Precoding method and apparatus, user equipment, RIS array, base station and storage medium
A precoding method is performed by a reconfigurable intelligent surface (RIS) array. The method includes: determining incident angle information, the incident angle information including incident angle information of an incident beam transmitted by a base station to the RIS array; acquiring a precoding matrix index (PMI), the PMI being determined according to channel information between the RIS array and a user equipment (UE); determining reflection angle information corresponding to the RIS array according the PMI; and determining a target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information, to precode the RIS array.
1 . A precoding method, performed by a reconfigurable intelligent surface (RIS) array, the method comprising:
determining incident angle information, the incident angle information comprising incident angle information of an incident beam transmitted by a base station to the RIS array;
acquiring a precoding matrix index (PMI), the PMI being determined according to channel information between the RIS array and a user equipment (UE);
determining reflection angle information corresponding to the RIS array according to the PMI; and
determining a target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information, to precode the RIS array;
wherein determining the target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information comprises:
determining deflection phase angles supported by each RIS array element; and
determining the target deflection phase angle of each RIS array element from the deflection phase angles supported by each RIS array element;
wherein determining the target deflection phase angle of each RIS array element from the deflection phase angles supported by each RIS array element comprises:
determining, among the deflection phase angles supported by each RIS array element, a deflection phase angle that minimizes a value of formula 1, as the target deflection phase angle of each RIS array element;
wherein, the formula 1 comprises:
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and wherein ω i is a deflection phase angle supported by an i th RIS array element, i=0, 1, . . . , N−1, N is a number of RIS array elements, d is a distance between RIS array elements, λ is a wavelength of the incident beam, α is the incident angle information, the incident angle information comprises a sum of a horizontal-dimension incident angle and a vertical-dimension incident angle of the incident beam, β is the reflection angle information, and the reflection angle information comprises the sum of the horizontal-dimension reflection angle and the vertical-dimension reflection angle corresponding to the RIS array, determined according to the PMI.
2 . The method according to claim 1 , wherein determining the incident angle information comprises:
acquiring a horizontal-dimension incident angle and a vertical-dimension incident angle of the incident beam transmitted by the base station, and/or acquiring a sum of the horizontal-dimension incident angle and the vertical-dimension incident angle of the incident beam transmitted by the base station; and
determining the sum of the horizontal-dimension incident angle and the vertical-dimension incident angle as the incident angle information.
3 . The method according to claim 2 , wherein the horizontal-dimension incident angle comprises: an angle between the incident beam and an antenna array surface of the RIS array in a horizontal dimension, and the vertical-dimension incident angle comprises: an angle between the incident beam and the antenna array surface of the RIS array in a vertical dimension.
4 . The method according to claim 1 , wherein acquiring the PMI comprises at least one of following acts:
acquiring the PMI transmitted by the UE; or
acquiring the PMI forwarded by the base station.
5 . The method according to claim 1 , wherein determining the reflection angle information corresponding to the RIS array according to the PMI comprises:
determining a precoding matrix corresponding to the PMI;
determining a horizontal-dimension precoding vector and a vertical-dimension precoding vector corresponding to the precoding matrix;
determining a horizontal-dimensional reflection angle and a vertical-dimensional reflection angle corresponding to the RIS array according to the horizontal-dimensional precoding vector and the vertical-dimensional precoding vector; and
determining a sum of the horizontal-dimension reflection angle and the vertical-dimension reflection angle as the reflection angle information.
6 . The method according to claim 5 , wherein the horizontal-dimension reflection angle comprises: an angle between a reflection beam and an antenna array surface of the RIS array in a horizontal dimension, and the vertical-dimension reflection angle comprises: an angle between the reflection beam and the antenna array surface of the RIS array in a vertical dimension.
7 . A precoding method, performed by a communication system comprising a base station, a reconfigurable intelligent surface (RIS) array and a user equipment (UE), the method comprising:
determining, by the UE, a precoding matrix index (PMI) according to channel information between the RIS array and the UE; and
transmitting, by the UE, the PMI to the base station and/or the RIS array;
the method further comprises:
acquiring, by the base station, the PMI from the UE; and
forwarding, by the base station, the PMI to the RIS array; and
the method further comprises:
determining, by the RIS array, incident angle information, the incident angle information comprising incident angle information of an incident beam transmitted by the base station to the RIS array;
acquiring, by the RIS array, the PMI, the PMI being determined according to channel information between the RIS array and the UE;
determining reflection angle information corresponding to the RIS array according to the PMI; and
determining a target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information, to precode the RIS array;
wherein determining the target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information comprises:
determining deflection phase angles supported by each RIS array element; and
determining the target deflection phase angle of each RIS array element from the deflection phase angles supported by each RIS array element;
wherein determining the target deflection phase angle of each RIS array element from the deflection phase angles supported by each RIS array element comprises:
determining, among the deflection phase angles supported by each RIS array element, a deflection phase angle that minimizes a value of formula 1, as the target deflection phase angle of each RIS array element;
wherein, the formula 1 comprises:
❘
"\[LeftBracketingBar]"
ω
i
-
2
π
(
d
×
(
cos
(
α
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+
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β
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λ
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×
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"\[RightBracketingBar]"
;
and wherein ω i is a deflection phase angle supported by an i th RIS array element, i=0, 1, . . . , N−1, N is a number of RIS array elements, d is a distance between RIS array elements, λ is a wavelength of the incident beam, α is the incident angle information, the incident angle information comprises a sum of a horizontal-dimension incident angle and a vertical-dimension incident angle of the incident beam, β is the reflection angle information, and the reflection angle information comprises the sum of the horizontal-dimension reflection angle and the vertical-dimension reflection angle corresponding to the RIS array, determined according to the PMI.
8 . The method according to claim 7 , further comprising:
transmitting, to the RIS array, a horizontal-dimension incident angle and a vertical-dimension incident angle of an incident beam transmitted by the base station to the RIS array, and/or transmitting, to the RIS array, a sum of the horizontal-dimension incident angle and the vertical-dimension incident angle of the incident beam.
9 . A communication device, comprising a processor and a memory storing a computer program, wherein the processor executes the computer program stored in the memory, to cause the communication device to perform the method according to claim 7 .
10 . A non-transitory computer-readable storage medium storing instructions, wherein when the instructions are executed, the method according to claim 1 is implemented.
11 . A non-transitory computer-readable storage medium storing instructions, wherein when the instructions are executed, the method according to claim 7 is implemented.
12 . A communication device, comprising a processor and a memory storing a computer program, wherein the processor executes the computer program stored in the memory, to cause the communication device to perform:
determining incident angle information, the incident angle information comprising incident angle information of an incident beam transmitted by a base station to the RIS array;
acquiring a precoding matrix index (PMI), the PMI being determined according to channel information between the RIS array and a user equipment (UE);
determining reflection angle information corresponding to the RIS array according to the PMI; and
determining a target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information, to precode the RIS array;
wherein determining the target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information comprises:
determining deflection phase angles supported by each RIS array element; and
determining the target deflection phase angle of each RIS array element from the deflection phase angles supported by each RIS array element;
wherein determining the target deflection phase angle of each RIS array element from the deflection phase angles supported by each RIS array element comprises:
determining, among the deflection phase angles supported by each RIS array element, a deflection phase angle that minimizes a value of formula 1, as the target deflection phase angle of each RIS array element;
wherein, the formula 1 comprises:
❘
"\[LeftBracketingBar]"
ω
i
-
2
π
(
d
×
(
cos
(
α
)
+
cos
(
β
)
)
λ
)
×
i
❘
"\[RightBracketingBar]"
;
and wherein ω i is a deflection phase angle supported by an i th RIS array element, i=0, 1, . . . , N−1, N is a number of RIS array elements, d is a distance between RIS array elements, λ is a wavelength of the incident beam, α is the incident angle information, the incident angle information comprises a sum of a horizontal-dimension incident angle and a vertical-dimension incident angle of the incident beam, β is the reflection angle information, and the reflection angle information comprises the sum of the horizontal-dimension reflection angle and the vertical-dimension reflection angle corresponding to the RIS array, determined according to the PMI.