Mobility management for terminals with multiple subscriptions

Abstract

A scheme for providing mobility management for terminals with multiple subscriptions. The invention integrates Europe's Universal Mobile Telecommunications Standard (UMTS) subscriber identity module—specific procedures into single procedures, and which uses a common TMSI. An UMTS subscriber identity module is allocated for each subscription associated with a mobile terminal, wherein each UMTS subscriber identity module being identified by a identification code. A location area update is performed by providing a single location area update request message comprising a list of identification codes for each UMTS subscriber identity module associated with the mobile terminal. Each USIM is authenticated separately, and some USIMs may fail, while others may succeed authentication. The terminal and network each build their own Ordered List of Registered USIM-IDs (OLRU) which records the USIMs that succeeded. The network assigns a Base TMSI, which is similar to the current assignment of TMSIs. Subsequent Location Area Update procedures use the Base TMSI, which is common to all USIMs in the OLRU. Thus it does not have to be repeated for each USIM. Paging Request uses the Base TMSI, along with a USIM Specifier (USIMS) field, which specifies which USIM(s) is being paged. USIMS is kept very compact with bit string coding, which also gives flexibility to page multiple USIMs at the same time. The terminal and network interpret the bit string by using the OLRU. The terminal has to listen to only one paging subchannel. The paging subchannel is determined by calculating the sum modulo N of the last digits of the USIM-IDs in the OLRU. N is the number of possible subchannels. The scheme applies to UMTS as well as GSM/GPRS, if GSM/GPRS is enhanced to support multiple subscriptions per terminal.

Dependencies are inferred from the claim text.