Handover based on measured time of signals received from neighboring cells

Claim 1

A method for determining a handover candidate in at least one mobile unit communicating with a base station of a cellular radio communication system including a serving cell and a plurality of neighboring cells, wherein the serving cell and the neighboring cells comprise at least one umbrella cell and a plurality of microcells, each cell having a respective base station, the method including the steps of: measuring received signal parameters for at least some of the neighboring cells of the plurality of neighboring cells; starting a timer associated with a particular neighboring cell of said at least some of the neighboring cells when the particular neighboring cell has a measured received signal parameter that exceeds a first predetermined threshold; after a first predetermined period, determining whether the measured received signal parameter for the particular neighboring cell exceeds a second predetermined threshold to identify a requirement for a handover; and in response to the second predetermined threshold being exceeded, generating a prioritized handover candidate list for the at least some of the neighboring cells by applying differing weighting factors between the serving cell and each of the at least some of the neighboring cells, the weighting factors being based on: received signal strength levels of the at least some of the neighboring cells; power budget margins between the serving cell and the at least some of the neighboring cells; and elapsed time since starting the timer in the at least some of the neighboring cells.

Claim 2

A method for determining a handover candidate in at least one mobile unit communicating with a base station of a cellular radio communication system including a serving cell and a plurality of neighboring cells, wherein the serving cell and the neighboring cells comprise at least one umbrella cell and a plurality of microcells, each cell having a respective base station, the method including the steps of: measuring received signal parameters for at least some of the neighboring cells of the plurality of neighboring cells; starting a timer associated with a particular neighboring cell of said at least some of the neighboring cells when the particular neighboring cell has a measured received signal parameter that exceeds a first predetermined threshold; after a first predetermined period, determining whether the measured received signal parameter for the particular neighboring cell exceeds a second predetermined threshold to identify a requirement for a handover; and in response to the second predetermined threshold being exceeded, generating a prioritized handover candidate list for the at least some of the neighboring cells by applying differing weighting factors between the serving cell and each of the at least some of the neighboring cells, the weighting factors being based on: received signal strength levels of the at least some of the neighboring cells; power budget margins between the serving cell and the at least some of the neighboring cells; and elapsed time since starting the timer in the at least some of the neighboring cells.