Communication device and communication method

1. A communication device comprising:

a first antenna and a second antenna which receive wireless signals sent by a plurality of communication terminals, the wireless signals containing communication data;

a selection unit configured to select the first antenna in a first term, and the second antenna in a second term different from the first term;

a reception determination unit configured to determine whether or not the communication data contained in the wireless signals received by a selected one of the first antenna and the second antenna selected by the selection unit is successfully obtained; and

a storage unit which stores association between each of the communication terminals and one of the first antenna and the second antenna,

wherein the selection unit is configured to set a length of the first term and a length of the second term by referring to the association, the length of the first term and the length of the second term being set to make a ratio of the length of the second term to the length of the first term equal to a ratio of the number of times the communication data sent by the communication terminal associated with the second antenna is determined to be successfully obtained, to the number of times the communication data sent by the communication terminal associated with the first antenna is determined to be successfully obtained.

2. The communication device according to claim 1 , further comprising

a received signal strength indicator (RSSI) detection unit configured to detect RSSIs of the wireless signals received by the respective first antenna and the second antenna,

wherein the storage unit stores the association between the communication terminal which is a source terminal for sending a wireless signal and one of the first antenna and the second antenna that receives a wireless signal having a higher one of the RSSIs detected by the RSSI detection unit.

3. The communication device according to claim 2 ,

wherein the selection unit is configured to, when one of the RSSIs of the wireless signals received by one of the first antenna and the second antenna is lower than a predetermined value, set the length of the first term and the length of the second term based on the number of times that the communication data sent by the source terminal for sending the wireless signal is determined to be successfully obtained.

4. The communication device according to claim 2 ,

wherein the selection unit is configured to, when one of the RSSIs of the wireless signals received by the respective first antenna and the second antenna is higher than or equal to a predetermined value, set the length of the first term and the length of the second term without including the number of times that the communication data sent by the source terminal for sending the wireless signal is determined to be successfully obtained.

5. The communication unit according to claim 2 ,

wherein the storage unit is configured to store, as new association, the association between the communication terminal and one of the first antenna and the second antenna that receives the wireless signal which has the higher one of the RSSIs, upon receiving the communication data sent by the communication terminal.

6. The communication device according to claim 1 ,

wherein the selection unit is configured to repeat the first term and the second term in a cycle.

7. The communication device according to claim 6 ,

wherein the selection unit is configured to update a repeat cycle for the first term and the second term, based on the number of times that the communication data sent by the communication terminal associated with the first antenna is determined to be successfully obtained and the number of times that the communication data sent by the communication terminal associated with the second antenna is determined to be successfully obtained.

8. The communication device according to claim 6 ,

wherein the selection unit is configured to set the length of the first term and the length of the second term under a condition that retransmission latency for the communication terminal to retransmit the communication data is set as a repeat cycle.

9. The communication device according to claim 1 ,

wherein the selection unit is configured to keep selection of the first antenna or selection of the second antenna during reception of the wireless signals by the first antenna or the second antenna.

10. A communication method for use in a communication device including a first antenna and a second antenna for receiving wireless signals which contain communication data and are sent by a plurality of communication terminals, the communication method comprising:

selecting the first antenna in a first term, and the second antenna in a second term different from the first term;

determining whether or not the communication data contained in the wireless signals received by a selected one of the first antenna and the second antenna selected in the selecting is successfully obtained; and

associating each of the communication terminals with one of the first antenna and the second antenna,

wherein in the selecting, with reference to association in the associating, a length of the first term and a length of the second term are set to make a ratio of the length of the second term to the length of the first term equal to a ratio of the number of times the communication data sent by the communication terminal associated with the second antenna is determined to be successfully obtained, to the number of times the communication data sent by the communication terminal associated with the first antenna is determined to be successfully obtained.

11. A non-transitory computer-readable recording medium which records a program causing a computer to execute the communication method according to claim 10 .