DIGITAL BROADCASTING SYSTEM AND METHOD OF PROCESSING DATA

• US 20080240293A1
• Filed: 07/06/2007
• Published: 10/02/2008
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Byoung Gill, Lee, Hyoung Gon, Choi, In Hwan, Kim, Jong Moon, Song, Won Gyu, Kwak, Kook Yeon, Kim, Jin Woo
• Granted Patent: US 7,822,134 B2
• Time in Patent Office: Days
• US Class Current: 375/316
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• 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 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 21/238 Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams hybrid fiber coaxial [HFC] networks for downstream channel allocation for video distribution H04L12/2801; flow control in packet networks H04L47/10; real-time communication protocols in data switching networks H04L65/00; scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/2389 Multiplex stream processing, e.g. multiplex stream encrypting

Abstract

A digital broadcast system and method of processing data are disclosed. A channel equalizer includes a frequency domain converter receiving a known data sequence, when the known data sequence is periodically inserted and transmitted in general data, and converting the received data to frequency domain data, a CIR estimator using the data being received during a known data section and known data generated by a receiving system, so as to estimate a CIR, a CIR calculator interpolating or extrapolating the CIR estimated by the CIR estimator in accordance with characteristics of the general data being received, a coefficient calculator converting the CIR being outputted from the CIR calculator to a frequency domain CIR and calculating and outputting an equalization coefficient, and a distortion compensator multiplying the equalization coefficient calculated by the coefficient calculator with the data converted to frequency domain data by the frequency domain converter, thereby compensating channel distortion.

Claims

1. A channel equalizer of a digital broadcast receiving system, comprising:

a frequency domain converter receiving a known data sequence, when the known data sequence is periodically inserted and transmitted in general data, and converting the received data to frequency domain data;

a CIR estimator using the data being received during a known data section and known data generated by a receiving system, so as to estimate a channel impulse response (CIR);

a CIR calculator interpolating or extrapolating the CIR estimated by the CIR estimator in accordance with characteristics of the general data being received;

a coefficient calculator converting the CIR being outputted from the CIR calculator to a frequency domain CIR and calculating and outputting an equalization coefficient; and

a distortion compensator multiplying the equalization coefficient calculated by the coefficient calculator with the data converted to frequency domain data by the frequency domain converter, thereby compensating channel distortion.

2. The channel equalizer of claim 1, wherein the frequency domain converter overlaps the received data at a pre-determined overlapping ratio so as to convert the overlapped data to frequency domain data.

3. The channel equalizer of claim 2, further comprising:

a time domain converter converting the frequency domain data having the channel distortion compensated to time domain data, and extracting and outputting valid data from the overlapped data.

4. The channel equalizer of claim 1, wherein the CIR calculator interpolates and outputs a plurality of estimated CIRs within a field synchronization section and/or a known data section, when the general data correspond to data in-between known data sequences within the data group being received.

5. The channel equalizer of claim 1, wherein the CIR calculator interpolates and outputs a plurality of estimated CIRs within a field synchronization section and/or a known data section, when the general data correspond to data between a field synchronization section and a known data sequence within the data group being received.

6. The channel equalizer of claim 1, wherein the CIR calculator extrapolates and outputs a plurality of estimated CIRs within a field synchronization section and/or a known data section, when the general data correspond to data being received earlier than the field synchronization section within the data group being received.

7. The channel equalizer of claim 1, wherein the CIR calculator extrapolates and outputs a plurality of estimated CIRs within a field synchronization section and/or a known data section, when the general data correspond to data being received later than a last known data sequence within the data group being received.

8. The channel equalizer of claim 1, further comprising:

a first pre-CIR cleaner at an inputting end of the CIR calculator, the first pre-CIR cleaner being operated when the CIR calculator performs extrapolation, thereby removing a jitter included in the CIR estimated by the CIR estimator; and

a second pre-CIR cleaner at an outputting end of the CIR calculator, the second pre-CIR cleaner being operated when the CIR calculator performs interpolation, thereby removing a jitter included in the interpolated CIR.

9. The channel equalizer of claim 8, wherein at least one of the first pre-CIR cleaner and the second pre-CIR cleaner removes a portion of a CIR element being inputted having a power equal to or below a pre-determined threshold value.

10. The channel equalizer of claim 1, further comprising:

a zero-padding unit adding a number of zeros corresponding to a difference in a FFT size and a CIR length to the CIR, when the length of the CIR being outputted from the CIR calculator and the size of the FFT of the coefficient calculator are not equal to one another.

11. The channel equalizer of claim 1, wherein the coefficient calculator calculates an equalization coefficient of the frequency domain that is able to provide a minimum mean square error (MMSE) from the CIR.

12. A channel equalizing method of a digital broadcast receiving system, comprising the steps of:

receiving a known data sequence, when the known data sequence is periodically inserted and transmitted in general data, and converting the received data to frequency domain data;

using the data being received during a known data section and known data generated by a receiving system, so as to estimate a channel impulse response (CIR);

interpolating or extrapolating the CIR estimated by the CIR estimator in accordance with characteristics of the general data being received;

converting the CIR being interpolated or extrapolated to a frequency domain CIR, and calculating and outputting an equalization coefficient; and

multiplying the calculated equalization coefficient with the data converted to frequency domain data, thereby compensating channel distortion.

13. The method of claim 12, wherein the received data are overlapped at a pre-determined overlapping ratio so as to convert the overlapped data to frequency domain data.

14. The method of claim 13, further comprising a step of:

converting the frequency domain data having the channel distortion compensated to time domain data, and extracting and outputting valid data from the overlapped data.

15. The method of claim 12, wherein a plurality of estimated CIRs within a field synchronization section and/or a known data section are interpolated and outputted, when the general data correspond to data in-between known data sequences within the data group being received.

16. The method of claim 12, wherein a plurality of estimated CIRs within a field synchronization section and/or a known data section are interpolated and outputted, when the general data correspond to data between a field synchronization section and a known data sequence within the data group being received.

17. The method of claim 12, wherein a plurality of estimated CIRs within a field synchronization section and/or a known data section are extrapolated and outputted, when the general data correspond to data being received earlier than the field synchronization section within the data group being received.

18. The method of claim 12, wherein a plurality of estimated CIRs within a field synchronization section and/or a known data section are extrapolated and outputted, when the general data correspond to data being received later than a last known data sequence within the data group being received.

19. The method of claim 12, wherein, when extrapolating a plurality of estimated CIRs, removing a jitter included in the estimated CIR, performing extrapolation, and outputting the processed data so as to calculate an equalization coefficient.

20. The method of claim 12, wherein, when interpolating a plurality of estimated CIRs, performing interpolation, removing a jitter included in the interpolated CIR, and outputting the processed data so as to calculate an equalization coefficient.

21. The method of claim 12, further comprising a step of:

adding a number of zeros corresponding to a difference in a FFT size and a CIR length to the CIR, when the length of the calculated CIR and the size of the FFT are not equal to one another.

22. The method of claim 12, wherein an equalization coefficient of the frequency domain that is able to provide a minimum mean square error (MMSE) from the CIR is calculated.