METHOD AND APPARATUS FOR FACILITATING REFERENCE SIGNAL TRANSMISSION

Embodiments of the present disclosure provide methods, apparatuses and computer program for facilitating reference signal transmission. An example method can be implemented at a base station in a wireless communication system for communicating with a terminal device. The terminal device is configured with a primary carrier and a secondary carrier for carrier aggregation. The method comprises determining a measurement gap. The measurement gap indicates a time interval for a terminal device to switch from the primary carrier to the secondary carrier for transmitting a reference signal to the base station over the secondary carrier and switch back to the primary carrier. The method also comprises triggering the terminal device to transmit the reference signal over the secondary carrier according to the measurement gap and obtaining a channel estimation based on the reference signal received from the terminal device during the measurement gap. By virtue of the method, the base station is enabled to request and control reference signal transmission on a secondary carrier from the terminal device, thereby obtaining CSI of the secondary carrier. Furthermore, since transmission of the reference signal is restricted to the measurement gap known by the base station, negative impact to the primary carrier can be minimized.