Communication method, and transmitting apparatus and receiving apparatus using that communication method

1. A method for generating a transmission signal to transmit a modulated signal generated using orthogonal frequency division multiplexing, from a transmitting apparatus with a plurality of antennas, toward a plurality of terminals, the method comprising:

assigning transmission data for the plurality of terminals to a plurality of carrier groups, each carrier group including a plurality of carriers;

selecting, from the plurality of antennas, one or more antennas to be used for transmission toward each of the plurality of terminals;

selecting, as a transmission mode for each of the plurality of carrier groups, one of a first transmission mode in which one modulated signal is transmitted and a second transmission mode in which a plurality of modulated signals are transmitted by using the selected antennas; and

generating a transmission signal for transmitting the transmission data assigned to the plurality of carrier groups during an identical time period, using the selected transmission mode.

2. The method according to claim 1 , wherein the antennas are selected based on feedback information that is received from each of the plurality of terminals.

3. The method according to claim 2 , wherein the feedback information comprises radio wave propagation environment information, the radio wave propagation environment information comprising information related to one or more of received signal field intensity, channel state, and interference wave intensity.

4. The method according to claim 2 , wherein the feedback information comprises one or more of request information related to a transmission speed, modulation method and transmission quality that each terminal requests, antenna information related to a number of receiving antennas with which each terminal is provided, and multiplexing information related to a number of multiplexing of modulated signals for each terminal.

5. The method according to claim 1 , wherein the transmission modes are selected based on feedback information that is received from each of the plurality of terminals.

6. The method according to claim 5 , wherein the feedback information comprises radio wave propagation environment information, the radio wave propagation environment information comprising information related to one or more of received signal field intensity, channel state, and interference wave intensity.

7. The method according to claim 5 , wherein the feedback information comprises one or more of request information related to a transmission speed, modulation method and transmission quality that each terminal requests, antenna information related to a number of receiving antennas with which each terminal is provided, and multiplexing information related to a number of multiplexing of modulated signals for each terminal.

8. The method according to claim 1 , wherein the modulated signal comprises:

a data symbol for transmitting transmission data to one of the plurality of terminals; and

a control symbol that is allocated ahead of the data symbol on a time axis, and that is usable by a terminal having received the modulated signal upon decoding the transmission data.

9. The method according to claim 1 , wherein the modulated signal comprises:

a data symbol for transmitting transmission data to one of the plurality of terminals; and

an estimation symbol that is allocated ahead of the data symbol on a time axis for estimating one of time synchronization, frequency offset and propagation path distortion.

10. The method according to claim 1 , wherein, in the second transmission mode, the plurality of modulated signals are transmitted over an identical frequency band by using two or more of the plurality of antennas.

11. A method for generating a transmission signal to transmit a modulated signal generated using orthogonal frequency division multiplexing, from a transmitting apparatus with a plurality of antennas, toward a plurality of terminals, the method comprising:

configuring a transmission frame including a first carrier group where transmission data for a first terminal is assigned and a second carrier group where transmission data for a second terminal is assigned, each of the first carrier group and the second carrier group including a plurality of carriers;

selecting, from the plurality of antennas, one or more antennas to be used for transmission toward each of the first terminal and the second terminal;

selecting, as a transmission mode for the first carrier group, one of a first transmission mode in which one modulated signal is transmitted, and a second transmission mode, in which a plurality of modulated signals are transmitted by using the selected antennas;

selecting, as a transmission mode for the second carrier group, one of the first transmission mode, in which one modulated signal is transmitted, and the second transmission mode, in which a plurality of modulated signals are transmitted by using the selected antennas; and

generating a transmission signal for transmitting the transmission data assigned to the first carrier group and the second carrier group during an identical time period, using the selected transmission mode.

12. The method according to claim 11 , wherein:

during a first time period, the transmission data for the first terminal is transmitted by using the first carrier group and the transmission data for the second terminal is transmitted by using the second carrier group; and

during a second time period, the transmission data for a third terminal is transmitted by using the first carrier group and the transmission data for a fourth terminal is transmitted by using the second carrier group.

13. An apparatus for generating a transmission signal to transmit a modulated signal generated using orthogonal frequency division multiplexing, from a transmitting apparatus with a plurality of antennas, toward a plurality of terminals, the apparatus comprising:

an antenna selector that selects, from the plurality of antennas, one or more antennas to be used for transmission toward each of the plurality of terminals;

a transmission mode selector that assigns transmission data for the plurality of terminals to a plurality of carrier groups, each carrier group including a plurality of carriers, and selects, as a transmission mode for each of the plurality of carrier groups, one of a first transmission mode, in which one modulated signal is transmitted, and a second transmission mode, in which a plurality of modulated signals are transmitted by using the antennas selected in the antenna selector; and

a transmission signal generator that generates a transmission signal for transmitting the transmission data assigned to the plurality of carrier groups during an identical time period, using the transmission mode selected in the transmission mode selector.

14. The apparatus according to claim 13 , wherein the antenna selector selects the antennas based on feedback information that is received from each of the plurality of terminals.

15. The apparatus according to claim 14 , wherein the feedback information comprises radio wave propagation environment information, the radio wave propagation environment information comprising information related to one or more of received signal field intensity, channel state, and interference wave intensity.

16. The apparatus according to claim 14 , wherein the feedback information comprises one or more of request information related to a transmission speed, modulation method and transmission quality that each terminal requests, antenna information related to a number of receiving antennas with which each terminal is provided, and multiplexing information related to a number of multiplexing of modulated signals for each terminal.

17. The apparatus according to claim 13 , wherein the transmission mode selector selects one of the first transmission mode and the second transmission mode based on feedback information that is received from each of the plurality of terminals.

18. The apparatus according to claim 17 , wherein the feedback information comprises radio wave propagation environment information, the radio wave propagation environment information comprising information related to one or more of received signal field intensity, channel state, and interference wave intensity.

19. The apparatus according to claim 17 , wherein the feedback information comprises one or more of request information related to a transmission speed, modulation method and transmission quality that each terminal requests, antenna information related to a number of receiving antennas with which each terminal is provided, and multiplexing information related to a number of multiplexing of modulated signals for each terminal.

20. The apparatus according to claim 13 , wherein the modulated signal comprises:

a data symbol for transmitting transmission data to one of the plurality of terminals; and

a control symbol that is allocated ahead of the data symbol on a time axis, and that is usable by a terminal having received the modulated signal upon decoding the transmission data.

21. The apparatus according to claim 13 , wherein the modulated signal comprises:

a data symbol for transmitting transmission data to one of the plurality of terminals; and

an estimation symbol that is allocated ahead of the data symbol on a time axis for estimating one of time synchronization, frequency offset and propagation path distortion.

22. The apparatus according to claim 13 , wherein, in the second transmission mode, the plurality of modulated signals are transmitted over an identical frequency band by using two or more of the plurality of antennas.

23. An apparatus for generating a transmission signal to transmit a modulated signal generated using orthogonal frequency division multiplexing, from a transmitting apparatus with a plurality of antennas, toward a plurality of terminals, the apparatus comprising:

an antenna selector that selects, from the plurality of antennas, one or more antennas to be used for transmission to each of the first terminal and the second terminal;

a transmission mode selector that:

configures a transmission frame including a first carrier group where transmission data for a first terminal is assigned and a second carrier group where transmission data for a second terminal is assigned, each of the first carrier group and the second carrier group including a plurality of carriers;

selects, as a transmission mode for the first carrier group, one of a first transmission mode, in which one modulated signal is transmitted, and a second transmission mode, in which a plurality of modulated signals are transmitted by using the antennas selected by the antenna selector; and

selects, as a transmission mode for the second carrier group, one of the first transmission mode, in which one modulated signal is transmitted, and the second transmission mode, in which a plurality of modulated signals are transmitted by using the antennas selected by the antenna selector; and

a transmission signal generator that generates a transmission signal for transmitting the transmission data assigned to the first carrier group and the second carrier group during an identical time period, using the transmission mode selected by the transmission mode selector.

24. The apparatus according to claim 23 , wherein:

during a first time period, the transmission data for the first terminal is transmitted by using the first carrier group and the transmission data for the second terminal is transmitted by using the second carrier group; and

during a second time period, the transmission data for a third terminal is transmitted by using the first carrier group and the transmission data for a fourth terminal is transmitted by using the second carrier group.