SIGNAL PROCESSING METHOD AND APPARATUS

Abstract

This application discloses a signal processing method and an apparatus. The method includes: A transmit device generates a PPDU, where the PPDU includes a preamble, the preamble includes an LTF, the LTF includes a plurality of LTF symbols, and the plurality of LTF symbols may be used to carry a sequence obtained according to a first matrix; and then sends the PPDU. Correspondingly, a receive device receives the PPDU, and then processes, according to the first matrix, signals received on the plurality of LTF symbols. The first matrix is a P.sub.n×n matrix, or the first matrix is obtained according to a P.sub.n×n matrix, where P.sub.n×n×P.sub.n×n.sup.T=n×I, I is an identity matrix, the P.sub.n×n matrix includes n rows and n columns, the P.sub.n×n.sup.T matrix is a transpose matrix of the P.sub.n×n matrix, and n is an integer greater than 8.

Claims

1. A signal processing method, wherein the method comprises: receiving a physical layer protocol data unit (PPDU), wherein the PPDU comprises a preamble, the preamble comprises a long training field (LTF), and the LTF comprises a plurality of LTF symbols; and processing, according to a first matrix A.sub.LTF.sup.k, signals received on the plurality of LTF symbols, wherein the first matrix A.sub.LTF.sup.k is a P.sub.n×n matrix, or the first matrix A.sub.LTF.sup.k is obtained according to a P.sub.n×n matrix, wherein P.sub.n×n×P.sub.n×n.sup.T=n×I, I is an identity matrix, the P.sub.n×n matrix comprises n rows and n columns, the P.sub.n×n.sup.T matrix is a transpose matrix of the P.sub.n×n matrix, n is an integer greater than 8, and k indicates a k.sup.th subcarrier in each of the plurality of LTF symbols.

2. The method according to claim 1, wherein $P_{n\times n}=\left[\begin{array}{cc}{S}_{\left(n‐1\right)\times \left(n‐1\right)}& a\\ a^T& 1\end{array}\right];$ $P_{n\times n}=\left[\begin{array}{cc}a& S_{\left(n‐1\right)\times \left(n‐1\right)}\\ 1& a^T\end{array}\right];$ $P_{n\times n}=\left[\begin{array}{cc}{S}_{\left(n‐1\right)\times \left(n‐1\right)}& -a\\ a^T& 1\end{array}\right];\mathrm{or}$ $P_{n\times n}=\left[\begin{array}{cc}-a& S_{\left(n‐1\right)\times \left(n‐1\right)}\\ 1& a^T\end{array}\right],$ wherein the S.sub.(n-1)×(n-1) matrix is a submatrix of the P.sub.n×n matrix, the S.sub.(n-1)×(n-1) matrix comprises n−1 rows and n−1 columns, α is a column vector comprising n−1 elements, each element is 1, α.sup.T is a transpose vector of α, and −α indicates a vector obtained through negation of all elements in α.

3. The method according to claim 2, wherein the S.sub.(n-1)×(n-1) matrix is a circulant matrix or a Hankel matrix.

4. The method according to claim 2, wherein a first row of the S.sub.(n-1)×(n-1) matrix is equal to a first vector x, and x=[1 1 1 −1 1 −1 −1 1 −1 −1 −1]; a first row of the S.sub.(n-1)×(n-1) matrix is obtained by performing one or more of three operations: cyclic shift, reversing, and overall negation on a first vector x, and x=[1 1 1 −1 1 −1 −1 1 −1 −1 −1]; a first row of the S.sub.(n-1)×(n-1) matrix is equal to a second vector y, and y=[1 1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1 −1]; or a first row of the S.sub.(n-1)×(n-1) matrix is obtained by performing one or more of three operations: cyclic shift, reversing, and overall negation on a second vector y, and y=[1 1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1 −1].

5. The method according to claim 1, wherein when n=12, $P_{12\times 12}=\left[\begin{array}{cccccccccccc}1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1\\ -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& 1\\ -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& 1\\ -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& 1\\ 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1\\ -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& 1\\ -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& 1\\ 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1\\ -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& 1\\ 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right];$

6. The method according to claim 1, wherein when n=16, $P_{16*16}=\left[\begin{array}{cccccccccccccccc}1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1\\ -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& 1\\ 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1\\ 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1\\ -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& 1\\ -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& 1\\ 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1\\ -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& 1\\ 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1\\ -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& 1\\ -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& 1\\ -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& 1\\ -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& 1\\ 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1\\ 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right];$

7. The method according to claim 1, wherein when n=16, $P_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& P_{8\times 8}\\ P_{8\times 8}& -P_{8\times 8}\end{array}\right];$ $P_{16\times 16}=\left[\begin{array}{cc}-P_{8\times 8}& P_{8\times 8}\\ P_{8\times 8}& P_{8\times 8}\end{array}\right];$ $P_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& -P_{8\times 8}\\ P_{8\times 8}& P_{8\times 8}\end{array}\right];\mathrm{or}$ $P_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& P_{8\times 8}\\ -P_{8\times 8}& P_{8\times 8}\end{array}\right],\mathrm{wherein}$ $P_{8\times 8}=\left[\begin{array}{cccccccc}1& -1& 1& 1& 1& -1& 1& 1\\ 1& 1& -1& 1& 1& 1& -1& 1\\ 1& 1& 1& -1& 1& 1& 1& -1\\ -1& 1& 1& 1& -1& 1& 1& 1\\ 1& -1& 1& 1& -1& 1& -1& -1\\ 1& 1& -1& 1& -1& -1& 1& -1\\ 1& 1& 1& -1& -1& -1& -1& 1\\ -1& 1& 1& 1& 1& -1& -1& -1\end{array}\right]$

8. The method according to claim 1, wherein the first matrix A.sub.LTF.sup.k meets the following conditions: $A_{LTF}^k=\{\begin{array}{c}{R}_{n\times n}\mathrm{if}\mathrm{the}{k}^{th}\mathrm{subcarrier}\mathrm{is}a\mathrm{pilot}\mathrm{subcarrier}\\ P_{n\times n}\mathrm{if}\mathrm{the}{k}^{th}\mathrm{subcarrier}\mathrm{is}a\mathrm{non}-\mathrm{pilot}\mathrm{subcarrier}\mathrm{or}a\mathrm{data}\mathrm{subcarrier}\end{array},$ wherein the R.sub.n×n matrix comprises n rows and n columns, and each row of the R.sub.n×n matrix is equal to a first row of the P.sub.n×n matrix.

9. The method according to claim 1, wherein when the k.sup.th subcarrier is a non-pilot subcarrier, the first matrix is equal to an overall negation matrix of the P.sub.n×n matrix; the first matrix is equal to a transpose matrix of the P.sub.n×n matrix; the first matrix is equal to a transpose matrix of an overall negation matrix of the P.sub.n×n matrix; or the first matrix is equal to an overall negation matrix of a transpose matrix of the P.sub.n×n matrix.

10. The method according to claim 8, wherein the R.sub.n×n matrix is used for phase tracking and/or frequency offset estimation, and the P.sub.n×n matrix is used for channel estimation.

11. A communication apparatus, wherein the communication apparatus comprises: a transceiver unit, configured to receive a physical layer protocol data unit (PPDU), wherein the PPDU comprises a preamble, the preamble comprises a long training field (LTF), and the LTF comprises a plurality of LTF symbols; and a processing unit, configured to process, according to a first matrix A.sub.LTF.sup.k, signals received on the plurality of LTF symbols, wherein the first matrix A.sub.LTF.sup.k is a P.sub.n×n matrix, or the first matrix A.sub.LTF.sup.k is obtained according to a P.sub.n×n matrix, wherein P.sub.n×n×P.sub.n×n.sup.T=n×I, I is an identity matrix, the P.sub.n×n matrix comprises n rows and n columns, the P.sub.n×n matrix is a transpose matrix of the P.sub.n×n matrix, n is an integer greater than 8, and k indicates a k.sup.th subcarrier in each of the plurality of LTF symbols.

12. The communication apparatus according to claim 11, wherein $P_{n\times n}=\left[\begin{array}{cc}{S}_{\left(n‐1\right)\times \left(n‐1\right)}& a\\ a^T& 1\end{array}\right];$ $P_{n\times n}=\left[\begin{array}{cc}a& S_{\left(n‐1\right)\times \left(n‐1\right)}\\ 1& a^T\end{array}\right];$ $P_{n\times n}=\left[\begin{array}{cc}{S}_{\left(n‐1\right)\times \left(n‐1\right)}& -a\\ a^T& 1\end{array}\right];\mathrm{or}$ $P_{n\times n}=\left[\begin{array}{cc}-a& S_{\left(n‐1\right)\times \left(n‐1\right)}\\ 1& a^T\end{array}\right],$ wherein the S.sub.(n-1)×(n-1) matrix is a submatrix of the P.sub.n×n matrix, the S.sub.(n-1)×(n-1) matrix comprises n−1 rows and n−1 columns, α is a column vector comprising n−1 elements, each element is 1, α.sup.T is a transpose vector of α, and −α indicates a vector obtained through negation of all elements in α.

13. The communication apparatus according to claim 12, wherein the S.sub.(n-1)×(n-1) matrix is a circulant matrix or a Hankel matrix.

14. The communication apparatus according to claim 12, wherein a first row of the S.sub.(n-1)×(n-1) matrix is equal to a first vector x, and x=[1 1 1 −1 1 −1 −1 1 −1 −1 −1]; a first row of the S.sub.(n-1)×(n-1) matrix is obtained by performing one or more of three operations: cyclic shift, reversing, and overall negation on a first vector x, and x=[1 1 1 −1 1 −1 −1 1 −1 −1 −1]; a first row of the S.sub.(n-1)×(n-1) matrix is equal to a second vector y, and y=[1 1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1 −1]; or a first row of the S.sub.(n-1)×(n-1) matrix is obtained by performing one or more of three operations: cyclic shift, reversing, and overall negation on a second vector y, and y=[1 1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1−1].

15. The communication apparatus according to claim 11, wherein when n=12, $P_{12\times 12}=\left[\begin{array}{cccccccccccc}1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1\\ -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& 1\\ -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& 1\\ -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& 1\\ 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1\\ -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& 1\\ -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& 1\\ 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1\\ -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& 1\\ 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right];$

16. The communication apparatus according to claim 11, wherein when n=16, $P_{16*16}=\left[\begin{array}{cccccccccccccccc}1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1\\ -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& 1\\ 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1\\ 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1\\ -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& 1\\ -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1& 1\\ 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& -1& 1\\ -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1& 1\\ 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& -1& 1\\ -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& -1& 1\\ -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& -1& 1\\ -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& -1& 1\\ -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1& 1\\ 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1& 1\\ 1& 1& -1& -1& -1& -1& 1& -1& 1& -1& -1& 1& 1& -1& 1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right];$

17. The communication apparatus according to claim 11, wherein when n=16, $P_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& P_{8\times 8}\\ P_{8\times 8}& -P_{8\times 8}\end{array}\right];$ $P_{16\times 16}=\left[\begin{array}{cc}-P_{8\times 8}& P_{8\times 8}\\ P_{8\times 8}& P_{8\times 8}\end{array}\right];$ $P_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& -P_{8\times 8}\\ P_{8\times 8}& P_{8\times 8}\end{array}\right];\mathrm{or}$ $P_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& P_{8\times 8}\\ -P_{8\times 8}& P_{8\times 8}\end{array}\right],\mathrm{wherein}$ $P_{8\times 8}=\left[\begin{array}{cccccccc}1& -1& 1& 1& 1& -1& 1& 1\\ 1& 1& -1& 1& 1& 1& -1& 1\\ 1& 1& 1& -1& 1& 1& 1& -1\\ -1& 1& 1& 1& -1& 1& 1& 1\\ 1& -1& 1& 1& -1& 1& -1& -1\\ 1& 1& -1& 1& -1& -1& 1& -1\\ 1& 1& 1& -1& -1& -1& -1& 1\\ -1& 1& 1& 1& 1& -1& -1& -1\end{array}\right]$

18. The communication apparatus according to claim 11, wherein the first matrix A.sub.LTF.sup.k meets the following conditions: $A_{LTF}^k=\{\begin{array}{c}{R}_{n\times n}\mathrm{if}\mathrm{the}{k}^{th}\mathrm{subcarrier}\mathrm{is}a\mathrm{pilot}\mathrm{subcarrier}\\ P_{n\times n}\mathrm{if}\mathrm{the}{k}^{th}\mathrm{subcarrier}\mathrm{is}a\mathrm{non}-\mathrm{pilot}\mathrm{subcarrier}\mathrm{or}a\mathrm{data}\mathrm{subcarrier}\end{array},$ wherein the R.sub.n×n matrix comprises n rows and n columns, and each row of the R.sub.n×n matrix is equal to a first row of the P.sub.n×n matrix.

19. The communication apparatus according to claim 11, wherein when the k.sup.th subcarrier is a non-pilot subcarrier, the first matrix is equal to an overall negation matrix of the P.sub.n×n matrix; the first matrix is equal to a transpose matrix of the P.sub.n×n matrix; the first matrix is equal to a transpose matrix of an overall negation matrix of the P.sub.n×n matrix; or the first matrix is equal to an overall negation matrix of a transpose matrix of the P.sub.n×n matrix.

20. The communication apparatus according to claim 18, wherein the R.sub.n×n matrix is used for phase tracking and/or frequency offset estimation, and the P.sub.n×n matrix is used for channel estimation.

Description

DESCRIPTION OF DRAWINGS

[0058] FIG. 1 is a schematic diagram of a communication system according to an embodiment of this application;

[0059] FIG. 2 is a schematic diagram of a structure of an access point (access point, AP) device or a station (station, STA) device according to an embodiment of this application;

[0060] FIG. 3a is a schematic diagram of a structure of a PPDU according to an embodiment of this application;

[0061] FIG. 3b is a schematic diagram of a relationship between a spatial stream and an LTF symbol according to an embodiment of this application;

[0062] FIG. 4a is a schematic flowchart of a signal processing method according to an embodiment of this application;

[0063] FIG. 4b is a schematic diagram of a structure of another PPDU according to an embodiment of this application; and

[0064] FIG. 5 to FIG. 7 are schematic diagrams of a structure of a communication apparatus according to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

[0065] To make objectives, technical solutions, and advantages of this application clearer, the following further describes this application with reference to the accompanying drawings.

[0066] In the specification, claims, and the accompanying drawings of this application, terms such as “first” and “second” are only intended to distinguish between different objects but do not describe a particular order. In addition, terms “include”, “have”, or any other variant thereof are intended to cover a non-exclusive inclusion. For example, a process, a method, a system, a product, or a device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes an unlisted step or unit, or optionally further includes another step or unit inherent to the process, the method, the product, or the device.

[0067] An “embodiment” mentioned in this specification means that a particular characteristic, structure, or feature described with reference to embodiments may be included in at least one embodiment of this application. The phrase shown in various locations in the specification may not necessarily refer to a same embodiment, and is not an independent or optional embodiment exclusive from another embodiment. It may be explicitly and implicitly understood by a person skilled in the art that the embodiments described in the specification may be combined with another embodiment.

[0068] In this application, “at least one piece (item)” means one or more, “a plurality of” means two or more, and “at least two pieces (items)” means two, three, or more. The term “and/or” is used to describe an association relationship between associated objects, and indicates that three relationships may exist. For example, “A and/or B” may represent the following three cases: Only A exists, only B exists, and both A and B exist, where A and B may be singular or plural. The character “/” usually indicates an “or” relationship between the associated objects. “At least one of the following items (pieces)” or a similar expression thereof means any combination of these items. For example, at least one (piece) of a, b, or c may represent: a, b, c, a and b, a and c, b and c, or a, b, and c.

[0069] A method provided in this application may be applied to various communication systems, for example, an Internet of things (Internet of things, IoT) system, a narrow band Internet of things (narrow band Internet of things, NB-IoT) system, a long term evolution (long term evolution, LTE) system, a 5th generation (5th generation, 5G) communication system, and a new communication system (for example, 6G) emerging in future communication development. The method provided in this application may further be applied to a wireless local area network (wireless local area network, WLAN) system, for example, wireless fidelity (wireless fidelity, Wi-Fi).

[0070] The method provided in this application may be implemented by a communication apparatus in a wireless communication system. For example, the communication apparatus may be an access point (access point, AP) device or a station (station, STA) device. For another example, the communication apparatus may alternatively be a wireless communication device that supports concurrent transmission on a plurality of links. For example, the communication apparatus may be referred to as a multi-link device (multi-link device, MILD) or a multi-band device (multi-band device).

[0071] The method provided in this application may be applied to a scenario in which one node performs data transmission with one or more nodes, or may be applied to single-user uplink/downlink transmission or multi-user uplink/downlink transmission, or may be applied to a device-to-device (device-to-device, D2D) transmission. Details are not described herein. The node may be an AP or a STA. For ease of description, the following uses communication between the AP and the STA as an example for description.

[0072] For example, a communication system to which the method provided in this application may be applied may include an access point (access point, AP) device and a station (station, STA) device. The access point device may also be understood as an access point entity, and the station device may also be understood as a station entity. For example, this application is applicable to a scenario in which an AP communicates with a STA in a WLAN. Optionally, the AP may communicate with a single STA, or the AP simultaneously communicates with a plurality of STAs. Specifically, communication between the AP and the plurality of STAs may further be classified into downlink transmission in which the AP simultaneously sends signals to the plurality of STAs, and uplink transmission in which the plurality of STAs send signals to the AP. The AP and the STA may support a WLAN communication protocol. The communication protocol may include the IEEE 802.11be (which is also referred to as Wi-Fi 7 or the EHT protocol) protocol, and may further include protocols such as the IEEE 802.11ax protocol and the IEEE 802.11ac protocol. It is clear that with continuous evolution and development of communication technologies, the communication protocol may further include a next-generation protocol of IEEE 802.11be, and the like.

[0073] FIG. 1 is a schematic diagram of an architecture of a communication system according to an embodiment of this application. The communication system may include one or more APs and one or more STAs. FIG. 1 shows one access point device, for example, an AP, and three station devices, for example, a STA 1, a STA 2, and a STA 3. It may be understood that FIG. 1 shows only one AP and three STAs as an example. However, there may be more or less APs or STAs. This is not limited in this application.

[0074] The access point (for example, the AP in FIG. 1) is an apparatus with a wireless communication function, supports communication according to a WLAN protocol, and has a function of communicating with another device (for example, a station or another access point) in a WLAN. It is clear that the access point may further have a function of communicating with another device. Alternatively, the access point is equivalent to a bridge that connects a wired network and a wireless network. A main function of the access point is to connect various wireless network clients together and then connect the wireless network to the Ethernet. In a WLAN system, an access point may be referred to as an access point station (AP STA). The apparatus with a wireless communication function may be an entire device, or may be a chip or a processing system installed in an entire device. The device in which the chip or the processing system is installed may implement a method and a function in embodiments of this application under control of the chip or the processing system. The AP in this embodiment of this application is an apparatus that provides a service for the STA, and may support the 802.11 series protocols. For example, the access point may be an access point for a terminal device (for example, a mobile phone) to access a wired (or wireless) network, and is mainly deployed in a home, a building, and a park. A typical coverage radius is tens of meters to 100-odd meters. It is clear that the access point may alternatively be deployed outdoors. For another example, the AP may be a communication entity, for example, a communication server, a router, a switch, or a bridge, or the AP may include various forms of macro base stations, micro base stations, relay stations, and the like. It is clear that the AP may alternatively be a chip or a processing system in these devices in various forms, to implement the method and function in embodiments of this application. The access point in this application may be a high-efficiency (high-efficiency, HE) AP, an extremely high throughput (extremely high throughput, EHT) AP, or an access point applicable to a future Wi-Fi standard.

[0075] The station (for example, the STA 1, the STA 2, or the like in FIG. 1) is an apparatus with a wireless communication function, supports communication according to a WLAN protocol, and has a function of communicating with another station or access point in a WLAN. In the WLAN system, a station may be referred to as a non-access point station (non-access point station, non-AP STA). For example, the STA is any user communication device that allows a user to communicate with an AP and then communicate with a WLAN. The apparatus with a wireless communication function may be an entire device, or may be a chip or a processing system installed in an entire device. The device in which the chip or the processing system is installed may implement a method and a function in embodiments of this application under control of the chip or the processing system. For example, the station may be a wireless communication chip, a wireless sensor, or a wireless communication terminal, and may also be referred to as a user. For another example, the station may be a mobile phone supporting a Wi-Fi communication function, a tablet computer supporting a Wi-Fi communication function, a set-top box supporting a Wi-Fi communication function, a smart television supporting a Wi-Fi communication function, an intelligent wearable device supporting a Wi-Fi communication function, a vehicle-mounted communication device supporting a Wi-Fi communication function, or a computer supporting a Wi-Fi communication function.

[0076] The WLAN system can provide high-speed and low-latency transmission. With continuous evolution of WLAN application scenarios, the WLAN system is to be applied to more scenarios or industries, for example, the Internet of things industry, the Internet of vehicles industry, the banking industry, enterprise offices, exhibition halls of stadiums, concert halls, hotel rooms, dormitories, wards, classrooms, supermarkets, squares, streets, production workshops and warehousing. It is clear that a device (such as an access point or a station) that supports WLAN communication may be a sensor node (for example, a smart water meter, a smart electricity meter, or a smart air detection node) in a smart city, a smart device (for example, a smart camera, a projector, a display, a television, a stereo, a refrigerator, or a washing machine) in a smart home, a node in the Internet of things, an entertainment terminal (for example, an AR, a VR, or another wearable device), a smart device (for example, a printer, a projector, a loudspeaker, or a stereo) in smart office, an Internet of vehicles device in the Internet of vehicles, an infrastructure (for example, a vending machine, a self-service navigation station of a supermarket, a self-service cash register device, or a self-service ordering machine) in daily life scenarios, a device in a large sports and music venue, and the like. For example, the access point and the station may be devices applied to the Internet of vehicles, Internet of things nodes or sensors in the Internet of things (Internet of things, IoT), smart cameras, smart remote controls, and smart water meters in a smart home, and sensors in a smart city. Specific forms of the STA and the AP are not limited in this embodiment of this application. This is merely an example for description herein.

[0077] Although this application is mainly described by using a network in which IEEE 802.11 is deployed as an example, a person skilled in the art easily understands that various aspects of this application can be expanded to other networks that use various standards or protocols, for example, Bluetooth (Bluetooth), a high performance radio LAN (high performance radio LAN, HIPERLAN) (a wireless standard that is similar to the IEEE 802.11 standard, and is mainly used in Europe), a wide area network (WAN), a wireless local area network (wireless local area network, WLAN), a personal area network (personal area network, PAN), or another known or later developed network.

[0078] For example, FIG. 2 is a schematic diagram of a structure of an access point and a structure of a station according to an embodiment of this application. The AP may have a plurality of antennas, or may have a single antenna. As shown in FIG. 2, the AP includes a physical layer (physical layer, PHY) processing circuit and a media access control (media access control, MAC) processing circuit. The physical layer processing circuit may be configured to process a physical layer signal, and the MAC layer processing circuit may be configured to process a MAC layer signal. The 802.11 standard focuses on the PHY and the MAC. As shown in FIG. 2, FIG. 2 further shows a schematic diagram of a structure of a STA having a single antenna. In an actual scenario, the STA may alternatively have a plurality of antennas, and may be a device having more than two antennas. The STA may include a PHY processing circuit and a MAC processing circuit. The physical layer processing circuit may be configured to process a physical layer signal, and the MAC layer processing circuit may be configured to process a MAC layer signal.

[0079] In this application, a transmit device may be an access point device or a station device. Alternatively, a receive device may be an access point device or a station device. For example, the transmit device may be an access point device, and the receive device may also be an access point device. For another example, the transmit device is a station device, and the receive device may also be a station device. For another example, the transmit device is an access point device, and the receive device is a station device. For another example, the transmit device is a station device, and the receive device is an access point device. It may be understood that the transmit device and the receive device shown herein may also be collectively referred to as a communication apparatus.

[0080] It may be understood that a signal processing method provided in this application is described by using an example in which the transmit device sends a PPDU to the receive device in this application. However, the method shown in this application is further applicable to various types of PPDUs. For example, the PPDU may include a multi-user physical layer protocol data unit (multi-user PHY protocol data unit, MU PPDU), a single-user physical layer protocol data unit (single-user PHY protocol data unit, SU PPDU), a trigger-based physical layer protocol data unit (trigger based PHY protocol data unit, TB PPDU), or the like.

[0081] The following describes terms related to this application.

[0082] 1. Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, OFDM)

[0083] Orthogonal frequency division multiplexing is a multi-carrier transmission technology. The technology may use a plurality of adjacent orthogonal subcarriers, and each subcarrier may be modulated by using a modulation technology. Therefore, the orthogonal frequency division multiplexing technology can implement high-rate transmission and can effectively resist frequency selective fading (frequency selective fading). For example, a VHT-LTF 1 to a VHT-LTF N in FIG. 3a may also be understood as OFDM symbols. In other words, a VHT-LTF in a physical (physical, PHY) layer protocol data unit (PHY protocol data unit, PPDU) shown in FIG. 3a may also be understood as including N OFDM symbols.

[0084] 2. Physical (Physical, PHY) Layer Protocol Data Unit (PHY Protocol Data Unit, PPDU)

[0085] For example, FIG. 3a is a schematic diagram of a frame structure of a very high throughput (very high throughput, VHT) PPDU (which may also be referred to as an 802.11ac PPDU). As shown in FIG. 3a, the VHT PPDU includes data (VHT data), a legacy physical layer preamble (legacy preamble), and a very high throughput preamble (VHT preamble). The legacy physical layer preamble includes a legacy short training field (legacy short training field, L-STF), a legacy long training field (legacy long training field, L-LTF), and a legacy signal field (legacy signal field, L-SIG). The very high throughput preamble includes a very high throughput signal field A (very high throughput signal field A, VHT-SIG A), a very high throughput short training field (very high throughput short training field, VHT-STF), a very high throughput long training field (very high throughput long training field, VHT-LTF), and a very high throughput signal field B (very high throughput signal field B, VHT-SIG B). The VHT-SIG A (which may also be referred to as a VHTSIGA) may include two OFDM symbols, and duration of each symbol is 4 s. The VHT-LTF may include N VHT-LTF symbols, and the VHT-LTF may be used to help the receive device correctly estimate a channel, to help the receive device correctly decode received data information.

[0086] As shown in FIG. 3a, the PPDU may further include a service field (service field), a VHT data (VHT data) field, and padding and tail (padding & tail) fields.

[0087] 3. Pilot Subcarrier (Pilot Subcarrier) and Data Subcarrier (Data Subcarrier)

[0088] In the WLAN communication protocol, each OFDM symbol may include a pilot subcarrier and a data subcarrier. The pilot subcarrier is a subcarrier on which a preset sequence is placed or carried in an OFDM symbol, and the data subcarrier is a subcarrier on which data is placed or carried. In the communication system, the pilot subcarrier may be used to help detect and correct a subcarrier phase offset, to improve accuracy of data subcarrier resolution. For example, each VHT-LTF symbol (which may also be referred to as an LTF symbol) included in the LTF shown in FIG. 3a, namely, each VHT-LTF symbol in the VHT-LTF 1 to the VHT-LTF N, may include a pilot subcarrier and a data subcarrier.

[0089] The 802.11ac protocol supports simultaneous transmission of data of a maximum of eight streams, including a single-user multiple-input multiple-output (multiple-input multiple-output, MIMO) technology and a multi-user MIMO technology. When a quantity of spatial streams is N.sub.STS, a quantity N.sub.LTF of OFDM symbols included in the LTF shown in FIG. 3a may meet the following relationship:

[00004]$\begin{array}{cc}{N}_{LTF}=\{\begin{array}{c}{N}_{\mathrm{STS}}\\ N_{\mathrm{STS}}+1\end{array}\begin{array}{c}\mathrm{if}{N}_{STS}=1,2,4,6,8\\ \mathrm{if}{N}_{STS}=3,5,7\end{array}& \left(1\right)\end{array}$

[0090] N.sub.STS indicates a maximum quantity of spatial streams supported by the communication apparatus (the quantity of spatial streams may also be referred to as a quantity of streams for short), and N.sub.LTF indicates a quantity of OFDM symbols included in the LTF (namely, a quantity of LTF symbols included in the LTF). For example, the VHT-LTF 1 to the VHT-LTF N shown in FIG. 3a are quantities of OFDM symbols included in the LTF, and N is a positive integer. In addition, each LTF symbol included in the LTF may include a data subcarrier and a pilot subcarrier. For example, the VHT-LTF 1 shown in FIG. 3a may include a plurality of data subcarriers and a plurality of pilot subcarriers, the VHT-LTF 2 may also include a plurality of data subcarriers and a plurality of pilot subcarriers, the VHT-LTF 3 may also include a plurality of data subcarriers and a plurality of pilot subcarriers, and the like. For example, the LTF includes N LTF symbols, and each of the N LTF symbols may include a plurality of data subcarriers and a plurality of pilot subcarriers. It may be understood that a quantity of data subcarriers and a quantity of pilot subcarriers included in each LTF symbol are not limited in this application. For specific quantities of data subcarriers and pilot subcarriers, refer to a related standard or protocol. Details are not described herein. For example, data subcarriers included in each of the N LTF symbols included in the LTF may be the same, and pilot subcarriers included in each LTF symbol may also be the same.

[0091] The LTF may be used to help the receiving end simultaneously estimate channels of a plurality of spatial streams. To accurately estimate the channel of the spatial stream and keep the LTF symbols of each stream orthogonal, a P matrix is proposed in the 802.11ac protocol. For example, N.sub.STS=4, and a corresponding P matrix is:

[00005]$\begin{array}{cc}{P}_{4\star 4}=\left[\begin{array}{cccc}1& -1& 1& 1\\ 1& 1& -1& 1\\ 1& 1& 1& -1\\ -1& 1& 1& 1\end{array}\right]& \left(2\right)\end{array}$

[0092] In this case, a relationship between a spatial stream of the VHT-LTF and time may be shown in FIG. 3b. A structure of the VHT-LTF when N.sub.STS=1, N.sub.STS=2, or N.sub.STS=3 may be part of content in a structure shown in FIG. 3b. Time marked in FIG. 3b, for example, 0 ns, −400 ns, −200 ns, or −600 ns, may be understood as a cyclic shift delay (cyclic shift diversity, CSD) corresponding to each spatial stream.

[0093] For example, when sending the PPDU, the transmit device may multiply a j.sup.th LTF symbol corresponding to an i.sup.th spatial stream by an element in an i.sup.th row and a j.sup.th column in a P.sub.4×4 matrix. Herein, i may be a positive integer greater than or equal to 1 and less than or equal to 4, and j may be a positive integer greater than or equal to 1 and less than or equal to 4. It may be understood that FIG. 3b shows four LTF symbols, and FIG. 3b only marks a first LTF symbol as an example. It may be understood that i shown in this application may vary with a quantity of spatial streams, and j may also vary with the quantity of spatial streams. For example, when the quantity of spatial streams is eight, i may be an integer greater than or equal to 1 and less than or equal to 8, and j is an integer greater than or equal to 1 and less than or equal to 8.

[0094] Therefore, after a k.sup.th subcarrier corresponding to each LTF symbol passes through a channel H.sub.k, a frequency domain signal Y.sub.k received by the receive device may be represented as:

Y.sub.k=H.sub.k×P.sub.4×4×LTF.sub.k  (3)

[0095] The P.sub.4×4 matrix is an orthogonal matrix, that is, P.sub.4×4×P.sub.4×4=4I, I is an identity matrix, and P.sub.4×4.sup.T is a conjugate transpose matrix of the P.sub.4×4 matrix. Therefore, the receive device may estimate, according to the P.sub.4×4 matrix, an LTF.sub.k sequence, and the received frequency domain signal Y.sub.k, the MIMO channel H.sub.k corresponding to the k.sup.th subcarrier.

[0096] In other words, when the transmit device sends the PPDU, the signal sent on the data subcarrier in each LTF symbol may be obtained by multiplying the P matrix by the LTF sequence. When receiving the signal, the receive device may perform channel estimation according to the P matrix, the signal received on the data subcarrier in each LTF symbol, and the LTF sequence, to obtain a channel response H.sub.k.

[0097] In addition, when the transmit device sends the PPDU, the signal sent on the pilot subcarrier in each LTF symbol may be obtained by multiplying an R matrix by the LTF sequence. When receiving the signal, the receive device may perform phase tracking, frequency offset estimation, and the like according to the R matrix, the signal received on the pilot subcarrier in each LTF symbol, and the LTF sequence.

[0098] In other words, when the transmit device sends the PPDU, the data subcarrier in the j.sup.th LTF symbol corresponding to the i.sup.th spatial stream (namely, the j.sup.th LTF symbol in the LTF in the PPDU) may be multiplied by the element in the i.sup.th row and the j.sup.th column of the P matrix, and the pilot subcarrier in the j.sup.th LTF symbol corresponding to the i.sup.th spatial stream is multiplied by an element in an i.sup.th row and a j.sup.th column of the R matrix. For example, the i.sup.th row of the R matrix may be equal to a first row of the P matrix. A relationship between the R matrix and the P matrix may be shown as follows:

R(i,j)=P(1,j)  (4)

[0099] It can be seen that each row of the R matrix may be the same, and each row of the R matrix may be equal to the first row of the P matrix.

[0100] It may be understood that the LTF sequence shown above may be defined by a related standard, a protocol, or the like. This is not limited in this application. For example, the LTF sequence may be {1, 1, −1, −1, 1, 1, −1, 1, −1, 1, 1, 1, 1, 1, 1, −1, −1, 1, 1, −1, 1, −1, 1, 1, 1, 1}. For example, the LTF sequence may be {1, −1, −1, 1, 1, −1, 1, −1, 1, −1, −1, −1, −1, −1}.

[0101] The foregoing P matrix is shown by using an example in which a quantity of spatial streams is four. For example, when N.sub.STS=2, a corresponding P matrix is:

[00006]$\begin{array}{cc}{P}_{2\star 2}=\left[\begin{array}{cc}1& -1\\ 1& 1\end{array}\right]& \left(5\right)\end{array}$

[0102] For example, when N.sub.STS=6, a corresponding P matrix is:

[00007]$\begin{array}{cc}{P}_{6\times 6}=\left[\begin{array}{cccccc}1& -1& 1& 1& 1& -1\\ 1& -w^1& w^2& w^3& w^4& -w^5\\ 1& -w^2& w^4& w^6& w^8& -w^{10}\\ 1& -w^3& w^6& w^9& w^{12}& -w^{15}\\ 1& -w^4& w^8& w^{12}& w^{16}& -w^{20}\\ 1& -w^5& w^{10}& w^{15}& w^{20}& -w^{25}\end{array}\right]& \left(6\right)\end{array}$$w=\exp \left(-j2\pi /6\right).$

[0103] For example, when N.sub.STS=8, a corresponding P matrix is:

[00008]$\begin{array}{cc}{P}_{8\star 8}=\left[\begin{array}{cc}{P}_{4\star 4}& P_{4\star 4}\\ P_{4\star 4}& -P_{4\star 4}\end{array}\right]& \left(7\right)\end{array}$

[0104] For example, a specific expression of Formula (7) may be:

[00009]$\begin{array}{cc}{P}_{8\times 8}=\left[\begin{array}{cccccccc}1& -1& 1& 1& 1& -1& 1& 1\\ 1& 1& -1& 1& 1& 1& -1& 1\\ 1& 1& 1& -1& 1& 1& 1& -1\\ -1& 1& 1& 1& -1& 1& 1& 1\\ 1& -1& 1& 1& -1& 1& -1& -1\\ 1& 1& -1& 1& -1& -1& 1& -1\\ 1& 1& 1& -1& -1& -1& -1& 1\\ -1& 1& 1& 1& 1& -1& -1& -1\end{array}\right]& \left(8\right)\end{array}$

[0105] It can be seen from the foregoing descriptions that a maximum quantity of streams supported in the 802.11ax protocol is eight. However, in the next-generation EHT standard, a maximum quantity of spatial streams allowed is 16. Consequently, the P matrix cannot be directly applied to a scenario in which a quantity of streams is greater than 8.

[0106] In view of this, this application provides a signal processing method and an apparatus. The method provided in this application is applicable to a scenario in which a quantity of streams is greater than 8. For example, the method provided in this application may support channel estimation of 16 streams, for example, MIMO channel estimation of 16 streams. For another example, the method provided in this application may further support channel estimation of 32 streams or 24 streams. In addition, a P.sub.n×n matrix provided in this application can further reduce space in which a communication apparatus stores the P.sub.n×n matrix.

[0107] It may be understood that for descriptions of the communication apparatus and a communication system in the signal processing method provided in this application, refer to the foregoing descriptions. Details are not described herein again. It may be understood that the following describes the method provided in embodiments of this application by using an example in which the communication apparatus includes a transmit device and a receive device. The transmit device shown in the following may be understood as a device for sending a PPDU, and the receive device may be understood as a device for receiving a PPDU.

[0108] FIG. 4a is a schematic flowchart of a signal processing method according to an embodiment of this application. As shown in FIG. 4a, the method includes the following steps.

[0109] 401: A transmit device generates a PPDU, where the PPDU includes a preamble, the preamble includes an LTF, the LTF includes a plurality of LTF symbols, the plurality of LTF symbols are used to carry a sequence obtained according to a first matrix, the first matrix is a P.sub.n×n matrix, or the first matrix is obtained according to a P.sub.n×n matrix, where P.sub.n×n×P.sub.n×n.sup.T=n×I, I is an identity matrix, the P.sub.n×n matrix includes n rows and n columns, the P.sub.n×n matrix is a transpose matrix of the P.sub.n×n matrix, n is an integer greater than 8, and k indicates a k.sup.th subcarrier in each of the plurality of LTF symbols.

[0110] n may indicate a quantity of rows and a quantity of columns of the P.sub.n×n matrix (which may also be referred to as a P matrix for short), and a maximum quantity of spatial streams supported when the transmit device sends a signal. In other words, when the transmit device sends the PPDU, the maximum quantity of spatial streams supported by the transmit device may be greater than 8.

[0111] For example, when n=12, the P.sub.n×n matrix may include 12 rows and 12 columns. Therefore, the first matrix includes 12 rows and 12 columns. In addition, the maximum quantity of spatial streams supported by the transmit device may be 12, and the transmit device may further multiply an n.sup.th LTF symbol corresponding to an m.sup.th spatial stream by an m.sup.th row and an n.sup.th column in the first matrix (as shown in FIG. 3b). Correspondingly, a receive device may simultaneously estimate channels of spatial streams whose quantity is less than or equal to 12. For example, the receive device may further simultaneously estimate channels of eight spatial streams, or the receive device may further simultaneously estimate channels of four spatial streams. In other words, the receive device may perform channel estimation, phase tracking, frequency offset estimation, or the like according to some or all content of the first matrix. For example, when n=16, the first matrix may include 16 rows and 16 columns. In addition, the maximum quantity of spatial streams supported by the transmit device may be 16. Correspondingly, the receive device may simultaneously estimate channels of 16 spatial streams, or the receive device may further simultaneously estimate channels of spatial streams whose quantity is less than 16. For example, the receive device may further estimate channels of 2 to 15 spatial streams, for example, channels of two spatial streams, channels of three spatial streams, channels of four spatial streams, channels of six spatial streams, channels of eight spatial streams, channels of 12 spatial streams, or channels of 15 spatial streams, according to the P.sub.n×n matrix provided in this embodiment of this application. This is not limited in this embodiment of this application.

[0112] For example, the maximum quantity of spatial streams supported by the transmit device may alternatively be 32 (or 24) or the like. In addition, the receive device may simultaneously estimate channels of spatial streams whose quantity is less than or equal to 32 (or 24).

[0113] The quantity of LTF symbols shown in this application may be greater than or equal to the quantity of spatial streams. For example, the quantity of LTF symbols is equal to the quantity n of spatial streams. For another example, the quantity of LTF symbols is equal to the quantity n+1 of spatial streams.

[0114] For example, the plurality of LTF symbols include data subcarriers. In this case, the first matrix may be equal to the P.sub.n×n matrix. Alternatively, the first matrix is a transpose matrix (for example, P.sub.n×n.sup.T) of the P.sub.n×n matrix. Alternatively, the first matrix is equal to an overall negation matrix (for example, −P.sub.n×n) of the P.sub.n×n matrix. Alternatively, the first matrix is a transpose matrix (for example, (−P.sub.n×n).sup.T) of an overall negation matrix of the P.sub.n×n matrix. Alternatively, the first matrix is an overall negation matrix (for example, —P.sub.n×n.sup.T) of a transpose matrix of the P.sub.n×n matrix. In other words, a data subcarrier in each of the plurality of LTF symbols in the LTF sent by the transmit device may be obtained according to the first matrix. It may be understood that the relationship between the first matrix and the P matrix shown herein is merely an example. However, any first matrix obtained based on the P matrix falls within the protection scope of this application.

[0115] For example, the plurality of LTF symbols include pilot subcarriers. In this case, the first matrix may be equal to an R.sub.n×n matrix, and the R.sub.n×n matrix may be obtained based on a T.sup.th row (or referred to as a row) of the P.sub.n×n matrix. Herein, T is an integer greater than or equal to 1 and less than n. For example, the R.sub.n×n matrix may be obtained based on a first row of the P.sub.n×n matrix. For example, each row in the R.sub.n×n matrix may alternatively be a first row of the P.sub.n×n matrix. Alternatively, each row in the R.sub.n×n matrix may be a first row of an overall negation matrix of the P.sub.n×n matrix. Alternatively, each row in the R.sub.n×n matrix may be a transpose matrix of an overall negation matrix of the P.sub.n×n matrix.

[0116] For an example of the first matrix, refer to Formula (84) to Formula (89) shown in the following. For a relationship between the R.sub.n×n matrix and the P.sub.n×n matrix, refer to Formula (10) or the like shown in the following.

[0117] Therefore, that the plurality of LTF symbols included in the LTF are used to carry the sequence obtained according to the first matrix includes: data subcarriers in the plurality of LTF symbols are used to carry a sequence obtained according to the P.sub.n×n matrix (which may also be referred to as a P matrix) and an LTF sequence, and pilot subcarriers in the plurality of LTF symbols are used to carry a sequence obtained according to the R.sub.n×n matrix (which may also be referred to as an R matrix) and the LTF sequence. Further, the receive device receives the PPDU. A part that corresponds to the data subcarrier and that is in the plurality of LTF symbols included in the LTF in the PPDU may be obtained by multiplying the P.sub.n×n matrix by the LTF sequence and performing inverse Fourier transform (which may also be referred to as inverse Fourier transform). A part that corresponds to the pilot subcarrier and that is in the plurality of LTF symbols may be obtained by multiplying the R.sub.n×n matrix by the LTF sequence and performing inverse Fourier transform.

[0118] It may be understood that for the LTF sequence, the data subcarrier, the pilot subcarrier, a relationship between the P matrix and the data subcarrier, and a relationship between the R matrix and the pilot subcarrier, refer to the foregoing descriptions, for example, FIG. 3a or FIG. 3b. Details are not described herein again.

[0119] For example, FIG. 4b is a schematic diagram of a structure of another PPDU according to an embodiment of this application. As shown in FIG. 4b, the PPDU includes data (data), a legacy physical layer preamble, an extremely high throughput (extremely high throughput, EHT) preamble (EHT preamble), and packet extension (packet extension, PE). The EHT preamble includes a repeated legacy signal field (repeated Legacy signal field, RL-SIG), a universal signal field (universal signal field, U-SIG), an extremely high throughput short training field (EHT short training field, EHT-STF), and an LTF. The LTF includes N EHT-LTFs (which may also be referred to as LTF symbols), and the N EHT-LTF symbols include an EHT-LTF 1 to an EHT-LTF N.

[0120] It may be understood that the PPDU generated by the transmit device may be shown in FIG. 4b, and the LTF symbol may include an EHT-LTF symbol.

[0121] 402: The transmit device sends the PPDU. Correspondingly, the receive device receives the PPDU.

[0122] 403: The receive device processes, according to the first matrix, signals received on the plurality of LTF symbols.

[0123] For example, the receive device may perform channel estimation according to the first matrix and the signal received on the data subcarrier in the plurality of LTF symbols. For example, the receive device may perform channel estimation according to the first matrix, the LTF sequence, and the signal received on the data subcarrier in the plurality of LTF symbols. For example, the receive device may alternatively perform phase tracking and/or frequency offset estimation according to the first matrix and the signal received on the pilot subcarrier in the plurality of LTF symbols. For example, the receive device may alternatively perform phase tracking and frequency offset estimation according to the first matrix, the LTF sequence, and the signal received on the pilot subcarrier in the plurality of LTF symbols.

[0124] A relationship between the first matrix A.sub.LTF.sup.k and the P.sub.n×n matrix or the R.sub.n×n matrix may be shown in Formula (9). For example, for the k.sup.th subcarrier in each LTF symbol, when generating the LTF, the transmit device may generate the LTF according to a mapping matrix shown in the following.

[00010]$\begin{array}{cc}{A}_{\mathrm{LTF}}^k=\{\begin{array}{c}{R}_{n\times n}\mathrm{if}\mathrm{the}{k}^{\mathrm{th}}\mathrm{subcarrier}\mathrm{is}a\mathrm{pilot}\mathrm{subcarrier}\\ \begin{array}{c}\begin{array}{c}{P}_{n\times n}\mathrm{if}\mathrm{the}{k}^{\mathrm{th}}\mathrm{subcarrier}\mathrm{is}a\mathrm{non}-\mathrm{pilot}\mathrm{subcarrier}\\ \mathrm{or}a\mathrm{data}\mathrm{subcarrier}\end{array}\\ \left(\mathrm{which}\mathrm{may}\mathrm{also}\mathrm{be}\mathrm{referred}\mathrm{to}\mathrm{as}\mathrm{another}\mathrm{case}\right)\end{array}\end{array}& \left(9\right)\end{array}$

[0125] It may be understood that the another case in Formula (9) may indicate a case in which the k.sup.th subcarrier is a non-pilot subcarrier. For example, if the k.sup.th subcarrier is a data subcarrier, the first matrix A.sub.LTF.sup.k=P.sub.n×n.

[0126] For example, the relationship between the R.sub.n×n matrix and the P.sub.n×n matrix may be shown as follows:

[R].sub.m,n=[P].sub.1,n  (10)

[0127] [R].sub.m,n indicates an m.sup.th row of the R.sub.n×n matrix, [P].sub.1,n indicates the first row of the P.sub.n×n matrix, and both m and n are integers greater than or equal to 1 and less than or equal to 16.

[0128] It may be understood that each row of the R.sub.n×n matrix shown in this embodiment of this application may further be equal to a first row of an overall negation matrix of the P.sub.n×n matrix, a first row of a transpose matrix of the P.sub.n×n matrix, a first row of a transpose matrix of an overall negation matrix of the P.sub.n×n matrix, or the like.

[0129] According to the method provided in this embodiment of this application, the receive device may implement channel estimation of more than eight streams. For example, the receive device may support MIMO channel estimation of up to 16 streams. In addition, the P matrix provided in this application can further adapt to requirements of different quantities of streams. Therefore, the receive device can implement MIMO channel estimation of 12 streams, 16 streams, and the like. MIMO channel estimation of a plurality of different quantities of streams can be implemented by using one P.sub.n×n matrix, and redundancy of MIMO channel estimation is effectively reduced.

[0130] Usually, for a matrix with 16 rows and 16 columns, a communication apparatus usually needs to store values of 256 elements. Therefore, when generating the LTF, the communication apparatus (for example, the transmit device) may sequentially read the elements of the matrix. However, in the P.sub.n×n matrix provided in this embodiment of this application, an S.sub.(n-1)×(n-1) submatrix and the P.sub.n×n matrix can be restored by storing only a vector (or the first vector x, the second vector y, or the like) of the first row or the first column of the S.sub.(n-1)×(n-1) submatrix. Therefore, the complete P.sub.n×n matrix does not need to be stored. In this way, storage space occupied by the matrix can be effectively reduced, and implementation complexity can be reduced. Alternatively, the P.sub.n×n matrix provided in this application may include an element 1 and an element −1, and can further simplify calculation complexity. Alternatively, n elements in the T.sup.th row of the P.sub.n×n matrix provided in this application are different, to effectively resolve spectral bump (spectral line).

[0131] The following describes the P.sub.n×n matrix provided in this embodiment of this application based on a feature of the P.sub.n×n matrix. It may be understood that one or more of a plurality of features shown in the following may be the feature of the P.sub.n×n matrix. For example, one of the following features 1 to 7 may be the feature of the P.sub.n×n matrix. Alternatively, a combination of any two of the following features 1 to 7 is features of the P.sub.n×n matrix. Alternatively, a combination of any three or the like of the following features 1 to 7 is features of the P.sub.n×n matrix. Alternatively, the following features 1 to 7 may all be features of the P.sub.n×n matrix.

[0132] Feature 1:

[0133] The P.sub.n×n matrix includes an element 1 and an element −1.

[0134] In this embodiment of this application, the P.sub.n×n matrix may be a matrix including an element 1 and an element −1. This resolves complex implementation caused by storing another more complex element (for example, a complex number) by the communication apparatus. In other words, the P.sub.n×n matrix provided in this embodiment of this application may effectively simplify calculation complexity.

[0135] Feature 2:

[0136] n elements in the T.sup.th row of the P.sub.n×n matrix are different, and T is an integer greater than or equal to 1 and less than n.

[0137] In this embodiment of this application, for example, n elements in the first row of the P.sub.n×n matrix are different. Alternatively, n elements in a second row of the P.sub.n×n matrix are different. Alternatively, n elements in the T.sup.th row of the P.sub.n×n matrix are different. Therefore, the n elements in each row of the R.sub.n×n matrix obtained according to the P.sub.n×n matrix may also be different. This effectively resolves spectral bump.

[0138] With reference to the feature 1 and the feature 2, the elements of the P.sub.n×n matrix provided in this embodiment of this application are simple, and n elements in each row of the P.sub.n×n matrix are different. This resolves a complex operation of the communication apparatus, and effectively resolves spectral bump.

[0139] Feature 3:

[0140] The submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is a circulant matrix or a Hankel matrix.

[0141] The circulant matrix may be a special form of a Toeplitz (Toeplitz) matrix (which may also be referred to as a diagonal-constant matrix). Each element of a column vector of the circulant matrix may be a result obtained by sequentially shifting each element of a previous column vector to the right by one bit.

[0142] The Hankel matrix (Hankel matrix) is a square matrix in which elements on each skew-diagonal are equal.

[0143] In this embodiment of this application, the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is set to a circulant matrix or a Hankel matrix, and the communication apparatus can restore the submatrix only by storing a first row or a first column of the submatrix S.sub.(n-1)×(n-1). This can effectively save storage space of the communication apparatus, and reduce implementation complexity.

[0144] It may be understood that for an example in which the submatrix S.sub.(n-1)×(n-1) is a Hankel matrix, refer to Formula (51) and Formula (52) shown in the following.

[0145] Feature 4:

[0146] The first row of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is equal to the first vector x, or is obtained based on the first vector x, and x=[1 1 1 −1 1 −1 −1 1 −1 −1 −1] (in this case, n=12). Alternatively, the first row of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is equal to the second vector y, or is obtained based on the second vector y, and y=[1 1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1 −1] (in this case, n=16).

[0147] In this embodiment of this application, another row of the submatrix S.sub.(n-1)×(n-1) may also be obtained based on the first vector x or the second vector y. For ease of description, the following describes each matrix provided in embodiments of this application by using an example in which the first row of the submatrix S.sub.(n-1)×(n-1) is equal to the first vector x (or the second vector y) or obtained based on the first vector x (or the second vector y). However, this should not be construed as a limitation on embodiments of this application.

[0148] For example, the first row of the submatrix S.sub.(n-1)×(n-1) may be obtained by performing one or more of three operations: cyclic shift, reversing, or overall negation on the first vector x.

[0149] For example, the first row of the submatrix S.sub.(n-1)×(n-1) may be obtained by performing one or more of three operations: cyclic shift, reversing, or overall negation on the second vector y.

[0150] For example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to an overall negation vector of the first vector, for example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 1 1 −1 1 1 1] (which may also be denoted as −x).

[0151] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to a reversing vector of the first vector, for example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 −1 1 −1 1 1 1] (which may also be denoted as a reversing vector of x).

[0152] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to a cyclic shift vector of the first vector, for example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 1 1 −1 1 −1 −1 1 −1 −1]. In other words, the first row of the submatrix S.sub.(n-1)×(n-1) is obtained by shifting the first vector x to the right by one bit. For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 1 −1 −1 1 −1 −1 −1 1]. In other words, the first row of the submatrix S.sub.(n-1)×(n-1) is obtained by shifting the first vector x to the left by one bit.

[0153] For example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to an overall negation vector of the second vector, for example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 1 1 1 −1 1 −1 1 1 −1 −1 1] (which may also be denoted as −y).

[0154] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to a reversing vector of the second vector, for example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 1 −1 −1 1 −1 1 −1 −1 −1 −1 1 1 1] (which may also be denoted as a reversing vector of y).

[0155] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to a cyclic shift vector of the second vector, for example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1]. In other words, the first row of the submatrix S.sub.(n-1)×(n-1) is obtained by shifting the second vector y to the right by one bit. For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1 −1 1]. In other words, the first row of the submatrix S.sub.(n-1)×(n-1) is obtained by shifting the second vector y to the left by one bit.

[0156] For example, when the first row of the submatrix S.sub.(n-1)×(n-1) is obtained based on the first vector x, a second row of an S matrix P.sub.(n-1)×(n-1) may also be obtained based on cyclic shift of the first vector x, and a third row of the S matrix P.sub.(n-1)×(n-1) may also be obtained based on cyclic shift of the first vector x. Alternatively, after the first row of the submatrix S.sub.(n-1)×(n-1) is determined based on the first vector x, the second row to an (n−1).sup.th row of the submatrix S.sub.(n-1)×(n-1) may also be obtained based on cyclic shift of the first row.

[0157] For example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 1 −1 1 −1 −1 1 −1 −1 −1], the second row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 1 1 −1 1 −1 −1 1 −1 −1] (namely, shifting 11 elements of x to the right by one bit), and the third row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 1 1 1 −1 1 −1 −1 1 −1] (namely, shifting 11 elements of x the right by two bits). The rest can be deduced by analogy, and the submatrix S.sub.(n-1)×(n-1) may be obtained.

[0158] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 1 −1 1 −1 −1 1 −1 −1 −1], the second row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 1 −1 −1 1 −1 −1 −1 1] (namely, shifting 11 elements of x to the left by one bit), and the third row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 −1 1 −1 −1 1 −1 −1 −1 1 1] (namely, shifting 11 elements of x the left by two bits). The rest can be deduced by analogy, and the submatrix S.sub.(n-1)×(n-1) may be obtained.

[0159] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 1 1 −1 1 1 1], the second row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 −1 −1 −1 1 −1 1 1 −1 1 1] (namely, shifting 11 elements of an overall negation vector of x to the right by one bit), and the third row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 −1 −1 1 −1 1 1 −1 1]. The rest can be deduced by analogy, and the submatrix S.sub.(n-1)×(n-1) may be obtained.

[0160] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 1 1 −1 1 1 1], the second row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 1 −1 1 1 −1 1 1 1 −1] (namely, shifting 11 elements of an overall negation vector of x to the left by one bit), and the third row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 −1 1 1 −1 1 1 1 −1 −1]. The rest can be deduced by analogy, and the submatrix S.sub.(n-1)×(n-1) may be obtained.

[0161] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 −1 1 −1 1 1 1], the second row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 −1 −1 −1 1 −1 −1 1 −1 1 1] (namely, shifting 11 elements of a reversing vector of x to the right by one bit), and the third row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 −1 −1 1 −1 −1 1 −1 1]. The rest can be deduced by analogy, and the submatrix S.sub.(n-1)×(n-1) may be obtained.

[0162] For another example, the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 −1 1 −1 1 1 1], the second row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 1 −1 −1 1 −1 1 1 1 −1] (namely, shifting 11 elements of a reversing vector of x to the left by one bit), and the third row of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 −1 −1 1 −1 1 1 1 −1 −1]. The rest can be deduced by analogy, and the submatrix S.sub.(n-1)×(n-1) may be obtained.

[0163] In other words, each element of a row vector of the submatrix S.sub.(n-1)×(n-1) is a result obtained by sequentially shifting each element of a previous row vector to the right by one bit. Alternatively, each element of a row vector of the submatrix S.sub.(n-1)×(n-1) is a result obtained by sequentially shifting each element of a previous row vector to the left by one bit.

[0164] For example, when the first row of the submatrix S.sub.(n-1)×(n-1) is equal to the second vector y or obtained based on the second vector y, the second row to an (n−1).sup.th row of the submatrix S.sub.(n-1)×(n-1) may also be obtained based on cyclic shift of the first row.

[0165] It may be understood that, for descriptions of the submatrix S.sub.(n-1)×(n-1) and the second vector y, refer to the foregoing examples of the submatrix S.sub.(n-1)×(n-1) and the first vector x. Details are not described herein again.

[0166] In this embodiment of this application, after obtaining the first row of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix based on the first vector or the second vector, the communication apparatus may obtain S.sub.(n-1)×(n-1). Therefore, the communication apparatus only needs to store a row of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix, to restore the submatrix. Alternatively, when a relationship between a row of the submatrix and the first vector or the second vector is determined, the communication apparatus can restore the submatrix only by storing the first vector or the second vector. Therefore, the complete P.sub.n×n matrix does not need to be stored. Further, this can reduce space occupied by the P.sub.n×n matrix, save storage space, and effectively reduce implementation complexity of the communication apparatus (for example, the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix can be restored based on an operation such as cyclic shift).

[0167] Feature 5:

[0168] The first column of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is equal to a third vector x′, or is obtained based on a third vector x′ (in this case, n=12). Alternatively, the first column of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is equal to a fourth vector y′, or is obtained based on a fourth vector y′ (in this case, n=16).

[0169] The third vector x′ may be shown as follows:

[00011]$\begin{array}{cc}x’=\left[\begin{array}{c}1\\ -1\\ -1\\ -1\\ 1\\ -1\\ -1\\ 1\\ -1\\ 1\\ 1\end{array}\right]& \left(11\right)\end{array}$

[0170] The fourth vector y′ may be shown as follows:

[00012]$\begin{array}{cc}y’=\left[\begin{array}{c}1\\ -1\\ 1\\ 1\\ -1\\ -1\\ 1\\ -1\\ 1\\ -1\\ -1\\ -1\\ -1\\ 1\\ 1\end{array}\right]& \left(12\right)\end{array}$

[0171] For example, the first column of the submatrix S.sub.(n-1)×(n-1) may be obtained by performing one or more of three operations: cyclic shift, reversing, or overall negation on the third vector.

[0172] For example, the first column of the submatrix S.sub.(n-1)×(n-1) may be obtained by performing one or more of three operations: cyclic shift, reversing, or overall negation on the fourth vector y′.

[0173] For example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to a reversing vector of the third vector, for example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 1 −1 −1 1 −1 −1 −1 1].sup.T.

[0174] For another example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to an overall negation vector of the third vector, for example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 1 1 −1 1 1 −1 1 −1 −1].sup.T.

[0175] For another example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to a transpose vector of a cyclic shift vector of the third vector, for example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 −1 −1 1 −1 −1 1 −1 1 1 1].sup.T. In other words, the first column of the submatrix S.sub.(n-1)×(n-1) is obtained by cyclically shifting the third vector x′ upwards by one bit. For another example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 −1 −1 1 −1 −1 1 −1 1].sup.T. In other words, the first column of the submatrix S.sub.(n-1)×(n-1) is obtained by cyclically shifting the third vector x′ downwards by one bit.

[0176] It may be understood that, after the first column of the submatrix S.sub.(n-1)×(n-1) is determined based on the third vector x′, a second column to an (n−1).sup.th column of the submatrix S.sub.(n-1)×(n-1) may also be obtained based on cyclic shift of the first column.

[0177] For example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to an overall negation vector of the fourth vector, for example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 −1 −1 1 1 −1 1 −1 1 1 1 1 −1 −1].sup.T.

[0178] For another example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to a reversing vector of a transpose vector of the fourth vector, for example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 −1 −1 −1 1 −1 1 −1 −1 1 1 −1 1].sup.T.

[0179] For another example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to a transpose vector of a cyclic shift vector of the fourth vector, for example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [−1 1 1 −1 −1 1 −1 1 −1 −1 −1 −1 1 1 1].sup.T. In other words, the first column of the submatrix S.sub.(n-1)×(n-1) is obtained by cyclically shifting the fourth vector y′ upwards by one bit. For another example, the first column of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 −1 1 1 −1 −1 1 −1 1 −1 −1 −1 −1 1].sup.T. In other words, the first row of the submatrix S.sub.(n-1)×(n-1) is obtained by cyclically shifting the fourth vector y′ downwards by one bit.

[0180] It may be understood that, for descriptions of a relationship between the first column of the submatrix S.sub.(n-1)×(n-1) and the third vector x′ or the fourth vector y′, refer to descriptions of the feature 4. Details are not described herein again.

[0181] For ease of description, the following describes the P.sub.n×n matrix provided in embodiments of this application by using an example in which the first row of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is equal to the first vector (or the second vector) or obtained based on the first vector (or the second vector). The following does not describe in detail an example in which the first column of the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix is equal to the third vector (or the fourth vector) or obtained based on the third vector (or the fourth vector).

[0182] Feature 6:

[00013]$\begin{array}{cc}{P}_{n\times n}=\left[\begin{array}{cc}{S}_{\left(n-1\right)\times \left(n-1\right)}& a\\ a^T& 1\end{array}\right]& \left(13\right)\end{array}$$\begin{array}{cc}{P}_{n\times n}=\left[\begin{array}{cc}a& S_{\left(n-1\right)\times \left(n-1\right)}\\ 1& a^T\end{array}\right]& \left(14\right)\end{array}$$\begin{array}{cc}{P}_{n\times n}=\left[\begin{array}{cc}{S}_{\left(n-1\right)\times \left(n-1\right)}& -a\\ a^T& 1\end{array}\right]& \left(15\right)\end{array}$$\begin{array}{cc}{P}_{n\times n}=\left[\begin{array}{cc}-a& S_{\left(n-1\right)\times \left(n-1\right)}\\ 1& a^T\end{array}\right]& \left(16\right)\end{array}$

[0183] The S.sub.(n-1)×(n-1) matrix is a submatrix of the P.sub.n×n matrix, the S.sub.(n-1)×(n-1) matrix includes n−1 rows and n−1 columns, α is a column vector including n−1 elements, each element is 1, α.sup.T is a transpose vector of α, and −α indicates a vector obtained through negation of all elements in a.

[0184] In this embodiment of this application, S.sub.(n-1)×(n-1) may be a circulant matrix or a Hankel matrix.

[0185] In this embodiment of this application, it can be ensured that the P.sub.n×n matrix is an orthogonal matrix, and the submatrix S.sub.(n-1)×(n-1) is a circulant matrix or a Hankel matrix. The communication apparatus can restore the submatrix and the P.sub.n×n matrix by storing a vector (or the first vector x, the second vector y, or the like) of the first row or the first column of the submatrix S.sub.(n-1)×(n-1). Therefore, the complete P.sub.n×n matrix does not need to be stored. In this way, storage space occupied by the P.sub.n×n matrix can be effectively reduced, storage space can be saved, and implementation complexity of the communication apparatus can be effectively reduced.

[00014]$\begin{array}{cc}{P}_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& P_{8\times 8}\\ P_{8\times 8}& -P_{8\times 8}\end{array}\right]& \left(17\right)\end{array}$$\begin{array}{cc}{P}_{16\times 16}=\left[\begin{array}{cc}-P_{8\times 8}& P_{8\times 8}\\ P_{8\times 8}& P_{8\times 8}\end{array}\right]& \left(18\right)\end{array}$$\begin{array}{cc}{P}_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& -P_{8\times 8}\\ P_{8\times 8}& P_{8\times 8}\end{array}\right]& \left(19\right)\end{array}$$\begin{array}{cc}{P}_{16\times 16}=\left[\begin{array}{cc}{P}_{8\times 8}& P_{8\times 8}\\ -P_{8\times 8}& P_{8\times 8}\end{array}\right]& \left(20\right)\end{array}$

[0186] In other words, the P.sub.16×16 matrix (namely, the P.sub.n×n matrix when n=16) may be obtained according to the P.sub.8×8 matrix. The P.sub.8×8 matrix is a corresponding P matrix when a maximum quantity of spatial streams supported by the communication apparatus is 8.

[0187] For example,

[00015]$\begin{array}{cc}{P}_{8\times 8}=\left[\begin{array}{cccccccc}1& -1& 1& 1& 1& -1& 1& 1\\ 1& 1& -1& 1& 1& 1& -1& 1\\ 1& 1& 1& -1& 1& 1& 1& -1\\ -1& 1& 1& 1& -1& 1& 1& 1\\ 1& -1& 1& 1& -1& 1& -1& -1\\ 1& 1& -1& 1& -1& -1& 1& -1\\ 1& 1& 1& -1& -1& -1& -1& 1\\ -1& 1& 1& 1& 1& -1& -1& -1\end{array}\right]& \left(21\right)\end{array}$

[0188] In this embodiment of this application, the P.sub.8×8 matrix is extended, to generate the P.sub.16×16 matrix. This can ensure that the communication apparatus supports transmission of data of 16 streams or fewer than 16 streams, and avoid excessive complex operations.

[0189] It may be understood that, in this embodiment of this application, a P.sub.32×32 matrix may be obtained according to the P.sub.16×16 matrix, and a P.sub.24×24 matrix may be obtained according to the P.sub.12×12 matrix. A specific obtaining method is similar to the manner of generating the P.sub.16×16 matrix by extending the P.sub.8×8 matrix. For brevity, the following does not describe in detail a method for obtaining the P.sub.24×24 matrix according to the P.sub.12×12 matrix and a method for obtaining the P.sub.32×32 matrix according to the P.sub.16×16 matrix.

[0190] The P.sub.12×12 matrix is extended, to generate the P.sub.24×24 matrix, or the P.sub.16×16 matrix is extended, to generate the P.sub.32×32 matrix. This can ensure that the communication apparatus supports transmission of data of 32 streams or fewer than 32 streams, and avoid excessive complex operations.

[0191] For example, the following first describes in detail the P.sub.n×n matrix provided in embodiments of this application, then describes the R.sub.n×n matrix provided in embodiments of this application, and finally describes the first matrix provided in embodiments of this application.

[0192] In a possible implementation, the P.sub.12×12 matrix may be shown as follows:

[00016]$\begin{array}{cc}{P}_{12\times 12}=\left[\begin{array}{cccccccccccc}1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1\\ -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& 1\\ -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& 1\\ -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& 1\\ 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1\\ -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& 1\\ -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& 1\\ 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1\\ -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& 1\\ 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right]& \left(22\right)\end{array}$

[0193] Alternatively,

[00017]$\begin{array}{cc}{P}_{12\times 12}=\left[\begin{array}{cccccccccccc}1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1\\ 1& -1& 1& 1& 1& -1& 1& -1& -1& 1& 1& 1\\ -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& 1\\ 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1\\ -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& 1\\ -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& 1\\ 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1\\ -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& 1\\ 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right]& \left(22\right)\end{array}$

[0194] Formula (22) is shown by using an example in which a first row of a submatrix S.sub.(n-1)×(n-1) is equal to [1 1 1 −1 1 −1 −1 1 −1 −1 −1] (namely, equal to the first vector). However, it should not be understood as a limitation on this embodiment of this application. It may be understood that each element of a row vector of the submatrix S.sub.(n-1)×(n-1) shown in Formula (22) is a result obtained by sequentially shifting each element of a previous row vector to the right by one bit. Each element of a row vector of the submatrix S.sub.(n-1)×(n-1) shown in Formula (23) is a result obtained by sequentially shifting each element of a previous row vector to the left by one bit. It may be understood that Formula (22) and Formula (23) shown herein may also be understood as the P.sub.n×n matrix obtained according to Formula (13). A result obtained by sequentially shifting each element of a row vector of S.sub.(n-1)×(n-1) to the right by two (or three, four, or the like) bits, or a result obtained by sequentially shifting each element of a row vector of S.sub.(n-1)×(n-1) to the left by two (or three, four, or the like) bits shall also fall within the protection scope of this application. Therefore, for brevity, the following only shows a result obtained by sequentially shifting each element of a row vector of the submatrix S.sub.(n-1)×(n-1) to the right by one bit as an example. In addition, for brevity, matrices obtained based on any one or more of the three operations of cyclic shift, overall negation, and reversing in Formula (22) or Formula (23) are not enumerated herein.

[0195] It can be seen from Formula (22) and Formula (23) that the submatrix S.sub.(n-1)×(n-1) of the P.sub.n×n matrix shown in this embodiment of this application is a circulant matrix or a Hankel matrix, and the communication apparatus can obtain the complete P.sub.n×n matrix only by storing the first row of the submatrix S.sub.(n-1)×(n-1). This can effectively save storage space of the communication apparatus, and reduce complexity of restoring the P.sub.n×n matrix. It may be understood that the descriptions are also applicable to P.sub.n×n matrices shown in the following or the first matrix obtained according to the P.sub.n×n matrix. To avoid repetition, details are not described again in the following.

[0196] In a possible implementation, the P.sub.12×12 matrix may be shown as follows:

[00018]$\begin{array}{cc}{P}_{12\times 12}=\left[\begin{array}{cccccccccccc}1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1\\ 1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1\\ 1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1\\ 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1\\ 1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1\\ 1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1\\ 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1\\ 1& 1& -1& -1& 1& -1& -1& -1& 1& 1& -1& -1\\ 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1\\ 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right]& \left(22\right)\end{array}$

[0197] Formula (24) is shown by using an example in which the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 1 −1 1 −1 −1 1 −1 −1 −1], and the P.sub.12×12 matrix shown by using Formula (14) as an example. For brevity, matrices obtained based on any one or more of the three operations of cyclic shift, overall negation, and reversing in Formula (24) are not enumerated herein.

[0198] In a possible implementation, the P.sub.12×12 matrix may be shown as follows:

[0199] Alternatively,

[00019]$\begin{array}{cc}{P}_{12\times 12}=\left[\begin{array}{cccccccccccc}1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& -1\\ -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1\\ -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1\\ -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1\\ 1& -1& -1& -1& 1& 1& -1& 1& 1& -1& -1& -1\\ -1& 1& -1& -1& 1& 1& 1& 1& -1& 1& -1& -1\\ -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1\\ 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& -1\\ -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1\\ 1& -1& 1& -1& -1& 1& -1& -1& 1& 1& 1& -1\\ 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1& -1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right]& \left(25\right)\end{array}$

[0200] Formula (25) is shown by using an example in which the first row of the submatrix S.sub.(n-1)×(n-1) is equal to [1 1 1 −1 1 −1 −1 1 −1 −1 −1], and the P.sub.12×12 matrix shown by using Formula (15) as an example. For brevity, matrices obtained based on any one or more of the three operations of cyclic shift, overall negation, and reversing in Formula (24) are not enumerated herein.

[0201] In a possible implementation, the P.sub.12×12 matrix may be shown as follows:

[00020]$\begin{array}{cc}{P}_{12\times 12}=\left[\begin{array}{cccccccccccc}-1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1\\ -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1& -1\\ -1& -1& -1& 1& 1& 1& -1& 1& -1& -1& 1& -1\\ -1& -1& -1& -1& 1& 1& 1& 1& 1& -1& -1& 1\\ -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1& -1\\ -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1& -1\\ -1& -1& -1& 1& -1& -1& -1& 1& 1& 1& -1& 1\\ -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& -1& -1\\ -1& -1& 1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ -1& 1& -1& -1& -1& 1& -1& -1& -1& 1& 1& 1\\ -1& 1& 1& -1& 1& -1& -1& 1& -1& -1& -1& 1\\ 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1& 1\end{array}\right]& \left(26\right)\end{array}$