Cross-talk mitigation in global navigation satellite systems

Abstract

The embodiments are directed to increasing receiver sensitivity in GNSS systems. The embodiments utilize a first direct-sequence spreading code and a second direct-sequence spreading code modulated on each GNSS signal for enhancing the receiver sensitivity. In the following the term “direct-sequence spread spectrum code” may also be referred to as “direct-sequence code” or simply “code”.

1 . A method comprising:
 selecting at a receiver a starting time for integrating a first global navigation satellite signal, the first global navigation satellite signal being modulated by a first Chip sequence associated with a first spreading code and a second Chip sequence associated with a second spreading code, the first spreading code having a longer time period than the second spreading code;   starting at the starting time an integration of the first global navigation satellite signal; and   determining a position based on the integration of the global navigation satellite signal.   
     
     
         2 . The method according to  claim 1 , further comprising:
 receiving a second global navigation satellite signal, the second global navigation satellite signal being modulated by a third Chip sequence associated with the first spreading code and a fourth Chip sequence associated with the second spreading code; and   selecting the starting time based on the characteristic of the first Chip sequence of the first global navigation satellite signal during a time interval with respect to the third Chip sequence of the second global navigation satellite signal during the time interval.   
     
     
         3 . The method according to  claim 1 , wherein the starting time is selected such that a parameter is at a minimum or a local minimum or at least near a minimum or a local minimum for the selected starting time compared to other potential starting times, the parameter being dependent on the characteristic of the first Chip sequence for an integration time interval after the starting time relative to the third Chip sequence for the integration time interval. 
     
     
         4 . The method according to  claim 3 , wherein the difference of a first value and a second value is at a minimum or a local minimum for the selected starting time compared to other potential starting times, the first value representing a total time duration within the time interval during which the first Chip sequence and the third Chip sequence have a same value and the second value representing a total time duration within the time interval during which the first Chip sequence and the third Chip sequence have a different value. 
     
     
         5 . The method according to  claim 1 , further comprising receiving information, wherein the information comprises information allowing a prediction in time of at least a part of the received first Chip sequence, the method further comprising:
 selecting the starting time at the receiver based on the received information.   
     
     
         6 . The method according to  claim 1 , wherein the second spreading code is a primary code for global navigation satellite signals and the first code is a secondary code for global navigation satellite signals. 
     
     
         7 . The method according to  claim 1 , wherein the first and second Chip sequences are predetermined Chip sequences, wherein integrating the first global navigation satellite signal includes applying the predetermined second Chip sequence to the received first global navigation satellite signal. 
     
     
         8 . A system comprising:
 a receiver configured to:
 select a starting time for integrating a first global navigation signal, the first global navigation signal being modulated by a first Chip sequence associated with a first spreading code and a second Chip sequence associated with a second spreading code, 
 receive a second global navigation satellite signal, the second navigation satellite signal being modulated by a third Chip sequence associated with the first spreading code and a fourth Chip sequence associated with the second spreading code, 
 select the starting time based on a characteristic of the first Chip sequence of the first global navigation satellite signal during a time interval with respect to the third Chip sequence of the second global navigation satellite signal during the time interval. 
   
     
     
         9 . The system according to  claim 8 , wherein a parameter is at a minimum or a local minimum for the selected starting time compared to other potential starting times, the parameter being dependent on a characteristic of the first Chip sequence in an integration time interval after the starting time relative to the third Chip sequence in the integration time interval. 
     
     
         10 . The system according to  claim 9 , wherein the starting time is selected such that the difference of a first value and a second value is at a minimum or a local minimum compared to other potential starting times, the first value representing a total time duration within the time interval during which the first Chip sequence and the third Chip sequence have a same value and the second value representing a total time duration within the time interval during which the first Chip sequence and the third Chip sequence have a different value in the time interval after the starting time. 
     
     
         11 . The method according to claim  16 , wherein the receiver is further configured to receive information allowing a prediction of a receive time of at least a part of the received first Chip sequence, and wherein the receiver is configured to determine the starting time based on the received information. 
     
     
         12 . A device comprising:
 a computing entity configured to:
 determine a starting time for integrating a first satellite signal associated with a first satellite, the satellite signal being modulated by a first Chip sequence associated with a first direct-sequence spreading code and a second Chip sequence associated with a second direct-sequence spreading code, the first direct-sequence spreading code having a longer time period than the second direct-sequence spreading code, 
 select the starting time based on a characteristic of the first Chip sequence during a time interval relative to the third Chip sequence during the time interval, wherein the second satellite signal is associated with a second satellite and the third Chip sequence is associated with the first direct-sequence spreading code. 
   
     
     
         13 . The device according to  claim 12 , wherein the computing entity is configured to select the starting time such that the difference of a first value and a second value is at a minimum or a local minimum or at least near a minimum or a local minimum for the selected starting time compared to other potential starting times, the first value representing a total time duration within an integration time interval during which the first Chip sequence and the third Chip sequence have a same value and the second value representing a total time duration within the integration time interval during which the first Chip sequence and the third Chip sequence have a different value in the time interval after the starting time. 
     
     
         14 . The device according to  claim 12 , wherein the starting time is selected such that a parameter indicative of a characteristic of the first Chip sequence and the third Chip sequence during a time interval after the starting time is at a minimum or local minimum or at least near a minimum or near a local minimum compared to other potential starting times. 
     
     
         15 . The device according to  claim 12 , wherein the starting time is selected such that a difference of a first value and a second value is at a minimum or a local minimum or at least near a minimum or local minimum for the selected starting time compared to other potential starting times, the first value representing a total time duration within the time interval during which the first Chip sequence and the third Chip sequence are at a same value, the second value representing a total time duration within the time interval during which the first Chip sequence and the third Chip sequence are at a different value.