Channel Allocation for Burst Transmission to a Diversity of Satellites

• US 20090274113A1
• Filed: 05/01/2008
• Published: 11/05/2009
• Est. Priority Date: 05/01/2008
• Status: Active Grant

• Current Assignee: Mobit Telecom Ltd.
• Original Assignee: Daniel A. Katz
• Inventors: Katz, Daniel A.
• Granted Patent: US 7,606,567 B1
• Time in Patent Office: Days
• US Class Current: 370/330
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

A method for allocating transmission channels to devices configured to communicate short data packets to a diversity of non geostationary satellites is disclosed hereby. The method suggests a dynamic cellular partitioning of the earth surface, based on the smallest intersections of overlapping satellite service areas (“footprints”), defined as mega-cells, and reusing channels in different mega-cells. In addition, a transmission cycle is defined and divided to time slots, synchronized at each device by GPS timing signals, and mega-cells served by more satellites are allocated with fewer time slots, in order to increase the chance of transmitters placed in mega-cells served by fewer satellites to be detected. Further, each mega-cell is divided to cells, and different channels and time slots are allocated to each cell, from those allocated to the corresponding mega-cell. Consequently, collision of transmissions from different mega-cells is reduced, and collision of transmissions from different cells in a mega-cell is avoided.

Claims

1. A method for allocating transmission channels to a plurality of devices configured to communicate with a diversity of satellites, comprising, at each device, the steps of:

a) determining the current time and self location via a Global Navigation Satellite System (GNSS);

b) determining the current service areas (“

footprints”

) of said diversity of satellites on earth surface;

c) defining as a mega-cell each entire area covered by the same footprints;

d) determining a transmission cycle divided to time slots, synchronized with said GNSS signals;

e) allocating at least one channel or one time slot to each mega-cell, wherein channels and time slots are reused in different mega-cells, and at least for two mega-cells, fewer time slots are allocated to the mega-cell served by more satellites;

f) dividing each mega-cell into cells, at least one cell in a mega-cell;

g) allocating different channels and/or different time slots to different cells in a mega-cell, from those allocated to the corresponding mega-cell;

h) selecting a specific channel and a specific time slot from those allocated to the corresponding cell, according to at least one of;

random or pseudo-random selection;

unique identification data (ID) stored at each device;

classification data stored and/or acquired at each device;

the nature of data to be transmitted;

signal/control input;

current geographical location;

coordination with other devices.

2. A method according to claim 1, wherein said channels are at least:

time slots for Time Division Multiple Access (TDMA);

or frequencies for Frequency Division Multiple Access (FDMA);

or codes for Code Division Multiple Access (CDMA);

or a combination thereof.

3. A system and method according to claim 1, wherein said GNSS is one of:

US Global Positioning System (GPS);

Russian GLONASS (or GLONAS);

European Galileo;

Chinese COMPASS;

Indian IRNSS, or a combination thereof.

4. A method according to claim 1, wherein a satellite footprint is determined according to at least one of:

the current time;

the satellite almanac;

the satellite ephemeris;

the satellite position;

wherein said satellite data is stored or received at said device.

5. A method according to claim 1, wherein cells statistically denser with devices are smaller, or cells statistically with more devices are allocated with more channels or with more time slots, or a combination thereof.

6. A method according to claim 1, wherein said devices transmit a service request, and said satellites are configured to detect this request and allocate a different channel to the requesting device.

7. A method according to claim 1, wherein said devices periodically transmit data packets, and for each transmission at least a channel or a time slot is selected by each device.

8. A method according to claim 1, wherein each of said devices comprises unique identification data (ID), and is configured to transmit said ID along with data representing its location.

9. A method according to claim 1, wherein a device is configured to skip at least one transmission cycle if data to be transmitted is substantially the same as previously transmitted, or if a previous transmission was acknowledged, or a combination thereof.

10. A method according to claim 8, wherein each of said devices is attached to an object to be located, from the following non limiting list:

person, animal, pet, vehicle, weapon, ammunition, valuable asset.

11. A computer program product comprising computer instructions embodied in a computer readable storage medium for a method for allocating transmission channels to a plurality of devices configured to communicate with a diversity of satellites, comprising:

a) determining the current time and self location via a Global Navigation Satellite System (GNSS);

b) determining the current service areas (“

footprints”

) of said diversity of satellites on earth surface;

c) defining as a mega-cell each entire area covered by the same footprints;

d) determining a transmission cycle divided to time slots, synchronized with said GNSS signals;

e) allocating at least one channel or one time slots to each mega-cell, wherein channels and time slots are reused in different mega-cells, and at least for two mega-cells, fewer time slots are allocated to the mega-cell served by more satellites;

f) dividing each mega-cell into cells, at least one cell in a mega-cell;

g) allocating different channels and/or different time slots to different cells in a mega-cell, from those allocated to the corresponding mega-cell;

h) selecting a specific channel and a specific time slot from those allocated to the corresponding cell, according to at least one of;

random or pseudo-random selection;

unique identification data (ID) stored at each device;

classification data stored and/or acquired at each device;

the nature of data to be transmitted;

signal/control input;

current geographical location;

coordination with other devices.

12. A computer program product according to claim 11, wherein said channels are at least:

time slots for Time Division Multiple Access (TDMA);

or frequencies for Frequency Division Multiple Access (FDMA);

or codes for Code Division Multiple Access (CDMA);

or a combination thereof.

13. A computer program product according to claim 11, wherein cells statistically denser with devices are smaller, or cells statistically with more devices are allocated with more channels or with more time slots, or a combination thereof.

14. A computer program product according to claim 11, wherein each of said devices comprises unique identification data (ID), and is configured to transmit said ID along with data representing its location.

15. A computer program product according to claim 11, wherein a device is configured to skip at least one transmission cycle if data to be transmitted is substantially the same as previously transmitted, or if a previous transmission was acknowledged, or a combination thereof.

16. A communication system and device for allocating transmission channels to a plurality of such devices configured to communicate with a diversity of satellites, each of said devices comprising at least an RF transmitter coupled to a Global Navigation Satellite System (GNSS) receiver, wherein each device is configured to:

a) determine the current time and self location via said GNSS;

b) determine the current service areas (“

footprints”

) of said diversity of satellites on earth surface;

c) define as a mega-cell each entire area covered by the same footprints;

d) determine a transmission cycle divided to time slots, synchronized with said GNSS signals;

e) allocate at least one channel or one time slot to each mega-cell, wherein channels and time slots are reused in different mega-cells, and at least for two mega-cells, fewer time slots are allocated to the mega-cell served by more satellites;

f) divide each mega-cell into cells, at least one cell in a mega-cell;

g) allocate different channels and/or different time slots to different cells in a mega-cell, from those allocated to the corresponding mega-cell;

h) select a specific channel and a specific time slot from those allocated to the corresponding cell, according to at least one of;

random or pseudo-random selection;

unique identification data (ID) stored at each device;

classification data stored and/or acquired at each device;

the nature of data to be transmitted;

signal/control input;

current geographical location;

coordination with other devices.

17. A communication system and device according to claim 16, wherein said channels are at least:

time slots for Time Division Multiple Access (TDMA);

or frequencies for Frequency Division Multiple Access (FDMA);

or codes for Code Division Multiple Access (CDMA);

or a combination thereof.

18. A communication system and device according to claim 16, wherein cells statistically denser with devices are smaller, or cells statistically with more devices are allocated with more channels or with more time slots, or a combination thereof.

19. A communication system and device according to claim 16, wherein each of said devices comprises unique identification data (ID), and is configured to transmit said ID along with data representing its location.

20. A communication system and device according to claim 16, wherein a device is configured to skip at least one transmission cycle if data to be transmitted is substantially the same as previously transmitted, or if a previous transmission was acknowledged, or a combination thereof.