Apparatus and method for fading frequency estimation

A fading frequency estimating apparatus comprising:

• a particular arithmetic operation unit which corrects a phase deviation in first and second symbols of a plurality p of symbols and then calculates an inner product thereof, the plurality p of symbols being associated with a same signal position and received at p different instants t1 to tp in time-series order, respectively, p being greater than or equal to 3, the phase deviation caused from a frequency deviation in a local frequency signal used for receiving the plurality p of symbols;
• an arithmetic operation unit which calculates magnitudes m2 to mp-1 of individual products of the first symbol and the third to pth symbols in their complex domain;
• a rough estimation unit which roughly estimates a fading frequency to be such a value that the inner product corresponds to a first time correlation value between the first and second symbols, the first time correlation value depending on a difference τ=t2−t1 between different instants t1 and t2 on the time axis and on a wavelength λ of a carrier wave used for transmission of the plurality p of symbols;
• a storing unit which stores therein in advance bands in which a fading frequency is obtained with desired accuracy at such values that correspond to second to (p-1)th time correlation values between the first symbol and the third to pth symbols, the second to (p-1) correlation values depending on the wavelength λ and respective differences τ1=t3−t1, . . . , τp-2 =tp−t1 between the instant t1 and different instants t3 to tp on the time axis;
• and
• an estimation unit which estimates a fading frequency to be such a value that a magnitude mi corresponds to an absolute value of an ith time correlation value of the second to (p-1)th time correlation values, the ith time correlation value corresponding to a particular band that is stored in said storing unit and including the roughly estimated fading frequency, i satisfying a relationship 2≦i≦p-1.

A fading frequency estimating apparatus comprising:

• a particular arithmetic operation unit which corrects a phase deviation in an inner product of first and second symbols among a plurality p of symbols that are associated with a same signal position and received at p different instants t1 to tp in time-series order, the phase deviation caused from a frequency deviation in a local frequency signal used for receiving the first and second symbols, p being greater than or equal to 3;
• an arithmetic operation unit which calculates magnitudes m2 to mp-1 of individual products of the first symbol and the third to pth symbols in their complex domain;
• a rough estimation unit which roughly estimates a fading frequency to be such a value that the corrected inner product corresponds to a first time correlation value between said first and second symbols, the first time correlation value depending on a difference τ=t2−t1 between different instants t1 and t2 on the time axis and on a wavelength λ of a carrier wave used for transmission of the plurality p of symbols;
• a storing unit which stores therein in advance bands in which a fading frequency is obtained with desired accuracy at such values that correspond to second to (p-1)th time correlation values between the first symbol and the third to pth symbols, the second to (p-1) time correlation values depending on the wavelength λ and respective differences τ1=t3−t1, . . . , τp-2 =tp−t1 between the instant t1 and different instants t3 to tp on the time axis;
• and
• an estimation unit which estimates a fading frequency to be such a value that a magnitude mi corresponds to an absolute value of an ith time correlation value of the second to (p-1)th time correlation values, the ith time correlation value corresponding to a particular band that is stored in said storing unit and including the roughly estimated fading frequency, i satisfying a relationship 2≦i≦p-1.