Airborne radiotelephone communications system

• US 5,559,865 A
• Filed: 07/08/1994
• Issued: 09/24/1996
• Est. Priority Date: 07/08/1994
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gilhousen, Klein S.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Trost, William G.
• Application Number:
  US08/272,060
• Time in Patent Office: 809 Days
• Field of Search: 379/57, 379/58, 379/59, 379/63, 379/60, 455/33.1, 455/54.1, 455/56.1, 455/62, 455/11.1, 455/33.4, 455/33.2, 455/54.2, 375/205
• US Class Current: 455/431
• CPC Class Codes: H04B 7/18506 Communications with or from aircraft, i.e. aeronautical mobile service
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

The airborne communication system enables one or more radiotelephones to communicate with a ground based cellular radiotelephone system. In the preferred embodiment, the aircraft is equipped with a repeater that relays a signal from the airborne radiotelephone to the ground base station and vice versa. Alternate embodiments use an airborne base station to register the radiotelephones before registering them with the ground system. Alternately, the antennas on the ground could be used to form aerial cell sites by pointing the antennas upward to where the aircraft flies through the cells. The system of the present invention provides the additional benefit of enabling the ground based cellular radio systems to source a call to the aircraft radiotelephone.

Claims

1. A communications system comprising:

a code division multiple access (CDMA) ground based subsystem comprising;

a plurality of base stations for transmitting communication signals having a quality level and receiving radio signals from an airborne based subsystem, the plurality of base stations being coupled to a public switched telephone network (PSTN);

the airborne based subsystem for transmitting the radio signals to, and receiving the communication signals from, a first base station of said plurality of base stations, and if the quality level of said first base station'"'"'s communication signal is less than a predetermined amount, transmitting the radio signals to, and receiving the communication signals from, a second base station of said plurality of base stations, the airborne based subsystem comprising;

an airborne wireless radio for originating the radio signals and receiving the communication signals and selecting the second base station in response to the quality level of the second base station'"'"'s communication signal; and

an airborne wireless repeater for repeating the radio signals to the ground based subsystem.

2. The communications system of claim 1 wherein the airborne wireless radio transmits and receives code division multiple access (CDMA) signals.

3. The communications system of claim 1 wherein the plurality of base stations are coupled to the PSTN through a mobile switching center.

4. A communications system comprising:

a code division multiple access (CDMA) ground based subsystem comprising;

a plurality of base stations for transmitting communication signals having a quality level and receiving radio signals from an airborne based subsystem, the plurality of base stations being coupled to a public switched telephone network (PSTN);

the airborne based subsystem for transmitting the radio signals to, and receiving the communication signals from, a first base station of said plurality of base stations, and if the quality level of said first base station'"'"'s communication signal is less than a predetermined amount, transmitting the radio signals to, and receiving the communication signals from, a second base station of said plurality of base stations, the airborne based subsystem comprising;

an airborne radiotelephone for originating the radio signals and receiving the communication signals; and

an airborne base station for registering the airborne radiotelephone with the ground based subsystem and relaying the communication signals to the airborne radiotelephone and the radio signals to the ground based subsystem.

5. The communications system of claim 4 wherein the airborne radiotelephone selects the second base station in response to the quality level of the second base station'"'"'s communication signal.

6. The communications system of claim 4 wherein the airborne base station selects the second base station in response to the quality level of the second base station'"'"'s communication signal.

7. A method for communicating in a wireless communications system comprising a ground based subsystem and an airborne based subsystem, the ground based subsystem having a plurality of base stations, each base station transmitting a pilot signal, the airborne based subsystem having a radiotelephone that transfers signals to and from an airborne base station, the method comprising the steps of:

the radiotelephone registering with the airborne base station;

the ail;

borne base station detecting the pilot signals from the plurality of ground base stations;

the airborne base station registering the radiotelephone with a first ground base station of the plurality of base stations in response to a quality indication of the first ground base station'"'"'s pilot signal;

the airborne base station relaying signals between the radiotelephone and the first ground base station;

if the quality indication of the pilot signal is less than a predetermined threshold, the airborne base station detecting the pilot signals from the plurality of ground base stations; and

if the quality indication of the pilot signal is less than a predetermined threshold, the airborne base station registering the radiotelephone with a second ground base station of the plurality of base stations in response to the quality indication of the second ground base station'"'"'s pilot signal.