Patent ID: 8948125
Filing Date: 2015-02-03
Classification: H04W

Abstract:
1. A method for handover of a User Equipment (UE) from a source packet system to a target packet system in a packet switched domain of a wireless communications network while transferring the UE from the packet switched domain to a circuit switched domain, wherein the source packet system includes a Mobility Management Entity (MME), the target packet system includes a target Serving GPRS Support Node (target SGSN) and a target base station system (target BSS), and the circuit switched domain includes a Mobile Switching Center (MSC), the method comprising the steps of: the target SGSN receiving from the MME in the source packet system, a Forward Relocation Request message requesting handover from the source packet system to the target packet system, wherein the Forward Relocation Request message includes an International Mobile Subscriber Identity (IMSI) of the UE and a target cell identifier including a Location Area Identity (LAI); the target SGSN performing a Location Update on behalf of the UE during a handover preparation phase by sending a Location Update request to the MSC on a Gs interface, the Location Update request including the IMSI of the UE and the LAI of the target cell identifier, wherein the MSC updates the UE location in a Home Location Register/Home Subscriber Server (HLR/HSS) and retrieves subscriber information from the HLR/HSS; the target SGSN sending a packet-switched Handover Request to the target BSS; the target SGSN sending to the UE via the MME, an indication that the Location Update has already been performed for the LAI of the target cell identifier; completing the handover from the source packet system to the target packet system after the Location Update has been performed; and performing only a Routing Area Update after completion of the handover.