{array}\right].$

[0255] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0256] the transceiver is configured to send coherent capability indication information, where the coherent capability indication information is used to indicate that the terminal device has a non-coherent capability.

[0257] The terminal device having the non-coherent capability supports a non-coherent codeword set, the non-coherent codeword set includes only at least one fourth codeword, and each column of the fourth codeword includes only one non-zero element.

[0258] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0259] the first codeword set further includes a second codeword, the second codeword is a 4×2 matrix, and each element in the second codeword is a non-zero element; and

[0260] the second codeword is one of the following codewords:

$\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ 1& -1\\ 1& -1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ j& -j\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ 1& -1\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ j& -j\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ 1& -1\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ j& -j\\ -j& j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ 1& -1\\ -j& j\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ j& -j\\ 1& -1\end{array}\right].$

[0261] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0262] the first codeword set further includes a third codeword, the third codeword is a 4×3 matrix, and each element in the third codeword is a non-zero element; and

[0263] the third codeword is one of the following codewords:

$\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ 1& 1& -1\\ 1& -1& -1\end{array}\right],$

$\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 1\\ j& j& -j\\ j& -j& -j\end{array}\right],\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ 1& 1& -1\\ -1& 1& 1\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{3}}\left[\begin{array}{ccc}1& 1& 1\\ -1& 1& -1\\ j& j& -j\\ -j& j& j\end{array}\right].$

[0264] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0265] the first codeword set further includes at least one fourth codeword, and a quantity of columns of the fourth codeword included in the first codeword set is not greater than 3; and

[0266] a value of a power scaling factor corresponding to the fourth codeword included in the first codeword set is 1.

[0267] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0268] the first codeword set further includes at least one fifth codeword, the fifth codeword is a 4×1 matrix, and each column of the matrix includes only two non-zero elements; and the at least one fifth codeword includes one or more of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right]\mathrm{or}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right],$

and a value of a power scaling factor corresponding to the fifth codeword included in the first codeword set is 1.

[0269] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0270] the transceiver is further configured to send first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset includes a codebook subset 1 or a codebook subset 2, where

[0271] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword; and

[0272] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0273] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0274] the transceiver is further configured to send first capability indication information, where the first capability indication information is used to indicate that the terminal device supports a first codebook subset included in the first codeword set, and the first codebook subset is a codebook subset 1, a codebook subset 2, a codebook subset 3, or a codebook subset 4, where

[0275] the codebook subset 1 includes the first codeword, the second codeword, and the third codeword;

[0276] the codebook subset 2 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right];$

[0277] the codebook subset 3 includes the first codeword, the second codeword, the third codeword, and

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right];$

and

[0278] the codebook subset 4 includes the first codeword, the second codeword, the third codeword,

$\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 0\\ 0\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 0\\ 1\\ 0\end{array}\right],\mathrm{and}\frac{1}{2}\left[\begin{array}{c}0\\ 1\\ 0\\ 1\end{array}\right].$

[0279] With reference to the ninth aspect, in a possible implementation of the ninth aspect,

[0280] the codebook subset 2 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right];$

and/or

[0281] the codebook subset 4 further includes the at least one fourth codeword and/or a codeword

$\frac{1}{2}\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\\ 0& 0& 0\end{array}\right],$

and the fourth codeword is a codeword whose dimension is 4×2 in the first codeword set.

[0282] With reference to the ninth aspect, in a possible implementation of the ninth aspect, the transceiver is further configured to:

[0283] receive first DCI, where the first DCI is used to indicate to select a seventh codeword from the first codebook subset; and

[0284] send, based on the seventh codeword, uplink data scheduled by using the first DCI.

[0285] For technical effects achieved by the ninth aspect or the possible implementations of the ninth aspect, refer to the descriptions of the technical effects achieved by the first aspect or the possible implementations of the first aspect.

[0286] According to a tenth aspect, a communications apparatus is provided. The communications apparatus includes a processor, and optionally, may further include a transceiver. The processor and the transceiver are coupled to each other, and are configured to implement the method according to the second aspect or the possible implementations of the second aspect. For example, the communications apparatus is a communications device. Alternatively, for example, the communications apparatus is a chip disposed in a communications device. For example, the communications device is a network device. For example, the transceiver is implemented by using an antenna, a feeder, a codec, and the like in the communications device. Alternatively, if the communications apparatus is the chip disposed in the communications device, the transceiver is, for example, a communications interface in the chip. The communications interface is connected to a radio frequency transceiver component in the communications device, to receive and send information by using the radio frequency transceiver component.

[0287] The processor is configured to determine a first codeword set, where the first codeword set includes a first codeword, the first codeword is a 4×1 matrix, and each element in the matrix is a non-zero element; and

[0288] the first codeword is one of the following codewords:

$\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ 1\\ -j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ 1\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ j\\ -1\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ j\\ -j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -1\\ -j\\ j\end{array}\right],\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ 1\\ -j\end{array}\right],\mathrm{or}\frac{1}{2}\left[\begin{array}{c}1\\ -j\\ -1\\ j\end{array}\right].$

[0289] With reference to the tenth aspect, in a possible implementation of the tenth aspect,

[0290] the transceiver is configured to receive coherent capability indication information, where the coherent capability indication information is used to indicate that a terminal device has a non-coherent capability.

[0291] The terminal device having the non-coherent capability supports a non-coherent codeword set, the non-coherent codeword set includes only at least one fourth codeword, and each column of the fourth codeword includes only one non-zero element.

[0292] With reference to the tenth aspect, in a possible implementation of the tenth aspect, the first codeword set further includes a second codeword, the second codeword is a 4×2 matrix, and each element in the second codeword is a non-zero element; and

[0293] the second codeword is one of the following codewords:

$\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ 1& -1\\ 1& -1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ 1& 1\\ j& -j\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ 1& -1\\ j& -j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ j& j\\ j& -j\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ 1& -1\\ -1& 1\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -1& -1\\ j& -j\\ -j& j\end{array}\right],\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ 1& -1\\ -j& j\end{array}\right],\mathrm{or}\frac{1}{2\sqrt{2}}\left[\begin{array}{cc}1& 1\\ -j& -j\\ j& -j\\ 1& -1\end{array}\right].$