Airborne onboard base transceiver station for mobile communication

Abstract

The invention refers to a base station (BTS) and a method for a BTS, for a cellular communication system comprising a user equipment (UE) onboard an aircraft, when at a predetermined altitude, and a terrestrial network. The invention is characterised in that the BTS is arranged to be an airborne onboard BTS comprising a screening device generating a first signal (S 1 ) matched to screen a second signal (S 2 ) from the terrestrial network at a predetermined altitude. The onboard BTS also comprises a signal generator generating a third signal (S 3 ) stronger than both the first signal (S 1 ) and the second signal (S 2 ), the onboard BTS arranged to establish a communication link with the UE via the third signal (S 3 ).

1 . A base station for use on an aircraft to provide communications between a user equipment (UE) onboard said aircraft, when at a predetermined altitude, and a terrestrial network, said base station comprising:
 a screening device arranged to generate a first signal (S 1 ) matched to screen a second signal (S 2 ) from the terrestrial network at a predetermined altitude;   a signal generator arranged to generate a third signal (S 3 ) stronger than both the first signal (S 1 ) and/or the second signal (S 2 ), the onboard base station being arranged to establish a communication link with the UE via the third signal (S 3 );
 wherein the second signal (S 2 ) is pertaining to a GSM cellular communication system; 
 the first signal (S 1 ) has a signal strength less than the signal strength of the second signal (S 2 ) but not less than 7 dB below the signal strength of the second signal (S 2 ); and, 
 the third signal (S 3 ) is at least 7 dB above the second signal (S 2 ). 
   
     
     
         2 . A base station according to  claim 1 , wherein the third signal (S 3 ) has a third frequency band being at least partly or completely within a first frequency band (S 1 F 2 ) of the first signal (S 1 ). 
     
     
         3 . A base station according to  claim 2 , wherein the first frequency band (S 1 F 1 ) is equal to or greater than a second frequency band (S 2 F 2 ) of the second signal (S 2 ). 
     
     
         4 . A base station according to  claim 1 , wherein the screening device is arranged to generate the first signal (S 3 ) in the form of a pulsed first signal (S 3 ) matched to screen a control channel (F;S;B) in the second signal (S 2 ). 
     
     
         5 . A base station according to  claim 4 , wherein the screening device is arranged to generate the pulsed first signal (S 1 ) with a pulse length of the same length or at least of the same length as the pulse length of the control channel (F; S; B) and with a repetition interval less than a broadcast channel burst length. 
     
     
         6 . A base station according to  claim 4 , wherein that the screening device is arranged to generate the pulsed first signal (S 1 ) with a pulse length at least 7 ms and with a repetition interval of maximum or equal to 23.5 ms. 
     
     
         7 . A base station according to  claim 1 , wherein the onboard base station is connected to an onboard antenna. 
     
     
         8 . A base station according to  claim 1 , wherein the onboard antenna is in the form of a leaky cable extending in the longitudinal direction of the aircraft and in the vicinity of a passenger using a UE. 
     
     
         9 . A base station according to  claim 1 , wherein the onboard base station is connected to a satellite link handling traffic between the onboard base station and a dedicated base station in the terrestrial network. 
     
     
         10 . A base station according to  claim 1 , wherein the satellite link comprises an onboard satellite antenna arranged to send signals to a satellite positioned at a higher level than the aircraft. 
     
     
         11 . A method performed in a base station on an aircraft to provide communications between a user equipment (UE) onboard said aircraft, when at a predetermined altitude, and a terrestrial network, said method comprising:
 generating a first signal (S 1 ) matched to screen a second signal (S 2 ) from the terrestrial network at a predetermined altitude;   generating a third signal (S 3 ) stronger than both the first signal (S 1 ) and the second signal (S 2 ); and,   establishing a communication link with the UE via the third signal (S 3 );
 wherein the second signal (S 2 ) is pertaining to a GSM cellular communication system; 
 the first signal (S 1 ) has a signal strength less than the signal strength of the second signal (S 2 ) but not less than 7 dB below the signal strength of the second signal (S 2 ); and, 
 the third signal (S 3 ) is at least 7 dB above the second signal (S 2 ). 
   
     
     
         12 . A method according to  claim 11 , wherein the third signal (S 3 ) has a third frequency band at least partly or completely within a first frequency band (S 1 F 2 ) of the first signal (S 1 ). 
     
     
         13 . A method according to  claim 11 , wherein the first frequency band (S 1 F 1 ) is equal to or greater than a second frequency band (S 2 F 2 ) of the second signal (S 2 ). 
     
     
         14 . A method according to  claim 11 , wherein the first signal (S 3 ) is in the form of a pulsed first signal (S 3 ) matched to screen a control channel (F;S;B) in the second signal (S 2 ).