System for generating and using global radio frequency maps

• US 5,905,943 A
• Filed: 04/29/1997
• Issued: 05/18/1999
• Est. Priority Date: 04/29/1997
• Status: Expired due to Fees

• Current Assignee: Globalstar Incorporated
• Original Assignee: Globalstar Incorporated
• Inventors: Wiedeman, Robert A, Gallagher, Vijaya K, Serri, John A
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): TROST IV, WILLIAM GEORGE
• Application Number:
  US08/840,370
• Time in Patent Office: 749 Days
• Field of Search: 455/11.1, 455/12.1, 455/13.4, 455/422, 455/427, 455/429, 455/430, 455/450, 455/452, 455/454
• US Class Current: 455/11.1
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18532 Arrangements for managing transmission, i.e. for transporting data or a signalling message
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method for defining a radio frequency map to be used to isolate negative effects of undesirable radio frequency emitters on radio device communications handheld and stationary. The method includes the steps of measuring C-band power corresponding to an L-band beam as part of an L-band footprint of a communication satellite, calculating various identifiable interference errors associated with the signal transmission path, and subtracting the interference errors from the original C-band power measurement resulting in a power value corresponding to undesirable radio frequency emitter interference at the location of the L-band beam. The resultant radio frequency map can then be used to reallocate frequency channels of operation used by radio devices, mobile phones for example, resulting in power savings in the radio device while maintaining a suitable signal-to-noise ratio.

Claims

1. A method for generating a radio frequency map comprising the steps of:

measuring received frequency power spectrum values corresponding to a specific location;

calculating interference errors;

subtracting said interference errors from said power measurement, wherein a resultant radio frequency interference value is calculated; and

storing said resultant radio frequency interference value in a database, wherein said stored value is electronically accessible and retrieved for making frequency channel assignments, wherein the step of measuring received frequency power spectrum values comprises receiving C-band frequency power spectrum values corresponding to an L-band beam of a satellite footprint;

further comprising the step of selecting additional L-band beams of said satellite footprint, wherein a resultant radio frequency interference value is calculated for every L-band beam as part of said L-band footprint of said satellite;

and further comprising the step of selecting additional L-band footprints each of said additional L-band footprints defining a different location, wherein a resultant radio frequency interference value is calculated for every L-band beam as part of every L-band footprint;

wherein the step of calculating interference errors further comprises the steps of calculating a thermal noise interference error;

calculating a C-band feederlink interference error; and

calculating a user terminal interference error;

wherein the step of calculating a user terminal interference error further comprises the step of determining the number and location of said user terminals being served by said gateway, wherein the signals generated by said user terminals define said user terminal interference error;

and further comprising the step of reallocating said user terminal channel of operation wherein the power usage of said user terminal is reduced while a minimum signal-to-noise-interference ratio is maintained, said ratio being defined as;

##EQU4## where Y_kc =the transmitter output power of said user terminal at a k^th gridpoint traffic concentrator in said channel;

W_kc =is the number of said user terminals at a traffic concentrator gridpoint k to be supported by said channel;

N_o =is the total thermal noise due to both uplink and downlink paths, measured at the gateway receiver;

I_ext,c =external interference density in channel c as measured at the gateway receiver;

C_Ksbg^user→

GW =total gain encountered by a signal in going from a user at k to gateway g via beam b of satellite s;

T_bit =bit time, which is the reciprocal of data rate; and

T_chip =chip time, which is the reciprocal of chip rate.

2. A method as set forth in claim 1, wherein the step of calculating a C-band feederlink interference error further comprises the steps of:

directing a gateway antenna away from said satellite; and

measuring the frequency power spectrum values of a signal received by said gateway, wherein said measurements define said C-band feederlink interference error.

3. A method as in claim 1, wherein the step of reallocating a user terminal channel of operation further comprises the steps of:

recalling said stored resultant values;

comparing a current frequency of operation of said user terminal with said resultant values;

determining a new frequency channel of operation within said channel thereby conserving power of said user terminal; and

sending a frequency channel assignment message to said user terminal wherein said frequency selection message instructs said user terminal.

4. A radio frequency map generating system comprising:

at least one satellite having a coverage area, said coverage area further comprising a plurality of beams, said at least one satellite comprising a first transponder;

at least one user terminal within said coverage area of said at least one satellite, said user terminal communicating with said at least one satellite; and

at least one gateway having at least one communication antenna for communicating with said at least one user terminal via said at least one satellite, wherein said first transponder of said at least one satellite is responsive to a plurality of received signals, desirable and undesirable, within the operating frequency range of said at least one user terminal, said plurality of received signals emanating from said coverage area, said at least one satellite transmitting said received signals to said gateway;

wherein

said at least one gateway is responsive to said received signals for generating a database, said database defining a radio frequency map wherein said gateway assigns or reassigns said at least one user terminal to a frequency channel selected by said gateway for reducing an amount of power required to provide a desired quality of service to said at least one user terminal;

wherein the power usage of said user terminal is reduced while a minimum signal-to-noise-interference ratio is maintained said ratio being defined as;

##EQU5## where Y_kc =the transmitter output power of said user terminal at a k^th gridpoint traffic concentrator in said channel;

W_kc =is the number of said user terminals at a traffic concentrator gridpoint k to be supported by said channel;

N_o =is a total thermal noise due to both uplink and downlink paths, measured at a gateway receiver;

I_ext,c =external interference density in channel c as measured at the gateway receiver;

C_Ksbg^user→

GW =total gain encountered by a signal in going from a user at k to gateway g via beam b of satellite s;

T_bit =bit time, which is the reciprocal of data rate; and

T_chip =chip time, which is the reciprocal of chip rate.

5. A radio frequency map generating system as set forth in claim 4 wherein said at least one satellite is a geostationary satellite wherein said coverage area of said at least one satellite is constant with respect to the Earth and wherein said radio frequency map generated by said at least one gateway represents at least a portion of the surface area of the Earth, a portion of said radio frequency map corresponding to said converge area of said at least one satellite being dynamically updated.

6. A radio frequency map generating system as set forth in claim 4 wherein said at least one satellite is a non-geostationary satellite wherein said coverage area of said at least one satellite moves with respect to the Earth and wherein said radio frequency map generated by said at least one gateway represents at least a portion of the surface area of the Earth, a portion of said radio frequency map corresponding to said moving converge area being dynamically updated.

7. A radio frequency map generating system as set forth in claim 4 wherein said at least one satellite further comprises at least one additional transponder in addition to said first transponder, said at least one additional transponder being tunable within a desired frequency range, wherein said database generated by said gateway defines a radio frequency map covering a frequency range that corresponds to said desired frequency range.

8. A radio frequency map generating system as set forth in claim 4 further comprising a network control center, said network control center communicating with said at least one gateway wherein said database is generated in part by said network control center.

9. A radio frequency map generating system as set forth in claim 4 further comprising:

second satellite, said second satellite having a coverage area, said coverage area of said second satellite further comprising a plurality of beams, said second satellite comprising a first transponder;

a second user terminal within said coverage area of said second satellite;

a second communication antenna at said at least one gateway for communicating with said second user terminal via said second satellite, wherein said first transponder of said second satellite is responsive to a plurality of received signals, desirable and undesirable, within the operating frequency range of said second user terminal, said plurality of received signals emanating from said coverage area of said second satellite, said second satellite transmitting said received signals to said second communication antenna at said at least one gateway;

wherein

said at least one gateway is responsive to said received signals from said at least one satellite and said second satellite for generating said database, said database defining said radio frequency map.

10. A radio frequency map generating system as set forth in claim 9 wherein said coverage area of said at least one satellite moves with respect to said coverage area of said second satellite, said coverage area of said at least one satellite overlapping said coverage area of said second satellite, wherein said at least one gateway correlates said received signals from said at least one satellite corresponding to said overlapping coverage area with said signals received from said second satellite corresponding to said overlapping coverage area, wherein the accuracy of said database corresponding to said overlapping coverage area is increased.

11. A radio frequency map generating system as set forth in claim 9 further comprising a second gateway wherein said second communication antenna is part of said second gateway, said at least one gateway and said second gateway communicate wherein said at least one gateway generates said database, said database comprising said received signals from said second antenna at said second gateway.

12. A radio frequency map generating system as set forth in claim 11 wherein said database is generated at said second gateway, said database comprising said received signals from said at least one antenna at said at least one gateway, said database defining said radio frequency map.