Soft swap handoff method in a CDMA cellular system
AssigneeSamsung Electronics Co., Ltd.
InventorJin Soo Jung
Life of this patent
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Abstract
A method for providing soft swap handoff in a CDMA communication system is provided. The pilot signal strengths of newly detected base stations that are above a predetermined level are compared with those of the base stations presently in active state. If the pilot signal strength of a newly detected base station is above the predetermined level and also stronger than the weakest one among those of the base stations presently in active state by a prescribed value, then the base station controller (BSC) instructs the mobile station to drop the weakest base station among the base stations that are presently in active state.
Claims13
A method for soft swap handoff in a CDMA system wherein a mobile station maintains communications with one or more base stations, and a base, station in communication with the mobile station is in an active state, the method comprising the steps of:
- detecting, by a mobile station, pilot signal strength of all neighboring base stations;
- dropping a base station with the weakest pilot signal strength among the base stations presently in the active state, if
- (i) there is at least one base station among said neighboring base stations having a pilot signal strength greater than a predetermined level, and
- (ii) said at least one neighboring base station has a pilot signal strength greater than the pilot signal strength of the weakest base station among those presently in the active state by a prescribed value;
- and
- adding a base station with the strongest pilot signal strength among a set of candidates, said set of candidates including said dropped base station and said neighboring base stations whose pilot signal strengths are above said predetermined level and said prescribed value.
A CDMA system using a soft swap handoff method, the system comprising:
- a mobile station for detecting pilot signal strengths of all neighboring base stations;
- a base station controller for receiving reports from said mobile station of the pilot signal strengths of neighboring base stations which are above a predetermined level, comparing said reported pilot signal strengths with those of base stations currently communicating with said mobile station, and dropping a base station with the weakest pilot signal strength among the base stations currently communicating with said mobile station, if said weakest pilot signal strength is weaker than any of said reported pilot signal strengths by a prescribed value;
- and
- a base station transfer system, connected to said base station controller, for transferring base stations.
A method for soft swap handoff in a CDMA cellular system comprising the steps of:
- detecting, in a mobile station, pilot signal strengths of all neighboring base stations;
- determining whether the pilot signal strength of any of said neighboring base stations is above a predetermined level (T.sub.-- ADD);
- sending a pilot signal measurement message (PSMM) to a base station controller (BSC) having the pilot signal strengths of the base stations above T.sub.-- ADD;
- comparing the pilot signal strengths of a plurality of base stations currently communicating with said mobile station with all neighboring base stations;
- determining if the pilot signal strength of any neighboring base station is stronger than the weakest pilot signal strength among the plurality of base stations currently communicating with said mobile station by a predetermined amount (T.sub.-- COMP);
- and
- performing handoff when a neighboring base station has a pilot signal strength stronger than the weakest pilot strength among the plurality of base stations currently communicating with said mobile station by at least the predetermined amount T.sub.-- COMP.
Dependencies are inferred from the claim text.