DOWNSTREAM WAVEFORM MODIFICATION

• US 20090022085A1
• 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 8,208,421 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 gateway configured to transmit a signal to respective subscriber terminals via a satellite, the gateway comprising:

a receiver unit configured to;

receive a set of data to be transmitted via the satellite destined for a first subscriber terminal; and

receive data identifying link conditions for the first subscriber terminal;

an adaptive coding and modulation unit, communicatively coupled with the receiver unit, and configured to dynamically assign a modulation and coding format for the set of data based at least in part on the link conditions;

an encapsulation unit, communicatively coupled with the receiver unit and adaptive coding and modulation unit, and configured to;

receive the assigned modulation and coding format for the set of data;

utilize the assigned modulation and coding format to dynamically set a block size for a payload for a first physical layer frame, the block size set to produce a physical layer frame of substantially equal duration in reference to adjacent physical layer frames to be transmitted from the gateway; and

encapsulate a subset of the set of data in the set block size for the payload of the first physical layer frame, the first physical layer frame including a header with a sub-channel identifier formatted to allow subscriber terminal filtering; and

a transmitter unit, communicatively coupled with the encapsulation unit, and configured to upconvert the physical layer frame and transmit the upconverted frame to the satellite.

2. The gateway of claim 1, further comprising:

a bandwidth allocation unit configured to dynamically vary a bandwidth for the respective subscriber terminals via assignment of the sub-channel identifier.

3. The gateway of claim 1, further comprising:

a bandwidth allocation unit configured to;

determine an increased bandwidth requirement for the first subscriber terminal;

increase a proportional allocation of physical layer frames including the sub-channel identifier associated with the first subscriber terminal; and

control the encapsulation unit to generate the physical layer frames with the sub-channel identifier in the increased proportion.

4. The gateway of claim 1, further comprising:

a memory unit configured to store a table associating each of a plurality of different modulation and coding formats with respective block sizes, wherein the encapsulation unit queries the memory unit to identify the block size.

5. The gateway of claim 1, wherein the encapsulation unit is further configured to generate a header identifier to allow the first subscriber terminal to identify boundaries of the payload for the first physical layer frame.

6. The gateway of claim 1, wherein the sub-channel identifier is formatted to provide information allowing the first subscriber terminal to identify a location for a next header identifier detection analysis in a set of physical layer frames received after the first physical layer frame.

7. The gateway of claim 1, wherein the sub-channel identifier is formatted to provide information allowing the first subscriber terminal to identify the first physical layer frame as a frame to be demodulated and decoded.

8. The gateway of claim 1, wherein the header includes information on spacing between a plurality additional headers transmitted from the transmitter unit and received after the first physical layer frame.

9. The gateway of claim 1, wherein physical layer frames of substantially equal duration comprise physical layer frames with substantially equal numbers of symbols.

10. The gateway of claim 1, wherein,

the first physical layer frame comprises a modified digital video broadcasting physical layer frame transmitted on a single carrier;

and

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

11. The gateway of claim 10, wherein the encapsulation unit is further configured to include an identifier in a baseband header within the frame to allow further filtering at the first subscriber terminal.

12. A processor for encapsulating a physical layer frame, the processor comprising:

a receiver unit configured to receive a set of data to be transmitted via a satellite destined for a first subscriber terminal;

an adaptive coding and modulation unit, communicatively coupled with the receiver unit, and configured to assign a modulation and coding format for the set of data based at least in part on data identifying link conditions from the satellite to the first subscriber terminal; and

an encapsulation unit, communicatively coupled with the receiver unit and the adaptive coding and modulation unit, and configured to;

receive the assigned modulation and coding format for the set of data;

utilize the assigned modulation and coding format to dynamically set a block size for payload for a first physical layer frame, the block size set to produce a physical layer frame of substantially equal duration in reference to adjacent physical layer frames to be transmitted;

identify a subset of the set of data for the payload for the frame; and

encapsulate the identified subset to produce the physical layer frame.

13. A method of producing a physical layer frame to be directed to a subscriber terminal via a satellite, the method comprising:

receiving an identification of a modulation and coding format for data to be transmitted to a first subscriber terminal, the format dynamically assigned at least in part based on link conditions for a first subscriber terminal;

utilizing the identified modulation and coding format to dynamically set a block size for payload for a first physical layer frame, the block size set to produce a physical layer frame of substantially equal duration in reference to adjacent physical layer frames to be transmitted;

encapsulating an amount of data of the set block size to produce the payload for the first physical layer frame; and

appending a header to the payload to produce the physical layer frame, the header formatted with an identifier to allow subscriber terminal filtering of packets before the payload is demodulated or decoded.

14. The method of claim 13, further comprising:

determining an increased bandwidth requirement for the first subscriber terminal; and

dynamically increasing a proportion of physical layer frames including the sub-channel identifier associated with the first subscriber terminal.

15. The method of claim 13, further comprising:

storing a table associating each of a plurality of different modulation and coding formats with respective block sizes

accessing the stored table to identify the block size.

16. The method of claim 13, further comprising:

generating a header identifier to allow the first subscriber terminal to identify boundaries of the payload for the first physical layer frame and to filter the first physical layer frame based on the header identifier.

17. The method of claim 13, further comprising:

setting the sub-channel identifier to provide information allowing the first subscriber terminal to omit a header identifier detection analysis at known header identifier locations in a set of physical layer frames received after the first physical layer frame.

18. The method of claim 13, further comprising:

setting the sub-channel identifier to provide information allowing the first subscriber terminal to;

identify a location for a next header identifier detection analysis in a set of physical layer frames received after the first physical layer frame; and

identify the first physical layer frame as a frame to be demodulated and decoded.

19. The method of claim 13, further comprising:

generating the header comprising a physical layer header including the sub-channel identifier formatted to allow the respective subscriber terminals to filter the first physical layer frame before the payload of the first physical layer frame is decoded.

20. The method of claim 13, further comprising:

varying spacing between a plurality of additional headers to be transmitted.

21. The method of claim 13, further comprising:

upconverting the physical layer frame; and

transmitting the upconverted frame to the satellite.

22. A satellite communications system comprising:

a gateway comprising;

an adaptive coding and modulation unit configured to dynamically assign a modulation and coding format for data destined for a subscriber terminal based at least in part on link conditions between a satellite and the subscriber terminal;

an encapsulation unit, communicatively coupled with the adaptive coding and modulation unit, and configured to;

receive the assigned modulation and coding format for the set of data;

utilize the assigned modulation and coding format to dynamically set a block size for payload for a physical layer frame, the block size set to produce a physical layer frame of substantially equal duration in reference to adjacent physical layer frames transmitted from the gateway; and

encapsulate a subset of the set of data as the payload to produce the physical layer frame; and

a transmitter unit, communicatively coupled with the encapsulation unit, and configured to upconvert the physical layer frame and transmit the upconverted frame as a wireless signal to the satellite;

the satellite, communicatively coupled with the subscriber terminal and the gateway, and configured to receive the wireless signal from the gateway and retransmit the received signal to the subscriber terminal; and

the subscriber terminal configured to receive the signal transmitted via the satellite.

23. A signal embodied in a transmission medium, the signal comprising a plurality of physical layer frames, the signal comprising:

a first physical layer frame including;

a first payload in a dynamically assigned first modulation and coding format; and

a first physical layer header with a first sub-channel identifier formatted to allow subscriber terminal filtering of packets before the first payload is demodulated or decoded; and

a second physical layer frame including;

a second payload in a dynamically assigned second modulation and coding format, wherein the block size of data for the second payload was dynamically set to produce a physical layer frame of substantially equal duration to the first physical layer frame; and

a second physical layer header with a second sub-channel identifier formatted to allow subscriber terminal filtering of packets before the second payload is demodulated or decoded.

24. The signal of claim 23, wherein assignment of the first or the second sub-channel identifiers vary a bandwidth allocated to respective subscriber terminals.

25. The signal of claim 23, wherein the first physical layer frame is adjacent to the second physical layer frame.