System and method for facilitating a handoff of at least one mobile unit in a telecommunication system

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A method and system for facilitating a handoff of a remote mobile subscriber unit from a source base station to a target base station in a communication system having a plurality of base stations, such as in a code division multiple access communication system, employs target base stations along a coverage area seam that have a soft handoff subsystem collocated with conventional base station circuitry to facilitate soft handoff.
The soft handoff subsystem includes a transceiver for generating and receiving a first group of dedicated soft handoff channels that are an orthogonally related subset of a separate second group of spread spectrum coded traffic channels wherein the soft handoff subsystem is under control of the source base station controller.
The dedicated soft handoff channels are assigned to a specified source base station controller.
Preferably the soft handoff subsystem generates only the first group of dedicated soft handoff channels without pilot channels or synchronization channels.
The soft handoff subsystem includes a synchronizing circuit to facilitate at least time synchronization of the dedicated soft handoff channels with the second group of spread spectrum coded traffic channels.
The soft handoff subsystem includes a controller which sends and receives information through a controller at the source base station to communicate synchronization data such as pilot channel arrival time data from a pilot channel receiver that receives pilot channel information from the conventional base station system.
The conventional base station system generates the second group of spread spectrum traffic channels over a collocated antenna system and the second group of spread spectrum channels are orthogonally related to the first group of dedicated soft handoff channels so that the dedicated soft handoff channels are not completely different from the conventional traffic channels of the second group.
For example, the dedicated soft handoff channels could be a subset of the traffic channels normally assigned to a base station