Blind correlation for high precision ranging of coded OFDM signals
An apparatus having a corresponding method and computer program comprises a front end to receive an orthogonal frequency division modulation (OFDM) signal comprising a plurality of OFDM symbols each comprising N samples and a cyclic prefix comprising M of the N samples, wherein M<N; a buffer to store the cyclic prefix for one of the OFDM symbols; and a correlator to generate a correlation output based on the cyclic prefix and the one of the OFDM symbols.
1 . An apparatus comprising:
a front end to receive an orthogonal frequency division modulation (OFDM) signal comprising a plurality of OFDM symbols each comprising N samples and a cyclic prefix comprising M of the N samples, wherein M<N;
a buffer to store the cyclic prefix for one of the OFDM symbols; and
a correlator to generate a correlation output based on the cyclic prefix and the one of the OFDM symbols.
2 . The apparatus of claim 1 , further comprising:
a synchronizer to identify boundaries of the OFDM symbols.
3 . The apparatus of claim 1 , further comprising:
an accumulator to accumulate the correlation output for a plurality of the OFDM symbols.
4 . The apparatus of claim 3 , wherein the correlator comprises:
a fast Fourier transform (FFT) engine.
5 . The apparatus of claim 1 , wherein:
the correlator generates frequency-domain representations of the one of the OFDM symbols and the cyclic prefix for the one of the OFDM symbols, generates a product of the frequency-domain representations; and generates a time-domain representation of the product.
6 . The apparatus of claim 1 , wherein:
a location of the apparatus is determined based upon the correlation output.
7 . The apparatus of claim 1 , further comprising:
a ranging unit to determine a location of the apparatus based upon the correlation output.
8 . The apparatus of claim 1 , further comprising:
a demodulator to demodulate the OFDM signal based upon the correlation output.
9 . The apparatus of claim 1 , wherein the OFDM signal comprises at least one of the group consisting of:
a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal;
a ETSI Digital Video Broadcasting-Handheld (DVB-H) signal; and
a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.
10 . A method comprising:
receiving an orthogonal frequency division modulation (OFDM) signal comprising a plurality of OFDM symbols each comprising N samples and a cyclic prefix comprising M of the N samples, wherein M<N;
storing the cyclic prefix for one of the OFDM symbols; and
generating a correlation output based on the cyclic prefix and the one of the OFDM symbols.
11 . The method of claim 10 , further comprising:
identifying boundaries of the OFDM symbols.
12 . The method of claim 10 , further comprising:
accumulating the correlation output for a plurality of the OFDM symbols.
13 . The method of claim 10 , wherein generating a correlation output based on the cyclic prefix and the one of the OFDM symbols comprises:
generating frequency-domain representations of the one of the OFDM symbols and the cyclic prefix for the one of the OFDM symbols;
generating a product of the frequency-domain representations; and
generating a time-domain representation of the product.
14 . The method of claim 10 , wherein:
a location is determined based upon the correlation output.
15 . The method of claim 10 , further comprising:
determining a location based upon the correlation output.
16 . The method of claim 10 , further comprising:
demodulating the OFDM signal based upon the correlation output.
17 . The method of claim 10 , wherein the OFDM signal comprises at least one of the group consisting of:
a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal;
a ETSI Digital Video Broadcasting-Handheld (DVB-H) signal; and
a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.
18 . An apparatus comprising:
front end means for receiving an orthogonal frequency division modulation (OFDM) signal comprising a plurality of OFDM symbols each comprising N samples and a cyclic prefix comprising M of the N samples, wherein M<N;
buffer means for storing the cyclic prefix for one of the OFDM symbols; and
correlator means for generating a correlation output based on the cyclic prefix and the one of the OFDM symbols.
19 . The apparatus of claim 18 , further comprising:
means for identifying boundaries of the OFDM symbols.
20 . The apparatus of claim 18 , further comprising:
means for accumulating the correlation output for a plurality of the OFDM symbols.
21 . The apparatus of claim 20 , wherein the correlator means comprises:
means for performing a fast Fourier transform (FFT).
22 . The apparatus of claim 18 , wherein:
the correlator means generates frequency-domain representations of the one of the OFDM symbols and the cyclic prefix for the one of the OFDM symbols, generates a product of the frequency-domain representations; and generates a time-domain representation of the product.
23 . The apparatus of claim 18 , wherein:
a location of the apparatus is determined based upon the correlation output.
24 . The apparatus of claim 18 , further comprising:
means for determining a location of the apparatus based upon the correlation output.
25 . The apparatus of claim 18 , further comprising:
means for demodulating the OFDM signal based upon the correlation output.
26 . The apparatus of claim 18 , wherein the OFDM signal comprises at least one of the group consisting of:
a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal;
a ETSI Digital Video Broadcasting-Handheld (DVB-H) signal; and
a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.