Adaptive data rate control for narrowcast networks

• US 7,215,650 B1
• Filed: 03/06/2000
• Issued: 05/08/2007
• Est. Priority Date: 08/16/1999
• Status: Expired due to Term

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Dankberg, Mark D., Miller, Mark J.
• Primary Examiner(s): Vu; Huy D.
• Assistant Examiner(s): Ryman; Daniel
• Application Number:
  US09/519,155
• Time in Patent Office: 2,619 Days
• Field of Search: 370/281, 370/295, 370/319, 370/344, 370/480
• US Class Current: 370/315
• 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 FDM carriers, each of potentially differing data rates. The subscribers are assigned a particular FDM carrier, based upon their link quality, to receive packets addressed to them. The lower data rate FDM carriers 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 narrowcast satellite communication network having a hub station transmitting to a satellite repeater and a plurality of receiving subscriber terminals, a method comprising:

transmitting data from said hub station addressed to selected ones of said receiving subscriber terminals to said satellite repeater on a selection of channels;

receiving and relaying at said satellite repeater, said data on said selection of channels to a selected subset of said receiving subscriber terminals using less than all available signal carriers;

at each receiving subscriber terminal, determining signal quality metrics on the basis of qualities of said signal carriers received from said satellite repeater and addressed to said receiving subscriber terminal;

communicating said signal quality metrics determined at said receiving subscriber terminals to said hub station;

at said hub station, grouping pluralities of said receiving subscriber terminals into subgroups according to said signal quality metrics;

varying at least one of a frequency bandwidth, a power level, a coding scheme, a modulation scheme and a data rate to produce a plurality of redefined carriers, and

signaling said subgroups to use at least one of said redefined carriers for subsequent reception of said data; and

narrowcasting from said hub station said subsequent data to said subgroups of receiving subscriber terminal using said at least one of said redefined carriers via said satellite repeater.

2. The method of claim 1 further include providing ground-based communication links between said hub station and each of said receiving subscriber terminals, wherein said step of communicating to said hub station is performed via said ground-based communication links.

3. The method of claim 1 wherein said carriers are FDM carriers.

4. The method of claim 1 wherein one of said signal quality metrics is a signal-to-noise ratio.

5. A narrowcast network system comprising:

a terrestrial hub station for selectively narrowcasting data to subscribers;

a satellite repeater for receiving and relaying narrowcast data from said hub station to selected subscribers via a plurality of carriers;

a plurality of terrestrially deployed receiving subscriber terminals associated with said subscribers, each said receiving subscriber terminal in selectable communication with said satellite;

said subscriber terminals having;

circuit means operative to receive transmissions from said satellite repeater via at least one selectable carrier;

at least some of said subscriber terminals having;

means for determining a signal quality metric, said signal quality metric based on received signals from said satellite repeater; and

circuit means operative to communicate said signal quality metric to said hub station;

said hub station comprising circuit means for adapting data transmission modes narrowcasted to said receiving subscriber terminals based on said at least one signal quality metric,

including;

means for grouping said receiving subscriber terminals according to their associated signal quality metric into subgroups and for associating said subgroups with a carrier at said satellite repeater; and

circuit means for selectively narrowcasting to said subgroups via said satellite repeater, including means for generating control signals to said satellite repeater to cause said satellite repeater to generate a plurality of carriers according to said subgroups, said carriers varying in frequency and at least in one of bandwidth, power level, coding scheme, modulation scheme, and data rate.

6. The narrowcast network system according to claim 5 further including circuitry operative to receive data packets addressed to specific ones of said receiving subscriber terminals and circuitry operative to transmit each data packet using at least one of said carriers having attributes based on said destination address and said signal quality metrics.

7. The narrowcast network system of claim 5 wherein said at least one signal quality metric is a signal-to-noise ratio.

8. The narrowcast network system of claim 5 further including a plurality of return channels, each return channel effective for communication between one of said receiving satellite terminals and said hub station, and further including circuitry to communicate said signal quality metrics over said return channels.

9. The narrowcast network system of claim 8 wherein said return channels are communication links to said satellite.

10. The narrowcast network system of claim 8 wherein said return channels are land lines coupling said receiving subscriber terminals to said hub station.

11. The narrowcast network system of claim 8 wherein said return channels are line-of-sight wireless communication links coupling said receiving subscriber terminals to said hub station.

12. In a narrowcast network system, a hub station for communicating with selected receiving satellite terminals via a satellite repeater comprising:

first circuitry configured to receive signal quality metrics for carriers from said satellite repeater from said receiving subscriber terminals;

second circuitry configured to receive data packets destined for a plurality of said receiving subscriber terminals, each data packet having an address of one of said receiving subscriber terminals;

third circuitry configured to transmit each data packet using a carrier having attributes based on said destination address; and

fourth circuitry operative to group pluralities of said receiving subscriber terminal according to said signal quality metrics and to adapt mode of information transfer via said satellite repeater to said groups of said receiving subscriber terminals by selecting at least one carrier for each said group and varying at least bandwidth, power level, coding scheme, a modulation scheme and data rate.

13. The hub station in the narrowcast network system of claim 12 further including circuitry for transmitting control signals to the satellite repeater to control transmitted power of said carriers.