Digital broadcast signal receiving apparatus and method
View Patent ↗A signal receiving apparatus and method which is high in deduction accuracy of transfer characteristic and less in error rate during signal decoding. For each detection signal of a pilot carrier allotted in an OFDM symbol space, a transfer function thereof is calculated. The transfer function is subjected to two-dimensional Fourier transform as to impulse delay time and symbol frequency thereby generating a two-dimensional data space. A predetermined domain of the two-dimensional data space is extracted by a filter extracting domain. The data included in the extracted domain is subjected to two-dimensional inverse Fourier transform as to carrier frequency and symbol time, thereby generating a deduced transfer function.
1. A signal receiving apparatus comprising:
a signal detecting section which receives an OFDM signal including a pilot carrier having a particular known complex amplitude at a predetermined carrier location, and allots each of a plurality of reception complex amplitudes obtained by detecting carrier signals included in a plurality of successive ones of OFDM symbols in a two-dimensional data domain corresponding to carrier frequency and symbol time;
a transfer characteristic estimating section which estimates a reception signal transfer characteristic relative to each of the carrier signals based on a reception complex amplitude corresponding to the pilot carrier among the plurality of reception complex amplitudes allotted in the two-dimensional data domain; and
a data decode section which decodes transmission data based on the reception complex amplitude and the reception signal transfer characteristics;
wherein the transfer characteristic estimating section includes;
a calculator which calculates pilot carrier transfer characteristics based on the reception complex amplitude corresponding to the pilot carrier among the plurality of reception complex amplitudes allotted in the two-dimensional data domain;
a transformer which generates two-dimensional Fourier transformed data on a two-dimensional space corresponding to on-transmission-line delay time and on-transmission-line variation frequency by performing a two-dimensional Fourier transform on the pilot carrier transfer characteristics;
a filter which selectively extracts a data group within a particular domain defined by a filter extracting domain from the two-dimensional Fourier transformed data;
a supplier which supplies the filter with a setting parameter to regulate a setting position of the filter extracting domain depending upon an input instruction, the filter defining the particular domain depending upon the setting parameter; and
a generator which generates two-dimensional inverse transformed data on the two-dimensional space corresponding to the carrier frequency and the symbol time by performing a two-dimensional inverse Fourier transform on the selectively extracted data group, and generates the reception signal transfer characteristic based on the generated two-dimensional inverse transformed data,
wherein the setting parameter is a reference pointer representative of a domain reference point of the filter extracting domain and a domain width of the filter extracting domain.
2. A signal receiving apparatus comprising:
a signal detecting section which receives an OFDM signal including a pilot carrier having a particular known complex amplitude at a predetermined carrier location, and allots each of a plurality of reception complex amplitudes obtained by detecting carrier signals included in a plurality of successive ones of OFDM symbols in a two-dimensional data domain corresponding to carrier frequency and symbol time;
a transfer characteristic estimating section which estimates a reception signal transfer characteristic relative to each of the carrier signals based on a reception complex amplitude corresponding to the pilot carriers among the plurality of reception complex amplitudes allotted in the two-dimensional data domain; and
a data decode section which decodes the transmission data based on the reception complex amplitude and the reception signal transfer characteristics;
wherein the transfer characteristic estimating section includes:
a calculator which calculates pilot carrier transfer characteristics based on the reception complex amplitude corresponding to the pilot carrier among the plurality of reception complex amplitudes allotted in the two-dimensional data domain;
a transformer which generates two-dimensional Fourier transformed data on a two-dimensional space corresponding to on-transmission-line delay time and on-transmission-line variation frequency by performing a two-dimensional Fourier transform on the pilot carrier transfer characteristics;
a filter which selectively extracts a data group within a particular domain defined by a filter extracting domain from the two-dimensional Fourier transformed data; and
a generator which generates two-dimensional inverse transformed data on the two-dimensional space corresponding to the carrier frequency and the symbol time by performing a two-dimensional inverse Fourier transform on the selectively extracted data group, and generates the reception signal transfer characteristic based on the generated two-dimensional inverse transformed data,
wherein the filter selectively extracts only data having a power equal to or greater than a reference value out of the data group included within the filter extracting domain, and takes a noise power measurement value in a domain other than the filter extracting domain on the two-dimensional Fourier transformed data space as the reference value and a window function of the filter extracting domain is adjusted in accordance with the noise power measurement value.
3. A signal receiving apparatus comprising:
a signal detecting section which receives an OFDM signal including a pilot carrier having a particular known complex amplitude at a predetermined carrier location, and allots each of a plurality of reception complex amplitude obtained by detecting carrier signals included in a plurality of successive ones of OFDM symbols in a two-dimensional data domain corresponding to carrier frequency and symbol time;
a transfer characteristic estimating section which estimates a reception signal transfer characteristic relative to each of the carrier signals based on a reception complex amplitude corresponding to the pilot carrier among the plurality of reception complex amplitudes allotted in the two-dimensional data domain; and
a data decode section which decodes the transmission data based on the reception complex amplitude and the reception signal transfer characteristics;
wherein the transfer characteristic estimating section includes:
a calculator which calculates pilot carrier transfer characteristics based on the reception complex amplitude corresponding to the pilot carrier among the reception complex amplitudes allotted in the two-dimensional data domain;
a transformer which generates two-dimensional Fourier transformed data on a two-dimensional space corresponding to on-transmission-line delay time and on-transmission-line variation frequency by performing a two-dimensional Fourier transform on the pilot carrier transfer characteristics;
a filter which selectively extracts a data group within a particular domain defined by a filter extracting domain from the two-dimensional Fourier transformed data; and
a generator which generates two-dimensional inverse transformed data on the two-dimensional space corresponding to the carrier frequency and the symbol time by performing a two-dimensional inverse Fourier transform on the selectively extracted data group, and generates the reception signal transfer characteristic based on the generated two-dimensional inverse transformed data,
wherein the filter divides the filter extracting domain into a plurality of segments and calculates a mean power for each of the segments, to thereby selectively extract only data included in a segment where the mean power has a power equal to or greater than a reference value, and takes a noise power measurement value in a domain other than the filter extracting domain on the two-dimensional Fourier transformed data space as the reference value and a window function of the filter extracting domain is adjusted in accordance with the noise power measurement value.
4. A signal receiving apparatus according to claim 2 , wherein the data decode section includes a reliability information calculator for calculating reliability information about each reception signal depending upon the reception transfer characteristic and noise power measurement value supplied from the transfer characteristic estimating section, and a weighter for giving a weighting to a decode parameter during decoding the reception signal depending upon the reliability information.
5. A signal receiving apparatus according to claim 4 , wherein the reliability information calculator uses as the reliability information a carrier/noise power ratio calculated depending upon the reception signal transfer characteristic and noise power measurement value.
6. A signal receiving apparatus according to claim 4 , wherein the decode parameter is bit metric information in a viterbi decoder.
7. A signal receiving apparatus according to claim 5 , wherein the decode parameter is bit metric information in a viterbi decoder.
8. A signal receiving apparatus according to any one of claims 1 and 2 - 7 , wherein the transformer multiplies the two-dimensional data domain by a predetermined window function, during carrying out the two-dimensional Fourier transform.
9. A signal receiving apparatus according to claim 8 , wherein the window function has a multiplication coefficient decreasing at a constant rate from an estimating data domain to the two-dimensional data domain.
10. A signal receiving apparatus according to any one of claims 1 and 2 - 7 , wherein the calculator calculates a transfer characteristic of a virtual pilot carrier allotted within an extended domain obtained by extending the two-dimensional data domain in a direction of the carrier frequency.
11. A signal receiving apparatus according to claim 10 , wherein the calculator generates a rotation parameter depending upon a transfer characteristic of an extreme end pilot carrier of carrier frequency in the two-dimensional data domain, takes the extreme end pilot carrier as a symmetric point on the carrier frequency, and multiplies the rotation parameter on the transfer characteristics of the extreme end pilot carrier within the two-dimensional data domain lying in a mirror-image relationship with an extended domain thereby calculating a transfer characteristic of a virtual pilot carrier.
12. A signal receiving apparatus according to claim 10 , wherein the calculator generates a rotation parameter depending upon a transfer characteristic of an extreme end pilot carrier of carrier frequency in the two-dimensional data domain, and multiplies the rotation parameter on the transfer function of the pilot carrier within the two-dimensional data domain lying in a mirror-image relationship with the extended domain on the carrier frequency thereby calculating a transfer characteristic of a virtual pilot carrier.
13. A signal receiving apparatus according to claim 11 , wherein the rotation parameter is a ratio of the transfer characteristic of the extreme end pilot carrier and a conjugate complex transfer characteristic of the extreme end pilot carrier.
14. A signal receiving apparatus according to claim 12 , wherein the rotation parameter is a ratio of the transfer characteristic of the extreme end pilot carrier and a conjugate complex transfer characteristic of the extreme end pilot carrier.
15. A signal receiving method comprising:
a step of receiving an OFDM signal including a pilot carrier having a particular known complex amplitude at a predetermined carrier location, and allotting each of a plurality of reception complex amplitudes obtained by detecting carrier signals included in a plurality of successive ones of ODFM symbols in a two-dimensional data domain corresponding to carrier frequency and symbol time;
a step of estimating a reception signal transfer characteristic relative to each of the carrier signals based on a reception complex amplitude corresponding to the pilot carrier among the plurality of reception complex amplitudes allotted in the two-dimensional data domain; and
a step of decoding the transmission data based on the plurality of reception complex amplitudes and the reception signal transfer characteristics;
wherein the reception signal transfer characteristic estimating step includes:
calculating pilot carrier transfer characteristics based on the reception complex amplitude corresponding to the pilot carrier among the plurality of reception complex amplitudes allotted in the two-dimensional data domain;
making a two-dimensional Fourier transform on the pilot carrier transfer characteristics and generating two-dimensional Fourier transformed data on a two-dimensional space corresponding to on-transmission-line delay time and on-transmission-line variation frequency;
selectively extracting a data group of within a particular domain defined by a filter extracting domain from the two-dimensional Fourier transformed data; and
making a two-dimensional inverse Fourier transform on the selectively extracted data group and generating two-dimensional inverse transformed data of on the two-dimensional space corresponding to the carrier frequency and the symbol time, and generating the reception signal transfer characteristic based on the generated two-dimensional inverse transformed data,
wherein only data having a power equal to or greater than a reference value is selectively extracted out of the data group included within the filter extracting domain, and a noise power measurement value in a domain other than the filter extracting domain on the two-dimensional Fourier transformed data space is taken as the reference value and a window function of the filter extracting is adjusted in accordance with the noise power measurement value.