Wireless communication system supporting cell handover between terrestrial and non-terrestrial cells

摘要

A wireless communication system (200) supports cell handover between terrestrial cells and non-terrestrial cells, where each cell incorporates a wireless serving communication unit serving a plurality of subscriber units (270) with a communication resource. An airborne-capable subscriber unit (270) is capable of communicating to both terrestrial based cells and non-terrestrial based cells and receives transmissions from one or more wireless serving communication unit(s). The subscriber unit (270) calculates a derivative of a rate of change of the received one or more signal levels and determines whether to handover communication from a non-terrestrial cell to a terrestrial cell based on the calculation, or determines a substantially simultaneous increase in received signal levels from a plurality of terrestrial wireless communication units and hands over the communication to a terrestrial wireless serving communication unit. <??>A wireless subscriber unit and method for determining when to handover are also described. In this manner, by early determination of a handover need, calls are not dropped when the subscriber unit is landing, or severe interference caused when the unit is taking off. <IMAGE>