# US 2013/0155922 A1 · False lock detection for physical layer frame synchronization

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- Number: US 2013/0155922 A1
- Document ID: US20130155922A1
- Status: Published application
- Kind: A1
- Application number: 13/765,440
- Filed: 2013-02-12
- Published: 2013-06-20
- Earliest claimed: 2008-12-17
- Assignees: ViaSat, Inc.
- Inventors: Donald W. Becker; Matthew D. Nimmon; William H. Thesling
- Web page: https://patentgrep.com/patent/US20130155922A1

## CPC

- H04L 7/0016: {correction of synchronization errors}
- H04B 7/18504: {Aircraft used as relay or high altitude atmospheric platform}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION

## Abstract

Systems, devices, processors, and methods are described which may be used for the reception of a wireless broadband signal at a user terminal from a gateway via a satellite. A wireless signal may include a series of physical layer frames, each frame including a physical layer header and payload. The received signal is digitized and processed using various novel physical layer headers and related techniques to synchronize the physical layer frames and recover data from physical layer headers for purposes of demodulation and decoding.

## Claims

### Claim 1

A receiver to receive and process a plurality of physical layer frames of a received wireless signal, the receiver comprising:
a physical layer frame synchronization module configured to identify one or more start of frame locations for the plurality of physical layer frames to achieve frame synchronization;
a physical layer header decoder module, communicatively coupled with the physical layer frame synchronization module, and configured to decode a physical layer header associated with an identified start of frame location of a selected one of the plurality of physical layer frames according to a first decoding technique;
an error identification module, communicatively coupled with the physical layer header decoder module, and configured to:
decode the physical layer header according to a second decoding technique, wherein the physical layer header is divided into a plurality of sub-blocks and the second decoding technique decodes the sub-blocks of the physical layer header;
compare results from the first decoding technique to results of the second decoding technique; and
generate an error value associated with the physical layer header when the compared results do not match; and
an error accumulator module, communicatively coupled with the error identification module, and configured to:
receive the generated error value;
accumulate generated error values from one or more physical layer frames; and
determine that a false synchronization lock has occurred when the accumulated error value exceeds a threshold.

### Claim 2 (depends on 1)

The receiver of claim 1, wherein the first decoding technique comprises finding a maximum likelihood transmitted data pattern across the plurality of sub-blocks of encoded data comprising the physical layer header.

### Claim 3 (depends on 1)

The receiver of claim 1, wherein the plurality of sub-blocks comprise one or more sub-blocks of signaling information and one or more sub-blocks of parity information.

### Claim 4 (depends on 2)

The receiver of claim 2, wherein,
the second decoding technique comprises performing a max bin search over each of the plurality of sub-blocks; and
the error value is generated when each of the max bin searches does not match the maximum likelihood transmitted data pattern.

### Claim 5 (depends on 1)

The receiver of claim 1, wherein the threshold is a user configurable parameter.

### Claim 6 (depends on 1)

The receiver of claim 1, wherein the error accumulator module is further configured to weight the generated error values before accumulating the generated error value.

### Claim 7 (depends on 6)

The receiver of claim 6, wherein weighing the generated error value comprises weighting a first set of error values from more recently received physical layer frames more heavily than a second set of error values from physical layer frames received before the more recently received physical layer frames.

### Claim 8 (depends on 6)

The receiver of claim 6, wherein weighing the generated error value comprises weighting the generated error value in proportion to a degree of difference between the comparison of the results from the first technique to results of the second technique

### Claim 9 (depends on 1)

The receiver of claim 1, wherein the error accumulator module comprises an infinite impulse response filter.

### Claim 10 (depends on 1)

The receiver of claim 1, further comprising:
re-initializing frame synchronization in response to the determination that the false synchronization lock has occurred.

### Claim 11

A method for processing a plurality of physical layer frames, the method comprising:
acquiring frame synchronization for at least one physical layer frame of the plurality of physical layer frames;
decoding a code block of a physical layer header associated with a selected one of the at least one synchronized physical layer frame according to a first decoding technique;
decoding the code block of the physical layer header according to a second decoding technique, wherein the physical layer header is divided into a plurality of sub-blocks and the second decoding technique decodes the sub-blocks of the physical layer header;
comparing results from the first decoding technique to results of the second decoding technique;
generating an error value when the compared results do not match;
accumulating generated error values from one or more physical layer frames; and
determining that a false synchronization lock has occurred when an accumulated error value exceeds a threshold.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
re-initializing frame synchronization in response to the determination that the false synchronization lock has occurred.

### Claim 13 (depends on 11)

The method of claim 11, wherein the first decoding technique comprises:
finding a maximum likelihood transmitted data pattern across the plurality of sub-blocks of encoded data comprising the physical layer header.

### Claim 14 (depends on 11)

The method of claim 11, wherein each of the physical layer header comprises two code sub-blocks of signaling information and one code sub-block of parity information.

### Claim 15 (depends on 11)

The method of claim 11, further comprising:
utilizing the physical layer header to identify a start of frame.

### Claim 16 (depends on 11)

The method of claim 11, wherein the second decoding technique comprises:
performing a max bin search over each of the plurality of sub-blocks, wherein the error value is generated when each of the max bin searches does not match the maximum likelihood transmitted data pattern.

### Claim 17 (depends on 11)

The method of claim 11, further comprising:
weighting the generated error values before accumulating the generated error value.

### Claim 18 (depends on 17)

The method of claim 17, wherein weighing the generated error value comprises weighting error values from more recently received physical layer frames more heavily than error values from older physical layer frames.

### Claim 19 (depends on 17)

The method of claim 17, wherein weighing the generated error value comprises weighting the generated error value in proportion to a degree of difference between the comparison of the results from the first technique to results of the second technique.

### Claim 20

A device for processing a stream of physical layer frames, the device comprising:
means for acquiring frame synchronization for at least one physical layer frame of the plurality of physical layer frames;
means for decoding a code block of a physical layer header associated with a selected one of the at least one synchronized physical layer frame according to a first decoding technique;
means for decoding the code block of the physical layer header according to a second decoding technique, wherein the physical layer header is divided into a plurality of sub-blocks and the second decoding technique decodes the sub-blocks of the physical layer header;
means for comparing results from the first decoding technique to results of the second decoding technique;
means for generating an error value when the compared results do not match;
means for accumulating generated error values from one or more physical layer frames; and
means for determining that a false synchronization lock has occurred when an accumulated error value exceeds a threshold.