Wireless apparatus, method and non-transitory computer-readable storage medium

1. A wireless apparatus configured to be cascaded to another wireless apparatus through a transmission path and to be coupled to an antenna multiplexer, the another wireless apparatus being coupled to the antenna multiplexer, the wireless apparatus comprising:

a memory; and

a processor coupled to the memory and configured to:

specify a first time length for a first transmission signal having a first frequency band to pass through the wireless apparatus;

specify a second time length for a second transmission signal having a second frequency band to pass through the wireless apparatus, the transmission path, and the another wireless apparatus;

specify a difference between the first time length and the second time length;

delay the second transmission signal by the specified difference;

generate, based on the first transmission signal and the delayed second transmission signal, a cancellation signal for an intermodulation distortion that occurs in a received signal received by the antenna multiplexer due to intermodulation between the first transmission signal and the second transmission signal in the antenna multiplexer; and

combine the cancellation signal with the received signal.

2. The wireless apparatus according to claim 1 , wherein

the second frequency band is different from the first frequency band.

3. The wireless apparatus according to claim 2 , wherein

the processor is configured to:

detect a correlation value between the received signal and the cancellation signal;

based on the correlation value, sequentially change a delay amount by which the second transmission signal is delayed;

specify the correlation value in accordance with the delay amount; and

specify the delay amount so as to maximize the specified correlation value.

4. The wireless apparatus according to claim 3 , wherein

the processor is configured to:

sequentially change the delay amount at a first time interval in a first range;

specify the correlation value in accordance with a change in the delay amount;

specify a first delay amount with which the specified correlation value is greatest;

sequentially change the first delay amount at a second time interval narrower than the first time interval in a second range including the first delay amount and being narrower than the first range;

specify the correlation value in accordance with a change in the first delay amount; and

specify the first delay amount with which the specified correlation value is greatest.

5. The wireless apparatus according to claim 3 , wherein

the processor is configured to:

when power of the second transmission signal exceeds a threshold, suppress the power;

adjust the threshold based on the correlation value;

generate the cancellation signal based on the first transmission signal, the delayed second transmission signal and the suppressed power;

specify the correlation value in accordance with the threshold; and

specify the threshold so as to maximize the specified correlation value.

6. The wireless apparatus according to claim 3 , wherein

the processor is configured to:

adjust an average amplitude of the second transmission signal;

set an adjustment amount of the average amplitude based on the correlation value;

generate the cancellation signal based on the first transmission signal and the second transmission signal that is delayed and the average amplitude of which is adjusted;

specify the correlation value in accordance with the adjustment amount; and

set the adjustment amount so as to maximize the specified correlation value.

7. A method executed by a wireless apparatus configured to be cascaded to another wireless apparatus through a transmission path and to be coupled to an antenna multiplexer, the another wireless apparatus being coupled to the antenna multiplexer, the method comprising:

specifying a first time length for a first transmission signal having a first frequency band to pass through the wireless apparatus;

specifying a second time length for a second transmission signal having a second frequency band to pass through the wireless apparatus, the transmission path, and the another wireless apparatus;

specifying a difference between the first time length and the second time length;

delaying the second transmission signal by the specified difference;

generating, based on the first transmission signal and the delayed second transmission signal, a cancellation signal for an intermodulation distortion that occurs in a received signal received by the antenna multiplexer due to intermodulation between the first transmission signal and the second transmission signal in the antenna multiplexer; and

combining the cancellation signal with the received signal.

8. The method according to claim 7 , wherein

the second frequency band is different from the first frequency band.

9. The method according to claim 8 , further comprising:

detecting a correlation value between the received signal and the cancellation signal;

based on the correlation value, sequentially changing a delay amount by which the second transmission signal is delayed;

specifying the correlation value in accordance with the delay amount; and

specifying the delay amount so as to maximize the specified correlation value.

10. The method according to claim 9 , further comprising:

sequentially changing the delay amount at a first time interval in a first range;

specifying the correlation value in accordance with a change in the delay amount;

specifying a first delay amount with which the specified correlation value is greatest;

sequentially changing the first delay amount at a second time interval narrower than the first time interval in a second range including the first delay amount and being narrower than the first range;

specifying the correlation value in accordance with a change in the first delay amount; and

specifying the first delay amount with which the specified correlation value is greatest.

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

when power of the second transmission signal exceeds a threshold, suppressing the power;

adjusting the threshold based on the correlation value;

generating the cancellation signal based on the first transmission signal, the delayed second transmission signal and the suppressed power;

specifying the correlation value in accordance with the threshold; and

specifying the threshold so as to maximize the specified correlation value.

12. The method according to claim 9 , further comprising:

adjusting an average amplitude of the second transmission signal;

setting an adjustment amount of the average amplitude based on the correlation value;

generating the cancellation signal based on the first transmission signal and the second transmission signal that is delayed and the average amplitude of which is adjusted;

specifying the correlation value in accordance with the adjustment amount; and

setting the adjustment amount so as to maximize the specified correlation value.

13. A non-transitory computer-readable storage medium storing a program that causes an information processing apparatus to execute a process, the information processing apparatus being included in a wireless apparatus configured to be cascaded to another wireless apparatus through a transmission path and to be coupled to an antenna multiplexer, the another wireless apparatus being coupled to the antenna multiplexer, the process comprising:

specifying a first time length for a first transmission signal having a first frequency band to pass through the wireless apparatus;

specifying a second time length for a second transmission signal having a second frequency band to pass through the wireless apparatus, the transmission path, and the another wireless apparatus;

specifying a difference between the first time length and the second time length;

delaying the second transmission signal by the specified difference;

generating, based on the first transmission signal and the delayed second transmission signal, a cancellation signal for an intermodulation distortion that occurs in a received signal received by the antenna multiplexer due to intermodulation between the first transmission signal and the second transmission signal in the antenna multiplexer; and

combining the cancellation signal with the received signal.

14. The non-transitory computer-readable storage medium according to claim 13 , wherein

the second frequency band is different from the first frequency band.

15. The non-transitory computer-readable storage medium according to claim 14 , further comprising:

detecting a correlation value between the received signal and the cancellation signal;

based on the correlation value, sequentially changing a delay amount by which the second transmission signal is delayed;

specifying the correlation value in accordance with the delay amount; and

specifying the delay amount so as to maximize the specified correlation value.

16. The non-transitory computer-readable storage medium according to claim 15 , further comprising:

sequentially changing the delay amount at a first time interval in a first range;

specifying the correlation value in accordance with a change in the delay amount;

specifying a first delay amount with which the specified correlation value is greatest;

sequentially changing the first delay amount at a second time interval narrower than the first time interval in a second range including the first delay amount and being narrower than the first range;

specifying the correlation value in accordance with a change in the first delay amount; and

specifying the first delay amount with which the specified correlation value is greatest.

17. The non-transitory computer-readable storage medium according to claim 15 , further comprising:

when power of the second transmission signal exceeds a threshold, suppressing the power;

adjusting the threshold based on the correlation value;

generating the cancellation signal based on the first transmission signal, the delayed second transmission signal and the suppressed power;

specifying the correlation value in accordance with the threshold; and

specifying the threshold so as to maximize the specified correlation value.

18. The method according to claim 15 , further comprising:

adjusting an average amplitude of the second transmission signal;

setting an adjustment amount of the average amplitude based on the correlation value;

generating the cancellation signal based on the first transmission signal and the second transmission signal that is delayed and the average amplitude of which is adjusted;

specifying the correlation value in accordance with the adjustment amount; and

setting the adjustment amount so as to maximize the specified correlation value.