Radio communication system, base station apparatus, mobile station apparatus and radio communication method

Abstract

A reference signal for channel estimation is transmitted a predetermined number of times with one signaling. In a radio communication system including a base station apparatus and a mobile station apparatus, the base station apparatus transmits a radio resource control signal including information indicating a number of times of transmission of the reference signal for channel estimation to the mobile station apparatus, and transmits a physical downlink control channel including information indicating transmission of the reference signal to the mobile station apparatus. The mobile station apparatus transmits the reference signal to the base station apparatus until the number of transmissions of the reference signal reaches the number of times of transmission, according to information, which is included in the radio resource control signal, when the information indicating transmission of the reference signal is included in the physical downlink control channel.

Description

TECHNICAL FIELD[0001]The present invention relates to a radio communication system including a mobile station apparatus and a base station apparatus, and in particular, to a transmission control method of a reference signal for channel estimation for the mobile station apparatus.BACKGROUND ART[0002]Conventionally, a radio access system and a radio network that achieves higher-speed data communication (hereinafter referred to as “Long Term Evolution-Advanced (LTE-A)” or “Advanced Evolved Universal Terrestrial Radio Access (A-EUTRA)”) by use of evolution of a radio access system and a radio network in cellular mobile communication (hereinafter referred to as “Long Term Evolution (LTE)” or “Evolved Universal Terrestrial Radio Access (EUTRA)”), and by use of a wider frequency band than the LTE have been discussed in the 3rd Generation Partnership Project (3GPP).[0003]In the LTE-A, proposed is a reference signal for channel estimation transmitted only when a transmission request is notif...

AI Technical Summary

Benefits of technology

[0007]The present invention has been made in view of the above-mentioned problems and has an object to provide a radio communication system, a base station apparatus, a mobile station apparatus and a radio communication method that can efficiently transmit the reference signal for channel estimation when the transmission request is notified from the base station apparatus, thereby improving the channel estimate accuracy of the uplink.

[0036]According to the present invention, it is possible to provide the mobile station apparatus, the base station apparatus, the radio communication system and the radio communication method that can efficiently transmit the reference signal for channel estimation when the transmission request is notified from the base station apparatus, thereby improving the channel estimate accuracy of the uplink.

Problems solved by technology

However, according to the conventional technique, in the case where the mobile station apparatus transmits the reference signal for channel estimation A-SRS only when the transmission request is notified from the base station apparatus by use of a physical downlink control channel, the base station apparatus cannot obtain adequate channel estimate accuracy for an uplink.

Further, the mobile station apparatus transmits the reference signal that cannot provide adequate channel estimate accuracy, resulting in that a resource of an uplink signal is wasted, and efficient frequency selective scheduling cannot be performed also in the base station apparatus.

When the physical downlink control channel is used each time the base station apparatus requests transmission of the reference signal for channel estimation, a resource of a downlink signal is wasted, and efficient communication between the base station apparatus and the mobile station apparatus cannot be performed.

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