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A method and system for providing a reliable means to perform handoff from a code division multiple access (CDMA) system using a pilot signal to an alternative access communication technique system. Simple pilot box circuitry is added to a set of border base stations. The border base stations are ba

A method and system for providing a reliable means to perform handoff from a code division multiple access (CDMA) system using a pilot signal to an alternative access communication technique system. Simple pilot box circuitry is added to a set of border base stations. The border base stations are base stations which operate only in the alternative access communication technique and which have coverage areas which are contiguous with coverage areas of CDMA operation base stations. The mobile unit monitors for the pilot signal from the border base stations in the same manner as it monitors for pilot signals from the CDMA operation base stations. When the mobile unit detects the pilot signal corresponding to a border base station, it notifies a system controller in accordance with standard operation. The system controller is aware that the pilot signal corresponds to a border base station and thus triggers a hard handoff process to the alternative access communication technique system in response thereto.

대표청구항 ▼

In a system for providing communication with at least one mobile unit, said system comprising a first plurality of base stations providing code division multiple access (CDMA) communication, wherein said first plurality of base stations are clustered physically together, said system further comprisi

In a system for providing communication with at least one mobile unit, said system comprising a first plurality of base stations providing code division multiple access (CDMA) communication, wherein said first plurality of base stations are clustered physically together, said system further comprising a second plurality of base stations providing communication using an alternative access communication technique wherein said second plurality of base stations surrounds said first plurality of base stations thereby creating a border set of base stations wherein said border set of base stations is a subset of said second plurality of base stations wherein each base station in said border set has a coverage area with a contiguous boundary with a coverage area corresponding to a base station of said first plurality of base stations, a method for providing handoff from said CDMA communication to said alternative access communication technique comprising the steps of: transmitting from each base station in said first plurality of base stations an identifying pilot signal and CDMA call signals in a first frequency band; transmitting from each base station in said border set of base stations an identifying pilot signal in said first frequency band and alternative access communication technique call signals in a different frequency band; measuring at a first mobile unit a pilot signal strength of each of said identifying pilot signals corresponding to a neighboring set of base stations wherein said neighboring set of base stations comprises base stations having coverage areas in proximity to said first mobile unit; receiving at said first mobile unit a first pilot signal corresponding to a target base station wherein said target base station is a member of said border set of base stations and wherein said target base station is a member of said neighboring set of base stations; transmitting a message from said first mobile unit to a CDMA system controller via at least one base station in said first plurality of base stations wherein said message indicates receipt of said first pilot signal; and initiating by said CDMA system controller an intersystem handoff procedure for said first mobile unit with an alternative access communication technique system controller, said CDMA system controller determining availability of resources among said second plurality of base stations through intersystem communication with said alternative access communication technique system controller during said intersystem handoff procedure. A cellular communication system for providing communication with at least one mobile unit, said system comprising: a first plurality of base stations clustered physically together for providing code division multiple access (CDMA) communication signals wherein each base station of said first plurality of base stations transmits an identifying pilot signal and wherein said first plurality of base stations are controlled by a CDMA system controller; a border set of base stations controlled by an alternative system controller in intersystem communication with said CDMA system controller wherein said border set of base stations is a subset of a second plurality of base stations for providing communication using an alternative access communication technique wherein said second plurality of base stations surrounds said cluster of said first plurality of base stations and wherein each base station in said border set has a coverage area with a contiguous boundary with a coverage area corresponding to a base station of said first plurality of base stations and wherein each base station of said border set comprises a self contained pilot generator for providing a transmit pilot signal apparatus comprising: I channel short code generator means for receiving a universal time input and creating an I channel spreading sequence at a time offset; a first baseband filter for receiving said I channel spreading sequence and providing a filtered I channel spreading sequence; a first mixer for modulating said filtered I channel spreading sequence and producing a modulated I output signal; Q channel short code generator means for receiving a universal time input and creating a Q channel spreading sequence at said time offset; a second baseband filter for receiving said Q channel spreading sequence and providing a filtered Q channel spreading sequence; a second mixer for modulating said filtered Q channel spreading sequence and producing a modulated Q output signal; a summer for summing said modulated I output signal and said modulated Q output signal to produce a summed modulated signal; and upconversion and amplification means for receiving said summed modulated signal and producing said transmit pilot signal.