Cellular positioning system (CPS)

Abstract

Positioning system for locating a mobile body comprising a plurality of earth based spread spectrum (SS) broadcasting stations arranged geographically in a cellular pattern. Each SS broadcasting station include a modulator providing a channel signal structure which is substantially orthogonal with respect to adjacent stations in the cellular pattern, each channel signal including navigation beacon data including a unique beacon identification, station latitude and longitude, time_slot and phase characterizations and selected parameters of adjacent stations. In one embodiment, each modulator provides a chirped SS signal in which the navigation beacon is a frequency tone that is repeatedly swept over a selected frequency band for each station. In a further embodiment, each modulator provides a GPS like direct sequence SS signal in which the navigation beacon is a PN coded broadcast. A receiver on the mobile body receives the SS signals from at least three of the SS broadcasting stations and determines the location thereof. A fourth SS broadcasting station provides altitude CPS satellite signals can be used for timing control.

1. Positioning system for locating a mobile body comprising a plurality of earth based spread spectrum (SS) broadcasting stations arranged geographically in a hexagonal cellular pattern, each said SS broadcasting station including a modulator providing a channel signal structure which is substantially orthogonal with respect to adjacent SS broadcasting stations in said hexagonal cellular pattern, each channel signal including navigation beacon data including:
 (a) a unique beacon identification,  
 (b) station latitude and longitude,  
 (c) time slot frequency and phase characterizations and  
 (d) selected parameters of adjacent stations.  
 
     
     
       2. The positioning system defined in  claim 1  wherein each said modulator provides a GPS like direct sequence SS signal in which the navigation beacon data is a PN coded broadcast. 
     
     
       3. The positioning system defined in  claim 1  including receiver means for receiving the SS signals from at least three of said SS broadcasting stations and determining the location thereof. 
     
     
       4. The positioning system defined in  claim 1  in which GPS satellite signals are received in said hexagonal cellular pattern and including means at each said broadcasting station for receiving said GPS satellite signals and deriving therefrom a reference frequency signal and a time epoch signal, said modulator means being adapted to receive said reference frequency and time epoch signals and be timed thereby. 
     
     
       5. Positioning system for locating a mobile body comprising a plurality of earth based spread spectrum (SS) broadcasting stations arranged geographically in a hexagonal cellular pattern, each said SS broadcasting station including a modulator providing a channel signal structure which is substantially orthogonal with respect to adjacent SS broadcasting stations in said hexagonal cellular pattern, each channel signal including navigation beacon data including:
 (a) a unique beacon identification,  
 (b) station latitude and longitude,  
 (c) time slot frequency and phase characterizations and  
 (d) selected parameters of adjacent stations, each said modulator providing a GPS like direct sequence SS signal in which the navigation beacon is a PN coded broadcast, and receiver means for receiving the direct sequence SS signals from at least three of said SS broadcasting stations and determining the location thereof.  
 
     
     
       6. The positioning system defined in  claim 5  in which each said SS broadcasting station includes means to receive GPS satellite signals and means for deriving therefrom a reference frequency signal and a time epoch signal, said modulator means being adapted to receive said reference frequency and time epoch signals and be timed thereby. 
     
     
       7. A positioning apparatus suitable for use in an earth based spread spectrum ( SS )  broadcasting station among a plurality of earth based spread spectrum  ( SS )  broadcasting stations arranged geographically in a cellular pattern in a communication system for locating a mobile body, each said SS broadcasting station outputting a channel signal that is substantially orthogonal with respect to channel signals output by adjacent SS broadcasting stations in said cellular pattern, the apparatus comprising a modulator suitable to output such a substantially orthogonal channel signal including navigation beacon data including:    ( a )  a unique beacon identification,      ( b )  station latitude and longitude,      ( c )  time slot frequency and phase characterizations, and      ( d )  selected parameters of adjacent stations.     
     
     
       8. The positioning apparatus of  claim 7 , further comprising a time transfer receiver configured to receive GPS satellite signals and deriving therefrom a reference frequency signal and a time epoch signal, said modulator being connected to the receiver and adapted to receive and be timed by said reference frequency and time epoch signals. 
     
     
       9. The positioning apparatus of  claim 7 , wherein the modulator is configured to output a GPS- like direct sequence SS  ( DSSS )  signal having the navigation beacon data that is PN coded.   
     
     
       10. The positioning apparatus of  claim 9 , wherein the DSSS signal output from the modulator has at least one of a PN code and a PN phase that differs from PN codes and PN phases of the channel signals output by the adjacent SS broadcast stations. 
     
     
       11. The positioning apparatus of  claim 7 , wherein the modulator is configured to output a chirped spread spectrum ( CSS )  signal as the substantially orthogonal channel signal having chirp characteristics that are different from chirp characteristics of the channel signals output by the adjacent SS broadcasting stations.   
     
     
       12. The positioning apparatus of  claim 11 , wherein the different chirp characteristics include at least one of a chirp rate and a chirp phase. 
     
     
       13. A positioning apparatus suitable for use in a mobile body in a communication system having a plurality of earth based spread spectrum ( SS )  broadcasting stations arranged geographically in a pattern suitable for facilitating cellular communications, each SS broadcast station transmitting a navigation beacon that is substantially orthogonal with respect to navigation beacons transmitted from adjacent SS broadcasting stations in the cellular pattern, wherein the navigation beacons include:    ( a )  a unique beacon identification,      ( b )  station latitude and longitude,      ( c )  time slot frequency and phase characterizations, and      ( d )  selected parameters of adjacent stations,        the positioning apparatus comprising a receiver configured to receive said navigation beacons from at least three of said SS broadcasting stations in the communication system and determine a location of the mobile body therefrom.     
     
     
       14. The positioning apparatus of  claim 13 , wherein the navigation beacons transmitted by said at least three of said SS broadcasting stations are direct sequence SS ( DSSS )  signals having different PN characteristics, and the receiver is configured to receive such DSSS signals.   
     
     
       15. The positioning apparatus of  claim 14 , wherein the different PN characteristics include at least one of a PN code and a PN phase. 
     
     
       16. The positioning apparatus of  claim 13 , wherein the navigation beacons transmitted by said at least three of said SS broadcasting stations are chirped spread spectrum ( CSS )  signals having different chirp characteristics, and the receiver is configured to receive such CSS signals.   
     
     
       17. The positioning apparatus of  claim 16 , wherein the different chirp characteristics include at least one of a chirp rate and a chirp phase. 
     
     
       18. A method of determining a location of a mobile unit operating within a wireless communication system having a plurality of earth based broadcasting stations each transmitting a navigation beacon substantially orthogonal to navigation beacons transmitted by adjacent broadcasting stations, the method comprising:
   detecting on a control channel of a communication signal broadcast by one of the plurality of broadcasting stations a navigation message containing information concerning the navigation beacons transmitted by the plurality of broadcasting stations;        acquiring the navigation beacons transmitted by at least three of the broadcasting stations using the information contained in the detected navigation message and determining from the acquired navigation beacons range measurements to said at least three broadcasting stations; and        determining a position of the mobile unit based on the range measurements,        wherein the navigation message includes identifiers of at least the adjacent broadcast stations and characteristics of the navigation beacons transmitted by the adjacent broadcast stations.     
     
     
       19. The method of  claim 18 , wherein characteristics of the navigation beacons transmitted by the adjacent broadcast stations include for each navigation beacon at least one of: a time slot identifier of a time slot within a communication signal in which the navigation beacon is broadcast; phase information concerning a phase of the navigation beacon; and a frequency of the navigation beacon. 
     
     
       20. The method of  claim 19 , wherein the navigation beacons transmitted by the adjacent broadcast stations are direct sequence spread spectrum ( DSSS )  signals, and the characteristics of the navigation beacons include a PN code and PN code phase.   
     
     
       21. The method of  claim 19 , wherein the navigation beacons transmitted by the adjacent broadcast stations are chirped spread spectrum ( CSS )  signals, and the characteristics of the navigation beacons include a chirp rate and chirp phase.   
     
     
       22. The method of  claim 18 , wherein at least one of said navigation beacons is overlaid with a communication signal, and the method further comprising processing said communication signal. 
     
     
       23. The method of  claim 22 , further comprising transmitting to a call destination mobile unit position information based on the determined position of the mobile unit. 
     
     
       24. The method of  claim 23 , further comprising transmitting with the mobile unit position information, information identifying the mobile unit.