Patent ID: 8862123
Filing Date: 2014-10-14
Classification: H04B,H04K,H04W

Abstract:
1. A cellular communication system base station for use onboard an aircraft, the base station configured to communicate with a user equipment (UE) when the aircraft is at a predetermined altitude, the UE nominally configured to communicate with a terrestrial network, said base station comprising: a screening device operative to generate a first signal matched to screen a second signal from a terrestrial network when at said predetermined altitude; and, a signal generator operative to generate a third signal stronger than both the first signal and the second signal, the base station operative to establish a communication link with the UE via the third signal; wherein the first signal has a signal strength less than the signal strength of the second signal but not lower than a predetermined value below the signal strength of the second signal, whereby a noise ratio for the UE is not acceptable for homing in on a certain frequency within a frequency band of the second signal such that the UE cannot establish a communication link to the terrestrial network via the second signal; wherein the third signal is generated with a signal strength stronger than the first signal and at a certain frequency or frequencies and having an acceptable signal to noise ratio of at least 7 dB for the UE such that the UE can home in on the third signal in order for the onboard base station to establish said communication link with the UE; wherein the screening device is operative to generate the first signal in the form of a pulsed first signal matched to screen a control channel in the second signal; and, wherein the screening device is operative to generate the pulsed first signal with a pulse length at least of a same length as the pulse length of the control channel and with a repetition interval less than a broadcast channel burst length.