Radio communication system, radio communication method, and base station device

1. A wireless communication system that includes a base station, a plurality of relay stations that are moving, and a plurality of terminal stations in a service area, and performs downlink multiple access from the base station to each of the plurality of terminal stations via one or more relay stations of the plurality of relay stations, wherein

the base station is configured to frequency multiplex-transmit data signals to each of the plurality of terminal stations, and spatial multiplex-transmit data signals to terminal stations supporting spatial multiplex transmission;

the base station includes a processor; and a storage medium having computer program instructions stored thereon, when executed by the processor, perform to:

identify a relay station of the plurality of relay stations transmitting a respective signal receivable in the service area based on positions of the plurality of relay stations, and one of frequency multiplex-transmit the respective data signal in a different frequency band to each of the plurality of terminal stations via at least one relay station, or spatial multiplex-transmit the respective data signal to a given terminal station of the plurality of terminal stations supporting spatial multiplex transmission in a particular frequency band and via the plurality of relay stations, and transmit a downstream control signal, in a distinct frequency band, from the relay station transmitting the respective signal, the downstream control signal including a relay station ID,

wherein the given terminal station of the plurality of terminal stations is configured to receive the downstream control signal that is receivable, synchronize with the downstream control signal that is received, estimate channel information between the relay station and the given terminal station from the downstream control signal that is used for synchronization, select one or more relay stations of the plurality of relay stations transmitting a receivable signal based on the channel information, and notify the base station of the one or more relay stations that are selected, and

the computer program instructions further perform to allocate the particular frequency band in which the respective data signal addressed to the given terminal station is spatial multiplex-transmitted via the one or more relay stations selected by the given terminal station, notify the given terminal station of information regarding the particular frequency band that is allocated using the downstream control signal, and spatial multiplex-transmit the respective data signal addressed to the given terminal station.

2. The wireless communication system according to claim 1 , wherein

the downstream control signal and the data signal both addressed to the given terminal station are generated from a baseband signal and are synchronized with each other, and

the given terminal station is configured to demultiplex and demodulate the data signal that is spatial multiplex-transmitted using the channel information estimated from the downstream control signal.

3. The wireless communication system according to claim 1 , wherein the given terminal station is configured to monitor the downstream control signal of the one or more relay stations, re-select, when a relay station of the plurality of relay stations transmitting the receivable signal changes, a relay station of the plurality of relay stations through which the spatial multiplex transmission is requested to be performed, and notify the base station of the relay station that is re-selected.

4. A wireless communication system that includes a base station, a plurality of relay stations that are moving, and a plurality of terminal stations in a service area, and performs downlink multiple access from the base station to each of the plurality of terminal stations via one or more relay stations of the plurality of relay stations, wherein

the base station is configured to frequency multiplex-transmit data signals to each of the plurality of terminal stations, and spatial multiplex-transmit data signals to terminal stations supporting spatial multiplex transmission;

the base station includes a processor; and a storage medium having computer program instructions stored thereon, when executed by the processor, perform to:

identify a relay station of the plurality of relay stations transmitting a respective signal receivable in the service area based on positions of the plurality of relay stations, spatial multiplex-transmit the respective data signal to a given terminal station of the plurality of terminal stations supporting spatial multiplex transmission in a particular frequency band and via the plurality of relay stations, and transmit a downstream control signal, in a distinct frequency band, from the relay station transmitting the respective signal, the downstream control signal including a relay station ID,

wherein the given terminal station of the plurality of terminal stations is configured to receive the downstream control signal that is receivable, synchronize with the downstream control signal that is received, estimate channel information between the relay station and the given terminal station from the downstream control signal that is used for synchronization, select one or more relay stations of the plurality of relay stations transmitting a receivable signal based on the channel information, and notify the base station of the one or more relay stations that are selected, and

the computer program instructions further perform to allocate the particular frequency band in which the respective data signal addressed to the given terminal station is spatial multiplex-transmitted via the one or more relay stations selected by the given terminal station, notify the given terminal station of information regarding the particular frequency band that is allocated using the downstream control signal, and spatial multiplex-transmit the respective data signal addressed to the given terminal station.