Communication method and apparatus
Embodiments of this application provide a communication method and an apparatus. A correspondence between a plurality of MCS indexes and a plurality of modulation schemes is provided to achieve flexible selection of a modulation scheme. In the correspondence, at least one MCS index of the plurality of MCS indexes corresponds to a set modulation schemes which comprises π/2 binary phase shift keying (π/2-BPSK) modulation and quadrature phase shift keying (QPSK) modulation. A first communication device receives a target modulation and coding scheme (MCS) index from a second communication device, determines a target modulation scheme corresponding to the target index number based on the correspondence, and performs communication with the second communication device based on the target modulation scheme.
1. A communication method, comprising:
receiving, by a first communication device, a target modulation and coding scheme (MCS) index from a second communication device;
determining, by the first communication device, a target modulation scheme corresponding to the target MCS index based on a correspondence between a plurality of MCS indexes and a plurality of modulation schemes, wherein in the correspondence, at least one MCS index of the plurality of MCS indexes corresponds to one modulation scheme in a set of modulation schemes, the set of modulation schemes comprising: π/2 binary phase shift keying (π/2-BPSK) modulation and quadrature phase shift keying (QPSK) modulation; and
performing, by the first communication device, communication with the second communication device based on the target modulation scheme corresponding to the target MCS index;
wherein the plurality of MCS indexes includes MCS index 1, and a spectral efficiency corresponding to the MCS index 1 is 0.3066.
2. The method according to claim 1 , wherein the at least one MCS index is 0 or 1.
3. The method according to claim 1 , wherein the set of modulation schemes is represented by a modulation order of q, wherein q is configured to be 1 if π/2-BPSK modulation is supported by the first communication device, and q is configured to be 2 if π/2-BPSK modulation is not supported by the first communication device.
4. The method according to claim 3 , wherein the plurality of MCS indexes includes MCS index 0, and a spectral efficiency corresponding to the MCS index 0 is 0.2344.
5. The method according to claim 3 , wherein the plurality of MCS indexes includes MCS index 0, and a target code rate corresponding to the MCS index 0 is 240/q.
6. The method according to claim 3 , wherein the plurality of MCS indexes includes MCS index 1, and a target code rate corresponding to the MCS index 1 is 314/q.
7. The method according to claim 1 , wherein a part of the correspondence is represented by following table:
Target code
Spectral
MCS index
Modulation order
rate * 1024
efficiency
0
q
240/q
0.2344
1
q
314/q
0.3066
2
2
193
0.3770
3
2
251
0.4902
4
2
308
0.6016
5
2
379
0.7402
6
2
449
0.8770
7
2
526
1.0273
8
2
602
1.1758
9
2
679
1.3262
q is configured to be 1 or 2, wherein 1 is corresponding to π/2-BPSK modulation, and 2 is corresponding to QPSK modulation.
8. The method according to claim 1 , further comprising:
reporting, by the first communication device to the second communication device, information about whether the first communication device supports π/2-BPSK modulation.
9. The method according to claim 1 , further comprising:
when the first communication device does not supports π/2-BPSK modulation, determining, by the first communication device, that the target modulation scheme corresponding to the target MCS index is QPSK modulation.
10. The method according to claim 1 , wherein both MCS index 0 and MCS index 1 in the plurality of MCS indexes correspond to the set of modulation schemes.
11. An apparatus, comprising:
one or more memories configured to store instructions; and
one or more processors coupled to the one or more memories and configured to execute the instructions to cause the apparatus to:
receive a target modulation and coding scheme (MCS) index from a second communications device;
determine a target modulation scheme corresponding to the target MCS index based on a correspondence between a plurality of MCS indexes and a plurality of modulation schemes, wherein in the correspondence, at least one MCS index of the plurality of MCS indexes corresponding to one modulation scheme in a set of modulation schemes, the set of modulation schemes comprising: π/2 binary phase shift keying (π/2-BPSK) modulation and quadrature phase shift keying (QPSK) modulation; and
perform communication with the second communications device based on the target modulation scheme corresponding to the target MCS index;
wherein the plurality of MCS indexes includes MCS index 1, and a spectral efficiency corresponding to the MCS index 1 is 0.3066.
12. The apparatus according to claim 11 , wherein the at least one MCS index is 0 or 1.
13. The apparatus according to claim 11 , wherein the set of modulation schemes is represented by a modulation order of q, wherein q is configured to be 1 if π/2-BPSK modulation is supported by the apparatus, and q is configured to be 2 if π/2-BPSK modulation is not supported by the apparatus.
14. The apparatus according to claim 13 , wherein the plurality of MCS indexes includes MCS index 0, and a spectral efficiency corresponding to the MCS index 0 is 0.2344.
15. The apparatus according to claim 13 , wherein the plurality of MCS indexes includes MCS index 0, and a target code rate corresponding to the MCS index 0 is 240/q.
16. The apparatus according to claim 13 , wherein the plurality of MCS indexes includes MCS index 1, and a target code rate corresponding to the MCS index 1 is 314/q.
17. The apparatus according to claim 11 , wherein a part of the correspondence is represented by following table:
Target code
Spectral
MCS index
Modulation order
rate * 1024
efficiency
0
q
240/q
0.2344
1
q
314/q
0.3066
2
2
193
0.3770
3
2
251
0.4902
4
2
308
0.6016
5
2
379
0.7402
6
2
449
0.8770
7
2
526
1.0273
8
2
602
1.1758
9
2
679
1.3262
q is configured to be 1 or 2, wherein 1 is corresponding to π/2-BPSK modulation, and 2 is corresponding to QPSK modulation.
18. The apparatus according to claim 11 , wherein the one or more processors are further configured to execute the instructions to cause the apparatus to:
report information about whether the apparatus supports π/2-BPSK modulation to the second communications device.
19. The apparatus according to claim 11 , wherein the one or more processors are further configured to execute the instructions to cause the apparatus to:
when the apparatus does not supports π/2-BPSK modulation, determine that the target modulation scheme corresponding to the target MCS index is QPSK modulation.