Patent ID: 6584311
Filing Date: 2003-06-24
Classification: H04W

Abstract:
In a mobile station utilizing a preferred roaming list (PRL) and a multi-region data structure (MRDS), where the MRDS includes system identification numbers (SIDs) from the PRL, a method comprising:scanning and acquiring a system to provide service in a current geographic region; marking the acquired system as a current serving system, the current serving system having a SID matching an entry in the PRL; detecting that the current serving system matches an entry in the MRDS; updating, in response to the detecting and without modification to the PRL, an alternate scan list (ASL), the ASL defining a current union of all SIDs whose corresponding systems are more preferred than the system currently marked as the current serving system; scanning, after generating the ASL, to detect a newly available SID using the ASL, the newly available SID associated with a system servicing a geographic region which overlaps the current geographic region of the current serving system, the scanning involves periodically scanning for a signal indicative of a wireless service; acquiring the system servicing the overlapping geographic region when the newly acquired SID is more preferred than the SID of the system marked as the current serving system, using the MRDS and the PRL, the acquiring involving at least one of an intersystem hard handoff and an intrasystem hard handoff of the mobile station to a most desirable system; marking the acquired system servicing the overlapping geographic region as the current serving system to redefine the current serving system; and re-updating the ASL using the newly acquired SID.