Radio communication system, radio communication method, radio base station apparatus and user terminal

A radio communication system comprising:

• a first radio base station apparatus that transmits downlink data to a user terminal using a plurality of cells that respectively correspond to fundamental frequency blocks of varying frequency bands;
• and
• a plurality of second radio base station apparatuses that have lower transmission power than the first radio base station apparatus and that also have coverage areas that are each included in a coverage area of the first radio base station apparatus, wherein:
• the plurality of the second radio base station apparatuses transmit downlink data to the user terminal by performing coordinated multiple-point transmission using cells that correspond to fundamental frequency blocks of a same frequency band;
• the user terminal receives the downlink data transmitted from the plurality of the second radio base station apparatuses by coordinated multiple-point transmission;
• the first radio base station apparatus and/or the second radio base station apparatuses report information about a combination of cells that perform the coordinated multiple point transmission to the user terminal;
• the first radio base station apparatus and/or the second radio base station apparatuses transmit downlink control information to control downlink data that is transmitted from a cell that performs the coordinated multiple-point transmission, using a downlink control channel of a predetermined cell;
• and
• the user terminal identifies the cell where the downlink data is allocated by combination of a bit field of the downlink control information and higher layer signaling.

A radio communication method comprising the steps of:

• at a first radio base station apparatus, transmitting downlink data to a user terminal using a plurality of cells that respectively correspond to fundamental frequency blocks of varying frequency bands;
• at a second radio base station apparatus, transmitting downlink data to the user terminal using a cell that corresponds to fundamental frequency block of a same frequency band as one of the plurality of cells;
• and
• at the user terminal, receiving the downlink data in a system band that is formed with cells that are selected respectively from the first radio base station apparatus and the second radio base station apparatus,
• wherein the first radio base station apparatus and the second radio base station apparatus perform coordinated multiple-point transmission for the user terminal, between cells corresponding to a same fundamental frequency block;
• the first radio base station apparatus and/or the second radio base station apparatus report information about a combination of cells that perform the coordinated multiple-point transmission to the user terminal;
• the first radio base station apparatus and/or the second radio base station apparatus transmit downlink control information to control downlink data that is transmitted from a cell that performs the coordinated multiple-point transmission, using a downlink control channel of a predetermined cell;
• and
• the user terminal identifies the cell where the downlink data is allocated by combination of a bit field of the downlink control information and higher layer signaling.

A radio base station apparatus that transmits downlink data to a user terminal using a plurality of cells that respectively correspond to fundamental frequency blocks of varying frequency bands, the radio base station apparatus comprising:

• a transmission control section configured to execute coordinated multiple-point transmission with the user terminal, between a predetermined cell selected from the plurality of cells, and a cell of another radio base station apparatus corresponding to a fundamental frequency block of a same frequency band as the predetermined cell;
• and
• an information generating section configured to generate information about a combination of cells that perform the coordinated multiple-point transmission,
• wherein the information generating section generates downlink control information to control downlink data that is transmitted from a cell that performs the coordinated multiple-point transmission, using a downlink control channel of a predetermined cell;
• and
• the user terminal identifies the cell where the downlink data is allocated by combination of a bit field of the downlink control information and higher layer signaling.

A user terminal that receives data transmitted from a plurality of radio base station apparatuses using a system band that is forming with a plurality of fundamental frequency blocks, the user terminal comprising:

• a reception control section configured to receive downlink data that is transmitted from a plurality of radio base station apparatuses by coordinated multiple-point transmission between cells corresponding to fundamental frequency blocks of a same frequency band;
• and
• a determining section configured to demodulate the data transmitted from the plurality of radio base station apparatuses and determine a combination of cells that perform the coordinated multiple-point transmission,
• wherein the reception control section receives downlink control information to control downlink data that is transmitted from a cell that performs the coordinated multiple-point transmission, using a downlink control channel of a predetermined cell;
• and
• the determining section identifies the cell where the downlink data is allocated by combination of a bit field of the downlink control information and higher layer signaling.