Channel state information procedure for enhanced component carriers
Techniques are provided for transmitting reference signals and CSI reports within a wireless communications system using variable length downlink or uplink transmission time intervals (TTIs). CSI reference signals and CSI reports may be transmitted at times that accommodate the variable length TTIs. A UE may receive signaling that indicates when a CSI reference signal is to be transmitted, and when a CSI report is to be transmitted to a base station. CSI reporting may be performed periodically using a physical uplink control channel (PUCCH) in designated uplink symbols, may be aperiodic using a physical uplink shared channel (PUSCH), or a combination thereof. A UE may receive signaling indicating periodic CSI reporting, aperiodic CSI reporting, or both. Such signaling may be received, for example, via radio resource control (RRC) signaling or within a downlink or uplink grant.
1. A method for wireless communication, comprising:
receiving one or more downlink reference signals in a variable length downlink transmission time interval (TTI), wherein the variable length downlink TTI comprises a variable number of downlink symbols;
receiving signaling that includes a periodicity and an offset to be used for identifying when a channel state information (CSI) report is to be transmitted;
estimating CSI for at least one of the one or more downlink reference signals;
identifying at least a portion of the estimated CSI for transmission in the CSI report in a variable length uplink TTI; and
determining that an initial symbol for transmission of the CSI report is configured as a downlink symbol, wherein the identifying further comprises identifying a subsequent uplink symbol for transmission of the CSI report as a first available uplink symbol following the initial symbol.
2. The method of claim 1 , wherein the receiving the one or more downlink reference signals further comprises:
receiving an uplink grant comprising a variable number of uplink symbols and an indication that the CSI report is to be transmitted on a physical uplink shared channel (PUSCH) in one or more of the uplink symbols.
3. The method of claim 1 , wherein the signaling comprises radio resource control (RRC) signaling.
4. The method of claim 1 , further comprising:
skipping transmitting the CSI report.
5. The method of claim 4 , wherein the identifying further comprises identifying a subsequent symbol for transmission of a subsequent CSI report for a reference signal received in one or more subsequent downlink symbols.
6. The method of claim 1 , further comprising:
transmitting the CSI report on one or more of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), wherein the transmission on the PUCCH or PUSCH is determined based on at least one of a user equipment (UE) capability, a radio resource control (RRC) configuration of the UE, or whether the UE receives an uplink UL grant to transmit PUSCH data during the variable length uplink TTI, or a combination thereof.
7. An apparatus for wireless communication, comprising:
means for receiving one or more downlink reference signals in a variable length downlink transmission time interval (TTI), wherein the variable length downlink TTI comprises a variable number of downlink symbols;
means for receiving signaling that includes a periodicity and an offset to be used for identifying when a channel state information (CSI) report is to be transmitted;
means for estimating CSI for at least one of the one or more downlink reference signals;
means for identifying at least a portion of the estimated CSI for transmission in the CSI report in a variable length uplink TTI; and
means for determining that an initial symbol for transmission of the CSI report is configured as a downlink symbol, wherein the means for identifying is operable to identify a subsequent uplink symbol for transmission of the CSI report as a first available uplink symbol following the initial symbol.
8. The apparatus of claim 7 , wherein the means for receiving the one or more downlink reference signals is operable to receive an uplink grant comprising a variable number of uplink symbols and an indication that the CSI report is to be transmitted on a physical uplink shared channel (PUSCH) in one or more of the uplink symbols.
9. The apparatus of claim 7 , wherein the signaling comprises radio resource control (RRC) signaling.
10. The apparatus of claim 7 , further comprising:
means for skipping transmitting the CSI report.
11. The apparatus of claim 7 , further comprising:
means for transmitting the CSI report on one or more of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), wherein the transmission on the PUCCH or PUSCH is determined based on at least one of a user equipment (UE) capability, a radio resource control (RRC) configuration of the UE, or whether the UE receives an uplink UL grant to transmit PUSCH data during the variable length uplink TTI, or a combination thereof.
12. An apparatus for wireless communication, comprising:
a processor;
memory in electronic communication with the processor; and
instructions stored in the memory, the instructions being executable by the processor to cause the apparatus to:
receive one or more downlink reference signals in a variable length downlink transmission time interval (TTI), wherein the variable length downlink TTI comprises a variable number of downlink symbols;
receive signaling that includes a periodicity and an offset to be used for identifying when a channel state information (CSI) report is to be transmitted;
estimate CSI for at least one of the one or more downlink reference signals;
identify at least a portion of the estimated CSI for transmission in the CSI report in a variable length uplink TTI; and
determine that an initial symbol for transmission of the CSI report is configured as a downlink symbol, wherein the instructions are further executable to identify a subsequent uplink symbol for transmission of the CSI report as a first available uplink symbol following the initial symbol.
13. The apparatus of claim 12 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive an uplink grant comprising a variable number of uplink symbols and an indication that the CSI report is to be transmitted on a physical uplink shared channel (PUSCH) in one or more of the uplink symbols.
14. The apparatus of claim 12 , wherein the signaling comprises radio resource control (RRC) signaling.
15. The apparatus of claim 12 , wherein the instructions are further executable by the processor to cause the apparatus to:
skip transmitting the CSI report.
16. The apparatus of claim 12 , wherein the instructions are further executable by the processor to cause the apparatus to:
identify a subsequent symbol for transmission of a subsequent CSI report for a reference signal received in one or more subsequent downlink symbol.
17. The apparatus of claim 12 , wherein the instructions are further executable by the processor to cause the apparatus to:
transmit the CSI report on one or more of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), wherein the transmission on the PUCCH or PUSCH is determined based on at least one of a user equipment (UE) capability, a radio resource control (RRC) configuration of the UE, or whether the UE receives an uplink UL grant to transmit PUSCH data during the variable length uplink TTI, or a combination thereof.
18. A non-transitory computer-readable medium storing computer-executable code for wireless communication, the code executable to:
receive one or more downlink reference signals in a variable length downlink transmission time interval (TTI), wherein the variable length downlink TTI comprises a variable number of downlink symbols;
receive signaling that includes a periodicity and an offset to be used for identifying when a channel state information (CSI) report is to be transmitted;
estimate CSI for at least one of the one or more downlink reference signals;
identify at least a portion of the estimated CSI for transmission in the CSI report in a variable length uplink TTI; and
determine that an initial symbol for transmission of the CSI report is configured as a downlink symbol, wherein the code is further executable to identify a subsequent uplink symbol for transmission of the CSI report as a first available uplink symbol following the initial symbol.
19. The non-transitory computer-readable medium of claim 18 , wherein the code is further executable to:
receive an uplink grant comprising a variable number of uplink symbols and an indication that the CSI report is to be transmitted on a physical uplink shared channel (PUSCH) in one or more of the uplink symbols.
20. The non-transitory computer-readable medium of claim 18 , wherein the signaling comprises radio resource control (RRC) signaling.
21. The non-transitory computer-readable medium of claim 18 , wherein the code is further executable to:
skip transmitting the CSI report.
22. The non-transitory computer-readable medium of claim 18 , wherein the code is further executable to:
transmit the CSI report on one or more of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), wherein the transmission on the PUCCH or PUSCH is determined based on at least one of a user equipment (UE) capability, a radio resource control (RRC) configuration of the UE, or whether the UE receives an uplink UL grant to transmit PUSCH data during the variable length uplink TTI, or a combination thereof.