Patent ID: 6975608

Claim:
A method for performing a handoff from an asynchronous base station to a synchronous base station, comprising the steps of: a) receiving, at a mobile station from the asynchronous base station, a neighbor list that identifies one or more synchronous base stations neighboring the asynchronous base station; b) setting a common channel between a first synchronous base station and the mobile station; c) determining whether there is an asynchronous base station to be handed off in neighbor asynchronous base stations based on monitoring information of the neighbor asynchronous base stations; d) if there is no asynchronous base station, requesting a handoff to one of the synchronous base stations neighboring the asynchronous base station and receiving, from the first synchronous base station through the common channel, a compressed mode message that includes, for each synchronous base station neighboring the asynchronous base station, (i) pseudo noise (PN) sequence zero offset timing information based on a common code and a zero offset, (ii) long code state information, and (iii) synchronous channel super frame timing information; e) after receiving the PN sequence zero offset timing information for each synchronous base station neighboring the asynchronous base station, selecting, from among the one or more synchronous base stations identified by the neighbor list, a synchronous base station to be handed off based on that base station having a pilot signal with a maximum value; f) obtaining a long code state and a synchronous channel super frame timing from the long code state information and the synchronous channel super frame timing information for the synchronous base station selected; and g) performing the handoff from the asynchronous base station to the synchronous base station selected, wherein obtaining the long code state and the synchronous channel super frame timing involves: (i) obtaining a synchronization of the common channel, (ii) storing one period of the compressed message transmitted through the common channel, and (iii) selecting the maximum value among long code states and synchronous channel super frame timings obtained from the compressed message transmitted through the common channel at every period.