Sounding mechanism and configuration under carrier aggregation
A method of multi-set RRC signaling for ap-SRS configuration is provided to enhance ap-SRS flexibility. An eNB transmits a plurality of sets of UE-specific SRS parameters to a UE via upper layer messaging in a multi-carrier wireless communication system. The eNB also determines triggering information of a selected set of UE-specific SRS parameters and an indicated carrier for the UE. The eNB then transmits an uplink or downlink grant over a primary carrier, the grant comprises triggering information for the UE to send an ap-SRS over the indicated carrier using the selected set of UE-specific SRS parameters. In one embodiment of joint signaling, the plurality of sets of UE-specific SRS parameters are signaled together in a single RRC transmission. In another embodiment of separate signaling, each set of UE-specific SRS parameters is signaled independently.
1. A method comprising:
transmitting a plurality of sets of UE-specific sounding reference signal (SRS) parameters associated with aperiodic SRS (ap-SRS) transmission over different carriers to a user equipment via upper layer messaging in a multi-carrier wireless communication system, wherein the plurality of sets of UE-specific SRS parameters are jointly signaled together via a single radio resource control (RRC) message;
determining a selected set of UE-specific SRS parameters and an indicated carrier for the UE; and
transmitting a grant to the UE over a primary carrier, wherein the grant comprises information for the UE to send an aperiodic SRS (ap-SRS) over the indicated carrier using the selected set of UE-specific SRS parameters, and wherein the grant further comprises a carrier indicator field indicating the indicated carrier.
2. The method of claim 1 , wherein each set of UE-specific SRS parameters comprises an SRS bandwidth, a frequency domain position, a transmission comb, a cyclic shift, and a number of antenna ports.
3. The method of claim 1 , wherein the plurality of sets of UE-specific SRS parameters are configured as part of physical parameters of the RRC message, and wherein the RRC message configures ap-SRS for multiple secondary carriers.
4. The method of claim 1 , wherein the grant is transmitted in a physical downlink control channel (PDCCH) that supports multiple downlink control information (DCI) formats, and wherein each DCI format corresponds to one or more sets of predefined UE-specific SRS parameters configured via upper layer messaging.
5. The method of claim 1 , wherein the SRS parameters are transmitted via direct signaling or delta signaling.
6. A base station, comprising:
an information encoding module that encodes a plurality of sets of UE-specific SRS parameters associated with aperiodic SRS (ap-SRS) transmission over different carriers for a user equipment (UE); and
a transmitter that transmits the plurality of sets of UE-specific SRS parameters via upper layer messaging over a primary carrier, wherein the plurality of sets of UE-specific SRS parameters are jointly signaled together via a single radio resource control (RRC) message, wherein the transmitter also transmits a grant to the UE over the primary carrier, and wherein the grant comprises triggering information for the UE to send an aperiodic SRS (ap-SRS) over an indicated carrier using a selected set of UE-specific SRS parameters, and wherein the grant further comprises a carrier indicator field indicating the indicated carrier.
7. The base station of claim 6 , wherein each set of UE-specific SRS parameters comprises an SRS bandwidth, a frequency domain position, a transmission comb, a cyclic shift, and a number of antenna ports.
8. The base station of claim 6 , wherein the plurality of sets of UE-specific SRS parameters are configured as part of physical parameters of the RRC message, and wherein the RRC message configures ap-SRS for multiple secondary carriers.
9. The base station of claim 6 , wherein the grant is transmitted in a physical downlink control channel (PDCCH) that supports multiple downlink control information (DCI) formats, and wherein each DCI format corresponds to one or more sets of predefined UE-specific SRS parameters configured via upper layer messaging.
10. The base station of claim 6 , wherein the SRS parameters are transmitted via direct signaling or delta signaling.