Channel state information (CSI) acquisition for dynamic MIMO transmission
Certain aspects of the present disclosure provide techniques for dynamic switching of reference transmission schemes used by a UE for CSI measurement and reporting.
1 . A method for wireless communications by a user equipment (UE), comprising:
determining a reference basis for a measurement procedure based on signaling received from a base station (BS), wherein the reference basis indicates a reference transmission scheme (TS) for performing the measurement procedure, and wherein the signaling comprises an indication of the reference basis via higher layer signaling;
performing the measurement procedure based on the determination; and
transmitting a measurement report based on performing the measurement procedure.
2 . The method of claim 1 , wherein the indication is an explicit indication of the reference basis via the higher layer signaling.
3 . The method of claim 2 , wherein:
the signaling comprises a configuration of one or more channel state information (CSI) reference signals (CSI-RS) resources; and
the determination is based on an association of a transmission scheme configured for each of the one or more CSI-RS resources.
4 . The method of claim 2 , wherein:
the signaling comprises a configuration of one or more channel state information (CSI) processes; and
the determination is based on an association of a transmission scheme configured for each of the one or more CSI reference signal (CSI-RS) processes.
5 . The method of claim 2 , wherein:
the signaling comprises a configuration of one or more channel state information (CSI) reporting schemes; and
the determination is based on an association of a transmission scheme configured for each of the one or more CSI reference signal (CSI-RS) reporting schemes.
6 . The method of claim 2 , wherein:
the signaling comprises a configuration of one or more channel state information (CSI) processes belonging to multiple aperiodic CSI (A-CSI) triggering sets; and
the determination is based on an association of a transmission scheme configured for each of the one or more A-CSI triggering sets.
7 . The method of claim 6 , wherein:
when the UE is triggered to report CSI for an A-CSI triggering set, the UE assumes the transmission scheme associated with the CSI process in that A-CSI triggering set.
8 . The method of claim 1 , wherein the signaling comprises an explicit indication of a transmission scheme via Layer 1 signaling.
9 . The method of claim 8 , wherein:
the UE is configured with a subset of reference bases for the measurement procedure; and
the signaling indicates a basis in the configured subset.
10 . The method of claim 9 , wherein:
the signaling indicates a reference basis the UE is to use for the measurement procedure until receiving a release indication.
11 . The method of claim 10 , wherein release indication also indicates another basis in the configured subset to use for the measurement procedure until receiving a setup indication.
12 . The method of claim 10 , wherein the UE assumes a default basis for the measurement procedure after receiving the release indication.
13 . The method of claim 1 , wherein:
the UE is configured with a subset of reference bases for the measurement procedure; and
the signaling indicates the UE is to cycle through the bases in the subset for different periodic measurement reporting instances.
14 . The method of claim 13 , wherein the UE is to begin cycling with a first basis in the subset determined based on at least one of: an indication provided in the signaling, a particular basis in the subset, or derived based on an index for a subframe in which the signaling is received.
15 . The method of claim 13 , wherein the UE is configured to, after receiving the release signaling, use at least one of a default basis or same basis as before receiving the release signaling.
16 . The method of claim 1 , wherein the signaling comprises an implicit indication of the reference basis for the measurement procedure.
17 . The method of claim 16 , wherein the signaling comprises a subframe index.
18 . The method of claim 17 , wherein the subframe index comprises: a subframe index for a subframe in which aperiodic channel state information (CSI) (A-CSI) triggering or semi-persistent CSI reporting setup signaling is received.
19 . The method of claim 17 , wherein the subframe index comprises: a subframe index for a subframe in which the channel state information (CSI) reference signal (CSI-RS) for CSI measurement is transmitted.
20 . The method of claim 17 , wherein the subframe index comprises: a subframe index for a subframe in which the measurement report is transmitted.
21 . The method of claim 16 , wherein the signaling comprises signaling for a type of control channel.
22 . The method of claim 1 , wherein the signaling comprises a configuration of a number of resource elements (REs) for each basis assumed for reporting.
23 . The method of claim 1 , wherein the signaling comprises a configuration of a ratio of physical downlink shared channel (PDSCH) energy per resource element (EPRE) to channel state information (CSI) reference signal (RS) (CSI-RS) EPRE for each reference basis assumed for reporting.
24 . The method of claim 1 , wherein the UE uses different bases for aperiodic channel state information (CSI) reporting than for periodic CSI reporting.
25 . The method of claim 1 , wherein the UE provides to the BS an indication of the reference basis which is assumed for the measurement reporting.
26 . A method for wireless communications by a base station (BS), comprising:
providing signaling to a user equipment (UE) allowing the UE to determine a reference basis for a measurement procedure, wherein the reference basis indicates a reference transmission scheme (TS) for performing the measurement procedure, and wherein the signaling comprises an indication of the reference basis via higher layer signaling; and
receiving a measurement report from the UE based on the measurement performed according to the reference basis.
27 . The method of claim 26 , wherein the indication is an explicit indication of the reference basis via the higher layer signaling.
28 . The method of claim 27 , wherein:
the signaling comprises a configuration of one or more channel state information (CSI) reference signals (CSI-RS) resources; and
each of the one or more CSI-RS resources has an associated reference basis.
29 . The method of claim 27 , wherein:
the signaling comprises a configuration of one or more measurement processes; and
each of the one or more measurement processes has an associated reference basis for the measurement procedure.
30 . The method of claim 27 , wherein:
the signaling comprises a configuration of one or more measurement reporting schemes; and
each of the one or more measurement reporting schemes has an associated reference basis.
31 . The method of claim 27 , wherein:
the signaling comprises a configuration of one or more channel state information (CSI) processes belonging to multiple aperiodic CSI (A-CSI) triggering sets; and
each of the one or more A-CSI triggering sets has an associated reference basis.
32 . The method of claim 31 , wherein:
when the UE is triggered to report CSI for an A-CSI triggering set, the BS assumes the UE used the reference basis associated with the CSI process in that A-CSI triggering set.
33 . The method of claim 32 , wherein the signaling comprises an explicit indication of a reference basis for the measurement procedure via Layer 1 signaling.
34 . The method of claim 33 , wherein:
the UE is configured with a subset of reference bases for the measurement procedure; and
the signaling indicates a basis in the configured subset.
35 . The method of claim 33 , wherein:
the signaling indicates a reference basis the UE is to use for the measurement procedure until the BS sends the UE a release indication.
36 . The method of claim 35 , wherein release indication also indicates another basis in the configured subset to use for the measurement procedure until the BS transmits the UE a setup indication.
37 . The method of claim 35 , wherein the BS assumes the UE uses a default basis after receiving the release indication.
38 . The method of claim 26 , wherein:
the UE is configured with a subset of reference bases for the measurement procedure; and
the signaling indicates the UE is to cycle through the bases in the subset for different periodic CSI reporting instances.
39 . The method of claim 38 , wherein the UE is to begin cycling with a first basis in the subset determined based on at least one of: an indication provided in the signaling, a particular basis in the subset, or derived based on an index for a subframe in which the signaling is received.
40 . The method of claim 38 , wherein the BS is configured to assume, after transmitting the release signaling, that the UE uses at least one of a default basis or same basis as before the BS transmitted the release signaling.
41 . The method of claim 26 , wherein the signaling comprises an implicit indication of a reference basis for the measurement procedure.
42 . The method of claim 41 , wherein the signaling comprises a subframe index.
43 . The method of claim 42 , wherein the subframe index comprises: a subframe index for a subframe in which aperiodic channel state information (CSI) (A-CSI) triggering or semi-persistent CSI reporting setup signaling is received.
44 . The method of claim 42 , wherein the subframe index comprises: a subframe index for a subframe in which a channel state information (CSI) reference signal (CSI-RS) for CSI measurement is transmitted.
45 . The method of claim 42 , wherein the subframe index comprises: a subframe index for a subframe in which the measurement report is transmitted.
46 . The method of claim 41 , wherein the signaling comprises signaling for a type of control channel.
47 . The method of claim 26 , wherein the signaling comprises a configuration of a number of resource elements (REs) for each basis for the measurement procedure assumed for reporting.
48 . The method of claim 26 , wherein the signaling comprises a configuration of a ratio of physical downlink shared channel (PDSCH) energy per resource element (EPRE) to channel state information (CSI) reference signal (RS) (CSI-RS) EPRE for each reference basis for the measurement procedure assumed for reporting.
49 . The method of claim 26 , wherein the BS configures the UE to use different bases for aperiodic CSI reporting than for periodic CSI reporting.
50 . The method of claim 26 , further comprising receiving, from the UE, an indication of the reference basis which is assumed for the CSI reporting.