Communication system with satellite diversity and method of operation thereof

• US 6,104,911 A
• Filed: 11/14/1997
• Issued: 08/15/2000
• Est. Priority Date: 11/14/1997
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Diekelman, Dennis Paul
• Primary Examiner(s): Tsang, Fan
• Assistant Examiner(s): Nguyen, Simon
• Application Number:
  US08/970,857
• Time in Patent Office: 1,005 Days
• Field of Search: 455/13.1, 455/12.1, 455/13.2, 455/3.2, 455/427, 455/430, 455/302, 455/436, 455/439, 455/443, 455/442, 455/446, 455/448, 342/354, 342/352, 342/355
• US Class Current: 455/13.1
• CPC Class Codes: H04B 7/18534 for enhancing link reliablility, e.g. satellites diversity
• CPC Class Codes: H04B 7/18541 for handover of resources
• CPC Class Codes: H04B 7/195 Non-synchronous stations

Abstract

A method and apparatus for providing an economically viable satellite communication system (100) for voice, data, and video using satellite diversity to augment capacity of the system, to mitigate the effects of network operational issues such as the effects of satellite failure and/or satellite blockage, and to maintain service links (180) in a cost-effective manner. Satellite diversity is incorporated into the communication architecture, along with the ability to utilize all satellites (110) within a communication range (or view) of one or more service regions (197). Management methods are used to allocate satellite diversity to enhance service and mitigate network operational issues. Satellite constellation (120) is designed to maximize the availability of satellite diversity as a resource. The method and apparatus described herein also provide a satellite communication system (100) having flexibility to adapt to changing demand and capacity requirements in various service regions (197) and to unknown or unanticipated changes in demand developing over time after the satellite communication system (100) has been deployed in whole or part.

Claims

1. A satellite communication system for providing telecommunication services, the satellite communication system comprising:

at least one satellite constellation comprised of a plurality of satellites, each satellite of the plurality of satellites providing a coverage area;

at least one network control facility capable of communicating with the plurality of satellites and of directing activity of the plurality of satellites, the network control facility including;

capacity augmentation means for predicting variations in satellite coverage areas and directing satellites to communicate with specific communication units located within the satellite coverage area of each satellite such that more than one satellite will not actively communicate with the same communication unit at the same time during non-hand-off condition; and

a processor capable of applying a serving strategy for determining which satellite of multiple satellites capable of providing a service link to a communication unit in a service region should be designated to provide the service link to the communication unit at a particular time and capable of assigning one satellite of the multiple satellites capable of providing service to provide the service link to the communication unit, wherein the serving strategy is comprised, at least in part, of selecting a highest satellite in the sky from the multiple satellites capable of providing the service link to the communication unit;

one or more communication units, the one or more communication units capable of communicating with the satellite constellation,

wherein the one or more communication units are situated within a coverage area of multiple satellites of the plurality of satellites at substantially any time, and

wherein, during non-hand-off conditions, each communication unit of the one or more communication units actively communicates with only one satellite of the multiple satellites at any time.

2. The satellite communication system as claimed in claim 1, wherein the at least one satellite constellation is comprised of non-geosynchronous satellites.

3. The satellite communication system as claimed in claim 1, wherein the at least one satellite constellation is comprised of geosynchronous satellites.

4. The satellite communication system as claimed in claim 1, wherein the at least one satellite constellation is comprised of a combination of non-geosynchronous and geosynchronous satellites.

5. The satellite communication system as claimed in claim 1, wherein the at least one satellite constellation is a non-geostationary satellite constellation, wherein the satellites reside in at least seven orbital planes that are inclined at a predetermined inclination angle with respect to an equatorial plane of the earth, and wherein there are at least nine satellites in each orbital plane of the at least seven orbital planes.

6. The satellite communication system as claimed in claim 1, wherein the capacity augmentation means comprises a processor for predicting variations in satellite coverage areas in each service region at any particular time and for directing satellites to communicate with specific communication units located within the coverage area of each satellite such that more than one satellite will not actively communicate with the same communication unit at the same time during the non-hand-off conditions.

7. The satellite communication system as claimed in claim 1, wherein the at least one network control facility includes detecting means for detecting a service failure of a first satellite of the satellite constellation, and directing means for directing a second satellite having a coverage area that overlaps at least in part with a coverage area of the first satellite to provide service to at least one communication unit previously receiving service from the first Satellite.

8. A satellite communication system for providing telecommunication services, the satellite communication system comprising:

at least one satellite constellation comprised of a plurality of satellites, each satellite of the plurality of satellites providing a coverage area;

at least one network control facility capable of communicating with the plurality of satellites and of directing activity of the plurality of satellites, the network control facility including a processor capable of applying a serving strategy for determining which satellite of multiple satellites capable of providing a service link to a communication unit in a service region should be designated to provide the service link to the communication unit at a particular time and capable of assigning one satellite of the multiple satellites capable of providing service to provide the service link to the communication unit, wherein the serving strategy is comprised, at least in part, of selecting a highest satellite in the sky from the multiple satellites capable of providing the service link to the communication unit;

one or more communication units, the one or more communication units capable of communicating with the satellite constellation,

wherein the one or more communication units are situated within a coverage area of multiple satellites of the plurality of satellites at substantially any time, and

wherein, during non-hand-off conditions, each communication unit of the one or more communication units actively communicates with only one satellite of the multiple satellites at any time.

9. The satellite communication system of claim 8, wherein the serving strategy is comprised, at least in part, of selecting a highest satellite in the sky from the multiple satellites capable of providing the service link to the communication unit.

10. The satellite communication system of claim 8, wherein the serving strategy varies according to the service region currently being serviced by the multiple satellites.

11. The satellite communication system of claim 8, wherein the serving strategy varies according to demands from one or more individual communication units.

12. A method for managing resources in a satellite communication system having at least one satellite constellation comprised of a plurality of satellites, at least one network control facility capable of communicating with the satellites and directing activity of the satellites, and one or more communication units capable of communicating with the at least one satellite constellation, each communication unit of the one or more communication units being located within a coverage area of more than one satellite of the at least one satellite constellation, the method comprising the steps of:

a) receiving a request for service from a first communication unit of the one or more communication units;

b) identifying at least two satellites having coverage areas which correspond, at least in part, with a location of the first communication unit;

c) determining which satellite of the at least two satellites should provide a service link to the first communication unit by applying at least one predetermined serving strategy that determines which satellite of the at least two satellites should provide the service link to the first communication unit and identifies a highest satellite in the sky capable of providing the service link; and

d) designating a first satellite of the at least two satellites to provide the service link to the first communication unit for a first period of time by assigning the highest satellite in the sky to provide the service link to the first communication unit.

13. The method as claimed in claim 12, wherein the location of the first communication unit corresponds to a service region.

14. The method as claimed in claim 12, wherein the determining step c) comprises the step of applying at least one predetermined serving strategy to determine which satellite of the at least two satellites should provide the service link to the first communication unit.

15. The method as claimed in claim 14, wherein in the applying step comprises the step of applying the predetermined serving strategy which identifies a highest satellite in the sky capable of providing the service link, and wherein the designating step d) comprises the step of assigning the highest satellite in the sky to provide the service link to the first communication unit.

16. The method as claimed in claim 12, further comprising the step of:

e) instructing the first communication unit to communicate with the satellite designated to provide the service link in the designating step d).

17. A method for managing resources in a satellite communication system having at least one satellite constellation comprised of at least two satellites and one or more communication units, wherein the at least two satellites reside in one or more predetermined orbits, and wherein each satellite has a coverage area which overlaps, at least in part, with the coverage area of another satellite in the satellite constellation, to provide an overlapping coverage region, the method comprising the steps of:

a) receiving a request for service from a communication unit located within the overlapping coverage region of a set of satellites;

b) determining which satellite of the set of satellites should provide a service link to the communication unit in the overlapping coverage region; and

c) designating a first satellite of the set of satellites to provide the service link to the communication unit in the overlapping coverage region;

d) instructing the first satellite designated to provide the service link;

e) receiving by the first satellite an instruction to provide the service link;

f) configuring communication resources in the satellite to provide the service link; and

g) providing the service link between the first satellite and the communication unit.

18. The method as claimed in claim 17, further comprising the steps of:

d) instructing the first satellite designated in step c) to provide the service

e) receiving by the first satellite an instruction to provide the service link;

f) configuring communication resources in the satellite to provide the service link; and

g) providing the service link between the first satellite and the communication unit.

19. The method as claimed in claim 18, further comprising the step of:

h) instructing the communication unit to communicate through the service link from the first satellite.

20. The method as claimed in claim 17, wherein the determining step b) further comprises the step of ascertaining whether a link obstacle exists between the communication unit and at least one satellite of the set of satellites, and the designating step c) further comprises the step of, if the link obstacle is ascertained, designating a satellite other than a satellite to which the link obstacle was ascertained to provide the service link.

21. A method for mitigating satellite failure in a satellite communication system having at least one satellite constellation comprised of at least two satellites, and one or more communication units, wherein the at least two satellites reside in one or more predetermined orbits, and wherein each satellite has a coverage area which overlaps, at least in part, with the coverage area of another satellite in the satellite constellation, to provide an overlapping coverage region, the method comprising the steps of:

a) detecting a service failure of a first satellite of the at least one satellite constellation;

b) identifying a second satellite, which is capable of providing a service link to one or more communication units located in the overlapping coverage region, to provide the service link to at least one of the one or more communication units previously communicating with the first satellite; and

c) directing the second satellite to provide the service link to the at least one of the one or more communication units without adjusting a relative position of the second satellite in its predetermined orbit.

22. The method as claimed in claim 21, further comprising the steps of:

d) instructing a third satellite, which is capable of providing the service link to the one or more communication units located in the overlapping coverage region which are not communicating with the second satellite, to provide the service link to at least one of the one or more communication units not communicating with the second satellite.

23. A method for augmenting capacity in a satellite communication system using satellite diversity, the satellite communication system having at least one satellite constellation comprised of at least two satellites, wherein the at least two satellites reside in one or more predetermined orbits, and wherein each satellite of the at least two satellites has a coverage area which overlaps, at least in part, with a coverage area of another satellite of the at least two satellites, the method comprising the steps of:

a) identifying a first service region within a service area of the at least one satellite constellation;

b) ascertaining a service capacity requirement for the first service region at a first time;

c) identifying one or more satellites each having a coverage area which corresponds at least in part to a location of the first service region; and

d) allocating responsibility for satisfying the service capacity requirement for the first service region at the first time among the two or more satellites in accordance with a responsibility allocation method.

24. The method of claim 23, wherein the responsibility allocation method comprises the steps of:

d1) determining a minimum number of satellites of the one or more satellites needed to meet the service capacity requirement for the first service region; and

d2) actively employing, to meet the service capacity requirement for the first service region, no more than the minimum number of satellites of the one or more satellites.

25. The method as claimed in claim 23, wherein the responsibility allocation method comprises providing a first service level through a plurality of satellites when the service capacity requirement is relatively high, and providing a second service level during a second time when the service capacity requirement is relatively low.

26. The method as claimed in claim in claim 23, further comprising the steps of:

e) ascertaining a second service capacity requirement for a second service region at a second time;

f) identifying a plurality of satellites each having a coverage area which corresponds at least in part to a location of the second service region; and

g) allocating responsibility for satisfying the second service capacity for the second service region at the second time among the plurality of satellites in accordance with a second allocation method.

27. The communication unit as claimed in claim 26, further comprising:

an antenna, coupled to the transceiver, which is adapted to change a direction of the service link in response to instructions from the satellite communication system directing the communication unit to communicate with the first designated satellite such that the service link can be directed to facilitate communications with the first designated satellite through the service link.

28. A communication unit for communicating in a satellite communication system having a satellite constellation including a plurality of satellites, the plurality of satellites including multiple satellites situated within a communication range of the communication unit and able to provide simultaneous service to the communication unit, the communication unit comprising:

a processor for creating a service request and for processing instructions from the satellite communication system directing the communication unit to communicate at a particular time only with a first designated satellite of the multiple satellites situated within a communication range of the communication unit through a service link with the first designated satellite of the plurality of satellites; and

a transceiver, coupled to the processor, for sending the service request for receiving the instructions, and for communicating with the first designated satellite through the service link.

29. A network control facility for use in a satellite communication system having at least one satellite constellation comprised of at least two satellites, and one or more communication units, wherein the at least two satellites reside in one or more predetermined orbits, and wherein each satellite has a coverage area which overlaps, at least in part, with the coverage area of another satellite in the satellite constellation to provide an overlapping coverage region, the network control facility comprising:

a receiver for receiving a request for service from a communication unit located within the overlapping coverage region; and

a processor, coupled to the receiver, for predicting variations in satellite coverage areas and determining a particular satellite of the at least two satellites having an area of coverage that corresponds, at least in part, to the overlapping coverage region, and for designating only the particular satellite to provide the service link to the communication unit at a particular time such that more than one satellite of the at least two satellites will not actively communicate with the same communication unit at the same time during non-hand-off conditions.

30. A satellite communication system using satellite diversity for augmenting capacity, maintaining service links and mitigating network operational issues including effects of satellite failure and service blockage, the satellite communication system comprising:

at least one satellite constellation comprised of a plurality of satellites, the satellite constellation having a service area, and each satellite of the plurality of satellites providing a coverage area within the service area;

means for communicating with the plurality of satellites and directing activity of the plurality of satellites;

one or more communication units, the communication units capable of communicating with the at least one satellite constellation, wherein the one or more communication units are situated within coverage area of multiple satellites at substantially any time;

means for receiving a request for service from a first communication unit of the one or more communication units situated within the coverage areas of the multiple satellites;

means for determining which satellite of the multiple satellites should provide a service link to the first communication unit, wherein the means for determining includes means for applying a predetermined serving strategy to determine which satellite of the multiple satellites should provide the communication link;

means for designating a first satellite of the multiple satellites to provide the service link to the first communication unit;

means for ascertaining whether a link obstacle exists between the first communication unit and the first satellite;

means for designating a second satellite to provide the service link if the link obstacle exists between the first communication unit and the first satellite;

means for detecting a failed satellite in the satellite constellation;

means for identifying another second satellite capable of providing the service link to the first communication unit previously communicating with the failed satellite and for directing the second satellite to communicate with the communication unit previously communicating with the failed satellite;

means for identifying a first service region within the service region of the satellite constellation;

means for ascertaining a service capacity requirement for the first service region at a first time;

means for identifying the multiple satellites having coverage areas which correspond at least in part to the first service region; and

means for allocating responsibility for satisfying the service capacity requirement for the first service region at the first time among the multiple satellites in accordance with a responsibility allocation method.