초록 ▼

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

A method and apparatus for providing a reliable means to perform handoff from a code division multiple access (CDMA) system using a pilot signal to an alternative access 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 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 technique system in response thereto. The border base stations use a time division duplex technique to monitor a pilot and synchronization sequence from a neighboring one of the CDMA operation base stations to obtain an estimate of absolute system time.

대표청구항 ▼

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 plurali

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 a border set of base stations 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: searcher and demodulator and filter circuitry for intermittently demodulating and pausing at least one of said identifying pilot signals transmitted by each base station of said first plurality of base stations to obtain an indication of a universal time; and a pilot generator for providing a transmit pilot signal during time when said searcher and demodulator and filter circuitry are paused.