Wireless communication device and wireless communication method

1. A wireless communication device comprising:

controlling circuitry configured to

set directivities of a plurality of antennas so that a synthesis directivity of the directivities becomes an omnidirectional directivity,

receive a first frame via the plurality of antennas having the synthesis directivity of the omnidirectional directivity and

adjust the directivities of the plurality of antennas based on a received power of each antenna of the first frame; and

a transmitter configured to transmit a second frame for response to the first frame after the directivities of the plurality of antennas are adjusted,

wherein the controlling circuitry is configured to specify an antenna having a highest received power among the plurality of antennas and adjust directivities of antennas other than the specified antenna among the plurality of antennas to a directivity of the specified antenna, respectively.

2. The wireless communication device according to claim 1 , wherein the controlling circuitry is configured to

calculate a difference between a received power of the specified antenna and each of received powers of the other antennas,

adjust the directivities of the other antennas to the directivity of the specified antenna, respectively, in a case where the difference is equal to or more than a threshold and

keep the directivities of the other antennas in a case where the difference is less than the threshold.

3. The wireless communication device according to claim 1 , wherein the controlling circuitry is configured to

specify two or more antennas having received powers which are highest among the plurality of antennas and

adjust directivities of other antennas than the two or more antennas to the directivity of one of the two or more antennas.

4. The wireless communication device according to claim 1 , wherein the controlling circuitry is configured to

specify two antennas having received powers which are highest among the plurality of antennas,

compare received powers of the two antennas to each other, and, in a case where a difference of the received powers is equal to or more than a threshold,

adjust the directivity of the antenna having a lower received power of the two antennas and the directivities of other antennas than the two antennas to the directivity of the antenna having a higher received power of the two antennas, respectively, and

in a case where the difference is less than the threshold, adjust the directivities of the other antennas to the directivity of any one of the two antennas.

5. The wireless communication device according to claim 1 , wherein

the controlling circuitry is configured to adjust the directivities of the plurality of antennas when the first frame is received after the transmitter has unsuccessfully transmitted a third frame.

6. The wireless communication device according to claim 1 , further comprising the plurality of antennas.

7. A wireless communication device comprising:

controlling circuitry configured to

set directivities of a plurality of antennas so that a synthesis directivity of the directivities becomes an omnidirectional directivity,

receive a first frame via the plurality of antennas having the synthesis directivity of the omnidirectional directivity and

adjust the directivities of the plurality of antennas based on a received power of each antenna of the first frame; and

a transmitter configured to transmit a second frame for response to the first frame after the directivities of the plurality of antennas are adjusted,

wherein the controlling circuitry is configured to receive capability information of another wireless communication device that has transmitted the first frame, the capability information including information on a number of antennas of the other wireless communication device or information whether the other wireless communication device can carry out beam forming,

the controlling circuitry is configured to adjust the directivities of the plurality of antennas so that the synthesis directivity of the directivities becomes the omnidirectional directivity

when the number of the antennas of the other wireless communication device is two or more or the other wireless communication device can carry out the beam forming and

when a received power of a signal received from the other wireless communication device is a threshold value or more, and

the transmitter is configured to transmit the second frame after the directivities of the plurality of antennas are adjusted to the omnidirectional directivity.

8. The wireless communication device according to claim 7 , wherein

the controlling circuitry is configured to determine whether to adjust the directivities of the plurality of antennas based on the capability information and channel communication quality of a channel used for communication with the other wireless communication device.

9. A wireless communication method comprising:

setting directivities of a plurality of antennas so that a synthesis directivity of the directivities becomes an omnidirectional directivity;

receiving a first frame via the plurality of antennas having the synthesis directivity of the omnidirectional directivity;

adjusting the directivities of the plurality of antennas based on a received power of each antenna of the first frame; and

transmitting a second frame for response to the first frame after the directivities of the plurality of antennas are adjusted,

wherein the adjusting includes specifying an antenna having highest received power among plurality of antennas and adjusting directivities of antennas other than the specified antenna the plurality of antenna a directivity of the specified antenna, respectively.

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

calculating a difference between the received power of the specified antenna and each of received powers of the other antennas;

adjusting the directivities of the other antennas to the directivity of the specified antenna, respectively, in a case where the difference is equal to or more than a threshold; and

keeping the directivities of the other antennas in a case where the difference is less than the threshold.

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

specifying two or more antennas having received powers which are highest among the plurality of antennas and adjusting directivities of other antennas than the two or more antennas to the directivity of one of the two or more antennas.

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

specifying two antennas having received powers which are highest among the plurality of antennas;

comparing received powers of the two antennas to each other;

adjusting, in a case where a difference of the received powers is equal to or more than a threshold, the directivity of the antenna having a lower received power of the two antennas and the directivities of other antennas than the two antennas to the directivity of the antenna having a higher received power of the two antennas, respectively; and

adjusting, in a case where the difference is less than the threshold, the directivities of the other antennas to the directivity of any one of the two antennas.

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

adjusting the directivities of the plurality of antennas when the first frame is received after a third frame has been unsuccessfully transmitted.

14. A wireless communication method comprising:

setting directivities of a plurality of antennas so that a synthesis directivity of the directivities becomes an omnidirectional directivity;

receiving a first frame via the plurality of antennas having the synthesis directivity of the omnidirectional directivity;

adjusting the directivities of the plurality of antennas based on a received power of each antenna of the first frame;

transmitting a second frame for response to the first frame after the directivities of the plurality of antennas are adjusted; and

receiving capability information of another wireless communication device that transmitted the first frame, the capability information including information on a number of antennas of the other wireless communication device or information on whether the other wireless communication device can carry out beam forming,

wherein the adjusting includes adjusting the directivities of the plurality of antennas so that the synthesis directivity of the directivities becomes the omnidirectional directivity

when the number of the antennas of the other wireless communication device is two or more or the other wireless communication device can carry out the beam forming and

when a received power of a signal received from the other wireless communication device is a threshold value or more, and

the transmitting includes transmitting the second frame after the directivities of the plurality of antenna are adjusted to the omnidirectional directivity.

15. The wireless communication method according to claim 14 , comprising:

determining whether to adjust the directivities of the plurality of antennas based on the capability information and channel communication quality of a channel used for communication with the other wireless communication device.