Method and apparatus for cell reselection of user equipment between lte inter frequency or inter radio access technology in a mobile communication system

In the present invention, a method of selecting/reselecting a cell by user equipment in a mobile communication system is defined. The present invention may be embodied in a 3rd generation partnership program (3GPP) long term evolution (LTE)/LTE-advanced system that is currently discussed by the 3GPP as a mobile communication system. The cell reselection method of a terminal operating in an idle mode includes the steps of: receiving system information that is broadcasted from a cell when performing measurement for cell reselection to a neighbor cell; confirming whether the system information contains a movement condition threshold value; configuring at least one among a cell selection receive level and a cell selection quality level value as comparison criteria for the cell reselection according to the determination result; and performing the cell reselection of the terminal according to the comparison result. [Reference numerals] (301) Start measurement for cell reselection to neighbor LTE frequency (Inter-frequency) or neighbor UTRAN FDD frequency cells; (311) ThreshServingLowQ value provided in SIB 3?; (321) Does a corresponding LTE fequency/UTRAN FDD frequency have a priority higher than a priority of a serving LTE frequency band?; (323) Calculate Srxlev & Squal of a serving cell and Srxlev & Squal of the corresponding neighbor LTE frequency/UTRAN FDD frequency cell based on the measurement result and information on a SIB of a serving LTE cell; (325) During the duration of Treselection, Srxlev of the corresponding LTE frequency/UTRAN FDD cell > ThreshX, HighP & Squal >0?; (327) Time of 1 second has elapsed since the movement to the current serving LTE cell?; (329) Cell reselection to the corresponding LTE frequency/UTRAN FDD cell; (331) Calculate Squal of the serving cell and Srxlev of the corresponding neighbor LTE frequency/UTRAN FEE frequency cell based on the measurement result and information on a SIB of the serving LTE cell; (335) During the duration of Treselection, Srxlev of the corresponding LTE frequency/UTRAN FDD cell > ThreshX, lowP & Srxlev of the serving cell 0?; (347) Time of 1 second has elapsed since the movement to the current serving LTE cell?; (349) Cell reselection to the corresponding LTE frequency/UTRAN FDD cell; (353) During the duration of Treselection, Squal of the corresponding LTE frequency/UTRAN FDD cell > ThreshX, LowQ & Squal of the serving cell < ThreshServing, LowQ?