Frequency-selective precoding for uplink transmissions in mobile communications
Various examples with respect to frequency-selective precoding for uplink (UL) transmissions in mobile communications are described. A processor of a user equipment (UE) receives signaling from a network node of a wireless network. The processor then performs a codebook-based UL transmission to the network node with frequency-selective precoding in a subband of a plurality of subbands according to the signaling received from the network. For non-codebook-based UL transmissions, the processor performs a non-codebook-based UL transmission of a beamformed sounding reference signal (SRS) to the network node by determining a precoder and performing frequency-selective precoding on the SRS using the precoder with a size of precoder bundling for the frequency-selective precoding in a frequency domain known by the network node.
1. An apparatus implementable in a user equipment (UE), comprising:
a processor which, when in operation, performs a codebook-based uplink (UL) transmission or a non-codebook-based UL transmission to a network node of a wireless network with frequency-selective precoding,
wherein a size of precoder bundling for the frequency-selective precoding in a frequency domain in the codebook-based UL transmission or the non-codebook-based UL transmission is known by the UE, and
wherein the size of the precoder bundling defines a subband as a number of contiguous physical resource blocks (PRBs) precoded using a same precoder.
2. The apparatus of claim 1 , wherein a subband transmission precoder matrix indication(TPMI) is indicated by a TPMI index differentially with respect to a wideband TPMI according to a mapping between TPMI indices and a plurality of precoders, wherein the subband TPMI corresponds to a respective precoder of the plurality of precoders for precoding in a subband or in a plurality of subbands, wherein, in performing the codebook-based UL transmission, the processor further receives signaling from the network node an indication of the mapping between TPMI indices and the plurality of precoders, and wherein the indication comprises a permutation of a predefined mapping between the TPMI index and one of the plurality of precoders or a selection of one mapping from a plurality of predefined mappings between the TPMI index and one of the plurality of precoders.
3. The apparatus of claim 1 , wherein, in performing the codebook-based UL transmission, the processor further performs:
receiving from the network node an indication of the size of the precoder bundling,
wherein, in performing the codebook-based UL transmission, the processor bundles the PRBs into a plurality of PRB bundles each corresponding to a respective subband of one subband or a plurality of subbands, and wherein a number of PRBs in each of the PRB bundles corresponds to the size of the precoder bundling.
4. The apparatus of claim 1 , wherein, in performing the non-codebook-based UL transmission, the processor further performs:
measuring a channel state information reference signal (CSI-RS) transmitted by the network node; and
performing the non-codebook-based UL transmission with a beamformed sounding reference signal (SRS) to the network node by:
determining a precoder based on a result of the measuring; and
performing frequency-selective precoding on the SRS using the precoder.
5. The apparatus of claim 1 , wherein the size of the precoder bundling is predefined or signaled to the UE from the network node.
6. The apparatus of claim 1 , wherein, in performing the non-codebook-based UL transmission, the processor further performs:
modifying the size of the precoder bundling; and
transmitting a report to the network node indicating a modification of the size of the precoder bundling.
7. The apparatus of claim 1 , wherein, in performing the non-codebook-based UL transmission, the processor further performs:
determining the size of the precoder bundling; and
transmitting a report to the network node indicating the size of the precoder bundling.
8. The apparatus of claim 1 , wherein, in performing the codebook-based UL transmission, the processor performs:
receiving a subband transmission precoder matrix indication (TPMI) containing information supporting the frequency-selective precoding for the codebook-based UL transmission; and
performing the codebook-based UL transmission to the network node with the frequency-selective precoding in one subband or a plurality of subbands according to the subband TPMI.
9. A method, comprising:
performing, by a processor of a user equipment (UE), a codebook-based uplink (UL) transmission or a non-codebook-based UL transmission to a network node of a wireless network with frequency-selective precoding;
wherein a size of precoder bundling for the frequency-selective precoding in a frequency domain in the codebook-based UL transmission or the non-codebook-based UL transmission is known by the UE, and
wherein the size of the precoder bundling defines a subband as a number of contiguous physical resource blocks (PRBs) precoded using a same precoder.
10. The method of claim 9 , wherein a subband transmission precoder matrix indication (TPMI) is indicated by a TPMI index differentially with respect to a wideband TPMI according to a mapping between TPMI indices and a plurality of precoders, wherein the subband TPMI corresponds to a respective precoder of the plurality of precoders for precoding in a subband or in a plurality of subbands, wherein the performing of the codebook-based UL transmission further comprises receiving signaling from the network node an indication of the mapping between TPMI indices and the plurality of precoders, and wherein the indication comprises a permutation of a predefined mapping between the TPMI index and one of the plurality of precoders or a selection of one mapping from a plurality of predefined mappings between the TPMI index and one of the plurality of precoders.
11. The method of claim 9 , wherein the performing of the codebook- based UL transmission further comprises:
receiving from the network node an indication of the size of the precoder bundling,
wherein the performing of the codebook-based UL transmission comprises bundling the PRBs into a plurality of PRB bundles each corresponding to a respective subband of one subband or a plurality of subbands, and
wherein a number of PRBs in each of the PRB bundles corresponds to the size of the precoder bundling.
12. The method of claim 9 , wherein the performing of the non-codebook- based UL transmission further comprises:
measuring a channel state information reference signal (CSI-RS) transmitted by the network node; and
performing the non-codebook-based UL transmission with a beamformed sounding reference signal (SRS) to the network node by:
determining a precoder based on a result of the measuring; and
performing frequency-selective precoding on the SRS using the precoder.
13. The method of claim 12 , wherein the size of the precoder bundling is predefined or signaled to the UE from the network node.
14. The method of claim 13 , wherein the performing of the non-codebook- based UL transmission further comprises:
modifying the size of the precoder bundling; and
transmitting a report to the network node indicating a modification of the size of the precoder bundling.
15. The method of claim 12 , wherein the performing of the non-codebook- based UL transmission further comprises:
determining the size of the precoder bundling; and
transmitting a report to the network node indicating the size of the precoder bundling.
16. The method of claim 9 , wherein the performing of the codebook- based UL transmission comprises:
receiving a subband transmission precoder matrix indication (TPMI) containing information supporting the frequency-selective precoding for the codebook-based UL transmission; and
performing the codebook-based UL transmission to the network node with the frequency-selective precoding in one subband or a plurality of subbands according to the subband TPMI.