Multicarrier communication apparatus, integrated circuit, and multicarrier communication method

1. A multicarrier communication apparatus that receives a reception signal via a transmission line and detects a carrier of the reception signal, the multicarrier communication apparatus comprising:

a first carrier detector that detects the carrier based on time characteristics of the reception signal;

a second carrier detector that detects the carrier based on frequency characteristics of the reception signal; and

a controller that selects, based on status of the transmission line, one of the first carrier detector and the second carrier detector and switches the selected carrier detector between the first carrier detector and the second carrier detector,

wherein the controller selects the first carrier detector at beginning of communication,

wherein the controller selects the first carrier detector if the status of the transmission line has a higher quality than a predetermined value and selects the second carrier detector if the status of the transmission line has a lower quality than the predetermined value, and

wherein the controller switches from the first carrier detector to the second carrier detector in a case where carrier detection by using the first carrier detector has failed.

2. The multicarrier communication apparatus according to claim 1 , wherein the transmission line comprises a power line.

3. The multicarrier communication apparatus according to claim 1 , wherein the controller switches from the first carrier detector to the second carrier detector in a case where carrier detection of a carrier of a received beacon signal by using the first carrier detector has failed.

4. The multicarrier communication apparatus according to claim 1 , wherein the controller switches the selected carrier detector between the first carrier detector and the second carrier detector based on a result of carrier detection of a beacon signal received by one of the time carrier detection and the frequency carrier detection.

5. The multicarrier communication apparatus according to claim 1 , wherein the controller switches the selected carrier detector between the first carrier detector and the second carrier detector based on a result of carrier detection of a test signal received by one of the time carrier detection and the frequency carrier detection.

6. The multicarrier communication apparatus according to claim 1 , wherein the controller switches the selected carrier detector between the first carrier detector and the second carrier detector based on carrier to noise ratios (CNRs) respectively corresponding to at least one of the plurality of subcarriers.

7. The multicarrier communication apparatus according to claim 1 , wherein the controller selects one of the first carrier detector and the second carrier detector after communication terminates.

8. The multicarrier communication apparatus according to claim 1 , wherein the controller selects one of the first carrier detector and the second carrier detector according to transmission content.

9. The multicarrier communication apparatus according to claim 1 , wherein the controller selects one of the first carrier detector and the second carrier detector according to a connected appliance that utilizes the reception signal.

10. The multicarrier communication apparatus, according to claim 1 , wherein the controller selects the first carrier detector, and switches from the first carrier detector to the second carrier detector in a case where a rate of false carrier detection by the first carrier detector is above a predetermined rate.

11. The multicarrier communication apparatus according to claim 1 , wherein the controller switches the selected carrier detector between the first carrier detector and the second carrier detector in a case where carrier detection by the first carrier detector has succeeded.

12. The multicarrier communication apparatus according to claim 1 , wherein the first carrier detector detects time characteristics of the reception signal by using a correlation of the time waveform.

13. The multicarrier communication apparatus according to claim 12 , wherein communication that uses the plurality of carriers uses a wavelet filter bank.

14. A multicarrier communication apparatus that receives a reception signal via a transmission line and detects a carrier of the reception signal, the multicarrier communication comprising:

a first carrier detector that detects the carrier based on time characteristics of the reception signal;

a second carrier detector that detects the carrier based on frequency characteristics of the reception signal; and

a controller that selects, based on status of the transmission line, one of the first carrier detector and the second carrier detector,

wherein the controller selects the first carrier detector if the status of the transmission line has a higher quality than a predetermined value and selects the second carrier detector if the status of the transmission line has a lower quality than the predetermined value, and

wherein the second carrier detector detects frequency characteristics of the reception signal by using a correlation between complex subcarriers.

15. The multicarrier communication apparatus according to claim 14 , wherein communication that uses the plurality of carriers, uses a wavelet filter bank, and uses two subcarriers to form the complex subcarrier.

16. The multicarrier communication apparatus according to claim 1 , wherein the first carrier detector and the second carrier detector detect a carrier by using a signal during a period of time in which a certain amount of data of a received signal have a continuous data.

17. A multicarrier communication apparatus that receives a reception signal via a transmission line and detects a carrier of the reception signal, the multicarrier communication comprising:

a detector that has a first function detecting the carrier based on time characteristics of the reception signal and a second function detecting the carrier based on frequency characteristics of the reception signal, and selects, based on status of the transmission line, one of the first function and the second function and switches the selected carrier detector between the first function and the second function,

wherein the detector selects the first function at beginning of communication,

wherein the detector selects the first function if the status of the transmission line has a higher quality than a predetermined value and selects the second function if the status of the transmission line has a lower quality than the predetermined value, and

wherein the detector switches from the first function to the second function in a case where carrier detection by using the first function has failed.

18. An integrated circuit that receives a reception signal via a transmission line and detects a carrier of the reception signal, the integrated circuit comprising:

a first carrier detector that detects the carrier based on time characteristics of the reception signal;

a second carrier detector that detects the carrier based on frequency characteristics of the reception signal; and

a controller that selects, based on status of the transmission line, one carrier detector of the first carrier detector and the second carrier detector and switches the selected carrier detector between the first carrier detector and the second carrier detector,

wherein the detector selects the first carrier detector at beginning of communication,

wherein the controller selects the first carrier detector if the status of the transmission line has a higher quality than a predetermined value and selects the second carrier detector if the status of the transmission line has a lower quality than the predetermined value, and

wherein the controller switches from the first carrier detector to the second carrier detector in a case where carrier detection by using the first carrier detector has failed.

19. A multicarrier communication method to receive a reception signal via a transmission line and to detect a carrier of the reception signal, the multicarrier communication method comprising:

(a) detecting the carrier based on time characteristics of the reception signal;

(b) detecting the carrier based on frequency characteristics of the reception signal; and

(c) selecting, based on status of the transmission line, one step of steps (a) and (b), and switching the selected step between step (a) and step (b),

wherein step (a) is selected at beginning of communication,

wherein step (a) is selected in step (c) if the status of the transmission line has a higher quality than a predetermined value and step (b) is selected in step (c) if the status of the transmission line has a lower quality than said predetermined value, and

wherein in step(c) switching is performed from step (a) to step (b) in a case where carrier detection by using step (a) has failed.

20. A multicarrier communication apparatus that receives a reception signal via a transmission line and detects a carrier of the reception signal, the multicarrier communication comprising:

a detector that has first function detecting the carrier based on time characteristics of the reception signal and second function detecting the carrier based on frequency characteristics of the reception signal, and that selects, based on status of the transmission line, one of the first function and the second function,

wherein the detector selects the first function if the status of the transmission line has a higher quality than a predetermined value and selects the second function if the status of the transmission line has a lower quality than the predetermined value, and

wherein the detector detects frequency characteristics of the reception signal by using a correlation between complex subcarriers in the second function.

21. An integrated circuit that receives a reception signal via a transmission line and detects a carrier of the reception signal, the multicarrier communication comprising:

a first carrier detector that detects the carrier based on time characteristics of the reception signal;

a second carrier detector that detects the carrier based on frequency characteristics of the reception signal; and

a controller that selects, based on status of the transmission line, one of the first carrier detector and the second carrier detector;

wherein the controller selects the first carrier detector if the status of the transmission line has a higher quality than a predetermined value and selects the second carrier detector if the status of the transmission line has a lower quality than the predetermined value, and

wherein the second carrier detector detects frequency characteristics of the reception signal by using a correlation between complex subcarriers.

22. A multicarrier communication method to receive a reception signal via a transmission line and to detect a carrier of the reception signal, the multicarrier communication method comprising:

(a) detecting the carrier based on time characteristics of the reception signal;

(b) detecting the carrier based on frequency characteristics of the reception signal; and

(c) selecting, based on status of the transmission line, one step of steps (a) and (b),

wherein step (a) is selected in step (c) if the status of the transmission line has a higher quality than a predetermined value and step (b) is selected in step (c) if the status of the transmission line has a lower quality than the predetermined value, and

wherein step (b) includes detecting frequency characteristics of the reception signal by using a correlation between complex subcarriers.