CONFIGURING A MAXIMUM NUMBER OF LAYERS
Methods, systems, and devices for wireless communications are described. Generally, a user equipment (UE) may send a capabilities report to a base station. The capabilities report may include an explicit indication that the UE is capable of receiving a maximum layer radio resource control (RRC) parameter, or may include ambiguous (e.g., multiple) capabilities. The base station may receive the capabilities report, and may determine whether to transmit a maximum layer RRC parameter based on the explicit indication, or the ambiguous capabilities, which indicates a maximum number of layers to be used for subsequent communications. If the UE is capable of receiving the maximum layer RRC parameter, the base station may send the maximum layer RRC parameter to the UE, and may perform wireless communications according to the indicated maximum number of layers.
1 . A method for wireless communication at a user equipment (UE), comprising:
transmitting capability information indicating that the UE is capable of receiving, from a base station, an indication of a maximum number of layers that the base station will use to transmit to the UE in at least one set of frequency resources of a radio frequency (RF) spectrum band;
receiving, from the base station in response to the transmitted capability information, the indication of the maximum number of layers; and
receiving, according to the indicated maximum number of layers, signals from the base station using the at least one set of frequency resources.
2 . The method of claim 1 , wherein transmitting the capability information comprises:
transmitting, in the capability information, a parameter value indicating that the UE is capable of receiving the indication of the maximum number of layers.
3 . The method of claim 1 , wherein receiving the indication of the maximum number of layers comprises:
receiving radio resource control signaling comprising a parameter that identifies the maximum number of layers.
4 . The method of claim 1 , further comprising:
configuring, based at least in part on the indicated maximum number of layers, a size of a soft buffer at the UE.
5 . The method of claim 1 , further comprising:
selecting, by the UE, a CSI report format based at least in part on the indicated maximum number of layers; and
transmitting a CSI report to the base station according to the selected CSI report format.
6 . The method of claim 1 , further comprising:
determining, based at least in part on the indicated maximum number of layers, a sounding reference signal port sounding configuration; and
transmitting sounding reference signals to the base station according to the determined sounding reference signal port sounding configuration.
7 . The method of claim 1 , further comprising:
determining, by the UE, a downlink control information format based at least in part on the indicated maximum number of layers; and
receiving, from the base station, at least on downlink control information signal according to the determined downlink control information format.
8 . The method of claim 1 , wherein transmitting the capability information comprises:
transmitting, to the base station, a UE radio access capability parameter indicating that the UE is capable of receiving the indication of the maximum number of layers.
9 . The method of claim 1 , wherein the at least one set of frequency resources comprises a bandwidth part, or a subband, or a combination thereof, of the RF spectrum band.
10 . The method of claim 1 , wherein receiving the signals from the base station according to the indicated maximum number of layers comprises:
receiving the signals from the base station using a number of layers equal to or less than the indicated maximum number of layers.
11 . A method for wireless communication at a base station, comprising:
receiving, from a user equipment (UE) capability information indicating that the UE is capable of receiving an indication of a maximum number of layers that the base station will use to transmit to the UE in at least one set of frequency resources of a radio frequency (RF) spectrum band;
transmitting, to the UE in response to the received capability information, the indication of the maximum number of layers; and
transmitting, according to the indicated maximum number of layers, signals to the UE using the at least one set of frequency resources.
12 . The method of claim 11 , wherein receiving the capability information comprises:
receiving, with the capability information, a parameter value indicating that the UE is capable of receiving the indication of the maximum number of layers.
13 . The method of claim 11 , wherein transmitting the indication of the maximum number of layers comprises:
transmitting radio resource control signaling comprising a parameter that identifies the maximum number of layers.
14 . The method of claim 11 , further comprising:
determining a downlink control information format for the UE based at least in part on the maximum number of layers; and
transmitting, to the UE, at least on downlink control information signal according to the determined downlink control information format.
15 . The method of claim 11 , wherein receiving the capability information comprises:
receiving, from the UE, a UE radio access capability parameter indicating that the UE is capable of receiving the indication of the maximum number of layers.
16 . The method of claim 11 , wherein the at least one set of frequency resources comprises a bandwidth part, or a subband, or a combination thereof, of the RF spectrum band.
17 . The method of claim 11 , wherein transmitting the signals to the UE according to the indicated maximum number of layers comprises:
transmitting the signals to the UE using a number of layers equal to or less than the indicated maximum number of layers.
18 . An apparatus for wireless communication at a user equipment (UE), comprising:
a processor,
memory in electronic communication with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
transmit capability information indicating that the UE is capable of receiving, from a base station, an indication of a maximum number of layers that the base station will use to transmit to the UE in at least one set of frequency resources of a radio frequency (RF) spectrum band;
receive, from the base station in response to the transmitted capability information, the indication of the maximum number of layers; and
receive, according to the indicated maximum number of layers, signals from the base station using the at least one set of frequency resources.
19 . The apparatus of claim 18 , wherein the instructions to transmit the capability information are executable by the processor to cause the apparatus to:
transmit, in the capability information, a parameter value indicating that the UE is capable of receiving the indication of the maximum number of layers.
20 . The apparatus of claim 18 , wherein the instructions to receive the indication of the maximum number of layers are executable by the processor to cause the apparatus to:
receive radio resource control signaling comprising a parameter that identifies the maximum number of layers.
21 . The apparatus of claim 18 , wherein the instructions are further executable by the processor to cause the apparatus to:
configure, based at least in part on the indicated maximum number of layers, a size of a soft buffer at the UE.
22 . The apparatus of claim 18 , wherein the instructions are further executable by the processor to cause the apparatus to:
select, by the UE, a CSI report format based at least in part on the indicated maximum number of layers; and
transmit a CSI report to the base station according to the selected CSI report format.
23 . The apparatus of claim 18 , wherein the instructions are further executable by the processor to cause the apparatus to:
determine, based at least in part on the indicated maximum number of layers, a sounding reference signal port sounding configuration; and
transmit sounding reference signals to the base station according to the determined sounding reference signal port sounding configuration.
24 . The apparatus of claim 18 , wherein the instructions are further executable by the processor to cause the apparatus to:
determine, by the UE, a downlink control information format based at least in part on the indicated maximum number of layers; and
receive, from the base station, at least on downlink control information signal according to the determined downlink control information format.
25 . The apparatus of claim 18 , wherein the instructions to transmit the capability information are executable by the processor to cause the apparatus to:
transmit, to the base station, a UE radio access capability parameter indicating that the UE is capable of receiving the indication of the maximum number of layers.
26 . An apparatus for wireless communication at a base station, comprising:
a processor,
memory in electronic communication with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
receive, from a user equipment (UE) capability information indicating that the UE is capable of receiving an indication of a maximum number of layers that the base station will use to transmit to the UE in at least one set of frequency resources of a radio frequency (RF) spectrum band;
transmit, to the UE in response to the received capability information, the indication of the maximum number of layers; and
transmit, according to the indicated maximum number of layers, signals to the UE using the at least one set of frequency resources.
27 . The apparatus of claim 26 , wherein the instructions to receive the capability information are executable by the processor to cause the apparatus to:
receive, with the capability information, a parameter value indicating that the UE is capable of receiving the indication of the maximum number of layers.
28 . The apparatus of claim 26 , wherein the instructions to transmit the indication of the maximum number of layers are executable by the processor to cause the apparatus to:
transmit radio resource control signaling comprising a parameter that identifies the maximum number of layers.
29 . The apparatus of claim 26 , wherein the instructions are further executable by the processor to cause the apparatus to:
determine a downlink control information format for the UE based at least in part on the maximum number of layers; and
transmit, to the UE, at least on downlink control information signal according to the determined downlink control information format.
30 . The apparatus of claim 26 , wherein the instructions to receive the capability information are executable by the processor to cause the apparatus to:
receive, from the base station, a UE radio access capability parameter indicating that the UE is capable of receiving the indication of the maximum number of layers.