Channel measurement method and communications apparatus
A channel measurement method and a communications apparatus. The method includes: a terminal device receives precoded reference signals from a network device, where the precoded reference signals are obtained by precoding reference signals based on K angle vectors; and generates and sends first indication information, where the first indication information is used to indicate P weighting coefficients corresponding to P angle-delay pairs, the P weighting coefficients are determined based on the precoded reference signals, each of the P angle-delay pairs includes one angle vector and one delay vector corresponding to the angle vector, a delay vector corresponding to each angle vector is preconfigured, each angle vector and the delay vector corresponding to each angle vector are obtained through uplink channel measurement, and the P angle-delay pairs and the P weighting coefficients corresponding to the P angle-delay pairs are used to determine a precoding matrix.
1. A channel measurement method, comprising:
receiving precoded reference signals, wherein the precoded reference signals are obtained by precoding reference signals based on K angle vectors but not based on a delay vector;
generating first indication information, wherein the first indication information is used to indicate P weighting coefficients corresponding to P angle-delay pairs, the P weighting coefficients are determined based on the precoded reference signals, each of the P angle-delay pairs comprises one of the K angle vectors and one of one or more delay vectors corresponding to the one angle vector, one or more delay vectors corresponding to each angle vector are preconfigured, and the P angle-delay pairs and the P weighting coefficients corresponding to the P angle-delay pairs are used to determine a precoding matrix, wherein both K and P are positive integers; and
sending the first indication information.
2. The method according to claim 1 , further comprising:
receiving second indication information, wherein the second indication information is used to indicate the one or more delay vectors corresponding to each of the K angle vectors.
3. The method according to claim 2 , wherein the second indication information comprises K bitmaps, a k th bitmap in the K bitmaps is used to indicate L k delay vectors that are in a delay vector set and that correspond to a k th angle vector in the K angle vectors, and the delay vector set comprises a plurality of delay vectors, wherein L k ≥1, and L k is an integer.
4. The method according to claim 2 , wherein the second indication information comprises K indexes, a k th index in the K indexes is an index, in a delay vector set, of a combination of L k delay vectors corresponding to a k th angle vector in the K angle vectors, and the delay vector set comprises a plurality of delay vectors, wherein L k ≥1, and L k is an integer.
5. The method according to claim 4 , wherein the second indication information is further used to indicate a quantity of delay vectors corresponding to each angle vector.
6. The method according to claim 2 , wherein the second indication information is used to indicate an index of a combination of the P angle-delay pairs.
7. The method according to claim 1 , wherein in the K angle vectors and one or more delay vectors corresponding to a first angle vector are the same as one or more delay vectors corresponding to a second angle vector, and the first angle vector and the second angle vector are any two angle vectors in the K angle vectors.
8. The method according to claim 1 , wherein the K angle vectors and the one or more delay vectors corresponding to each angle vector are determined through uplink channel measurement.
9. The method according to claim 1 , wherein the P weighting coefficients comprise one or more weighting coefficients fed back for each of the K angle vectors; and for the k th angle vector in the K angle vectors, the first indication information is used to indicate L k weighting coefficients, the L k weighting coefficients correspond to L k angle-delay pairs in the P angle-delay pairs, and each of the L k angle-delay pairs comprises the k th angle vector and one of the L k delay vectors corresponding to the k th angle vector, wherein L k ≥1, and L k is an integer.
10. The method according to claim 1 , wherein the P weighting coefficients correspond to one receive antenna or one transport layer.
11. A channel measurement method, comprising:
sending precoded reference signals, wherein the precoded reference signals are obtained by precoding reference signals based on K angle vectors but not based on a delay vector;
receiving first indication information, wherein the first indication information is used to indicate P weighting coefficients corresponding to P angle-delay pairs, the P weighting coefficients are determined based on the precoded reference signals, each of the P angle-delay pairs comprises one of the K angle vectors and one of one or more delay vectors corresponding to the one angle vector, one or more delay vectors corresponding to each angle vector are preconfigured, and the P angle-delay pairs and the P weighting coefficients corresponding to the P angle-delay pairs are used to determine a precoding matrix, wherein both K and P are positive integers; and
determining the precoding matrix based on the first indication information.
12. The method according to claim 11 , further comprising:
sending second indication information, wherein the second indication information is used to indicate the one or more delay vectors corresponding to each of the K angle vectors.
13. The method according to claim 12 , wherein the second indication information comprises K bitmaps, a k th bitmap in the K bitmaps is used to indicate L k delay vectors that are in a delay vector set and that correspond to a k th angle vector in the K angle vectors, and the delay vector set comprises a plurality of delay vectors, wherein L k ≥1, and L k is an integer.
14. The method according to claim 12 , wherein the second indication information comprises K indexes, a k th index in the K indexes is an index, in a delay vector set, of a combination of L k delay vectors corresponding to a k th angle vector in the K angle vectors, and the delay vector set comprises a plurality of delay vectors, wherein L k ≥1, and L k is an integer.
15. The method according to claim 14 , wherein the second indication information is further used to indicate a quantity of delay vectors corresponding to each angle vector.
16. The method according to claim 12 , wherein the second indication information is used to indicate an index of a combination of the P angle-delay pairs.
17. The method according to claim 11 , wherein in the K angle vectors, one or more delay vectors corresponding to a first angle vector are the same as one or more delay vectors corresponding to a second angle vector, and the first angle vector and the second angle vector are any two angle vectors in the K angle vectors.
18. The method according to claim 11 , wherein the K angle vectors and the one or more delay vectors corresponding to each angle vector are determined through uplink channel measurement.
19. The method according to claim 11 , wherein the P weighting coefficients comprise one or more weighting coefficients fed back for each of the K angle vectors; and for the k th angle vector in the K angle vectors, the first indication information is used to indicate L k weighting coefficients, the L k weighting coefficients correspond to L k angle-delay pairs in the P angle-delay pairs, and each of the L k angle-delay pairs comprises the k th angle vector and one of the L k delay vectors corresponding to the k th angle vector, wherein L k ≥1, and L k is an integer.
20. The method according to claim 11 , wherein the P weighting coefficients correspond to one receive antenna or one transport layer.