CIRCUIT SWITCHED FALL BACK IMPROVEMENTS

摘要

An improved circuit switched fallback (CSFB) method is disclosed, in which failures following several abnormal cases not anticipated by the 3GGP specification are avoided. User equipment implementing the improved CSFB method demonstrate increased performance in terms of call success rate and hence provide an improved user experience and an edge over LTE modem competitors. The improved CSFB method can be included in the 3GPP standards for such abnormal case handling and CSFB call recovery.

主权项

1. An improved circuit switched fallback (CSFB) method to be performed in a user equipment operating in a multi-mode network comprising a universal terrestrial radio access network (UTRAN), a global system for mobile communication (GSM) edge radio access network (GERAN), and an evolved universal terrestrial radio access network (E-UTRAN), the improved CSFB method comprising:
determining that a radio resource control (RRC) connection release following an extended service request (ESR) resulting from a circuit switched fallback (CSFB) call provides no redirection information; and forcing redirection of the UE from E-UTRAN to a second radio access technology (RAT) such that the UE camps at the second RAT and is able to successfully complete a circuit-switched operation.