MF-TDMA frequency hopping

• US 8,077,652 B2
• Filed: 07/17/2008
• Issued: 12/13/2011
• Est. Priority Date: 10/03/2006
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Thesling, William H.
• Primary Examiner(s): PHUNKULH, BOB A
• Application Number:
  US12/174,676
• Publication Number:
  US 20090016260A1
• Time in Patent Office: 1,244 Days
• Field of Search: None
• 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, methods, and devices are described for scheduling and mapping upstream communications in a satellite communications system. The disclosure includes various channelization and frequency hopping techniques. A gateway is described to perform novel allocation of time slots on upstream frequency channels to allow frequency hopping. A subscriber terminal may perform frequency hopping according to the allocation, and the range may be limited to the transition range of a digitally controlled oscillator unit at the subscriber terminal. A gateway is described to allocate time slots on different upstream frequency channels in a prioritized manner. Subscriber terminals may receive the allocation, and then control the assignment of their upstream traffic to the time slots.

Claims

1. A device for generation of wireless upstream signals for satellite communications, the device comprising:

an analog frequency synthesizer configured to tune an output signal to a frequency within an upstream satellite communications frequency range;

a digitally controlled oscillator, communicatively coupled with the analog frequency synthesizer, and configured to vary the output signal among a set of carrier frequencies within a subset of the upstream satellite communications frequency range;

a receiver configured to receive data mapping the wireless upstream signals to different ones of the set of carrier frequencies in a series of time slots, the mapping limited to carrier frequencies within the subset of the frequency range; and

a processor, communicatively coupled with the digitally controlled oscillator and the receiver, and configured to control the digitally controlled oscillator to cause the output signal to hop between carrier frequencies according to the received data.

2. The device of claim 1, wherein the processor is further configured to:

determine the set of carrier frequencies, the set comprising carrier frequencies to which the digitally controlled oscillator unit is capable of transition during an available transition time.

3. The device of claim 1, wherein the processor is further configured to:

generate a set of data for transmission, the set of data identifying carrier frequencies to which the digitally controlled oscillator unit is capable of transition during a predetermined transition time.

4. The device of claim 1, wherein the processor is further configured to:

identify the different ones of the set of carrier frequencies based at least in part on a determination of settling time for transitions between the different ones.

5. The device of claim 1, wherein the processor is further configured to generate data for transmission identifying current bandwidth requirements and associated traffic types for the device.

6. The device of claim 1, wherein the processor is further configured to generate data for transmission estimating future bandwidth requirements and associated traffic types.

7. The device of claim 1, wherein,

the subset of the frequency range is allocated for upstream satellite communication for a subset of a plurality of subscriber terminals transmitting upstream in the frequency range, the subset of subscriber terminals associated with a selected sub-channel identifier of a plurality of sub-channel identifiers.

8. The device of claim 1, wherein,

each one of the set of carrier frequencies corresponds to a frequency channel allocated for use in upstream satellite communications;

and

the frequency channels comprise frequency channels in a multi-frequency time-division multiple access system.

9. The device of claim 1, wherein set of carrier frequencies comprise a plurality of adjacent frequency channels.

10. A method of generating wireless upstream signals for satellite communications, the method comprising:

receiving data including a mapping of time slots to different ones of a set of carrier frequencies within a subset of an upstream satellite communications frequency range allocated for the wireless upstream signals;

tuning an output signal to a frequency within the subset of the frequency range; and

varying the output signal to hop among the different ones of the set of carrier frequencies according to the received mapping data, the variance limited to carrier frequencies within a digitally controlled oscillator range to which the output signal is capable of transitioning from the tuned frequency during transitional periods.

11. The method of claim 10, further comprising:

determining the set of carrier frequencies during an available transition time.

12. The method of claim 10, further comprising:

identifying the different ones of the set of carrier frequencies based at least in part on a determination of settling time for transitions between the different ones.

13. The method of claim 10, further comprising:

generating data for transmission identifying current bandwidth requirements and associated traffic types for a device transmitting the wireless upstream signals.

14. The method of claim 10, further comprising:

generating data for transmission estimating future bandwidth requirements and associated traffic types.

15. A device for allocating time slots on a plurality of frequency channels for upstream satellite communications to a plurality of respective user terminals, the device comprising:

a monitor configured to;

monitor a traffic load on the plurality of frequency channels; and

determine that the traffic load on a first frequency channel of the plurality of frequency channels exceeds a first threshold capacity;

a scheduler, communicatively coupled with the monitor, and configured to;

identify a first user terminal of the plurality of respective user terminals, the first user terminal transmitting upstream on the first frequency channel;

select a second frequency channel of the plurality of frequency channels, the second frequency channel selected at least in part because the first user terminal is configured with a digitally controlled oscillator capable of transitioning between the first frequency channel and the second frequency channel;

allocate a first plurality of time slots in the first frequency channel to the first user terminal; and

allocate a second plurality of time slots in the second frequency channel to the first user terminal, the second of plurality of time slots different from the first plurality of time slots and allocated so as to allow the first user terminal to hop between the first frequency channel and the second frequency channel for respective time slot allocations; and

a transmitter, communicatively coupled with the scheduler, and configured to transmit data directed at the first user terminal, the data comprising the first plurality of time slots and the second plurality of time slots.

16. The device of claim 15, further comprising:

a receiver, communicatively coupled with the monitor, and configured to receive data from the plurality of respective user terminals each transmitting on the first frequency channel requesting future upstream bandwidth,

wherein the monitor is further configured to use the received data in the determination of whether the traffic load on the first frequency channel exceeds the first threshold capacity, the traffic load comprising a future traffic load.

17. The device of claim 15, further comprising:

a receiver, communicatively coupled with the monitor, and configured to receive data from the first user terminal transmitting on the first frequency channel and requesting additional upstream bandwidth,

wherein the additional upstream bandwidth causes the traffic load on the first frequency channel to exceed the first threshold capacity.

18. The device of claim 15, further comprising:

a receiver, communicatively coupled with the monitor, and configured to receive data from the first user terminal identifying a subset of the plurality of frequency channels, the identified subset comprising two or more frequency channels the digitally controlled oscillator is capable of transitioning to from the first frequency channel.

19. The device of claim 15, wherein the threshold capacity is less than a total capacity for the first frequency channel.

20. The device of claim 15, wherein the scheduler is configured to select the second frequency channel because the second frequency channel includes a time slot that can be transitioned to coherently from the first frequency channel.

21. The device of claim 15, wherein the scheduler is configured to select the second frequency channel because the frequency channel is a closest channel from the first frequency channel.

22. The device of claim 15, wherein the scheduler is configured to select the second frequency channel because the frequency channel is an available channel with more available capacity than other available channels.

23. The device of claim 15, wherein the scheduler is configured to select the second frequency channel responsive to a settling time associated with transition between the first frequency channel and the second frequency channel.

24. The device of claim 15, wherein the scheduler is further configured to:

identify a subset of the plurality of frequency channels, the subset comprising two or more frequency channels the digitally controlled oscillator is capable of transitioning to from the first frequency channel.

25. The device of claim 15, wherein the scheduler is further configured to:

assign a first subset of the plurality of frequency channels for exclusive use among a first subset of the plurality of respective user terminals; and

assign a second subset of the plurality of frequency channels for exclusive use among a second subset of the plurality of respective user terminals.

26. The device of claim 25, wherein the transmitter is further configured to:

transmit a first downstream packet with a first sub-channel identifier in a physical layer header, the first sub-channel identifier used to differentiate packets destined for the first subset of the plurality of respective user terminals; and

transmit a second downstream packet with a second sub-channel identifier in a physical layer header, the second sub-channel identifier used to differentiate packets destined for the second subset of the plurality of respective user terminals.

27. The device of claim 25, wherein each of the first subset of frequency channels is adjacent to at least one other frequency channel of the first subset of frequency channels, and each of the second subset of frequency channels is adjacent to at least one other frequency channel of the second subset of frequency channels.

28. The device of claim 15, wherein the plurality of frequency channels comprise a plurality of adjacent frequency channels.

29. A method of allocating time slots on a plurality of frequency channels for upstream satellite communications, the method comprising:

determining that a traffic load on a first frequency channel of the plurality of frequency channels exceeds a first threshold capacity;

identifying a user terminal transmitting upstream on the first frequency channel;

selecting a second frequency channel of the plurality of frequency channels, the second frequency channel selected at least in part because the user terminal is configured with a digitally controlled oscillator configured to transition between the first frequency channel and the second frequency channel;

allocating a first plurality of time slots in the first frequency channel to the user terminal; and

allocating a second plurality of time slots in the second frequency channel to the user terminal, the second plurality of time slots different from the first plurality of time slots,

wherein the first and the second pluralities of time slots are allocated to allow the user terminal to hop between the first frequency channel and the second frequency channel for respective time slot allocations.

30. The method of claim 29, further comprising:

receiving data from a plurality of user terminals some of which transmit on the first frequency channel and request future upstream bandwidth; and

using the received data in the determination that the traffic load on the first frequency channel exceeds the first threshold capacity, the traffic load comprising a future traffic load.

31. The method of claim 29, further comprising:

receiving data from the user terminal transmitting on the first frequency channel and requesting additional upstream bandwidth, wherein the received data causes the traffic load on the first frequency channel to exceed the first threshold capacity.

32. The method of claim 29, further comprising:

selecting the second frequency channel based at least in part on the second frequency channel having more available capacity than other available frequency channels.

33. A system for allocating time slots in frequency channels for upstream satellite communications, the system comprising:

a gateway configured to;

monitor a traffic load on the plurality of frequency channels;

determine that the traffic load on a first frequency channel of the plurality of frequency channels exceeds a first threshold capacity; and

select a second frequency channel of the plurality of frequency channels, the second frequency channel selected at least in part because a user terminal using the first frequency channel is configured with a digitally controlled oscillator to transition between the first frequency channel and the second frequency channel;

allocate a first plurality of time slots in the first frequency channel to the user terminal;

allocate a second plurality of time slots in the second frequency channel to the user terminal, the second plurality of time slots different from the first plurality of time slots and allocated so as to allow the user terminal to hop between the first frequency channel and the second frequency channel for respective time slot allocations; and

transmit mapping data including the first plurality of time slots and the second plurality of time slots directed at the user terminal via a satellite;

the satellite, in wireless communication with the gateway device and the user terminal, and configured to receive the transmitted data and retransmit the received data to the user terminal; and

the user terminal configured to;

receive the retransmitted data; and

hop between the first frequency channel and the second frequency channel according to the received mapping data.

34. The system of claim 33, wherein the subscriber terminal is configured to:

determine a set of carrier frequencies to which the digitally controlled oscillator unit is capable of transition, each carrier frequency of the set corresponding to a selected one of the adjacent frequency channels; and

transmit data comprising the determined set of carrier frequencies to the gateway device.

35. A device for generation of wireless upstream signals for satellite communications, the device comprising:

means for analog tuning an output signal to a frequency within an upstream satellite communications frequency range;

means for varying, using a digitally controlled oscillator, the output signal among a set of carrier frequencies within a subset of the upstream satellite communications frequency range;

means for receiving data mapping the wireless upstream signals to different ones of the set of carrier frequencies in a series of time slots, the mapping limited to carrier frequencies within the subset of the frequency range; and

means for controlling the digitally controlled oscillator to cause the output signal to hop between carrier frequencies according to the received data.

36. A device for allocating time slots on a plurality of frequency channels for upstream satellite communications, the device comprising:

means for determining that a traffic load on a first frequency channel of a plurality of adjacent frequency channels exceeds a first threshold capacity;

means for identifying a user terminal transmitting upstream on the first frequency channel;

means for selecting a second frequency channel of the plurality of adjacent frequency channels, the second frequency channel selected because the user terminal is configured with a digitally controlled oscillator configured to transition between the first frequency channel and the second frequency channel;

means for allocating a first plurality of time slots in the first frequency channel to the user terminal; and

means for allocating a second plurality of time slots in the second frequency channel to the user terminal, the second plurality of time slots different from the first plurality of time slots,

wherein the first and the second pluralities of time slots are allocated to allow the user terminal to hop between the first frequency channel and the second frequency channel for respective time slot allocations.