Method and apparatus for obtaining reference signal

1 . A method, comprising:

obtaining, by a terminal device, a first position and a first offset, wherein the first position is a quantity of physical resource blocks by which a smallest subcarrier within a bandwidth comprising a control channel resource set is offset from a frequency domain reference point, and wherein the first offset is a quantity of physical resource blocks by which a smallest subcarrier in the control channel resource set is offset from the smallest subcarrier within the bandwidth comprising the control channel resource set;

obtaining, by the terminal device, a demodulation reference signal sequence based on the first position and the first offset; and

demodulating, by the terminal device, by using the demodulation reference signal sequence, a control channel signal carried in the control channel resource set, to obtain downlink control information.

2 . The method according to claim 1 , wherein:

a physical resource block number of the frequency domain reference point is 0, and the frequency domain reference point is notified by system information; or

the frequency domain reference point is a candidate position of a channel raster.

3 . The method according to claim 1 , wherein the first position is indicated by higher layer signaling, wherein the higher layer signaling comprises radio resource control (RRC) signaling.

4 . The method according to claim 1 , wherein the first offset is determined based on configuration information comprised in higher layer signaling, wherein the higher layer signaling comprises radio resource control (RRC) signaling.

5 . The method according to claim 1 , wherein the demodulation reference signal sequence is mapped to a resource element in the control channel resource set.

6 . A communication apparatus, comprising:

one or more processors; and

at least one memory, wherein the at least one memory stores instructions, and when executing the instructions stored in the memory, the one or more processors executes operations comprising:

obtaining a first position and a first offset, wherein the first position is a quantity of physical resource blocks by which a smallest subcarrier within a bandwidth comprising a control channel resource set is offset from a frequency domain reference point, and wherein the first offset is a quantity of physical resource blocks by which a smallest subcarrier in the control channel resource set is offset from the smallest subcarrier within the bandwidth comprising the control channel resource set;

obtaining a demodulation reference signal sequence based on the first position and the first offset; and

demodulating, by using the demodulation reference signal sequence, a control channel signal carried in the control channel resource set, to obtain downlink control information.

7 . The apparatus according to claim 6 , wherein:

a physical resource block number of the frequency domain reference point is 0, and the frequency domain reference point is notified by system information; or

the frequency domain reference point is a candidate position of a channel raster.

8 . The apparatus according to claim 6 , wherein:

the first position is indicated by higher layer signaling, wherein the higher layer signaling comprises radio resource control (RRC) signaling.

9 . The apparatus according to claim 6 , wherein:

the first offset is determined based on configuration information comprised in higher layer signaling, wherein the higher layer signaling comprises radio resource control (RRC) signaling.

10 . The apparatus according to claim 6 , wherein:

the demodulation reference signal sequence is mapped to a resource element carrying a reference signal in the control channel resource set.

11 . One or more non-transitory computer-readable media storing computer instructions, that when executed by one or more processors, cause a computing device to perform operations comprising:

obtaining, by a terminal device, a first position and a first offset, wherein the first position is a quantity of physical resource blocks by which a smallest subcarrier within a bandwidth comprising a control channel resource set is offset from a frequency domain reference point, and wherein the first offset is a quantity of physical resource blocks by which a smallest subcarrier in the control channel resource set is offset from the smallest subcarrier within the bandwidth comprising the control channel resource set;

obtaining, by the terminal device, a demodulation reference signal sequence based on the first position and the first offset; and

demodulating, by the terminal device, by using the demodulation reference signal sequence, a control channel signal carried in the control channel resource set, to obtain downlink control information.

12 . The one or more non-transitory computer-readable media according to claim 11 , wherein:

a physical resource block number of the frequency domain reference point is 0, and the frequency domain reference point is notified by system information; or

the frequency domain reference point is a candidate position of a channel raster.

13 . The one or more non-transitory computer-readable media according to claim 11 , wherein the first position is indicated by higher layer signaling, wherein the higher layer signaling comprises radio resource control (RRC) signaling.

14 . The one or more non-transitory computer-readable media according to claim 11 , wherein the first offset is determined based on configuration information comprised in higher layer signaling, wherein the higher layer signaling comprises radio resource control (RRC) signaling.

15 . The one or more non-transitory computer-readable media according to claim 11 , wherein the demodulation reference signal sequence is mapped to a resource element in the control channel resource set.