Load shedding method to enhance uplink margin with combined FDMA/TDMA uplinks

• US 6,272,340 B1
• Filed: 03/24/1999
• Issued: 08/07/2001
• Est. Priority Date: 03/24/1999
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Wright, David A., Wilcoxson, Donald C.
• Primary Examiner(s): BANKS HAROLD, MARSHA DENISE
• Application Number:
  US09/275,594
• Time in Patent Office: 867 Days
• Field of Search: 455/427, 455/10, 455/12.1, 455/13.4, 455/13.1, 455/69, 455/13.3, 455/522, 455/504, 455/505, 455/506, 455/453, 455/451, 455/450, 455/452, 455/509, 455/464, 370/252, 370/318
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

A load shedding method and apparatus to enhance uplink margin between a terrestrial terminal (14) and a satellite (12) in a satellite based communications system (10) is provided. The terrestrial terminal (14) includes a multi-carrier network (40) that generates a plurality of uplink carrier channels. A RF transmit and receive system (48) transmits the plurality of uplink carrier channels to the satellite (12). A terminal control unit (46) determines an attenuation level on the plurality of uplink carrier channels transmitted to the satellite (12). The terminal control unit (46) also instructs the multi-carrier network (40) to increase or decrease the number of uplink carrier channels to be transmitted to the satellite.

Claims

1. A load shedding method to enhance uplink margin between a terrestrial terminal and a satellite in a satellite based communications system, said load shedding method comprising:

generating at the terrestrial terminal a first signal having a first carrier channel;

generating at the terrestrial terminal a second signal having a second carrier channel;

transmitting from the terrestrial terminal to the satellite a cumulative uplink signal formed by the first signal having the first carrier channel and the second signal having the second carrier channel;

determining by a terminal control unit in the terrestrial terminal a transmit power level P_T of the cumulative uplink signal formed by the first signal and the second signal transmitted from the terrestrial terminal;

determining a received power level P_R of the cumulative uplink signal formed by the first signal and the second signal received at the satellite;

transmitting a power control report from the satellite to the terrestrial terminal that identifies the received power level P_R of the cumulative uplink signal formed by the first signal and the second signal received at the satellite;

determining an attenuation level P_T-P_R by the terminal control unit in the terrestrial terminal;

terminating transmission of the second signal having the second carrier channel upon instruction by the terminal control unit when the attenuation level P_T-P_R of the cumulative uplink signal formed by the first signal and the second signal transmitted from the terrestrial terminal exceeds a first threshold; and

resuming transmission of the second signal having the second carrier channel upon instruction by the terminal control unit when the attenuation level P_T-P_R is less than a second threshold, wherein the first threshold is greater than the second threshold to provide a level of hysteresis.

2. The load shedding method as defined in claim 1 further comprising adjusting the transmit power level P_T of the uplink signal formed by the first signal and the second signal transmitted from the terrestrial terminal based upon the received power level P_R of the uplink signal formed by the first signal and the second signal received at the satellite.

3. The load shedding method as defined in claim 1 further comprising summing the first signal having the first carrier channel and the second signal having the second carrier channel and transmitting the summed uplink signal being a composite of the first signal having the first carrier channel and the second signal having the second carrier channel.

4. The load shedding method as defined in claim 1 wherein the first signal having the first carrier channel and the second signal having the second carrier channel is a combined frequency division multiple access (FDMA)/time division multiple access (TDMA) signal.