Channel state information reference signal transmission method and base station

A communication method for a terminal among a terminal group comprising a plurality of terminals which is grouped in a cell, comprising:

• receiving configuration information using radio resource control (RRC) signaling and an aperiodic Channel State Information Reference Signal (CSI-RS) to be used for the terminal group, and receiving a trigger signal using a downlink control information (DCI) field which indicates the aperiodic CSI-RS in a frequency domain in a bandwidth that is the same as a bandwidth for a time and frequency resource that is used for data transmission to the terminal;
• if the trigger signal is received then, based on the received configuration information and the received trigger signal, specifying a time and frequency resource for the aperiodic CSI-RS from a plurality of time and frequency resources;
• and
• performing rate matching related to the specified time and frequency resource based on the trigger signal, and if the trigger signal is not received and the configuration information is received, determining not to use the aperiodic CSI-RS.

A base station comprising:

• a transmitter that transmits configuration information using radio resource control (RRC) signaling, an aperiodic Channel State Information Reference Signal (CSI-RS) to be used for a terminal group comprising a plurality of terminals which is grouped in a cell, and a trigger signal using a downlink control information (DCI) field which indicates the CSI-RS;
• and
• a processor that controls to transmit the DCI field as the trigger signal which indicates the CSI-RS in a frequency domain in a bandwidth that is the same as a bandwidth for a time and frequency resource that is used for data transmission to a terminal of the terminal group,
• wherein if the terminal receives the trigger signal then the terminal, based on the configuration information and the trigger signal, specifies a time and frequency resource for the aperiodic CSI-RS from a plurality of time and frequency resources, and
• the terminal performs rate matching related to the specified time and frequency resource based on the trigger signal, and
• wherein if the terminal does not receive the trigger signal and the terminal receives the configuration information, the terminal determines not to use the aperiodic CSI-RS.

A system comprising a base station and a terminal among a terminal group comprising a plurality of terminals which is grouped in a cell, wherein

• the terminal comprises:
• a receiver that receives configuration information using radio resource control (RRC) signaling, an aperiodic Channel State Information Reference Signal (CSI-RS) to be used for the terminal group, and a trigger signal using a downlink control information (DCI) field which indicates the aperiodic CSI-RS in a frequency domain in a bandwidth that is the same as a bandwidth for a time and frequency resource that is used for data transmission to the terminal;
• and
• a processor,
• wherein if the trigger signal is received then the processor, based on the received configuration information and the received trigger signal, specifies a time and frequency resource for the aperiodic CSI-RS from a plurality of time and frequency resources, and
• the processor performs rate matching related to the specified time and frequency resource based on the trigger signal, and
• if the trigger signal is not received and the configuration information is received, the processor determines not to use the aperiodic CSI-RS, and the base station comprises:
• a transmitter that transmits the configuration information using the RRC signaling, the aperiodic CSI-RS to be used for the terminal group, and the DCI field.