Permitting a plurality of transmit antennas to transmit the same data to improve the reception quality through transmit diversity

1. A communication apparatus comprising:

a plurality of mapping units configured to:

receive a plurality of data signal sequences related to the same data signal sequence,

arrange the received data signal sequences in a frequency domain, and

output the arranged data signal sequences as transmission frequency spectra;

an assignment information acquisition unit configured to control the plurality of mapping units based on assignment information to cause the data signal sequences arranged in the frequency domain to partially overlap;

an amount-of-cyclic-shift decision unit configured to decide an amount of cyclic shift based on control of the assignment information acquisition unit;

a spectra cyclic shift unit configured to:

shift, under control of the amount-of-cyclic-shift decision unit, the at least one input data signal sequence in the frequency domain by the amount of cyclic shift to cause partially overlapping data signals to be identical, and

output the at least one data signal sequence; and

a plurality of transmit antennas configured to transmit, at a radio frequency, the transmission frequency spectra output by the plurality of mapping units, wherein

the plurality of mapping units are configured to receive at least one of the plurality of data signal sequences via the spectra cyclic shift unit.

2. The communication apparatus according to claim 1 , wherein

the plurality of mapping units are configured to receive all the plurality of data signal sequences via the spectra cyclic shift units.

3. The communication apparatus according to claim 1 , further comprising:

a precoding unit configured to:

change amplitudes, phases, or both amplitudes and phases of data signals of the data signal sequences, and

input the data signal sequences directly to the mapping units or input the data signal sequences to the mapping units via the spectra cyclic shift units.

4. The communication apparatus according to claim 1 , wherein

the spectra cyclic shift unit is configured to perform a cyclic shift by using, as a reference, the arrangement of the transmission frequency spectra for a specific transmit antenna among the plurality of transmit antennas.

5. The communication apparatus according to claim 1 , wherein

the spectra cyclic shift unit is configured to perform a cyclic shift by using, as a reference, the index of the transmission frequency spectrum.

6. A communication system comprising:

a first communication apparatus; and

a second communication apparatus,

wherein the first communication apparatus comprises:

a plurality of mapping units configured to:

receive a plurality of data signal sequences related to the same data signal sequence,

arrange the received data signal sequences in a frequency domain, and

output the arranged data signal sequences as transmission frequency spectra;

an assignment information acquisition unit configured to control the plurality of mapping units based on assignment information to cause the data signal sequences arranged in the frequency domain to partially overlap;

an amount-of-cyclic-shift decision unit configured to decide an amount of cyclic shift based on control of the assignment information acquisition unit;

a spectra cyclic shift unit configured to:

shift, under control of the amount-of-cyclic-shift decision unit, the at least one input data signal sequence in the frequency domain by the amount of cyclic shift to cause partially overlapping data signals to be identical, and

output the at least one data signal sequence; and

a plurality of transmit antennas configured to transmit, at a radio frequency, the transmission frequency spectra output by the plurality of mapping units, and

the plurality of mapping units are configured to receive at least one of the plurality of data signal sequences via the spectra cyclic shift unit, wherein

the second communication apparatus comprises:

one or more receive antennas, and

an equalization unit configured to perform, for each of transmission frequency spectra fed from the one or more receive antennas, equalization by using a SIMO weight for a case without interference, and

the first communication apparatus is configured to transmit or receive data signals to or from the second communication apparatus.

7. A communication method comprising:

preparing a plurality of data signal sequences related to the same data signal sequence;

changing amplitudes, phases, or both amplitudes and phases of data signals of each of the plurality of data signal sequences;

applying cyclic shifts to the plurality of changed data signal sequences in a frequency domain;

arranging the plurality of cyclically shifted data signal sequences in the frequency domain so that the plurality of data signal sequences partially overlap and overlapping data signals are identical; and

transmitting, at a radio frequency, a plurality of sets of transmission frequency spectra obtained by the arrangement in the frequency domain, from a plurality of transmit antennas.

8. A communication method comprising:

allocating a sequence of a plurality of data signals to a plurality of first transmission subcarriers in specific symbols;

allocating in a frequency domain, a sequence of data signals that are the same as the plurality of data signals to a plurality of second transmission subcarriers in the specific symbols so that the plurality of first transmission subcarriers and the plurality of second transmission subcarriers partially overlap;

applying in a frequency domain, a cyclic shift to the sequence of the plurality of data signals allocated to the plurality of first transmission subcarriers, the sequence of the plurality of data signals allocated to the plurality of second transmission subcarriers, or both the sequences, so that the same data signal is allocated to each of a plurality of subcarriers where the first transmission subcarriers and the second transmission subcarriers partially overlap; and

transmitting the sequence of the plurality of data signals allocated to the first transmission subcarriers from a first transmit antenna and transmitting the sequence of the plurality of data signals allocated to the second transmission subcarriers from a second transmit antenna.

9. The communication method according to claim 8 , wherein the first transmit antenna and the second transmit antenna are included in a single transmission apparatus.

10. The communication method according to claim 8 , wherein the first transmit antenna is included in one transmission apparatus, and the second transmit antenna is included in another transmission apparatus.

11. The wireless communication method according to claim 9 , further comprising:

applying precoding for changing amplitudes, phases, or both amplitudes and phases to the plurality of data signals.

12. A communication apparatus comprising:

a plurality of mapping units configured to:

arrange a plurality of data signal sequences related to the same data signal sequence in a frequency domain, and

output the arranged data signal sequences as transmission frequency spectra;

an assignment information acquisition unit configured to control the plurality of mapping units based on assignment information to cause the arrangements of the data signal sequences in the frequency domain to be identical, to be separated, or to partially overlap; and

a plurality of transmit antennas configured to transmit, at a radio frequency, the transmission frequency spectra output by the plurality of mapping units.

13. A communication apparatus comprising:

one or more receive antennas configured to receive a plurality of data signal sequences obtained by performing a cyclic shift to the same signal sequence in a frequency domain; and

an equalization unit configured to perform, for each of transmission frequency spectra fed from the one or more receive antennas, equalization by using a SIMO weight for a case without interference and a MIMO weight for a case with interference.

14. A communication system comprising:

a first communication apparatus; and

a second communication apparatus,

wherein the first communication apparatus comprises:

a plurality of mapping units configured to:

arrange a plurality of data signal sequences related to the same data signal sequence in a frequency domain, and

output the arranged data signal sequences as transmission frequency spectra;

an assignment information acquisition unit configured to control the plurality of mapping units based on assignment information to cause the arrangements of the data signal sequences in the frequency domain to be identical, to be separated, or to partially overlap; and

a plurality of transmit antennas configured to transmit, at a radio frequency, the transmission frequency spectra output by the plurality of mapping units, wherein

the second communication apparatus comprises:

one or more receive antennas; and

an equalization unit that performs, for each of transmission frequency spectra fed from the one or more receive antennas, equalization by using a SIMO weight for a case without interference and a MIMO weight for a case with interference, and

the first communication apparatus is configured to transmit or receive data signals to or from the second communication apparatus.

15. A communication method comprising:

preparing a plurality of data signal sequences related to the same data signal sequence;

arranging the plurality of data signal sequences in a frequency domain to cause the plurality of data signal sequences to be identical, to be separated, or to partially overlap; and

transmitting, at a radio frequency, a plurality of sets of transmission frequency spectra obtained by the arrangement in the frequency domain from a plurality of transmit antennas.

16. A communication method comprising:

receiving a plurality of data signal sequences obtained by performing a cyclic shift to the same signal sequence in a frequency domain; and

performing, for each of transmission frequency spectra, equalization by using a weight for a case without interference in a case without interference and by using a weight for a case with interference in a case with interference to restore the transmission frequency spectrum.

17. A communication apparatus comprising:

a transmit diversity unit configured to apply coding onto a plurality of data signal sequences, the coding belonging to open-loop diversity that includes space time block coding, space frequency block coding, and cyclic delay diversity;

a plurality of spectra cyclic shift units configured to cyclically shift by a predetermined amount, in a frequency domain, the plurality of data signal sequences output by the transmit diversity unit;

a plurality of mapping units configured to:

arrange the plurality of data signal sequences which are outputs of the plurality of spectra cyclic shift units in the frequency domain based on the predetermined amount so that the plurality of data signal sequences partially overlap, and

output the arranged data signal sequences as transmission frequency spectra; and

a plurality of transmit antennas configured to successively transmit, at a radio frequency, the transmission frequency spectra output by the plurality of mapping units at two adjacent timings.

18. The communication apparatus according to claim 17 , wherein

the plurality of data signal sequences output by the transmit diversity units are constituted by a first data signal sequence, a second data signal sequence, a third data signal sequence, and a fourth data signal sequence, wherein

the second signal sequence includes signals that are complex conjugates of signals of the first signal sequence,

the third data signal sequence is different from the first data signal sequence, and

the fourth data signal sequence includes signals that are obtained by multiplying complex conjugates of signals of the third data signal sequence by the negative sign.

19. A communication apparatus comprising:

a plurality of receive antennas configured to receive a plurality of data signal sequences obtained by performing a cyclic shift to the same signal sequence in a frequency domain; and

an equalization unit configured to perform equalization on each of transmission frequency spectra fed from the receive antennas, wherein

the equalization unit comprises:

a weight calculation unit configured to calculate a weight used in equalization,

a complex conjugation unit configured to selectively perform a complex conjugation operation, and

a negative sign multiplication unit configured to selectively multiply the negative sign.