Channel estimation device

1. A channel estimation device in wireless communication with use of a plurality of subcarriers for communication, comprising:

a first channel estimation section which performs channel estimation for each subcarrier based on pilot signals mapped to each subcarrier;

a second channel estimation section which further performs channel estimation for each subcarrier using channel estimation values estimated by the first channel estimation section; and

a channel selection section which selects and outputs first and second channel estimation values estimated by said first and second channel estimation sections, according to the subcarrier,

wherein said second channel estimation section includes:

a first conversion section which converts channel estimation values estimated by the first channel estimation section into time-domain channel estimation values;

a noise suppression section which suppresses noise included in the time-domain channel estimation values; and

a second conversion section which converts noise-suppressed time-domain channel estimation values into frequency-domain channel estimation values, and

wherein said channel selection section selects the channel estimation values estimated by said first channel estimation section as channel estimation values for subcarriers at both ends of an effective band, selects the channel estimation values estimated by said second channel estimation section as channel estimation values for subcarriers other than the subcarriers at both ends of the effective band, and outputs the selected values.

2. The channel estimation device according to claim 1 , wherein said channel selection section holds constant the number of said subcarriers at both ends of the effective band.

3. The channel estimation device according to claim 1 , wherein, when pilot signals are mapped to subcarriers in each band of a plurality of bands and transmitted, said channel estimation devices are provided for each of the bands.

4. A channel estimation device in wireless communication with use of a plurality of subcarriers for communication, comprising:

a first channel estimation section which performs channel estimation for each subcarrier based on pilot signals mapped to each subcarrier;

a second channel estimation section which further performs channel estimation for each subcarrier using channel estimation values estimated by the first channel estimation section; and

a channel selection section which selects and outputs first and second channel estimation values estimated by said first and second channel estimation sections, according to the subcarrier,

wherein said second channel estimation section includes:

a first conversion section which converts channel estimation values estimated by the first channel estimation section into time-domain channel estimation values;

a noise suppression section which suppresses noise included in the time-domain channel estimation values; and

a second conversion section which converts noise-suppressed time-domain channel estimation values into frequency-domain channel estimation values, and

wherein said channel selection section estimates a prescribed characteristic value, determines the number of subcarriers at both ends of the effective band based on the estimated characteristic value, selects, as the channel estimation values of subcarriers at both ends of the effective band in the number thus determined, the channel estimation values estimated by said first channel estimation section, selects, as the channel estimation values of subcarriers other than the subcarriers at both ends of the effective band, the channel estimation values estimated by said second channel estimation section, and outputs the selected values.

5. The channel estimation device according to claim 4 , wherein said characteristic value is reception SIR, and the number of said subcarriers at both ends of the effective band is determined based on the estimated reception SIR.

6. The channel estimation device according to claim 4 , wherein said characteristic value is multipath delay spread, and the number of said subcarriers at both ends of the effective band is determined based on the estimated delay spread.

7. The channel estimation device according to claim 4 , wherein said characteristic value is mobile terminal motion velocity, and the number of said subcarriers at both ends of the effective band is determined based on the estimated motion velocity.

8. A channel estimation device in wireless communication in use of a plurality of subcarriers for communication, comprising:

a first channel estimation section which performs channel estimation for each subcarrier based on a first channel estimation method using pilot signals mapped to each subcarrier;

a second channel estimation section which performs channel estimation for each subcarrier based on a second channel estimation method which is different from said first channel estimation method, using pilot signals mapped to each subcarrier; and

a channel selection section which selects and outputs first and second channel estimation values estimated by said first and second channel estimation sections, according to the subcarrier, wherein said channel selection section selects the channel estimation values estimated by said first channel estimation section as channel estimation values for a constant number of subcarriers at both ends of an effective band, selects the channel estimation values estimated by said second channel estimation section as channel estimation values for subcarriers other than the subcarriers at both ends of the effective band, and outputs the selected values.

9. A channel estimation device in wireless communication in use of a plurality of subcarriers for communication, comprising:

a first channel estimation section which performs channel estimation for each subcarrier based on a first channel estimation method using pilot signals mapped to each subcarrier;

a second channel estimation section which performs channel estimation for each subcarrier based on a second channel estimation method which is different from said first channel estimation method, using pilot signals mapped to each subcarrier; and

a channel selection section which selects and outputs first and second channel estimation values estimated by said first and second channel estimation sections, according to the subcarrier, wherein said channel selection section estimates a prescribed characteristic value, determines the number of subcarriers at both ends of the effective band based on the estimated characteristic value, selects, as the channel estimation values of subcarriers at both ends of the effective band in the number thus determined, the channel estimation values estimated by said first channel estimation section, selects, as the channel estimation values of subcarriers other than the subcarriers at both ends of the effective band, the channel estimation values estimated by said second channel estimation section, and outputs the selected values.

10. The channel estimation device according to claim 9 , wherein said characteristic value is reception SIR, and the number of said subcarriers at both ends of the effective band is determined based on the estimated reception SIR.

11. The channel estimation device according to claim 9 , wherein said characteristic value is multipath delay spread, and the number of said subcarriers at both ends of the effective band is determined based on the estimated delay spread.

12. The channel estimation device according to claim 9 , wherein said characteristic value is mobile terminal motion velocity, and the number of said subcarriers at both ends of the effective band is determined based on the estimated motion velocity.

13. A channel estimation method performed by a channel estimation device in wireless communication in which a plurality of subcarriers are used for communication, comprising:

performing first channel estimation for each subcarrier based on a first channel estimation method using pilot signals mapped to each subcarrier;

performing second channel estimation for each subcarrier based on a second channel estimation method which is different from said first channel estimation method, using pilot signals mapped to each subcarrier; and

selecting and outputting the channel estimation values estimated by said first channel estimation as channel estimation values for a constant number of subcarriers at both ends of an effective band, while selecting and outputting the channel estimation values estimated by said second channel estimation as channel estimation values for subcarriers other than the subcarriers at both ends of the effective band.

14. A channel estimation method performed by a channel estimation device in wireless communication in which a plurality of subcarriers are used for communication, comprising:

performing a first channel estimation for each subcarrier based on pilot signals mapped to each subcarrier and outputting a first channel estimation value for each subcarrier;

performing a second channel estimation for each subcarrier using the channel estimation values estimated by the first channel estimation and outputting a second channel estimation value for each subcarrier; and

selecting and outputting the first and second channel estimation values estimated by said first and second channel estimation, according to the subcarrier,

wherein said second channel estimation is performed by:

converting the first channel estimation values estimated by the first channel estimation into time-domain channel estimation values;

suppressing noise included in the time-domain channel estimation values; and

converting noise-suppressed time-domain channel estimation values into frequency-domain channel estimation values as the second channel estimation values, and

wherein the first and second channel estimation values are selected and output by:

selecting the first channel estimation values estimated by said first channel estimation as channel estimation values for subcarriers at both ends of an effective band;

selecting the second channel estimation values estimated by said second channel estimation as channel estimation values for subcarriers other than the subcarriers at both ends of the effective band; and

outputting the selected values.

15. A channel estimation method performed by a channel estimation device in wireless communication in which a plurality of subcarriers are used for communication, comprising:

performing a first channel estimation for each subcarrier based on pilot signals mapped to each subcarrier and outputting a first channel estimation value for each subcarrier;

performing a second channel estimation for each subcarrier using the channel estimation values estimated by the first channel estimation and outputting a second channel estimation value for each subcarrier; and

selecting and outputting the first and second channel estimation values estimated by said first and second channel estimation, according to the subcarrier,

wherein said second channel estimation is performed by:

converting the first channel estimation values estimated by the first channel estimation into time-domain channel estimation values;

suppressing noise included in the time-domain channel estimation values; and

converting noise-suppressed time-domain channel estimation values into frequency-domain channel estimation values as the second channel estimation values, and

wherein the first and second channel estimation values are selected and output by:

estimating a prescribed characteristic value;

determining the number of subcarriers at both ends of the effective band based on the estimated characteristic value;

selecting, as the channel estimation values of subcarriers at both ends of the effective band in the number thus determined, the first channel estimation values estimated by said first channel estimation;

selecting, as the channel estimation values of subcarriers other than the subcarriers at both ends of the effective band, the second channel estimation values estimated by said second channel estimation; and

outputting the selected values.

16. A channel estimation method performed by a channel estimation device in wireless communication in which a plurality of subcarriers are used for communication, comprising:

performing channel estimation for each subcarrier based on a first channel estimation method using pilot signals mapped to each subcarrier and outputting a first channel estimation value for each subcarrier;

performing channel estimation for each subcarrier based on a second channel estimation method which is different from said first channel estimation method, using pilot signals mapped to each subcarrier and outputting a second channel estimation value for each subcarrier; and

selecting and outputting the first and second channel estimation values estimated based on said first and second channel estimation methods, according to the subcarrier,

wherein the first and second channel estimation values are selected and output by:

selecting the first channel estimation values estimated based on said first channel estimation method as channel estimation values for a constant number of subcarriers at both ends of an effective band;

selecting the second channel estimation values estimated based on said second channel estimation method as channel estimation values for subcarriers other than the subcarriers at both ends of the effective band; and

outputting the selected values.

17. A channel estimation method performed by a channel estimation device in wireless communication in which a plurality of subcarriers are used for communication, comprising:

performing channel estimation for each subcarrier based on a first channel estimation method using pilot signals mapped to each subcarrier and outputting a first channel estimation value for each subcarrier;

performing a second channel estimation for each subcarrier based on a second channel estimation method which is different from said first channel estimation method, using pilot signals mapped to each subcarrier and outputting a second channel estimation value for each subcarrier; and

selecting and outputting the first and second channel estimation values estimated based on said first and second channel estimation methods, according to the subcarrier,

wherein the first and second channel estimation values are selected and output by:

estimating a prescribed characteristic value;

determining the number of subcarriers at both ends of the effective band based on the estimated characteristic value;

selecting, as the channel estimation values of subcarriers at both ends of the effective band in the number thus determined, the first channel estimation values estimated based on said first channel estimation method;

selecting, as the channel estimation values of subcarriers other than the subcarriers at both ends of the effective band, the second channel estimation values estimated based on said second channel estimation method; and

outputting the selected values.