Energy-Cognizant Scheduling of Store-and-Forward Communications with Multiple Priority Levels in Satellite Systems

Patent metadata

Field	Value
Publication number	US-2018294872-A1
Application number	US-201715480634-A
Country	US
Kind code	A1
Filing date	Apr 6, 2017
Priority date	Apr 6, 2017
Publication date	Oct 11, 2018
Grant date	—

Abstract

Delivery of a plurality of messages by a satellite is scheduled taking energy into account. An amount of time needed to deliver each of the plurality of messages received from a plurality of ground sources and intended for a plurality of ground recipients at respective different destinations is estimated based on the size of each of the messages. Each different destination has an associated contact time window during which the satellite will be in range of the ground recipients at that destination. An amount of energy that will be available from a power source for delivering the messages during each contact window is determined. Delivery of the plurality of messages to the ground recipients is scheduled such that a total time for delivery of the messages is minimized.

First claim

What is claimed is:

1 . A method for scheduling delivery of a plurality of messages by a satellite, comprising:
estimating, by a processor, an amount of time needed to deliver each of the plurality of messages received from a plurality of ground sources and intended for a plurality of ground recipients at respective different destinations based on a size of each of the messages, wherein each of the respective different destinations is associated with a contact time window during which the satellite will be in range of the ground recipients at that destination; determining, by the processor, an amount of energy that will be available from a power source for delivering the messages during each contact time window; scheduling, by the processor, delivery of the plurality of messages to the ground recipients based on the amount of energy that will be available for delivery of the messages during each contact time window and the amount of time needed to deliver each of the messages, such that a total time for delivery of the messages is minimized.

2 . The method of claim 1 , wherein estimating the amount of time needed to deliver each message includes calculating a mean busy time for delivery of each message.

3 . The method of claim 2 , wherein the mean busy time is an average point in time during which the message will be delivered.

4 . The method of claim 1 , wherein determining the amount of energy that will be available from the power source during each contact time window is based on a minimum amount of energy that must be maintained in the power source at any given time.

5 . The method of claim 1 , wherein determining an amount of energy that will be available from the power source during each contact time window is based on a maximum power storage capacity of the power source.

6 . The method of claim 1 , wherein determining an amount of energy that will be available from the power source during each contact time window is based on energy that will be harvested during charging time windows associated with the satellite during which the power source will be charged.

7 . The method of claim 1 , wherein the satellite also schedules delivery of the messages based on a priority assigned to each of the messages.

8 . The method of claim 7 , wherein the priority is assigned based on an amount of time a message has been waiting for delivery.

9 . A satellite, comprising:
a transceiver configured to receive a plurality of messages from a plurality of ground sources, wherein said messages are intended for a plurality of ground recipients at respective different destinations, and wherein each of the respective different destinations is associated with a contact time window during which the satellite will be in range of the ground recipients at that destination; a processor; and a memory having stored thereon instructions which, when executed by the processor, cause the processor to perform operations comprising:
determining a size of each of the messages;
estimating an amount of time needed to deliver each of the messages based on the size of each of the messages;
determining an amount of energy that will be available from a power source for delivery of the messages during each contact window, wherein delivery of a predefined unit size of message consumes a corresponding predefined unit amount of energy; and
optimizing a delivery schedule for delivering the plurality of messages to the ground recipients based on the amount of energy that will be available for delivery of the messages during each contact window and the amount of time needed to deliver each of the messages, such that a total time for delivery of the messages is minimized,
wherein the transceiver transmits the plurality of messages according to the delivery schedule.

10 . The satellite of claim 9 , wherein estimating the amount of time needed to deliver each message includes calculating a mean busy time for delivery of each message.

11 . The satellite of claim 10 , wherein the mean busy time is an average point in time during which the message will be delivered.

12 . The satellite of claim 9 , wherein determining the amount of energy that will be available from the power source during each contact time window is based on a minimum amount of energy that must be maintained in the power source at any given time.

13 . The satellite of claim 9 , wherein determining an amount of energy that will be available from the power source during each contact time window is based on a maximum power storage capacity of the power source.

14 . The satellite of claim 9 , wherein determining an amount of energy that will be available from the power source during each contact window is based on energy that will be harvested during charging time windows associated with the satellite during which the power source will be charged.

15 . The satellite of claim 14 , wherein the charging time windows occur during intervals in which the nanosatellite is in contact with sunlight.

16 . The satellite of claim 9 , wherein the processor performs optimization of the delivery schedule of the messages based also on a priority assigned to each of the messages.

17 . A device for scheduling delivery of a plurality of messages by a satellite, said messages intended for a plurality of ground recipients at respective different destinations, the device comprising:
a processor; and a memory having stored thereon instructions which, when executed by the processor, cause the processor to perform operations comprising:
determining, for each of said respective different destinations, an associated contact time window during which the satellite will be within range of the ground recipients at that destination;
determining a size of each of the messages;
estimating an amount of time needed to deliver each message based on the size of each message according to a mean busy time function;
determining an amount of energy that will be available from a power source for delivery of the messages during each contact time window; and
scheduling delivery of the plurality of messages to the ground recipients based on the amount of energy that will be available for delivery of the messages during each contact time window and the of amount of time needed to deliver each of the messages, such that a total time for delivery of the messages is minimized.

18 . The device of claim 17 , wherein determining the amount of energy that will be available from the power source during each contact time window is based on a minimum amount of energy that must be maintained in the power source at any given time.

19 . The device of claim 17 , wherein determining the amount of energy that will be available from the power source during each contact time window is based on a maximum power storage capacity of the power source.

20 . The device of claim 17 , wherein determining the amount of energy that will be available from the power source during each contact time window is based on power that will be harvested during charging time windows associated with the satellite during which the power source will be charged.

Assignees

• Spawar Systems Ct Pacific
• Us Navy

Inventors

• Wakayama Cherry Y
• Yoo Peter J
• Zabinsky Zelda B

Classifications

• H04B7/18519 Primary

  Operations control, administration or maintenance · CPC title

• H04B7/18513

  Transmission in a satellite or space-based system · CPC title

• H04W72/10

  Electricity · mapped topic

• H02J7/35

  with light sensitive cells · CPC title