Adaptive data rate control for narrowcast networks

• US 8,311,491 B2
• Filed: 05/14/2012
• Issued: 11/13/2012
• Est. Priority Date: 08/16/1999
• Status: Expired due to Fees

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Miller, Mark J., Dankberg, Mark D.
• Primary Examiner(s): Ajibade Akonai, Olumide T
• Application Number:
  US13/471,011
• Publication Number:
  US 20120225620A1
• Time in Patent Office: 183 Days
• Field of Search: 455/7, 455/11.1, 455/12.1, 455/13.1, 455/13.4, 455/16, 455/63.1, 455/67.11, 455/67.13, 455/69, 455/70, 455/71, 455/518, 455/427, 455/430, 370/315, 370/316, 370/317, 370/318, 370/328, 370/329, 370/330, 370/338, 370/341, 370/342, 370/343, 370/344, 370/345, 370/347, 370/432
• US Class Current: 455/70
• CPC Class Codes: H04B 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04L 1/0005 applied to payload information
• CPC Class Codes: H04L 1/0011 applied to payload information
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/22 using time-division multiplexing
• CPC Class Codes: H04W 28/0236 radio quality, e.g. interference, losses or delay
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/242 taking into account path loss

Abstract

A system to provide narrowcast communications uses adaptive data rate control to individual subscribers such that the effects of precipitation or other link conditions, which are not common to all subscribers, is mitigated. The invention takes advantage of the fact that the narrowcast data consist of packets which are individually addressed to specific subscribers, or groups of subscribers. The narrowcast data is communicated on a plurality of channels, each of potentially differing data rates. The subscribers are assigned a particular channel, based upon their link quality, to receive packets addressed to them. The lower data rate channel will be less affected by adverse link conditions and are hence assigned to subscribers most likely to incur adverse link conditions.

Claims

1. In a satellite communication network, a gateway for communicating with a plurality of user terminals via a satellite comprising:

a control unit configured to;

receive signal quality-of-reception parameters for a downlink signal from a user terminal from the plurality of user terminals over a return-channel,

wherein the signal quality-of-reception parameters is at least based on a carrier-to-noise ratio measured by the user terminal for the downlink signal;

determine downlink signal attributes for the user terminal based on the signal quality-of-reception parameters for the downlink signal received by the user terminal; and

generate a control signal for assignment of data packets destined for the user terminal from the plurality of user terminals to at least one attribute from the downlink signal attributes for the user terminal;

a router communicatively coupled to the control unit and configured to;

receive the data packets destined for the user terminal from the plurality of user terminals, the data packets having an address of the user terminal;

receive the control signal from the control unit for assignment of the data packets to the at least one attribute from the downlink signal attributes; and

route the data packets for the user terminal for assignment of the data packet to the at least one attribute from the downlink signal attributes for the user terminal based on the destination user terminal for the data packet and the control signal received from the control unit; and

a modulator communicatively coupled to the router and the control unit and configured to;

receive the data packets from the router destined for the user terminal;

determine a modulation and coding for the data packets based on the control signal generated by the control unit for the user terminal using the downlink signal attributes, wherein the at least one attribute of the downlink signal attributes is a modulation and coding attribute; and

apply the modulation and coding to the data packets for the user terminal.

2. The gateway of claim 1, wherein the downlink signal attributes further comprises at least one of a bandwidth, a power level, or a data rate and is varied in response to changes in the signal quality-of-reception parameters.

3. The gateway of claim 1, wherein the downlink signal is a frequency-division multiplexed (FDM) channel.

4. The gateway of claim 1, wherein the downlink signal is a time-division multiplexed (TDM) channel.

5. The gateway of claim 1, further comprising transmitting control information for demodulating the data packets from the gateway to the user terminal.

6. The gateway of claim 5, wherein the control information is time-division multiplexed with the data packets.

7. The gateway of claim 1, wherein the signal quality-of-reception parameters are received at the gateway via a satellite return-channel.

8. The gateway of claim 1, wherein the signal quality-of-reception parameters are received at the gateway via a terrestrial return-channel.

9. In a satellite communication network, a user terminal for receiving a downlink signal from a gateway via a satellite comprising:

a demodulator unit configured to;

receive a data packet contained within the downlink signal having an address for the user terminal;

demodulate a modulation and coding for the data packet; and

derive signal information associated with the downlink signal;

a frame decoder unit communicatively coupled to the demodulator unit and configured to decode the data packet received from the demodulator unit; and

a signal quality calculation unit communicatively coupled to the demodulator unit and configured to;

receive the signal information associated with the downlink signal from the demodulator unit;

determine a carrier-to-noise ratio using the signal information;

determine an at least one signal quality-of-reception parameter using the carrier-to-noise ratio; and

transmit the at least one signal quality-of-reception parameter to the gateway using a return-channel, wherein the user terminal transmits the at least one signal quality-of-reception parameter for at least adjusting the modulation and coding used by the gateway for a plurality of consecutive data packets destined for the user terminal.

10. The user terminal of claim 9, wherein determining the at least one signal quality-of-reception parameter further comprises using a second signal information received from the frame decoder unit.

11. The user terminal of claim 9, wherein the carrier-to-noise ratio is determined using bit error correction statistics.

12. The user terminal of claim 9, wherein an at least one of a bandwidth, power level, a coding scheme, a modulation scheme, or a data rate of the downlink signal is varied in response to changes in the at least one signal quality-of-reception parameter.

13. The user terminal of claim 9, wherein the downlink signal is a frequency-division multiplexed (FDM) channel.

14. The user terminal of claim 9, wherein the downlink signal is a time-division multiplexed (TDM) channel.

15. The user terminal of claim 9, further comprising receiving control information for demodulating data packets addressed to the user terminal.

16. The user terminal of claim 15, wherein the control information is time-division multiplexed with a group of data packets in the downlink signal.

17. The user terminal of claim 9, wherein the at least one signal quality-of-reception parameter is by the user terminal to the gateway via a satellite return-channel.

18. The gateway of claim 9, wherein the at least one signal quality-of-reception parameter is sent by the user terminal to the gateway via a terrestrial return-channel.