AGGREGATE RATE MODEM

• US 20090022087A1
• Filed: 07/16/2008
• Published: 01/22/2009
• Est. Priority Date: 10/03/2006
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Dankberg, Mark D., Thesling, William H.
• Granted Patent: US 8,243,651 B2
• Time in Patent Office: Days
• US Class Current: 370/316
• CPC Class Codes: H04B 7/18582 Arrangements for data linking, i.e. for data framing, for error recovery, for multiple access

Abstract

Systems, devices, processors, and methods are described for the transmission and reception of broadband signals between a gateway and subscriber terminals via satellite. In one set of embodiments, a wireless signal is generated and transmitted including a series of frames including a physical layer header and payload. A sub-channel identifier may be included in the physical layer header to identify the sub-channel for the payload, and allow for various novel filtering techniques at the subscriber terminal. The frames may be generated to be of substantially equal duration. Novel subscriber terminal configurations are described to leverage this formatting.

Claims

1. A terminal to receive a wireless signal from a satellite, the terminal comprising:

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

a header processing unit, communicatively coupled with the receiver unit, and configured to;

receive a digitized stream comprising a physical layer signal representative of the received wireless signal;

process the digitized stream to detect a first header identifier identifying a first header portion of the digitized stream; and

demodulate and decode the first header portion to detect a first sub-channel identifier for a physical layer payload associated with the first header portion; and

a filter unit, communicatively coupled with the header processing unit, and configured to;

store one or more sub-channel identifiers indicating whether an associated physical layer payload is to be demodulated and decoded by the terminal;

determine that the first sub-channel identifier matches one or more of the stored identifiers indicating that an associated physical layer payload should be filtered before demodulation and decoding; and

filter the physical layer payload associated with the first header portion to prevent demodulation and decoding.

2. The terminal of claim 1, wherein,

the header processing unit is further configured to demodulate and decode a second header portion of the digitized stream to detect a second sub-channel identifier for a physical layer payload associated with the second header portion;

and

the filter unit is further configured to;

determine that the second sub-channel identifier matches one or more of the stored identifiers indicating that an associated physical layer payload should be demodulated and decoded; and

forward the physical layer payload associated with the second header portion for demodulation and decoding.

3. The terminal of claim 2, further comprising:

a demodulation unit configured to receive and demodulate the forwarded physical layer payload associated with the second header; and

a decoder unit configured to decode the demodulated physical layer payload,

wherein the demodulation and decoder units are each configured to demodulate and decode only a subset of a plurality of physical layer payloads in the digitized stream.

4. The terminal of claim 3, wherein the demodulation and decoder units are each configured to demodulate and decode at most one in four of the plurality of physical layer payloads in the digitized stream.

5. The terminal of claim 1, further comprising:

a buffer unit, communicatively coupled with the receiver unit and the filter unit, and configured to store at least part of the digitized stream comprising the physical layer payload associated with the first header portion,

wherein the filter unit is further configured to filter the physical layer payload associated with the first header portion by controlling the buffer unit to overwrite the stored part of the digitized stream comprising the physical layer payload before it is forwarded for demodulation or decoding.

6. The terminal of claim 1, wherein the header processing unit is further configured to process the digitized stream to allow other header identifiers identifying other header portions of the digitized stream to pass without detection, wherein the other header identifiers are different than the first header identifier.

7. The terminal of claim 1, wherein,

the received wireless signal comprises a modified digital video broadcasting signal carried on a single carrier;

the first header identifier comprises a start of frame (SOF) pattern; and

the first header portion comprises a modified physical layer signaling (PLS) code including sub-channel identifier information.

8. The terminal of claim 1, wherein a subset of the digitized stream comprising the physical layer payload associated with the first header portion is not demodulated or decoded.

9. A processor for processing a digitized representation of a wireless signal received from a satellite, the processor comprising:

a header processing unit configured to;

receive a digitized stream comprising a physical layer signal representative of the wireless signal received from the satellite;

process the digitized stream to detect a first header identifier identifying a first header portion of the digitized stream;

extract the identified first header portion of the digitized stream; and

demodulate and decode the first header portion to detect a first sub-channel identifier for a physical layer payload associated with the first header portion; and

a filter unit, communicatively coupled with the header processing unit, and configured to;

access a listing of one or more sub-channel identifiers indicating whether an associated physical layer payload is to be demodulated and decoded;

determine whether the first sub-channel identifier matches one or more of the listed identifiers that indicate an associated physical layer payload is to be demodulated and decoded; and

filter the digitized stream comprising the physical layer payload associated with the first header portion to prevent the filtered payload from being demodulated or decoded.

10. The processor of claim 9, wherein,

the header processing unit is further configured to demodulate and decode a second header portion of the digitized stream to detect a second sub-channel identifier for a physical layer payload associated with the second header portion;

and

the filter unit is further configured to;

determine that the second sub-channel identifier matches one or more of the listed identifiers indicating that an associated physical layer payload is to be demodulated and decoded; and

forward the physical layer payload associated with the second header portion for demodulation and decoding.

11. The processor of claim 9, further comprising:

a demodulation unit configured to receive and demodulate the forwarded physical layer payload associated with the second header; and

a decoder unit configured to decode the demodulated physical layer payload,

wherein the demodulation and decoder units are each configured to demodulate and decode only a subset of a plurality of physical layer payloads in the digitized stream.

12. A method of processing a digital representation of a wireless signal received from a satellite, the method comprising:

receiving a digitized stream comprising a physical layer signal representative of the wireless signal received from the satellite;

processing the digitized stream to detect a header identifier identifying a first header portion of the digitized stream;

demodulating and decoding the header portion to detect a sub-channel identifier for a physical layer payload associated with the header portion; and

determining whether the sub-channel identifier comprises one or more of a set of sub-channel identifiers specifying that an associated physical layer payload is to be filtered from demodulation and decoding.

13. The method of claim 12, further comprising:

filtering the digitized stream comprising the physical layer payload to prevent the payload from being demodulated or decoded, based at least in part on the determining step.

14. The method of claim 13, further comprising:

buffering at least part of the digitized stream comprising the physical layer payload,

wherein the filtering step comprises overwriting the buffered part of the digitized stream comprising the physical layer payload without first forwarding the payload for demodulation or decoding.

15. The method of claim 12, further comprising:

forwarding the physical layer payload for demodulation and decoding, based at least in part on the determining step.

16. The method of claim 15, further comprising:

demodulating the forwarded physical layer payload associated with the header; and

decoding the demodulated physical layer payload,

wherein the demodulating and decoding steps are performed at a rate less than a rate payload data is received via the digitized stream.

17. The method of claim 12, further comprising:

processing the digitized stream to allow other header identifiers identifying other header portions of the digitized stream to pass without detection, wherein the other header identifiers comprise different identifiers than the first header identifier.

18. The method of claim 12, further comprising:

omitting an identifier detection analysis at one or more known physical layer header identifier locations.

19. The method of claim 12, further comprising:

performing symbol timing recovery and course carrier frequency recovery to produce the digitized signal.

20. A satellite communications system comprising:

a gateway configured to transmit a wireless signal sent to a satellite for retransmission to a terminal;

the satellite, in wireless communication with the terminal and the gateway, and configured to receive the wireless signal from the gateway and retransmit the received signal to the terminal; and

the terminal comprising;

a receiver unit configured to receive the retransmitted wireless signal from the satellite;

a header processing unit configured to;

receive a digitized stream comprising a physical layer signal representative of a signal received from a satellite;

process the digitized stream to recognize a header identifier identifying a header portion of the digitized stream; and

demodulate and decode the header portion to detect a sub-channel identifier for payload associated with the header portion; and

a filter unit, communicatively coupled with the header processing unit, and configured to;

access a listing of one or more sub-channel identifiers indicating whether an associated physical layer payload is to be demodulated and decoded;

determine that the first sub-channel identifier does not match one or more of the listed identifiers; and

filter the digitized stream comprising the payload to prevent the payload from being demodulated or decoded.

21. A signal embodied in a transmission medium, the signal comprising a physical layer frame including:

a physical layer header formatted to be extractable from the physical layer frame, the physical layer header including;

a header identifier identifying the physical layer header and formatted to be detectable by a terminal; and

a sub-channel identifier identifying a sub-channel for the frame; and

a physical layer payload associated with the physical layer header, and formatted to be filtered before demodulation and decode based at least in part on the sub-channel identifier.

22. The signal of claim 21, wherein the physical layer payload is filtered based on determining the sub-channel identifier does not match a table of sub-channel identifiers specifying physical layer payloads to be demodulated and decoded.

23. The signal of claim 21, wherein the physical layer is forwarded for demodulation and decoding based on determining the sub-channel identifier does match a table of sub-channel identifiers specifying physical layer payloads to be forwarded.

24. The signal of claim 21, wherein,

the signal comprises a modified digital video broadcasting signal carried on a single carrier;

the first header identifier comprises a start of frame (SOF) pattern; and

the first header portion comprises a modified physical layer signaling (PLS) code including sub-channel identifier information.

25. The signal of claim 24, wherein the physical layer payload further includes an identifier in a baseband header section to allow further filtering of a demodulated and decoded physical layer payload before link layer processing