Wireless transmitter and wireless transmission method

1. A wireless transmitter comprising:

a plurality of transmission antennas;

a transmission circuit controller that, based on reception qualities reported from terminals, assigns a communication frequency band and a communication time in a frame to each terminal, and sends a phase-control report signal that determines whether to perform phase-control; and

a transmission circuit unit that, at said communication frequency and communication time, applies a delay difference between at least two transmission antennas among said plurality of transmission antennas which diversity is to be given to, and performs phase-control based on said phase-control report signal.

2. The wireless transmitter according to claim 1 , wherein said transmission circuit controller sends a multi-user diversity/frequency diversity report signal that determines, for each communication frequency band and communication time, whether to make it a multi-user diversity region or a frequency diversity region, to the transmission circuit unit; and

said transmission circuit unit applies a different delay to each of said plurality of transmission antenna, based on said multi-user diversity/frequency diversity report signal.

3. The wireless transmitter according to claim 1 , wherein said transmission circuit controller, in assigning a communication frequency band having poor reception quality to a terminal, sends a phase-control report signal which determines that phase-control is to be performed.

4. The wireless transmitter according to claim 3 , wherein said transmission circuit controller sets, as said frequency band having poor reception quality, a frequency band other than one having the best reception quality.

5. The wireless transmitter according to claim 3 , wherein said transmission circuit controller sets, as said frequency band having poor reception quality, a frequency band having a reception quality that is no greater than a predetermined threshold, determined based on reception quality in a frequency band having the best reception quality.

6. The wireless transmitter according to claim 5 , wherein said transmission circuit controller uses at least one of MCS, SINR, and received power as said reception quality.

7. The wireless transmitter according to claim 5 , wherein said transmission circuit controller sets said predetermined threshold at one-half of the reception quality in the frequency band having the best reception quality.

8. The wireless transmitter according to claim 3 , wherein, when assigning a frequency band having poor reception quality to a terminal, said transmission circuit controller assigns a plurality of communication frequency bands and communication times to that terminal.

9. The wireless transmitter according to claim 1 , further comprising a transmission antenna circuit unit that, when said phase-control report signal reports that phase-control is to be performed, performs phase-control of at least one of said plurality of transmission antennas.

10. The wireless transmitter according to claim 9 , wherein, when said phase-control report signal reports that phase-control is to be performed, said transmission antenna circuit unit performs phase-control of one of said plurality of transmission antennas.

11. The wireless transmitter according to claim 1 , wherein said transmission circuit controller sends pilot arrangement information, which relates to an arrangement of pilot channels, and said phase-control report signal to said transmission circuit unit, re-receives the reception quality of the terminal for which the phase-control report signal reported that phase-control is to be performed, and, based on said pilot arrangement information, assigns a pilot channel.

12. The wireless transmitter according to claim 11 , wherein said transmission circuit controller assigns a pilot channel for propagation path estimation at a plurality of communication frequency bands and communication times, reports the fact that said pilot channel is one of least one phase-control patterns to the transmission circuit unit, and transmits said pilot channel.

13. The wireless transmitter according to claim 12 , wherein said transmission circuit controller sets said plurality of communication frequency bands and communication times such that they extend over a plurality of frames.

14. The wireless transmitter according to claim 12 , wherein said transmission circuit controller sets the number of communication frequency bands and communication times, and the number of frames, at the number of phase-control patterns.

15. The wireless transmitter according to claim 11 , wherein, based on the reception quality transmitted from the terminal, said transmission circuit controller compares the reception qualities of the phase-control patterns, and selects a phase-control pattern having the best reception quality.

16. The wireless transmitter according to claim 12 , wherein said plurality of transmission antennas includes a first transmission antenna, a second transmission antenna, a third transmission antenna, and a fourth transmission antenna;

there are three phase-control patterns; and

said transmission circuit controller performs phase-control of two transmission antennas from among said first transmission antenna to said fourth transmission antenna.

17. The wireless transmitter according to claim 1 , wherein said transmission circuit unit rotates the phase of a transmission antenna for phase-control by π.

18. A wireless transmitter comprising:

a plurality of transmission antennas; and

the wireless transmitter assigning, based on reception qualities reported from terminals, a communication frequency band and a communication time in a frame to each terminal, at said communication frequency and communication time, applying a delay difference between at least two transmission antennas among the plurality of transmission antennas which diversity is to be given to, and selecting a phase-control amount for phase-control.

19. The wireless transmitter according to claim 18 , wherein 0 or π is selected as said phase-control amount.

20. The wireless transmitter according to claim 18 , wherein the delay applied to each of said plurality of transmission antennas is selected based on a multi-user diversity/frequency diversity report signal that determines, for each communication frequency band and communication time, whether to make it a multi-user diversity region or a frequency diversity region.

21. A wireless transmission method for executing:

a first step of assigning, based on reception qualities reported from terminals, communication frequency band and a communication time in a frame, and sending a phase-control report signal that determines whether to perform phase-control, to each terminal; and

a second step of applying, at said communication frequency and communication time, a delay difference between at least two transmission antennas among a plurality of transmission antennas which diversity is to be given to, and performing phase-control based on said phase-control report signal.