Physical layer header structure for decoding and synchronization

• US 8,189,504 B2
• Filed: 06/17/2009
• Issued: 05/29/2012
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Becker, Donald W., Nimon, Matthew D., Thesling, William H.
• Primary Examiner(s): GESESSE, TILAHUN
• Application Number:
  US12/486,556
• Publication Number:
  US 20100150037A1
• Time in Patent Office: 1,077 Days
• Field of Search: 455/12.1, 455/13.1, 370/316, 370/320
• US Class Current: 370/316
• 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 for receiving the wireless signal transmitted via a satellite;

an A/D module, communicatively coupled with the receiver module, for processing 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,

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

for processing 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;

for utilizing 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

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

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

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

for decoding 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 signaling information comprises a modulation and coding format attributable to the payload.

5. 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.

6. 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.

7. The terminal of claim 6, 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.

8. 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;

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;

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.

9. The method of claim 8, further comprising:

decoding the code block to identify the signaling information.

10. The method of claim 8, wherein the code block of the second physical layer header is formatted to be useable by a receiver to identify a start of frame.

11. The method of claim 8, 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.

12. The method of claim 8, 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.

13. The method of claim 8, 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.

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

a gateway

for generating 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

for transmitting 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 a satellite,

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

for searching the digitized stream of symbols for the code block;

for processing a portion of the digitized stream comprising the code block to identify a start of frame location;

for 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

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