NOVEL PHYSICAL LAYER HEADER STRUCTURE FOR DECODING AND SYNCHRONIZATION

• US 20100150037A1
• Filed: 06/17/2009
• Published: 06/17/2010
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Thesling, William H., Becker, Donald W., Nimon, Matthew D.
• Granted Patent: US 8,189,504 B2
• Time in Patent Office: Days
• US Class Current: 370/310
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform
• CPC Class Codes: H04L 7/0016 correction of synchronization errors

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

1. A terminal to process a physical layer header for a received wireless signal, the terminal comprising:

a receiver module configured to receive the wireless signal transmitted via a satellite;

an A/D module, communicatively coupled with the receiver module, and configured to process the received wireless signal to generate a digitized stream of symbols comprising a physical layer signal; and

a header processing module, communicatively coupled with the A/D module, and configured to;

search the received wireless signal for a code block of a first physical layer header corresponding to a start of frame location; and

process the code block to identify the start of frame location, wherein the code block further comprises signaling information attributable to the payload of the frame.

2. The terminal of claim 1, wherein the header processing module is further configured to decode the code block to identify the signaling information.

3. The terminal of claim 1, wherein the header processing module is further configured to:

decode the code block utilizing a fast hadamard transform function on each of a plurality of sub-blocks comprising the code block to thereby identify a maximum likelihood transmitted data pattern.

4. The terminal of claim 1, wherein the header processing module is further configured to:

utilize the identified start of frame location to achieve frame synchronization and thereby identify a second physical layer header arriving after the first physical layer header; and

decode a code block of the second physical layer header to identify signaling information for a payload associated with the second physical layer header.

5. The terminal of claim 1, wherein the signaling information comprises a modulation and coding format attributable to the payload.

6. The terminal of claim 1, wherein the signaling information comprises a sub-channel identifier indicating whether the payload is to be demodulated and decoded by the terminal.

7. The terminal of claim 1, wherein the code block comprises a plurality of sub-blocks, wherein a first set of one or more of the sub-blocks includes the signaling information and a second set of one or more of the sub-blocks includes parity information.

8. The terminal of claim 7, wherein,

the plurality of sub-blocks comprises three adjacent Walsh code sub-blocks;

two of the Walsh code sub-blocks includes the signaling information and one of the Walsh code sub-blocks include the parity information; and

the start of frame location is identified by correlating a first half and a second half of a Walsh code block, for each of three adjacent Walsh code blocks.

9. A method of processing a wireless signal, the method comprising:

processing the wireless signal to generate a digitized stream of symbols comprising a physical layer signal representative of the wireless signal;

searching the digitized stream of symbols for a code block of a physical layer header corresponding to a start of frame location; and

processing a portion of the digitized stream comprising the code block to identify the start of frame location, wherein the code block further comprises signaling information attributable to a payload of the frame.

10. The method of claim 9, further comprising:

decoding the code block to identify the signaling information.

11. The method of claim 9, further comprising:

utilizing the identified start of frame location to achieve frame synchronization and thereby identify a second physical layer header in the digitized stream arriving after the first physical layer header; and

decoding a code block of the second physical layer header to identify signaling information for a payload associated with the second physical layer header.

12. The method of claim 11, wherein the code block of the second physical layer header is formatted to be useable by a receiver to identify a start of frame.

13. The method of claim 9, wherein the signaling information comprises a modulation and coding format attributable to the payload and a sub-channel identifier indicating whether the payload is to be demodulated and decoded by the terminal.

14. The method of claim 9, wherein,

the code block comprises a plurality of adjacent Walsh code sub-blocks;

and

a first set of one or more of the Walsh code sub-blocks includes the signaling information and a second one of the Walsh code sub-blocks includes parity information.

15. The method of claim 9, wherein the start of frame location is identified by:

correlating a first half and a second half of each of the adjacent Walsh code blocks.

16. A system for transmitting a wireless signal, the system comprising:

a gateway configured to;

generate a code block comprising a physical layer header of a physical layer frame, the code block identifying signaling information for a payload of the frame and further formatted to be useable by a receiver to identify a start of the frame; and

transmit the physical layer header and the payload appended thereto, the payload transmitted according to the signaling information; and

a terminal, in wireless communication with the gateway via satellite, and configured to;

receive and process the wireless signal to generate a digitized stream of symbols comprising a physical layer signal representative of the wireless signal;

search the digitized stream of symbols for the code block; and

process a portion of the digitized stream comprising the code block to identify a start of frame location.

17. A gateway to generate a wireless signal, the gateway comprising:

a receiver module configured to receive a set of data to be transmitted via a satellite destined for a user terminal;

an adaptive coding and modulation module, communicatively coupled with the receiver module, and configured to dynamically assign a modulation and coding format for the set of data based on link conditions for the user terminal;

a physical layer header encoder module, communicatively coupled with the adaptive coding and modulation module, and configured to generate a code block comprising a physical layer header identifying the assigned modulation and coding format, wherein the code block is formatted to be useable by a receiver to identify the start of frame; and

a transmitter module, communicatively coupled with the encoder module, and configured to transmit the physical layer header and the set of data appended thereto, the set of data transmitted according to the assigned modulation and coding format.

18. The gateway of claim 17, wherein to generate the code block, the physical layer header encoder module generates a plurality of adjacent sub-blocks together comprising the code block, a first set of one or more of the sub-blocks including the modulation and coding format and a second set of one or more of the sub-blocks including parity information for the first set.

19. The gateway of claim 18, wherein,

the plurality of sub-blocks comprise three Walsh code sub-blocks;

the start of frame location is identified by correlating a first half and a second half of a Walsh code block, for each of three adjacent Walsh code blocks; and

the physical layer header does not include a unique word or fixed synchronization pattern known at the receiver.

20. A method of generating a wireless signal, the method comprising:

setting signaling information attributable to a payload of a physical layer frame;

generating a code block comprising a physical layer header of the physical layer frame, the code block identifying the signaling information and further formatted to be useable by a receiving terminal to identify a start of frame; and

transmitting the physical layer frame comprising the physical layer header and the payload appended thereto, the payload transmitted according to the signaling information.

21. The method of claim 20, wherein generating the code block comprises:

generating the code block comprising signaling information including a modulation and coding format attributable to the payload and a sub-channel identifier indicating whether the payload is to be demodulated and decoded by a receiving terminal.

22. The method of claim 20, further comprising:

assigning a modulation and coding format to the payload based in a link condition for a receiving terminal,

wherein the code block comprises a plurality of sub-blocks, a first set of one or more of the sub-blocks including the assigned modulation and coding format and a second set of one or more of the sub-blocks including parity information for the first set.

23. The method of claim 22, wherein each of the plurality of sub-blocks is adjacent.

24. The method of claim 22, wherein,

the plurality of sub-blocks comprise three Walsh code sub-blocks;

and

the start of frame location is identified by correlating a first half and a second half of a Walsh code block, for each of three adjacent Walsh code blocks.