Patent ID: 9210632
Filing Date: 2015-12-08
Classification: H04W

Abstract:
1. A method for performing a circuit switched fallback (CSFB) procedure by a terminal in a mobile communication system, the method comprising: receiving a first control message including switching information from a first communication system based on a packet switched service to a second communication system based on a circuit switched service, from a base station; switching a serving cell from a first cell of the first communication system to a second cell of the second communication system based on the switching information; receiving first information from the second cell; determining whether second information of the second cell is stored; determining whether the second information has been changed based on a value tag included in the first information if the second information is stored; and transmitting a second control message without reception of the second information to the second cell if the value tag indicates that the second information has not been changed, wherein the second information is previously acquired in the second communication system.