Sounding Mechanism under Carrier Aggregation

摘要

Sounding mechanism for LTE-A systems under carrier aggregation is provided. A UE receives an uplink or downlink grant transmitted from an eNB over a primary carrier in a multi-carrier LTE-A system. The UE determines indicated carrier(s) and detects a triggering condition for aperiodic sounding transmission in the grant. The UE then selects UE-specific sounding reference signal (SRS) parameters. Finally, the UE transmits an aperiodic SRS (ap-SRS) over the indicated carrier(s) using the selected UE-specific SRS parameters. In one embodiment, the uplink or downlink grant is transmitted via a PDCCH carrying various DCI formats. Each DCI format contains a carrier indicator field (CIF) that indicates which carrier is used for ap-SRS transmission if cross-carrier scheduling is enabled. In another embodiment, DCI format 3/3A is transmitted via a PDCCH carrying a plurality of information fields, each field indicates if the UE should enable ap-SRS in a particular carrier.

主权项

1. A method comprising:
receiving, by a user equipment (UE), an uplink or downlink grant transmitted from a base station over a primary carrier in a multi-carrier wireless communication system; determining an indicated carrier from a carrier indication field (CIF) in the grant and detecting a triggering condition for aperiodic sounding transmission in the grant; selecting UE-specific sounding reference signal (SRS) parameters, wherein the grant contains an SRS request that specifies the UE-specific SRS parameters; and transmitting an aperiodic SRS (ap-SRS) over the indicated carrier using the UE-specific SRS parameters.