Mobile terminal apparatus, base station apparatus and communication control method

A base station apparatus comprising:

• a transmitter that transmits radio frames of a victim cell including a protected subframe in the victim cell corresponding to a subframe with reduced transmission power in an aggressor cell, and a non-protected subframe in the victim cell corresponding to a subframe with unreduced transmission power in the aggressor cell;
• a CSI-RS allocation circuit configured to multiplex a CSI-RS (Channel State Information-Reference Signal), which is one of reference signals, on the protected subframe or on the non-protected subframe, in a predetermined cycle;
• a CRS allocation circuit configured to multiplex a CRS (Cell-specific Reference Signal), which is one of the reference signals, on each subframe constituting the radio frames of the victim cell;
• a receiver that receives two types of channel quality information of the protected subframe and the non-protected subframe that is fed back from a mobile terminal apparatus having received the radio frames in the victim cell;
• and
• a user data allocation process configured to allocate radio resources to the mobile terminal apparatus using the two types of channel quality information fed back from the mobile terminal apparatus.

A CSI feedback method comprising the steps of:

• receiving radio frames including a protected subframe in a victim cell corresponding to a subframe with reduced transmission power in an aggressor cell, and a non-protected subframe in the victim cell corresponding to a subframe with unreduced transmission power in the aggressor cell, CRS (Cell-specific Reference Signal) being multiplexed on each of the subframes including the protected subframe and the non-protected subframe, CSI-RS (Channel State Information-Reference Signal) being multiplexed on the protected subframe or the non-protected subframe in a predetermined cycle, and the CRS and the CSI-RS being reference signals;
• measuring channel quality from the reference signals multiplexed individually on the protected subframe and the non-protected subframe;
• and
• notifying by a transmitter, a base station apparatus of measured two types of channel quality information of the protected subframe and the non-protected subframe.

A communication control method comprising the steps of:

• transmitting, by a transmitter, radio frames including a protected subframe in a victim cell corresponding to a subframe with reduced transmission power in an aggressor cell, and a non-protected subframe in the victim cell corresponding to a subframe with unreduced transmission power in the aggressor cell;
• multiplexing a CSI-RS (Channel State Information-Reference Signal), which is one of reference signals, on the protected subframe or on the non-protected subframe, in a predetermined cycle;
• multiplexing a CRS (Cell-specific Reference Signal), which is one of the reference signals, on each subframe constituting the radio frames of the victim cell;
• receiving two types of channel quality information of the protected subframe and the non-protected subframe that is fed back from a mobile terminal apparatus having received the radio frames in the victim cell;
• and
• allocating radio resources to the mobile terminal apparatus using the two types of channel quality information fed back from the mobile terminal apparatus.

A radio communication system comprising:

• a base station apparatus;
• and a mobile terminal apparatus connected to the base station apparatus,
• the base station apparatus comprising:
• a transmitter that transmits radio frames of a victim cell including a protected subframe in the victim cell corresponding to a subframe with reduced transmission power in an aggressor cell and a non-protected subframe in the victim cell corresponding to a subframe with unreduced transmission power in the aggressor cell;
• a CSI-RS allocation circuit configured to multiplex a CSI-RS (Channel State Information-Reference Signal), which is one of reference signals, on the protected subframe or on the non-protected subframe, in a predetermined cycle;
• a CRS allocation circuit configured to multiplex a CRS (Cell-specific Reference Signal), which is one of the reference signals, on each subframe constituting the radio frames of the victim cell;
• a receiver that receives two types of channel quality information of the protected subframe and the non-protected subframe that is fed back from the mobile terminal apparatus having received the radio frames in the victim cell;
• and
• a user data allocation process configured to allocate radio resources to the mobile terminal apparatus, and
• the mobile terminal apparatus comprising:
• a receiver that receives the protected subframe in the victim cell and the non-protected subframe in the victim cell, the CRS being multiplexed on each of the subframes including the protected subframe and the non-protected subframe, and the CSI-RS being multiplexed on the protected subframe or the non-protected subframe in a predetermined cycle;
• a measurement circuit configured to measure channel quality from the reference signals multiplexed individually on the protected subframe and the non-protected subframe;
• and
• a transmitter that notifies the base station apparatus of the two types of channel quality information of the protected subframe and the non-protected subframe, measured by the measurement circuit.