System and method for SRS switching, transmission, and enhancements
User Equipments (UEs) may be assigned a set of aggregated component carriers for downlink carrier aggregation and/or carrier selection. Some UEs may be incapable of transmitting uplink signals over all component carriers in their assigned set of aggregated component carriers. In such scenarios, a UE may need to perform SRS switching in order to transmit SRS symbols over all of the component carriers. Embodiments of this disclosure provide various techniques for facilitating SRS switching. For example, a radio resource control (RRC) message may be used to signal a periodic SRS configuration parameter. As another example, a downlink control indication (DCI) message may be used to signal an aperiodic SRS configuration parameter. Many other examples are also provided.
1. A method comprising:
receiving, by a user equipment (UE) from a base station, first configuration information for one or more uplink transmissions of the UE on a first component carrier (CC);
receiving, by the UE from the base station, second configuration information for sounding resource signal (SRS) carrier switching, the SRS carrier switching being for transmission of one or more sounding resource signals (SRSs) over a second CC different from the first CC; and
transmitting, by the UE, an SRS over the second CC by performing the SRS carrier switching in accordance with the second configuration information, with uplink transmission over the first CC suspended at least during transmission of the SRS and during a radio frequency (RF) retuning time.
2. The method of claim 1 , wherein the first CC is configured as a switching-from CC for the second CC.
3. The method of claim 1 , further comprising:
transmitting, by the UE, a random access preamble over the second CC to the base station based on the carrier switching, with the uplink transmission over the first CC suspended at least during transmission of the random access preamble over the second CC;
receiving, by the UE, a control signaling from the base station, the control signaling indicating a timing advance for the second CC; and
wherein transmitting, by the UE, the SRS over the second CC comprises:
transmitting, by the UE, the SRS over the second CC in accordance with the timing advance.
4. The method of claim 1 , further comprising:
switching, by the UE, from the first CC to the second CC, wherein the switching from the first CC to the second CC is associated with a switching time.
5. The method of claim 4 , wherein the switching time is in accordance with a capability reported by the UE, the capability indicating the RE retuning time for switching between a first frequency band and a second frequency band, wherein the first CC and the second CC are in the first frequency band and the second frequency band, respectively.
6. The method of claim 4 , further comprising:
suspending, by the UE, a transmission over a third CC different from the second CC when the transmission over the third CC overlaps with the transmission of the SRS over the second CC or overlaps with the switching time associated with the switching from the first CC to the second CC.
7. The method of claim 6 , wherein the third CC is in a same frequency band and a same timing advance group (TAG) as the first CC.
8. The method of claim 6 , wherein the third CC is in a different frequency band than the first CC.
9. The method of claim 4 , further comprising:
suspending, by the UE, a reception over a fourth CC different from the second CC when the reception over the fourth CC overlaps with transmission of the SRS over the second CC or overlaps with the switching time associated with the switching from the first CC to the second CC.
10. The method of claim 4 , further comprising:
dropping, by the UE, transmission of the SRS over the second CC, and performing, by the UE, a transmission over at least one of the first CC or a fifth CC different from the second CC during a time period scheduled for the transmission of the SRS over the second CC or during the switching time associated with the switching from the first CC to the second CC.
11. The method of claim 1 , wherein an uplink transmission over each CC in a first set of CCs includes at least one of a physical uplink shared channel (PUSCH) transmission or a physical uplink control channel (PUCCH) transmission, the first set of CCs in one or more frequency bands comprising one or more CCs including the first CC.
12. The method of claim 1 , wherein the second CC is a PUSCH-less CC not configured for PUSCH transmission.
13. The method of claim 1 , wherein a quantity of CCs of a first set of CCs in one or more frequency bands is in accordance with an uplink CC aggregation capability of the UE reported to the base station, the uplink CC aggregation capability including at least a maximum number of CCs in the one or more frequency bands supported by the UE for uplink transmission, the first set of CCs in the one or more frequency bands comprising one or more CCs including the first CC.
14. An apparatus comprising:
a non-transitory memory storage comprising instructions; and
one or more processors in communication with the non-transitory memory storage, wherein the instructions, when executed by the one or more processors, cause the apparatus to perform:
receiving, from a base station, first configuration information for one or more uplink transmissions of the apparatus on a first component carrier (CC);
receiving, from the base station, second configuration information for sounding resource signal (SRS) carrier switching, the SRS carrier switching being for transmission of one or more sounding resource signals (SRSs) over a second CC different from the first CC; and
transmitting an SRS over the second CC by performing the SRS carrier switching in accordance with the second configuration information, with uplink transmission over the first CC suspended at least during transmission of the SRS and during a radio frequency (RF) retuning time.
15. The apparatus of claim 14 , wherein the first CC is configured as a switching-from CC for the second CC.
16. The apparatus of claim 14 , wherein the instructions, when executed by the one or more processors, cause the apparatus further to perform:
transmitting a random access preamble over the second CC to the base station based on the carrier switching, with the uplink transmission over the first CC suspended at least during transmission of the random access preamble over the second CC;
receiving a control signaling from the base station, the control signaling indicating a timing advance for the second CC; and
wherein transmitting the SRS over the second CC comprises:
transmitting the SRS over the second CC in accordance with the timing advance.
17. The apparatus of claim 14 , wherein the instructions, when executed by the one or more processors, cause the apparatus further to perform:
switching from the first CC to the second CC, wherein the switching from the first CC to the second CC is associated with a switching time.
18. The apparatus of claim 17 , wherein the switching time is in accordance with a capability reported by the apparatus, the capability indicating the RF retuning time for switching between a first frequency band and a second frequency band, wherein the first CC and the second CC are in the first frequency band and the second frequency band, respectively.
19. The apparatus of claim 17 , wherein the instructions, when executed by the one or more processors, cause the apparatus further to perform:
suspending a transmission over a third CC different from the second CC when the transmission over the third CC overlaps with the transmission of the SRS over the second CC or overlaps with the switching time associated with the switching from the first CC to the second CC.
20. A non-transitory computer-readable media storing computer instructions that, when executed by one or more processors of an apparatus, cause the apparatus to perform:
receiving, from a base station, first configuration information for one or more uplink transmissions of the apparatus on a first component carrier (CC);
receiving, from the base station, second configuration information for sounding resource signal (SRS) carrier switching, the SRS carrier switching being for transmission of one or more sounding resource signals (SRSs) over a second CC different from the first CC; and
transmitting an SRS over the second CC by performing the SRS carrier switching in accordance with the second configuration information, with uplink transmission over the first CC suspended at least during transmission of the SRS and during a radio frequency (RF) retuning time.