Qualcomm Incorporated

Toni Lee Holcman

Noam A Ziv

Kuo-Chun Lee

Paul E Bender

Bibhu P Mohanty

Lindsay A Weaver, Jr

Todd Robert Sutton

Gadi Karmi

Roy F Quick

Kenneth Robert Baker

Venkat Tangirala

David B Munsinger

Steven P Stachwick

Robert C Ottinger

Suzanne M Lueder

A method and apparatus for operating a cellular telephone system that supports performing an inter-system soft handoff is described. A subscriber unit generates a pilot strength measurement report when the pilot channel from a base station is detected. When a base station controller receiving the pilot strength measurement report determines that the base station is part of a second cellular telephone system, a inter-system soft handoff request is generated. An admission control subsystem receives the inter-system soft handoff and either grants or denies the request base on the traffic level with the second cellular telephone system. In a preferred embodiment of the invention, the traffic level is determined based on link load messages received periodically by the admission control subsystem that are generated by an interface port coupled to an interconnect between the first cellular telephone system and the second cellular telephone system. The link load message include peak queue length and average frame rate information.

Inter-system soft handoff

In a communications network, a network user communicates using a remote unit with another user via at least one base station. The network is comprised of first and second mobile switching control stations respectively controlling communications through a first set of base stations including a first base station and through a second set of base stations including a second base station. To direct communications between the remote unit and the first and second base stations the first base station measures a round trip delay of an active communication signal between the first base station and the remote unit. The remote unit measures a first phase offset of a pilot signal received from a first candidate base station and reports it to the first mobile switching center via the first base station. The first mobile switching center calculates a candidate round trip delay between the remote unit and the first candidate base station based on the first phase offset and the round trip delay of the active communication signal. A active communication control unit accesses a measurement directed hard handoff table to determine a location of the remote unit based on the round trip delay corresponding to the first active communication signal and the candidate round trip delay.

Method and apparatus for measurement directed hard handoff in a CDMA

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San Diego, CA, United States of America

Toni Lee Holcman