US-20260129433-A1 - COMMUNICATION METHOD AND APPARATUS

US20260129433A1US 20260129433 A1US20260129433 A1US 20260129433A1US-20260129433-A1

Abstract

A communication method includes obtaining a first constellation diagram. The first constellation diagram includes a set of first constellation points. The first constellation points in the set of first constellation points are obtained by encrypting corresponding second constellation points in a set of second constellation points in a second constellation diagram based on a first key. The second constellation points in the set of second constellation points are obtained by mapping to-be-sent data. A phase of the first constellation points in the set of first constellation points is different from a phase of the second constellation points in the set of second constellation points. The communication method also includes sending a signal based on the first constellation diagram.

Inventors

Lu Yang
Wenhui Wang
Li Sun

Assignees

HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20260102

Claims (20)

1 . A communication method, comprising: obtaining a first constellation diagram, wherein the first constellation diagram comprises a set of first constellation points, the first constellation points in the set of first constellation points are obtained by encrypting corresponding second constellation points in a set of second constellation points in a second constellation diagram based on a first key, the second constellation points in the set of second constellation points are obtained by mapping to-be-sent data, and a phase of the first constellation points in the set of first constellation points is different from a phase of the second constellation points in the set of second constellation points; and sending a signal based on the first constellation diagram.
2 . The communication method according to claim 1 , wherein the first key represents a phase rotation amount between the first constellation points and the corresponding second constellation points.
3 . The communication method according to claim 2 , wherein the phase rotation amount is determined based on information about a legitimate channel, and the legitimate channel is used to carry the signal.
4 . The communication method according to claim 3 , wherein the information about the legitimate channel comprises channel gains in a channel gain matrix of the legitimate channel.
5 . The communication method according to claim 4 , wherein a phase rotation amount of any second constellation point in the set of second constellation points is determined based on an initial phase rotation amount, a unit phase rotation amount, and a quantity of unit phase rotation amounts, and the quantity of unit phase rotation amounts is determined based on the channel gains.
6 . The communication method according to claim 5 , wherein an expression of the phase rotation amount of the any second constellation point in the set of second constellation points is: e j(θ 0 +Δθ×η) , wherein θ 0 is the initial phase rotation amount, Δθ is the unit phase rotation amount, and η is the quantity of unit phase rotation amounts.
7 . The communication method according to claim 5 , wherein the unit phase rotation amount is a value obtained by dividing 2π by m, and m is an integer greater than or equal to 2 and less than or equal to a first threshold.
8 . The communication method according to claim 7 , wherein a value of the quantity of unit phase rotation amounts is greater than or equal to 0 and less than or equal to m−1.
9 . The communication method according to claim 1 , wherein the first key is represented by a first diagonal unitary matrix, a modulus of each diagonal element in the first diagonal unitary matrix is 1, and a value of a diagonal element in the first diagonal unitary matrix is a phase rotation amount between the first constellation points and the corresponding second constellation points.
10 . A communication method, comprising: determining a third constellation diagram based on a received signal; determining a fourth constellation diagram based on the third constellation diagram, wherein the fourth constellation diagram comprises a set of fourth constellation points, the fourth constellation points in the set of fourth constellation points are obtained by decrypting corresponding third constellation points in a set of third constellation points in the third constellation diagram based on a second key, and a phase of the third constellation points in the set of third constellation points is different from a phase of the fourth constellation points in the set of fourth constellation points; and demodulating the signal based on the fourth constellation diagram.
11 . The communication method according to claim 10 , wherein the second key represents a phase rotation amount between the corresponding third constellation points and the fourth constellation points.
12 . The communication method according to claim 11 , wherein the phase rotation amount is determined based on information about a legitimate channel, and the legitimate channel is used to carry the signal.
13 . The communication method according to claim 12 , wherein information about the legitimate channel comprises channel gains in a channel gain matrix of the legitimate channel.
14 . The communication method according to claim 13 , wherein a phase rotation amount of any third constellation point in the set of third constellation points is determined based on an initial phase rotation amount, a unit phase rotation amount, and a quantity of unit phase rotation amounts, and the quantity of unit phase rotation amounts is determined based on the channel gains.
15 . The communication method according to claim 14 , wherein an expression of the phase rotation amount of the any third constellation point in the set of third constellation points is: e j(θ 0 +Δθ×η) , wherein θ 0 is the initial phase rotation amount, Δθ is the unit phase rotation amount, and η is the quantity of unit phase rotation amounts.
16 . The communication method according to claim 14 , wherein the unit phase rotation amount is a value obtained by dividing 2π by m, and m is an integer greater than or equal to 2 and less than or equal to a first threshold.
17 . The communication method according to claim 16 , wherein a value of the quantity of unit phase rotation amounts is greater than or equal to 0 and less than or equal to m−1.
18 . The communication method according to claim 10 , wherein the second key is represented by a second diagonal unitary matrix, a modulus of each diagonal element in the second diagonal unitary matrix is 1, and a value of a diagonal element in the second diagonal unitary matrix is a phase rotation amount between the corresponding third constellation points and the fourth constellation points.
19 . A communication apparatus, comprising: a processor, wherein when the processor executes instructions, the communication apparatus is caused to: obtain a first constellation diagram, wherein the first constellation diagram comprises a set of first constellation points, the first constellation points in the set of first constellation points are obtained by encrypting corresponding second constellation points in a set of second constellation points in a second constellation diagram based on a first key, the second constellation points in the set of second constellation points are obtained by mapping to-be-sent data, and a phase of the first constellation points in the set of first constellation points is different from a phase of the second constellation points in the set of second constellation points; and send a signal based on the first constellation diagram.
20 . The communication apparatus according to claim 19 , wherein the first key represents a phase rotation amount between the first constellation points and the corresponding second constellation points.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/CN2023/106437, filed on Jul. 7, 2023, the disclosure of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD This application relates to the communication field, and in particular, to a communication method and an apparatus. BACKGROUND Currently, an air interface security mechanism of cellular networks is deployed at a high layer, to ensure security of information transmission over wireless channels. After a security context is activated, both encryption and integrity protection policies are deployed at a packet data convergence protocol (PDCP) layer or a higher layer. However, before the security context is activated, the network may be attacked as there is no security assurance mechanism established. In addition, new applications such as positioning and sensing raise new requirement on security of a physical layer, but it is difficult for high-layer security technologies to meet these requirements. For example, due to openness of wireless channels, signal transmission for ranging and positioning is vulnerable to attacks, which may cause serious consequences in some applications. However, it is difficult for the high-layer security technologies to resolve this problem. Therefore, how to improve security of information transmission at the physical layer is a current hot topic. SUMMARY Embodiments of this application provide a communication method and an apparatus, to improve security of information transmission at a physical layer. To achieve the foregoing objective, this application uses the following technical solutions. According to a first aspect, a communication method is provided. The method includes: A first communication apparatus obtains a first constellation diagram; and sends a first signal based on the first constellation diagram, where the first constellation diagram includes a set of first constellation points, the first constellation points in the set of first constellation points are obtained by encrypting corresponding second constellation points in a set of second constellation points in a second constellation diagram based on a first key, the second constellation points in the set of second constellation points are obtained by mapping to-be-sent data, and a phase of the first constellation points in the set of first constellation points is different from a phase of the second constellation points in the set of second constellation points. A second communication apparatus receives a second signal corresponding to the first signal; determines a third constellation diagram based on the second signal; determines a fourth constellation diagram based on the third constellation diagram; and demodulates the second signal based on the fourth constellation diagram, where the fourth constellation diagram comprises a set of fourth constellation points, the fourth constellation points in the set of fourth constellation points are obtained by decrypting corresponding third constellation points in a set of third constellation points in the third constellation diagram based on a second key, and a phase of the third constellation points in the set of third constellation points is different from a phase of the fourth constellation points in the set of fourth constellation points. It can be learned from the method according to the first aspect that the first communication apparatus (a transmit end) may encrypt a physical-layer signal, for example, rotate (that is, encrypt), based on the first key, the phase of the second constellation point that carries data, to obtain the first constellation point. Correspondingly, the second communication apparatus (a receive end) may decrypt a received physical-layer signal, for example, decrypt (or restore) the received third constellation point based on the second key, to obtain the fourth constellation point that carries the foregoing data. The first key and the second key are a pair of keys. For example, a phase of a constellation point may be rotated based on the first key, and a phase of the constellation point may be rotated reversely based on the second key, so that the phase of the constellation point is restored to the original phase, that is, the first key and the second key may represent opposite phase rotation amounts. If the first key and the second key each are represented by a diagonal unitary matrix, each diagonal element in a diagonal unitary matrix corresponding to the first key and each diagonal element in a diagonal unitary matrix corresponding to the second key are in a reciprocal relationship. In this case, because an eavesdropper does not have the accurate first key or second key, the eavesdropper cannot directly decrypt the stolen physical-layer signal, and cannot obtain the corresponding data. In this way, data leakage can be avoided, and security of transmission at a physical layer can be improved. In a possible