Delay profile generator
View Patent ↗A delay profile generator that includes a delay profile generating component, a delay profile extracting component, an integrating component, a comparing component and a correcting component, is provided. The integrating component, in the delay profile extracted by the delay profile extracting component, integrates a signal component of a delay profile of a first time period, and integrates a signal component of a delay profile of a second time period that does not overlap the first time period. The comparing component compares integration values of the two time periods obtained by the integrating component. The correcting component corrects a time position of the delay profile window on the basis of results of comparison of the comparing component.
1. A delay profile generator comprising:
a delay profile generating component that extracts pilot symbols from an OFDM signal in which pilot symbols are scattered among data symbols in a frequency direction and a time direction and which is modulated, and generates, from the extracted pilot symbols, a delay profile representing a time axis distribution of a delay wave;
a delay profile extracting component that, by using a delay profile window representing a time position for extracting a necessary delay profile, extracts a delay profile within the window from the delay profile generated by the delay profile generating component;
an integrating component that, in the delay profile extracted by the delay profile extracting component, integrates a signal component of a delay profile of a first time period, and integrates a signal component of a delay profile of a second time period that does not overlap the first time period;
a comparing component that compares integration values of the two time periods obtained by the integrating component; and
a correcting component that corrects a time position of the delay profile window on the basis of results of comparison of the comparing component.
2. The delay profile generator of claim 1 , wherein the first time period is a former-half time period when a time length of the extracted delay profile is divided into two time periods at a center of the time length, and the second time period is a latter-half time period.
3. The delay profile generator of claim 1 , wherein the integrating component changes the first time period and the second time period on the basis of a time length of the extracted delay profile and a correction amount of the correcting component.
4. The delay profile generator of claim 1 , wherein the correcting component corrects the time position of the delay profile window in a case in which a relationship of magnitudes of the two integration values is judged to satisfy a predetermined condition at the comparing component.
5. The delay profile generator of claim 1 , wherein the correcting component computes and accumulates a correction amount within a predetermined range each time the integration values of the two time periods are computed at the integrating component, and moves the time position of the delay profile window to a time position that is apart from a reference window position by the accumulated correction amount.
6. A method of correcting a time position of a delay profile window in a delay profile generator, the method comprising:
(a) extracting pilot symbols from an OFDM signal in which pilot symbols are scattered among data symbols in a frequency direction and a time direction and which is modulated, and generating, from the extracted pilot symbols, a delay profile representing a time axis distribution of a delay wave;
(b) by using a delay profile window representing a time position for extracting a necessary delay profile, extracting a delay profile within the window from the delay profile generated in (a);
(c) in the delay profile extracted in (b), integrating a signal component of a delay profile of a first time period, and integrating a signal component of a delay profile of a second time period that does not overlap the first time period;
(d) comparing integration values of the two time periods obtained in (c); and
(e) correcting a time position of the delay profile window on the basis of results of comparison of (d).
7. The method of correcting a time position of a delay profile window of claim 6 , wherein the first time period is a former-half time period when a time length of the extracted delay profile is divided into two time periods at a center of the time length, and the second time period is a latter-half time period.
8. The method of correcting a time position of a delay profile window of claim 6 , wherein the first time period and the second time period are changed on the basis of a time length of the extracted delay profile and a correction amount of (e).
9. The method of correcting a time position of a delay profile window of claim 6 , wherein the time position of the delay profile window is corrected in a case in which a relationship of magnitudes of the two integration values is judged to satisfy a predetermined condition in (d).
10. The method of correcting a time position of a delay profile window of claim 6 , wherein
a correction amount within a predetermined range is computed and accumulated each time the integration values of the two time periods are computed, and
the time position of the delay profile window is moved to a time position that is apart from a reference window position by the accumulated correction amount.