Channel equalizer and method of processing broadcast signal in DTV receiving system

• US 7,876,835 B2
• Filed: 02/12/2007
• Issued: 01/25/2011
• Est. Priority Date: 02/10/2006
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kwak, Kook Yeon, Kang, Kyung Won, Kim, Woo Chan, Kim, Byoung Gill, Choi, In Hwan
• Primary Examiner(s): Ghayour; Mohammad H
• Assistant Examiner(s): Giles; Eboni
• Application Number:
  US11/674,099
• Publication Number:
  US 20070230580A1
• Time in Patent Office: 1,443 Days
• Field of Search: 375/229, 375/231, 375/232, 37524025-24027, 375/240.01, 375/240.18, 348607-614, 348/723
• US Class Current: 375/240.27
• CPC Class Codes: H03M 13/2792 Interleaver wherein interleaving is performed jointly with another technique such as puncturing, multiplexing or routing
• CPC Class Codes: H03M 13/2906 using block codes H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/2936 comprising an outer Reed-Solomon code and an inner convolutional code
• CPC Class Codes: H03M 13/6538 ATSC VBS systems
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0232 by interpolation between sounding signals
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 19/895 in combination with error concealment
• CPC Class Codes: H04N 21/236 Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream multiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/631 Multimode Transmission, e.g. transmitting basic layers and enhancement layers of the content over different transmission paths or transmitting with different error corrections, different keys or with different transmission protocols
• CPC Class Codes: H04N 5/21 Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
• CPC Class Codes: H04N 5/38 Transmitter circuitry for the transmission of television signals according to analogue transmission standards H04N5/14 takes precedence
• CPC Class Codes: H04N 5/40 Modulation circuits
• CPC Class Codes: H04N 5/455 Demodulation-circuits
• CPC Class Codes: H04N 7/12 Systems in which the television signal is transmitted via one channel or a plurality of parallel channels, the bandwidth of each channel being less than the bandwidth of the television signal H04N7/24 takes precedence

Abstract

A channel equalizer includes a first transformer, an estimator, an average calculator, a second transformer, a coefficient calculator, a compensator, and a third transformer. The first transformer converts normal data into frequency domain data, where a known data sequence is periodically repeated in the normal data. The estimator estimates channel impulse responses (CIR) during known data intervals adjacent to each normal data block. The average calculator calculates an average value of the CIRs. The second transformer converts the average value into frequency domain data. The coefficient calculator calculates equalization coefficients using the average value, and the compensator compensates channel distortion of each normal data block using the coefficients. The third transformer converts the compensated data block into time domain data.

Claims

1. A method of processing a broadcast signal in a DTV receiving system, the method comprising:

receiving in a receiver the broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

converting the mobile data of the broadcast signal into frequency domain data;

estimating channel impulse responses during intervals in which first and second known data sequences located before and after each mobile data block in the broadcast signal are received;

calculating an average value of the estimated channel impulse responses;

converting the average value of the estimated channel impulse responses into frequency domain data;

calculating equalization coefficients using the average value of the estimated channel impulse responses in the frequency domain;

compensating channel distortion of each mobile data block in the frequency domain by multiplying each mobile data block with the equalization coefficients; and

converting the compensated mobile data block into time domain data.

2. The method of claim 1, wherein converting mobile data in a broadcast signal into frequency domain data comprises converting the mobile data in the broadcast signal using a fast Fourier transform (FFT).

3. The method of claim 1, wherein converting the average value into frequency domain data comprises converting the average value using a fast Fourier transform (FFT).

4. The method of claim 1, wherein converting the compensated mobile data block into time domain data comprises converting the compensated mobile data block using an inverse fast Fourier transform (IFFT).

5. A method of processing a broadcast signal in a DTV receiving system, the method comprising:

receiving in a receiver the broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

overlapping the mobile data of the broadcast signal at a predetermined overlap ratio;

converting the overlapped mobile data into frequency domain data;

estimating a channel impulse response using the known data sequences;

converting the estimated channel impulse response into frequency domain data;

calculating equalization coefficients using the estimated channel impulse response in the frequency domain;

compensating channel distortion of the mobile data in the frequency domain by multiplying the mobile data with the equalization coefficients;

converting the compensated mobile data into time domain data; and

saving the compensated mobile data in the time domain.

6. The method of claim 5, wherein converting the overlapped mobile data into frequency domain data comprises converting the overlapped normal data using a fast Fourier transform (FFT).

7. The method of claim 5, wherein converting the estimated channel impulse response into frequency domain data comprises converting the estimated channel impulse response using a fast Fourier transform (FFT).

8. The method of claim 5, wherein converting the compensated mobile data into time domain data comprises converting the compensated mobile data using an inverse fast Fourier transform (IFFT).

9. A method of processing a broadcast signal in a DTV receiving system, the method comprising:

receiving in a receiver the broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

overlapping the mobile data of the broadcast signal at a predetermined overlap ratio;

converting the overlapped mobile data into frequency domain data;

estimating a first channel impulse response during a known data interval;

estimating a second channel impulse response during a mobile data interval by interpolating the first channel impulse response;

converting the estimated second channel impulse response into frequency domain data;

calculating equalization coefficients using the second channel impulse response in the frequency domain;

compensating channel distortion of the mobile data in the frequency domain by multiplying the mobile data with the equalization coefficients;

converting the compensated mobile data into time domain data; and

saving the compensated mobile data in the time domain.

10. The method of claim 9, wherein converting the overlapped mobile data into frequency domain data comprises converting the overlapped mobile data using a fast Fourier transform (FFT).

11. The method of claim 9, wherein converting the estimated second channel impulse response into frequency domain data comprises converting the estimated second channel impulse response using a fast Fourier transform (FFT).

12. The method of claim 9, wherein converting the compensated mobile data into time domain data comprises converting the compensated mobile data using an inverse fast Fourier transform (IFFT).

13. A method of processing a broadcast signal in a DTV receiving system, the method comprising:

receiving in a receiver the broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

overlapping the mobile data of the broadcast signal at a predetermined overlap ratio;

converting the overlapped mobile data into frequency domain data;

compensating channel distortion of the mobile data in the frequency domain by multiplying the mobile data with equalization coefficients;

converting the compensated mobile data into time domain data;

saving the compensated mobile data in the time domain;

calculating an error of the saved mobile data using a decision value of the saved mobile data and the known data sequences;

padding zeros into the error according to the overlap ratio;

converting the zero-padded error into frequency domain data; and

updating the equalization coefficients based on the zero-padded error in the frequency domain.

14. The method of claim 13, wherein calculating an error of the saved mobile data comprises:

generating the decision value of the saved mobile data;

selecting the decision value using a mobile data interval and selecting the known data sequence during a known data interval in a data selector; and

generating the error of the saved mobile data by subtracting the saved mobile data from the data selected by the selector.

15. The method of claim 13, wherein converting the overlapped mobile data into frequency domain data comprises converting the overlapped mobile data using a fast Fourier transform (FFT).

16. The method of claim 13, wherein converting the compensated mobile data into time domain data comprises converting the compensated mobile data using an inverse fast Fourier transform (IFFT).

17. The method of claim 13, wherein converting the zero-padded error into frequency domain data comprises converting the zero-padded error using a fast Fourier transform (FFT).

18. A DTV receiving system comprising:

a receiver receiving a broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

a first transformer for converting the mobile data of the broadcast signal into frequency domain data;

an estimator for estimating channel impulse responses during intervals in which first and second known data sequences located before and after each mobile data block in the broadcast signal are received;

an average calculator for calculating an average value of the estimated channel impulse responses;

a second transformer for converting the average value of the estimated channel impulse responses into frequency domain data;

a coefficient calculator for calculating equalization coefficients using the average value of the estimated channel impulse responses in the frequency domain;

a compensator for compensating channel distortion of each mobile data block in the frequency domain by multiplying each mobile data block with the equalization coefficients; and

a third transformer for converting the compensated mobile data block into time domain data.

19. The DTV receiving system of claim 18, wherein the first transformer converts the mobile data using a fast Fourier transform (FFT).

20. The DTV receiving system of claim 18, wherein the second transformer converts the average value of the channel impulse responses using a fast Fourier transform (FFT).

21. The DTV receiving system of claim 18, wherein the third transformer converts the compensated mobile data block using an inverse fast Fourier transform (IFFT).

22. A DTV receiving system comprising:

a receiver receiving a broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

an overlap unit for overlapping the mobile data of the broadcast signal at a predetermined overlap ratio;

a first transformer for converting the overlapped mobile data into frequency domain data;

an estimator estimating a channel impulse response using the known data sequence;

a second transformer for converting the estimated channel impulse response into frequency domain data;

a calculator for calculating equalization coefficients using the estimated channel impulse response in the frequency domain;

a compensator for compensating channel distortion of the mobile data in the frequency domain by multiplying the mobile data with the equalization coefficients;

a third transformer for converting the compensated mobile data into time domain data; and

a save unit for saving the compensated mobile data in the time domain.

23. The DTV receiving system of claim 22, wherein the first transformer converts the overlapped mobile data using a fast Fourier transform (FFT).

24. The DTV receiving system of claim 22, wherein the second transformer converts the estimated channel impulse response using a fast Fourier transform (FFT).

25. The DTV receiving system of claim 22, wherein the third transformer converts the compensated mobile data using an inverse fast Fourier transform (IFFT).

26. A DTV receiving system comprising:

a receiver receiving a broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

an overlap unit for overlapping the mobile data of the broadcast signal at a predetermined overlap ratio;

a first transformer for converting the overlapped mobile data into frequency domain data;

an estimator estimating a first channel impulse response during a known data interval;

an interpolator estimating a second channel impulse response during a mobile data interval by interpolating the first channel impulse response;

a second transformer for converting the estimated second channel impulse response into frequency domain data;

a calculator for calculating equalization coefficients using the second channel impulse response in the frequency domain;

a compensator for compensating channel distortion of the mobile data in the frequency domain by multiplying the mobile data with the equalization coefficients;

a third transformer for converting the compensated mobile data into time domain data; and

a save unit for saving the compensated mobile data in the time domain.

27. The DTV receiving system of claim 26, wherein the first transformer converts the overlapped mobile data using a fast Fourier transform (FFT).

28. The DTV receiving system of claim 26, wherein the second transformer converts the estimated second channel impulse response using a fast Fourier transform (FFT).

29. The DTV receiving system of claim 26, wherein the third transformer converts the compensated mobile data using an inverse fast Fourier transform (IFFT).

30. A channel equalizer for use in a DTV receiving system, the channel equalizer comprising:

a receiver receiving a broadcast signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

an overlap unit for overlapping the mobile data of the broadcast signal at a predetermined overlap ratio;

a first transformer for converting the overlapped mobile data into frequency domain data;

a compensator for compensating channel distortion of the mobile data in the frequency domain by multiplying the mobile data with equalization coefficients;

a second transformer for converting the compensated mobile data into time domain data;

a save unit for saving the compensated mobile data in the time domain;

an error calculator for calculating an error of the saved mobile data using a decision value of the saved mobile data and the known data sequences;

a padding unit for padding zeros into the error according to the overlap ratio;

a third transformer for converting the zero-padded error into frequency domain data; and

a coefficient update unit for updating the equalization coefficients based on the zero-padded error in the frequency domain.

31. The DTV receiving system of claim 30, wherein the error calculator comprises:

a decision unit for generating the decision value of the saved mobile data;

a selector for selecting the decision value during a mobile data interval and selecting the known data sequence during a known data interval; and

a subtractor for generating the error of the saved mobile data by subtracting the saved mobile data from the data selected by the selector.

32. The DTV receiving system of claim 30, wherein the first transformer converts the overlapped mobile data using a fast Fourier transform (FFT).

33. The DTV receiving system of claim 30, wherein the second transformer converts the compensated mobile data using an inverse fast Fourier transform (IFFT).

34. The DTV receiving system of claim 30, wherein the third transformer converts the zero-padded error using a fast Fourier transform (FFT).

35. A method for processing a digital broadcasting signal in a receiver, the method comprising:

receiving the digital broadcasting signal having including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

equalizing the digital broadcasting signal in accordance with the received known data sequences by estimating a channel impulse response (CIR) by using the known data sequences; and

decoding the equalized broadcasting signal.

36. An apparatus for processing a digital broadcasting signal, the apparatus comprising:

a receiving unit for receiving the digital broadcasting signal including first 207-byte segments, second 207-byte segments and third 207-byte segments, the first 207-byte segments having mobile data and main data, the second 207-byte segments being positioned between the first and third 207-byte segments, the second 207-byte segments having mobile data and known data sequences and the third 207-byte segments having mobile data and main data, wherein the mobile data in the first, second and third 207-byte segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns;

an equalizing unit for equalizing the digital broadcasting signal in accordance with the received known data sequences by estimating a channel impulse response (CIR) by using the known data sequences; and

a decoding unit for decoding the equalized broadcasting signal.

37. A transmitter for processing a digital broadcasting signal, the transmitter comprising:

a generating unit for generating the digital broadcasting signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences for channel equalization and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns; and

a transmitting unit for transmitting the digital broadcasting signal modulated by a VSB modulation scheme.

38. A method for processing a digital broadcasting signal in a transmitter, the method comprising:

generating the digital broadcasting signal including a data group having first segments, second segments and third segments, the second segments being positioned between the first and third segments, the first segments having mobile data and main data, the second segments having mobile data and known data sequences for channel equalization and the third segments having mobile data and main data, wherein the mobile data in the first, second and third segments are encoded by RS-CRC (Reed Solomon-cyclic redundancy check) encoding and non-systematic RS encoding, the main data in the first and third segments are encoded by systematic RS encoding and at least two of the known data sequences have different patterns; and

transmitting the digital broadcasting signal modulated by a VSB modulation scheme.