FEED-FORWARD CARRIER RECOVERY SYSTEM AND METHOD

• US 20120045028A1
• Filed: 05/28/2010
• Published: 02/23/2012
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Schmitt, Dirk, Gao, Wen, Knutson, Paul Gothard
• Granted Patent: US 8,792,592 B2
• Time in Patent Office: Days
• US Class Current: 375/371
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H04L 2027/0053 Closed loops
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 27/2678 using cyclostationarities, e.g. cyclic prefix or postfix
• CPC Class Codes: H04L 27/2679 Decision-aided
• CPC Class Codes: H04L 7/0062 detection of error based on data decision error, e.g. Mueller type detection
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation
• CPC Class Codes: H04W 56/005 compensating for timing error by adjustment in the receiver

Abstract

A method of feedforward phase recovery on a data stream is described. Phase estimation base points are calculated, at a phase detector, for each block of the received data stream. A current phase, at a phase interpolator, between two phase estimation base points. Data stream delays within the phase detector are matched with delays within the phase interpolator.

Claims

1. A method of feedforward phase recovery on a data stream, comprising:

calculating phase estimation base points, at a phase detector, for each block of the received data stream;

setting a current phase, at a phase interpolator, between two phase estimation base points; and

matching data stream delays within the phase detector with delays within the phase interpolator.

2. The method of claim 1, wherein the data stream includes data frames segmented into data blocks.

3. The method of claim 1, wherein calculating phase estimation base points is performed by using a maximization of a likelihood function.

4. The method of claim 2, wherein calculating phase estimation base points comprises

calculating one of:

a number of sync symbols or a number of pilot symbols in each block;

processing each sync symbol or pilot symbol, at a matched filter; and

calculating a carrier phase offset, at the phase detector, over a block of sync symbols or pilot symbols.

5. The method of claim 4, wherein the number of sync symbols or the number of pilot symbols is calculated by the equation

6. The method of claim 4 wherein the carrier phase offset is calculated at a phase offset estimator.

7. The method of claim 6, wherein the carrier phase offset is calculated using an algorithm represented by F(|z(nT)|)e^jargz(nT)M.

8. The method of claim 1, wherein the two phase estimation base points are within a range defined by |θ

(i−

1)−

θ

(i)|<

π

/M, wherein M denotes the modulation factor.

9. The method of claim 1, wherein calculating the two phase estimation base points is performed at a sawtooth device.

10. The method of claim 9, wherein the sawtooth device uses the equation θ

″

(i)=θ

″

(i−

1)+SAW(θ

′

(i)−

θ

″

(i−

1)), where θ

′

(i−

1), θ

′

(i) denotes the estimate of the phase offset in the (i−

1)-th and the i-th blocks and where θ

″

(i−

1), θ

″

(i) denotes the corresponding un-wrapping values.

11. The method of claim 10, further comprising detecting and tracking out phase variations, at a post-processing block.

12. The method of claim 11, wherein detecting and tracking out phase variations is calculated using the equation:

θ

″

(i)=θ

″

(i−

1)+α

·

SAW(θ

′

(i)−

θ

′

(i−

1)) with α

≦

1.0.

13. The method of claim 9, further comprising frequency estimation, at a frequency estimation block.

14. An apparatus that performs feedforward phase recovery on a data stream, comprising:

a phase detector, that calculates phase estimation base points for each block of the received data stream;

a phase interpolator, that sets a current phase between two phase estimation base points; and

a delay line, that matches data stream delays within the phase detector with delays within the phase interpolator.

15. The apparatus of claim 14, wherein the data stream includes data frames segmented into data blocks.

16. The apparatus of claim 14, wherein the phase estimation base points are calculated using a maximization of a likelihood function.

17. The apparatus of claim 14, further comprising

a matched filter that calculates one of:

a number of sync symbols or a number of pilot symbols in each block and processes each sync symbol or pilot symbol; and

wherein the phase detector calculates the two phase estimation base points over a block of sync symbols or pilot symbols.

18. The apparatus of claim 17, wherein the number of data symbols or the number of pilot symbols is calculated by the equation

19. The apparatus of claim 17, further comprising a phase offset estimator that calculates the carrier phase offset.

20. The apparatus of claim 19, wherein the carrier phase offset is calculated using an algorithm represented by F(|z(nT)|)e^jargz(nT)M.

21. The apparatus of claim 14, wherein the two phase estimation base points are within a range defined by |θ

(i−

1)−

θ

(i)|<

π

/M, wherein M denotes the modulation factor.

22. The apparatus of claim 14, further comprising a sawtooth device that calculates the two phase estimation base points.

23. The apparatus of claim 22, wherein the sawtooth device uses the equation θ

″

(i)=θ

″

(i−

1)+SAW(θ

′

(i)−

θ

″

(i−

1)), where θ

′

(i−

1), θ

′

(i) denotes the estimate of the phase offset in the (i−

1)-th and the i-th blocks and where θ

″

(i−

1), θ

″

(i) denotes the corresponding un-wrapping values.

24. The apparatus of claim 23, further comprising a post-processing block, that detects and tracks out phase variations from the output of the sawtooth device.

25. The apparatus of claim 24, wherein the post-processing block uses the equation:

θ

″

(i)=θ

″

(i−

1)+α

·

SAW(θ

′

(i−

1)) with α

≦

1.0.

26. The apparatus of claim 22, further comprising a frequency estimation block, that estimates the frequency of the output from the sawtooth device.