Method and apparatus for performing soft hand-off in a wireless communication system

Claim 3

The method of claim 1 wherein said step of computing a threshold value comprises performing a linear operation upon said combination of signal energy measurements from base stations capable of communicating with said remote station.

Claim 4

In a wireless communications system wherein a first base station transmits a first pilot signal and a first traffic signal, and a second base station transmits a second pilot signal and a second traffic signal, and a remote station receives said first pilot signal and said first traffic signal, a method for determining whether to add a third base station to an Active Set of said remote station, comprising the steps of: demodulating said first pilot signal; measuring the energy of said demodulated first pilot signal; generating a threshold in accordance with said demodulated first pilot signal energy; demodulating said second pilot signal; measuring the energy of said demodulated second pilot signal; comparing said demodulated second pilot signal energy with said threshold; adding said second base station to said Active Set when said demodulated second pilot signal energy exceeds said threshold; generating a revised threshold in accordance with a combination of said demodulated first pilot signal energy and said demodulated second pilot signal energy; demodulating a third pilot signal from said third base station; measuring the energy of said demodulated third pilot signal; comparing said demodulated third pilot signal energy with said revised threshold; and adding said third base station to said Active Set when said demodulated third pilot signal energy exceeds said revised threshold.

Claim 5

In a wireless communications system wherein a first base station transmits a first pilot signal and a first traffic signal, and a second base station transmits a second pilot signal and a second traffic signal, and a remote station receives said first pilot signal and said first traffic signal, a method for determining whether to add a third base station to an Active Set of said remote station, comprising the steps of: demodulating said first pilot signal; measuring the energy of said demodulated first pilot signal; generating a threshold in accordance with said demodulated first pilot signal energy; demodulating said second pilot signal; measuring the energy of said demodulated second pilot signal; comparing said demodulated second pilot signal energy with said threshold; adding said second base station to said Active Set when said demodulated second pilot signal energy exceeds said threshold; generating a revised threshold in accordance with a combination of said demodulated first pilot signal energy and said demodulated second pilot signal energy; demodulating a third pilot signal from said third base station; measuring the energy of said demodulated third pilot signal; comparing said demodulated third pilot signal energy with said revised threshold; and adding said third base station to said Active Set when said demodulated third pilot signal energy exceeds said revised threshold.

Claim 6

In a wireless communications system in which a plurality of base stations are in communication with a base station controller, a method for determining an Active Set of base stations to communicate with a remote station at said base station controller, comprising the steps of: receiving a signal strength measurement message indicative of the signal strengths associated with each of said plurality of base stations as measured at said remote station; selecting a first base station as a member of said Active Set of base stations; calculating a threshold value in accordance with a signal strength of said selected first base station; selecting a second base station as a member of said Active Set of base stations in accordance with said threshold value; summing the signal strengths associated with each of said two selected base stations; determining a revised threshold value in accordance with said summed signal strengths; and determining remaining members of said Active Set in accordance with said revised threshold value.

Claim 7

In a wireless communications system in which a plurality of base stations are in communication with a base station controller, a method for determining an Active Set of base stations to communicate with a remote station at said base station controller, comprising the steps of: receiving a signal strength measurement message indicative of the signal strengths associated with each of said plurality of base stations as measured at said remote station; selecting a first base station as a member of said Active Set of base stations; calculating a threshold value in accordance with a signal strength of said selected first base station; selecting a second base station as a member of said Active Set of base stations in accordance with said threshold value; summing the signal strengths associated with each of said two selected base stations; determining a revised threshold value in accordance with said summed signal strengths; and determining remaining members of said Active Set in accordance with said revised threshold value.

Claim 8

The method of claim 4 wherein said step of revised determining said threshold value in accordance with said summed signal strengths, comprises the steps of: multiplying said summed signal strengths by a predetermined scaling value; and adding a predetermine value to said product.

Claim 11

The method of claim 6 further comprising the steps of: determining membership of said Candidate Set by comparing the received signal energy from a predetermined set of base stations with a predetermined threshold.

Claim 12

The method of claim 6 further comprising the steps of: sorting members of said Candidate Set in accordance with the corresponding strength of the received signal energy.

Claim 13

The method of claim 6 further comprising the steps of: comparing the received signal strengths of a member of said Active Set against a threshold determined in accordance with the aggregate energy of the received energy of signals from base stations in the Active Set; and removing a member from said Active Set when said received signal strength of said member is less than said threshold.

Claim 14

The method of claim 8 wherein said step of removing said member from the Active set is performed at said member has remained below said threshold for a predetermined time interval.

Claim 15

The method of claim 8 further comprising the step of transmitting a pilot strength measurement message indicating for each base station in said Candidate Set and said Active Set whether to keep said member in said Active Set.