Ofdm signal receiving apparatus and an ofdm signal receiving method

Abstract

An apparatus includes a converter separating the OFDM signal into the several sub-carriers, an extraction circuit extracting the reference symbol from at least one of a plurality of sub-carriers, an estimation circuit estimating a transmission distortion channel for every sub-carrier based on the amplitude and phase characteristic of the reference symbol, an adder adding channel estimation results of a first sub-carrier be set at least one of the plurality of sub-carriers, a second sub-carrier adjacent to a high-band side of the first sub-carrier and a third sub-carrier adjacent to a low-band side of the first sub-carrier, a calculator calculating the average of the added value to obtain amplitude and phase correction values with respect to the first sub-carrier, and a correction circuit correcting amplitude and phase with respect to each of the plurality of sub-carriers based on the amplitude and phase correction values.

1 . A computer system comprising:
 means for receiving an OFDM (Orthogonal Frequency Division Multiplexing) signal multiplexing a reference symbol having known amplitude and phase characteristic to at least one of a plurality of sub-carriers orthogonal to each other;   means for converting the OFDM signal into a plurality of sub-carriers;   means for extracting the reference symbol from at least one of a plurality of sub-carriers;   means for estimating a transmission channel distortion for each of the sub-carriers based on the known amplitude and phase characteristic of the reference symbol to obtain a plurality of channel estimation results;   means for adding the channel estimation results every several sub-carriers of the sub-carriers to obtain a plurality of added values, the several sub-carriers including a first sub-carrier corresponding to the at least one of the several sub-carriers, a second sub-carrier adjacent to a high-band side of the first sub-carrier and a third sub-carrier adjacent to a low-band side of the first sub-carrier;   means for obtaining amplitude and phase correction values on the first sub-carrier by averaging the added results, while the first sub-carrier is shifted sequentially; and   means for correcting amplitude and phase of each of the plurality of sub-carriers based on the amplitude and phase correction values;   wherein the means for adding multiplies the result of the first sub-carrier, the result of the second sub-carrier, and the result of the third sub-carrier by weight coefficients, respectively, and adds the plurality of multiplied values.   
   
   
       2 . The computer system according to  claim 1 , further comprising:
 when the OFDM signal has a transmission frame structure in which a header area and a data area exist, a guard interval and a preamble are arranged in the header area, and a plurality of data symbols with the guard interval is arranged in a following data area,   means for dividing the OFDM signal into the header area and the data area, and averaging the header area in a time axis direction.   
   
   
       3 . The computer system according to  claim 2 , wherein the means for dividing divides the OFDM signal into the header area and the data area, and averages them in a time axis direction. 
   
   
       4 . The computer system according to  claim 1 , wherein the reference symbol is a pilot symbol. 
   
   
       5 . The computer system according to  claim 1 , wherein the weight coefficients are a plurality of coefficients different from one another in accordance with a condition of the transmission channel. 
   
   
       6 . A computer readable storage medium storing instructions of a computer program which when executed by a computer results in performance of steps comprising:
 receiving an OFDM (Orthogonal Frequency Division Multiplexing) signal multiplexing a reference symbol having known amplitude and phase characteristic to at least one of a plurality of sub-carriers orthogonal to each other;   converting the OFDM signal into a plurality of sub-carriers;   extracting the reference symbol from at least one of a plurality of sub-carriers;   estimating a transmission channel distortion for each of the sub-carriers based on the known amplitude and phase characteristic of the reference symbol to obtain a plurality of channel estimation results;   adding the channel estimation results every several sub-carriers of the sub-carriers to obtain a plurality of added values, the several sub-carriers including a first sub-carrier corresponding to the at least one of the several sub-carriers, a second sub-carrier adjacent to a high-band side of the first sub-carrier and a third sub-carrier adjacent to a low-band side of the first sub-carrier;   obtaining amplitude and phase correction values on the first sub-carrier by averaging the added results, while the first sub-carrier is shifted sequentially; and   correcting amplitude and phase of each of the plurality of sub-carriers based on the amplitude and phase correction values;   wherein the adding includes multiplying the result of the first sub-carrier, the result of the second sub-carrier, and the result of the third sub-carrier by weight coefficients, respectively, and adding the plurality of multiplied values.   
   
   
       7 . The medium according to  claim 6 , further comprising:
 when the OFDM signal has a transmission frame structure in which a header area and a data area exist, a guard interval and a preamble are arranged in the header area, and a plurality of data symbols with the guard interval are arranged in the following data area,   dividing the OFDM signal into the header area and the data area, and averaging the header area in a time axis direction.   
   
   
       8 . The medium according to  claim 7 , wherein the dividing includes dividing the OFDM signal into the header area and the data area, and averaging them in a time axis direction. 
   
   
       9 . The medium according to  claim 6 , wherein the reference symbol is a pilot symbol. 
   
   
       10 . The medium according to  claim 6 , wherein the weight coefficients are a plurality of coefficients different from one another in accordance with a condition of the transmission channel.