Patent ID: 7684820

Claim:
A method of selecting a ground station in an air-ground communications network, comprising: initiating radio communications between an aircraft and a first ground station; determining an altitude of the aircraft while monitoring the signal strength value of the first ground station; comparing the altitude of the aircraft to a first reference value, a second reference value, and a third reference value; and discontinuing radio communications with the first ground station and initiating radio communications with a second ground station when the monitored signal strength of the first ground station is weaker than a threshold value associated with the reference value, wherein a first threshold value is associated with the first reference value, a second threshold value is associated with the first and second reference value, a third threshold value is associated with the second and third reference value, and a fourth threshold value is associated with the third reference value, wherein the third reference value is greater than the second reference value, which is greater than the first reference value, and wherein a fourth threshold value is less than the third threshold value, which is less than the second threshold value, which is less than the first threshold value.