Channel estimator

A channel estimator used in a receiver in a radio system where the transmitted signal consists of continuous frames having a configuration in which a known pattern signal formed by cyclically extending a specific code sequence is periodically inserted, the channel estimator comprising:

• a preceding wave position detection section configured to detect the position of a preceding wave of a received signal;
• a delay time estimation section configured to estimate a delay time of the received signal;
• a switching section configured to select any one of the preceding wave position detected by the preceding wave position detection section and the delay time estimated by the delay time estimation section;
• an FFT parameter determination section configured to determine an FFT window position and an FFT size on the basis of the output of the switching section;
• a first FFT section configured to transform the received signal to the frequency domain on the basis of the FFT window position and the FFT size that are determined by the FFT parameter determination section;
• a second FFT section configured to transform the known pattern signal to the frequency domain on the basis of the FFT size determined by the FFT parameter determination section;
• a channel response calculation section configured to perform division processing to divide the FFT output of the first FFT section by the FFT output of the second FFT section;
• and
• an IFFT section configured to apply IFFT to the output of the channel response calculation section on the basis of the FFT size determined by the FFT parameter determination section,
• wherein the delay time estimation section estimates a delay time on the basis of the output of the IFFT section.