Mobile station assisted soft handoff in a CDMA cellular communications system

In a spread spectrum cellular communication system in which a mobile station user communicates with another system user via at least one base station, wherein each base station transmits an identifying pilot signal of a different code phase with respect to other base stations in said system, a method for directing communications between said mobile station user and said base stations by a system controller comprising the steps of:

• providing to said mobile station a first list identifying a first set of base stations;
• measuring at said mobile station signal strength of said pilot signals transmitted by of each base station of said first set of base stations;
• comparing said measured pilot signal strength to a first predetermined level;
• generating at said mobile station a second list identifying a second set of base stations by removing from said first list a base station listing having a pilot signal strength measurement of a corresponding base station which exceeds said first predetermined level and placing said base station listing in said second list;
• providing by said mobile station said second list to said system controller;
• providing to said system controller from said base station identified in said second list availability information about resources at each of said base stations identified in said second list;
• generating at said system controller a third list identifying a third set of base stations based on said first list, said second list and said base station availability information;
• providing to said mobile station by said system controller said third list;
• removing at said mobile station each base station listing of said third set of base stations from said first list and said second list;
• and
• communicating by said mobile station through said third set of base stations.

In a cellular communication system in which a system controller directs communications between a mobile station and at least one base station, a method for mobile station assisted communications directing, comprising the steps of:

• storing in said mobile station an active list of base stations entries, wherein each entry in said active list corresponds to a base station in communication with said mobile station;
• storing in said mobile station a candidate list of base stations entries, wherein each entry in said candidate list corresponds to a base station having sufficient signal strength to establish communication with said mobile station;
• transmitting from each base station of said current system a signal identifying said base station;
• measuring at said mobile station a signal strength of said corresponding base station transmitted signal for each of said entries in said active list;
• measuring at said mobile station a signal strength of said corresponding base station transmitted signal for each of said entries in said candidate list;
• comparing said measurement of each of said candidate list entries to each of said measurements of said active list entries;
• and
• identifying by said mobile station to said system controller a particular base station having an entry on said candidate list and another base station having an entry on said active list, if a measurement of said particular base station exceeds a measurement of said another base station by a predetermined amount, T.sub.-- COMP.

In a cellular communication system in which a system controller directs communications between a mobile station and at least one base station, a method for mobile station assisted communications directing, comprising the steps of:

• identifying by said system controller to said mobile station a first set of base stations which are in a predetermined proximity of said mobile station;
• measuring at said mobile station a signal strength of a signal transmitted by each base station in said first set of base stations;
• identifying to said system controller by said mobile station a second set of base stations from said first set of base stations having said measured signal strengths sufficient at said mobile station to establish communications therewith;
• identifying by said system controller to said mobile station a third set of base stations corresponding to at least one base station of said second set having available resources to establish communication with said mobile station;
• notifying by said system controller each base station of said third set of base stations not currently in communication with said mobile station to establish communication with said mobile station;
• and
• establishing communications by said mobile station and each base station of said third set of base stations not currently in communication therewith.

In a cellular communication system in which a system controller controls a handoff in communications between a mobile station and a plurality of base stations, a method for mobile station assisted handoff in said communications comprising the steps of:

• identifying by said system controller to said mobile station a first set of base stations which are in a predetermined proximity of said mobile station;
• measuring at said mobile station a signal strength of a signal transmitted by each base station in said first set of base stations;
• determining at said mobile station from said signal strength measurements a second set of base stations, wherein said signal strength measurement of each base station of said second set of base stations is indicative of signal level sufficient to establish communication with said mobile station;
• identifying by said mobile station to said system controller said second set of base stations;
• determining at said system controller from said second set of base stations a third set of base stations having resources available to establish communication with said mobile station;
• notifying by said system controller each base station of said third set of base stations and said mobile station to establish communications between each base station of said third set of base stations if communications therebetween are not currently present;
• establishing communication between each base station of said third set of base stations and said mobile station if communications therebetween are not currently present;
• and
• terminating existing communication between said mobile station and each base station absent from said third set of base stations.