In a signal detection apparatus, power detection section 101 detects power of an inputted received signal, and upon detection of power exceeding a power detection threshold, outputs a trigger to storage section 102. Storage section 102 stores a first received signal upon reception of the trigger and outputs the stored first received signal to multiplier 103 and newly stores a second received signal upon receipt of the next trigger. Multiplier 103 multiplies the second received signal by the first received signal, integrator 104 integrates the multiplication result from multiplier 103 during a predetermined duration to obtain a correlation value of the second and first received signals, and absolute value calculation section 105 calculates an absolute value of the correlation value from integrator 104. Determination section 106 determines the presence/absence of a detection-target signal based on the absolute value of the correlation value from absolute value calculation section 105.
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1. A signal detection apparatus comprising: a power detector which, in operation, detects whether reception power of a first received signal exceeds a first threshold and detects whether reception power of a second received signal exceeds the first threshold, the first received signal and the second received signal being at least one of a noise signal exceeding the first threshold and a beacon from another wireless communication system exceeding the first threshold; a correlator which, in operation, receives the first received signal and the second received signal when the reception power of the first received signal and the reception power of the second received signal both exceed the first threshold, and calculates a correlation value of the first received signal and the second received signal; an absolute value calculator which, in operation, calculates an absolute value of the calculated correlation value; and a determiner which, in operation, determines that the second received signal is the beacon received from the another wireless communication system when the absolute value of the correlation value exceeds the second threshold, and that the second received signal is the noise signal when the absolute value of the correlation value is less than the second threshold.
2. The signal detection apparatus according to claim 1 , wherein beam-forming is applied to the beacon.
3. The signal detection apparatus according to claim 1 , further comprising a memory which, in operation, stores the first received signal when the power detector detects that the reception power of the first received signal exceeds the first threshold, and the correlator, in operation, receives from the memory the stored first received signal when the power detector detects that the reception power of the second received signal exceeds the first threshold.
4. The signal detection apparatus according to claim 1 , wherein the correlator includes a multiplier that multiplies the first received signal and the second received signal to produce a multiplication result, and an integrator that integrates the multiplication result for a defined duration.
5. The signal detection apparatus according to claim 1 , wherein when the determiner determines that the second received signal is the noise signal, the power detector sets the first threshold to a lower value.
6. The signal detection apparatus according to claim 1 , wherein the determiner determines that the first received signal and the second received signal are both noise signals when the absolute value of the correlation value is less than the second threshold.
7. A signal detection method comprising: detecting whether reception power of a first received signal exceeds a first threshold, detecting whether reception power of a second received signal exceeds the first threshold, the first received signal and the second received signal being at least one of a noise signal exceeding the first threshold and a beacon from another wireless communication system exceeding the first threshold; calculating a correlation value of the first received signal and the second received signal when the reception power of the first received signal and the reception power of the second received signal both exceed the first threshold; calculating an absolute value of the calculated correlation value; and determining that the second received signal is the beacon received from the another wireless communication system when the absolute value of the correlation value exceeds the second threshold, and that the second received signal is the noise signal when the absolute value of the correlation value is less than the second threshold.
8. The signal detection method according to claim 7 , further comprising: storing the first received signal when the reception power of the first received signal is detected to exceed the first threshold; and retrieving the stored first received signal, for calculating the correlation value, when the reception power of the second received signal is detected to exceed the first threshold.
9. The signal detection method according to claim 7 , wherein the step of calculating the correlation value includes multiplying the first received signal and the second received signal to produce a multiplication result, and integrating the multiplication result for a defined duration.
10. The signal detection method according to claim 7 , further comprising: when determining that the second received signal is the noise signal, setting the first threshold to a lower value.
11. The signal detection method according to claim 7 , further comprising: determining that the first received signal and the second received signal are both noise signals when the absolute value of the correlation value is less than the second threshold.
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March 12, 2013
February 23, 2016
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