Satellite transmission system with adaptive transmission loss compensation

• US 20020168974A1
• Filed: 02/06/2002
• Published: 11/14/2002
• Est. Priority Date: 04/29/1999
• Status: Active Grant

• Current Assignee: Arnold L. Berman, Harold A. Rosen, James D. Thompson, Robert E. Vaughan, Steven O. Lane, Todd K. Citron
• Original Assignee: Arnold L. Berman, Harold A. Rosen, James D. Thompson, Robert E. Vaughan, Steven O. Lane, Todd K. Citron
• Inventors: Citron, Todd K., Thompson, James D., Rosen, Harold A., Vaughan, Robert E., Lane, Steven O., Berman, Arnold L.
• Granted Patent: US 6,799,014 B2
• Time in Patent Office: Days
• US Class Current: 455/429
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system and method for adjusting satellite communication signal transmit power for signals transmitted to a localized region within a satellite coverage area utilize real-time information on weather conditions (172) and/or actual path losses (174) within the localized regions to adjust the effective isotropic radiated power (EIRP) of the satellite beams (188) to minimize the total radio frequency (RF) power required for transmission. The transmission system may be realized using a variety of antenna types for transmitting spot beams and/or area coverage beams. Representative antenna implementations include multi-beam antennas having a low-level beamforming network and hybrid matrix amplifier system, phased-array with independent input amplitude control and beamsteering for each beam, and a phased-array feeding a confocal imaging system for single broadcast beam per polarization. The present invention allows for the reduction of RF transmit power to achieve the same communications performance enabling either increases in satellite functionality and/or an increase in total capacity of the satellite communication system.

Claims

1. A method for compensating for communication signal attenuation within at least one localized region of a coverage area of a satellite, the method comprising:

determining communication signal attenuation within the at least one localized region;

calculating a communication signal transmit power compensation adjustment for each of the at least one localized region based on the signal attenuation; and

adjusting communication signal transmit power allocated to each of the at least one localized region to compensate for the communication signal attenuation.

2. The method of claim 1 wherein determining communication signal attenuation comprises obtaining weather data indicative of precipitation within the at least one localized region and estimating communication signal attenuation based on the weather data.

3. The method of claim 1 wherein determining communication signal attenuation comprises obtaining received signal power information for signals received within the at least one localized region.

4. The method of claim 1 wherein determining communication signal attenuation comprises polling communication signal receiving terminals within the at least one localized region to determine received communication signal power levels.

5. The method of claim 1 wherein adjusting the communication signal transmit power allocated comprises phase-only pattern optimization to form a beam shape based on the calculated compensation adjustment.

6. The method of claim 1 wherein determining communication signal attenuation comprises polling communication signal receiving terminals located within the at least one localized region to determine a bit error rate of received communication signals.

7. The method of claim 6 further comprising obtaining weather data indicative of precipitation within the at least one localized region and selecting communication signal receiving terminals for polling based on the weather data.

8. The method of claim 7 wherein polling frequency is modified based on the weather data such that polling frequency increases for terminals within areas experiencing precipitation as indicated by the weather data.

9. The method of claim 7 wherein polling frequency is modified based on the bit error rate of the received communication signals.

10. The method of claim 1 wherein the coverage area of the satellite includes a plurality of cells each covered by a corresponding one of a plurality of spot beams transmitted by the satellite, the at least one localized region includes at least one of the plurality of cells, and wherein adjusting communication signal transmit power comprises increasing transmit power for only those spot beams which cover at least a portion of the localized region.

11. A system for compensating for communication signal attenuation within at least one localized region of a coverage area of a satellite, the system comprising:

a receiver for receiving data indicative of communication signal attenuation within the at least one localized region;

a processor in communication with the receiver for calculating a communication signal transmit power compensation adjustment for each of the at least one localized region based on the signal attenuation;

a satellite transmission system in communication with the processor for adjusting communication signal transmit power allocated to each of the at least one localized region based on the compensation adjustment calculated by the processor to compensate for the communication signal attenuation.

12. The system of claim 11 wherein the receiver, the processor, and the satellite transmission system are collocated on a satellite.

13. The system of claim 11 wherein the satellite transmission system comprises:

a plurality of commandable attenuators for adjusting input power level;

a plurality of amplifiers in communication with corresponding ones of the plurality of commandable attenuators, the amplifiers including an anode voltage adjustment to adjust associated operating points; and

a plurality of antenna feed elements in communication with corresponding ones of the plurality of amplifiers wherein the plurality of feed elements transmits a corresponding plurality of beams with a single feed element per beam and wherein the processor calculates the signal transmit power compensation adjustment to control the commandable attenuators and the anode voltage adjustment for each of the amplifiers.

14. The system of claim 11 wherein the satellite transmission system comprises:

a plurality of commandable attenuators for adjusting input power level;

a matrix amplifier connected to the plurality of commandable attenuators, the matrix amplifier including an input hybrid matrix, a plurality of amplifiers, and an output hybrid matrix; and

a low-level beamforming network in communication with the matrix amplifier, wherein the processor calculates the signal transmit power compensation adjustment to control the commandable attenuators while maintaining a substantially constant total power at inputs to the plurality of amplifiers.

15. The system of claim 11 wherein the satellite transmission system comprises:

a plurality of commandable attenuators for adjusting input power level;

a plurality of power divider networks connected to the plurality of commandable attenuators;

a plurality of transmit modules each including a plurality of amplitude adjusters in communication with a corresponding plurality of phase adjusters having outputs combined by a summer, the amplitude adjusters and the phase adjusters providing beam steering and beam shaping functions;

a plurality of amplifiers connected to respective ones of the plurality of transmit modules; and

a plurality of antenna feed elements connected to the plurality of amplifiers, the feed elements forming a planar phased array, wherein the processor calculates the signal transmit power compensation adjustment to modify input power via the commandable attenuators to adjust spot beams.

16. The system of claim 15 wherein the processor calculates the signal transmit power compensation adjustment to modify amplitude or phase of area coverage beams via the plurality of transmit modules.

17. The system of claim 15 further comprising:

a confocal imaging system including at least two reflecting elements positioned to receive communication signals transmitted by the plurality of antenna feed elements.

19. The method of claim 18 wherein generating an attenuation map comprises processing radar data including at least one of the group consisting of reflectivity, differential phase, and differential reflectivity.

20. The method of claim 18 wherein receiving weather information comprises receiving data via a public switched telephone network.

18. A method for controlling satellite communication signal transmit power to compensate for attenuation of a downlink signal due to precipitation within a localized region of a coverage area of a satellite, the satellite in communication with a network operations control center which is in communication with at least one source of weather information, the method comprising:

receiving weather information at the network operations control center indicative of precipitation within the localized region;

generating an attenuation map by converting the weather information to estimated signal attenuation within the localized region using an analytical model;

transmitting control commands from the network operations control center to the satellite to increase communication signal transmit power within the localized region while substantially maintaining or reducing communication signal transmit power within other localized regions of the satellite coverage area to minimize total satellite transmit power.