Adaptive return link for two-way satellite communication systems

• US 7,653,349 B1
• Filed: 06/18/2003
• Issued: 01/26/2010
• Est. Priority Date: 06/18/2003
• Status: Active Grant

• Current Assignee: DIRECTV, LLC (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Patel, Harish N.
• Primary Examiner(s): Anderson; Matthew D
• Assistant Examiner(s): Aminzay; Shaima Q
• Application Number:
  US10/464,113
• Time in Patent Office: 2,414 Days
• Field of Search: 455/13.4, 455/13.2, 455/13.1, 455/12.1, 455/69, 455/522, 455/427, 455/340, 455/430, 375/285, 375/295, 375/308, 342/457, 342/258, 701/213, 701/214, 725/118, 725/124, 725/125, 370/316
• US Class Current: 455/13.4
• CPC Class Codes: H04B 7/18578 Satellite systems for providing broadband data service to individual earth stations for selecting H04W; provisions for broadband connection, H04Q11/0478
• CPC Class Codes: H04H 20/426 Receiver side
• CPC Class Codes: H04H 2201/30 characterised by the use of a return channel, e.g. for collecting users' opinions, for returning broadcast space/time information or for requesting data
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H04N 7/20 Adaptations for transmission via a GHz frequency band, e.g. via satellite

Abstract

A method and apparatus for adaptively transmitting an uplink signal comprising information from a ground station to a satellite is disclosed. The method comprises the steps of receiving a transmitted downlink signal at a ground station from the satellite; measuring the quality of the transmitted signal; computing a prediction of a degradation of the uplink signal using the quality of the received signal, and transmitting the uplink signal according to the predicted degradation of the uplink signal. The apparatus comprises a tuner for receiving a transmitted downlink signal from the satellite; a signal analyzer, communicatively coupled to the tuner, for measuring a characteristic of the received downlink signal; an uplink degradation estimation module, communicatively coupled to the signal analyzer, for estimating the degradation of the uplink signal from the received downlink signal characteristic; and a controller, communicatively coupled to the uplink degradation module, for controlling the transmission of the uplink signal according to the estimated degradation of the uplink signal.

Claims

1. In a system broadcasting downlink signal having a plurality of channels to a plurality of ground stations, each ground station receiving one of the plurality of channels, a method of adaptively transmitting an uplink signal from one of the ground stations to a satellite, comprising the steps of:

receiving a transmitted downlink signal at the ground station from the satellite;

measuring a quality of the received signal;

computing a prediction of a degradation of the uplink signal using the quality of the received signal; and

transmitting the uplink signal according to the predicted degradation of the uplink signal.

2. The method of claim 1, wherein the step of transmitting the uplink signal according to the predicted degradation of the uplink signal comprises the steps of:

transmitting the uplink signal according to a first transmission characteristic if the predicted degradation is less than a first value; and

transmitting the uplink signal at a second transmission characteristic if the predicted degradation is greater than the first value.

3. The method of claim 2, wherein the first transmission characteristic is a first transmission rate and the second transmission characteristic is a second transmission rate less than the first transmission rate.

4. The method of claim 2, wherein the first transmission characteristic is a first transmission modulation scheme and the second transmission characteristic is a second modulation scheme.

5. The method of claim 2, wherein the first transmission characteristic includes a first error correcting scheme, and the second transmission characteristic includes a second error correcting scheme.

6. The method of claim 2, further comprising the steps of:

determining if the predicted degradation is greater than a second value, wherein the second value is greater than the first value; and

if the predicted degradation is greater than the second value, performing the steps comprising the steps of;

(a) storing the information;

(b) receiving a second transmitted signal;

(c) measuring a quality of the received second transmitted signal;

(d) computing a subsequent prediction of the degradation of the uplink signal using the quality of a received second transmitted signal; and

(e) transmitting the uplink signal including the information after the subsequent prediction of the degradation of the uplink signal is less than the second value.

7. The method of claim 6, further comprising the step of:

repeating step (b) through (d) until the subsequent prediction of the degradation of the uplink signal is less than the second value.

8. The method of claim 6, further comprising the step of:

providing a message to a user indicating that the transmission of the uplink signal will be delayed.

9. The method of claim 2, further comprising the steps of:

determining if the predicted degradation is greater than a second value; and

if the predicted degradation is greater than the second value, performing the steps comprising the steps of;

(a) storing the information;

(b) receiving a second transmitted signal subsequent to the transmitted signal;

(c) measuring a quality of the received second transmitted signal;

(d) computing a subsequent prediction of the degradation of the uplink signal using the quality of the received second transmitted signal; and

(e) informing a user after the subsequent prediction of the degradation of the uplink signal is not greater than the second value.

10. The method of claim 1, wherein the transmission characteristic is selected from the group comprising:

a signal strength; and

a bit error rate.

11. The apparatus of claim 1, wherein:

the controller controls the transmitter to transmit the uplink signal according to a first transmission characteristic if the estimated degradation is less than a first value; and

the controller controls the transmitter to transmit the uplink signal according to a second transmission characteristic if the predicated degradation is greater than the first value.

12. The apparatus of claim 11, wherein the first transmission characteristic is a first transmission rate and the second transmission characteristic is a second transmission rate less than the first transmission rate.

13. The apparatus of claim 11, wherein the first transmission characteristic is a first modulation scheme and the second transmission is a second modulation scheme.

14. The apparatus of claim 13, wherein the first modulation scheme is a QPSK modulation scheme and the second modulation scheme is an n-PSK modulation scheme, wherein n is a positive integer greater than four.

15. The apparatus of claim 13, wherein the first transmission characteristic includes a first error correcting scheme and the second transmission characteristic includes a second error correcting scheme.

16. The apparatus of claim 13, wherein:

the apparatus further comprising a memory; and

the uplink degradation module computes a subsequent prediction of the degradation of the uplink signal using a quality of a received second transmitted signal; and

the controller stores the information in the memory and commands the transmitter to transmit the uplink signal including the stored information after the subsequent prediction of the degradation of the uplink signal is less than the second value.

17. The apparatus of claim 13, wherein

the apparatus further comprises a memory;

and

the uplink degradation module computes a subsequent prediction of the degradation of the uplink signal using the quality of a received second transmitted signal; and

the controller stores the information in the memory and informs a user when the subsequent prediction of the degradation of the uplink signal is not greater than the second value.

18. An apparatus for adaptively transmitting an uplink signal comprising information from a ground station to a satellite, comprising:

a tuner for receiving a transmitted downlink signal from the satellite;

a signal analyzer, communicatively coupled to the tuner, for measuring a characteristic of the received downlink signal;

an uplink degradation estimation module, communicatively coupled to the signal analyzer, for estimating a degradation of the uplink signal from the received downlink signal characteristic; and

a controller, communicatively coupled to the uplink degradation module for controlling the transmission of the uplink signal according to the estimated degradation of the uplink signal.

19. The apparatus of claim 18, further comprising a transmitter, communicatively coupled to the controller, for transmitting the uplink signal.

20. The apparatus of claim 18, wherein the signal analyzer is a power meter and the measured characteristic of the received downlink signal is a strength of the received downlink signal.

21. An apparatus for adaptively transmitting an uplink signal comprising information from a ground station to a satellite, comprising:

means for receiving a transmitted downlink signal at the ground station from the satellite;

means for measuring a quality of the received signal;

means for computing a prediction of a degradation of the uplink signal using the quality of the received signal; and

means for transmitting the uplink signal according to the predicted degradation of the uplink signal.

22. The apparatus of claim 21, wherein the means for transmitting the uplink signal according to the predicted degradation of the uplink signal comprises:

means for transmitting the uplink signal according to a first transmission characteristic if the predicted degradation is less than a first value; and

means for transmitting the uplink signal at a second transmission characteristic if the predicted degradation is greater than the first value.

23. The apparatus of claim 22, wherein the first transmission characteristic is a first transmission rate and the second transmission characteristic is a second transmission rate less than the first transmission rate.

24. The apparatus of claim 22, wherein the first transmission characteristic is a first transmission modulation scheme and the second transmission characteristic is a second modulation scheme.

25. The apparatus of claim 22, wherein the first transmission characteristic includes a first error correcting scheme, and the second transmission characteristic includes a second error correcting scheme.

26. The apparatus of claim 22, further comprising:

means for determining if the predicted degradation is greater than a second value, wherein the second value is greater than the first value; and

means for storing the information, receiving a second transmitted signal, measuring a quality of the received second transmitted signal, computing a subsequent prediction of the degradation of the uplink signal using the quality of a received second transmitted signal, and for transmitting the uplink signal including the information after the subsequent prediction of the degradation of the uplink signal is less than the second value.

27. The apparatus of claim 26, further comprising:

means for repeatedly receiving a second transmitted signal and computing a subsequent prediction of the degradation of the uplink signal using the quality of a received second transmitted signal.

28. The apparatus of claim 26, further comprising:

providing a message to a user indicating that the transmission of the uplink signal will be delayed.

29. The apparatus of claim 22, further comprising:

means for determining if the predicted degradation is greater than a second value; and

means for storing the information, for receiving a second transmitted signal subsequent to the transmitted signal, measuring a quality of the received second transmitted signal, for computing a subsequent prediction of the degradation of the uplink signal using the quality of the received second transmitted signal, and for informing a user after the subsequent prediction of the degradation of the uplink signal is not greater than the second value.

30. The apparatus of claim 21, wherein the transmission characteristic is selected from the group comprising:

a signal strength; and

a bit error rate.