Codebook subsampling for multi-antenna transmit precoder codebook
View Patent ↗Embodiments provide approaches for sub-sampling a two-component precoder codebook to reduce the overhead associated with signaling the codebook in periodic Channel State Information (CSI) reports from a user equipment (UE) to a base station. In one embodiment, a first component of the codebook is sub-sampled to accommodate a payload capacity of a Physical Uplink Control Channel (PUCCH) CSI Report of Type 1. In another embodiment, both the first component and the second component of the codebook are sub-sampled to accommodate a maximum payload capacity associated with a PUCCH CSI report.
1. A User Equipment (UE), comprising:
processor circuitry configured to:
generate an estimate of a downlink channel from a base station;
select a precoder matrix, based on the estimate, from a first precoder codebook when the precoder matrix is for signaling on an aperiodic uplink resource; and
select a first component and a second component of the precoder matrix, based on the estimate, from a second precoder codebook when the precoder matrix is for signaling on a periodic uplink resource, wherein the second precoder codebook is a joint sub-sampled codebook that is a sub-sampled version of the first precoder codebook; and
transceiver circuitry configured to transmit the precoder matrix to the base station.
2. The UE of claim 1 , wherein the aperiodic uplink resource is a Physical Uplink Shared Channel (PUSCH) resource, and the periodic resource is a Physical Uplink Control Channel (PUCCH) resource.
3. The UE of claim 1 , wherein the processor circuitry is further configured to jointly signal the first component and the second component in a Physical Uplink Control Channel (PUCCH) 1-1, sub-mode 2 Channel State Information (CSI) report to the base station.
4. The UE of claim 1 , wherein the joint sub-sampled codebook includes 16 entries.
5. The UE of claim 1 , wherein when the precoder matrix is selected for signaling on the periodic uplink resource, the processor circuitry is further configured to: select the precoder matrix from a sub-sampled codebook composed of Discrete Fourier Transform (DFT) form precoder matrices of the first precoder codebook.
6. The UE of claim 1 , wherein selecting the precoder matrix for signaling on the aperiodic uplink resource comprises selecting the precoder matrix, based on the estimate, from a complete precoder codebook.
7. A User Equipment (UE), comprising:
processor circuitry configured to:
generate an estimate of a downlink channel from a base station;
select a precoder matrix, based on the estimate, from a first precoder codebook when the precoder matrix is for signaling on an aperiodic uplink resource;
select the precoder matrix, based on the estimate, from a second precoder codebook when the precoder matrix is for signaling on a periodic uplink resource; and
transceiver circuitry configured to transmit the precoder matrix to the base station;
wherein when the precoder matrix is selected for signaling on the periodic uplink resource, the processor circuitry is further configured to:
select a first component of the precoder matrix from a sub-sampled space associated with the first component, and select a second component of the precoder matrix from a complete space associated with the second component; and
jointly signal the first component and a rank indicator (RI) in a Physical Uplink Control Channel (PUCCH) 1-1, sub-mode 1 Channel State Information (CSI) report to the base station, wherein the joint signaling of the first component and the RI includes a same set of bits that represents both the first component and the RI.
8. The UE of claim 7 , wherein a payload of the PUCCH 1-1, sub-mode 1 CSI report is 4 or 5 bits long.
9. The UE of claim 7 , wherein the sub-sampled space associated with the first component is configured to span a full range of a cross-polarization phase difference associated with transmit antennas of the base station.
10. The UE of claim 7 , wherein the aperiodic uplink resource is a Physical Uplink Shared Channel (PUSCH) resource, and the periodic resource is a Physical Uplink Control Channel (PUCCH) resource.
11. The UE of claim 7 , wherein selecting the precoder matrix for signaling on the aperiodic uplink resource comprises selecting the precoder matrix, based on the estimate, from a complete precoder codebook.
12. The UE of claim 7 , wherein the processor circuitry is further configured to signal the second component in a second CSI report to the base station.
13. A method, comprising:
generating an estimate of a downlink channel from a base station;
selecting a precoder matrix, based on the estimate, from a first precoder codebook when the precoder matrix is for signaling on an aperiodic uplink resource;
selecting a first component and a second component of the precoder matrix, based on the estimate, from a second precoder codebook when the precoder matrix is for signaling on a periodic uplink resource, wherein the second precoder codebook is a joint sub-sampled codebook that is a sub-sampled version of the first precoder codebook; and
transmitting the precoder matrix to the base station.
14. The method of claim 13 , wherein the aperiodic uplink resource is a Physical Uplink Shared Channel (PUSCH) resource, and the periodic resource is a Physical Uplink Control Channel (PUCCH) resource.
15. The method of claim 13 , further comprising:
jointly signaling the first component and the second component in a Physical Uplink Control Channel (PUCCH) 1-1, sub-mode 2 Channel State Information (CSI) report to the base station.
16. The method of claim 13 , wherein the joint sub-sampled codebook includes 16 entries.
17. A method, comprising:
generating an estimate of a downlink channel from a base station;
selecting a precoder matrix, based on the estimate, from a first precoder codebook when the precoder matrix is for signaling on an aperiodic uplink resource;
selecting the precoder matrix, based on the estimate, from a second precoder codebook when the precoder matrix is for signaling on a periodic uplink resource; and
transmitting the precoder matrix to the base station;
wherein when the precoder matrix is selected for signaling on the periodic uplink resource, the method further comprising:
selecting a first component of the precoder matrix from a sub-sampled space associated with the first component, and selecting a second component of the precoder matrix from a complete space associated with the second component; and
jointly signaling the first component and a rank indicator (RI) in a Physical Uplink Control Channel (PUCCH) 1-1, sub-mode 1 Channel State Information (CSI) report to the base station, wherein the jointly signaling of the first component and the RI includes a same set of bits that represents both the first component and the RI.
18. The method of claim 17 , wherein the sub-sampled space associated with the first component is configured to span a full range of a cross-polarization phase difference associated with transmit antennas of the base station.
19. The method of claim 17 , wherein the aperiodic uplink resource is a Physical Uplink Shared Channel (PUSCH) resource, and the periodic resource is a Physical Uplink Control Channel (PUCCH) resource.
20. The method of claim 17 , further comprising signaling the second component in a second CSI report to the base station.