Frequency offset estimation apparatus and method in wireless telecommunication system
View Patent ↗The present invention relates to an apparatus and method for estimating a frequency offset in a wireless telecommunication system. The present invention does not estimate an initial frequency offset using a preamble which is the initial symbol of a frame upon estimation of the frequency offset in the wireless telecommunication system, but estimates a frequency offset using correlation of a cyclic prefix (CP) existing in each symbol, thereby eliminating a need to reproduce information about separate preamble signals and preamble signals, and easily estimating a frequency offset using only input signals.
1. A frequency offset estimation apparatus in a wireless telecommunication system, comprising:
an analog to digital converter configured to convert analog signals received through an antenna into digital signals;
a decimator configured to re-sample over-sampled digital signals outputted from the analog to digital converter; and
a frequency offset estimator configured to buffer first N CP samples of each symbol on an individual symbol basis for samples output from the decimator, measure correlation values between the first N CP samples and last N CP samples of said each symbol when the last N CP samples are input, sum the correlation values, calculate an average value of the summed correlation values, and estimate a frequency offset value by performing an arctangent operation on the average value,
wherein the first N CP samples correspond to a cyclic prefix of each symbol.
2. The frequency offset estimation apparatus as claimed in claim 1 , further comprising:
a Radio Frequency (RF)/Intermediate Frequency (IF) module configured to perform at least one operation of demodulation, amplification, and filtering in RF/IF bandwidths,
wherein the frequency offset estimator is configured to transmit the estimated frequency offset value to the RF/IF module and the RF/IF module is configured to compensate for a frequency offset of a terminal based on the estimated frequency offset value.
3. The frequency offset estimation apparatus as claimed in claim 2 , wherein the frequency offset estimator performs scaling on the estimated frequency offset value and transmits the scaled estimated frequency offset value to the RF/IF module.
4. The frequency offset estimation apparatus as claimed in claim 1 , wherein the frequency offset estimation apparatus is a receiver or transceiver of a portable Internet system.
5. A frequency offset estimator of a wireless telecommunication system, comprising:
a cyclic prefix buffer configured to buffer first N CP samples of each symbol on an individual symbol basis, wherein the first N CP samples correspond to a cyclic prefix of each symbol;
a correlation measurement unit configured to measure correlation values between the first N CP samples and last N CP samples of said each symbol when the last N CP samples are input;
an average value calculator configured to sum the correlation values and calculate an average value of the summed correlation values; and
a frequency offset calculator configured to estimate a frequency offset value by performing an arctangent operation on the average value.
6. The frequency offset estimator as claimed in claim 5 , further comprising a scaling unit configured to adjust a dimension of the frequency offset value outputted from the frequency offset calculator.
7. A method of estimating a frequency offset in a wireless telecommunication system, comprising:
buffering first N CP samples of each symbol on an individual symbol basis, wherein the first N CP samples correspond to a cyclic prefix of each symbol;
measuring correlation values between the first N CP samples and last N CP samples of said each symbol on an individual symbol basis when the last N CP samples are input;
summing the correlation values and calculating an average value of the summed correlation values; and
estimating a frequency offset value by performing an arctangent operation on the average value.
8. The method as claimed in claim 7 , further comprising, prior to the buffering step, performing sampling on analog signals received from an antenna to convert the analog signals into digital signals.
9. The method as claimed in claim 7 , further comprising, after the estimating step, compensating for an initial frequency offset of a terminal based on the estimated frequency offset value.