A method of performing a cell reselection procedure in a wireless communication system which includes a user equipment and a plurality of cells, the method comprising: the user equipment camping on a first cell among the plurality of cells; the user equipment receiving system information containing a plurality of parameters and a plurality of threshold values from the first cell when camping on the first cell; the user equipment acquiring a first cell selection quality value, Squal, associated with the first cell, a second Squal associated with the second cell, and a third Squal associated with the third cell according to the plurality of parameters which include a measured cell quality value, a minimum required quality level in a cell, and an offset taken into account in a Squal evaluation as a result of a periodic search for a higher priority public land mobile network identity; the user equipment evaluating if the plurality of cells includes a second cell which satisfies a first cell reselection criterion when camping on the first cell if it is determined that the first cell is allowed to be selected in the cell reselection procedure or in a cell selection procedure; the method characterized by: the user equipment evaluating if the plurality of cells includes a third cell which satisfies a second cell reselection criterion when camping on the first cell if it is determined that the first cell is forbidden to be selected in the cell reselection procedure or in the cell selection procedure; the user equipment determining that the second cell satisfies the first cell reselection criterion when the first Squal remains smaller than a first threshold value and the second Squal remains larger than a second threshold value longer than a predetermined period of time; the user equipment determining that the third cell satisfies the second cell reselection criterion when the first Squal remains smaller than a third threshold value and the third Squal remains larger than the second threshold value longer than the predetermined period of time, wherein the third threshold value is larger than the first threshold value. the user equipment camping on a first cell among the plurality of cells; the user equipment receiving system information containing a plurality of parameters and a plurality of threshold values from the first cell when camping on the first cell; the user equipment acquiring a first cell selection quality value, Squal, associated with the first cell, a second Squal associated with the second cell, and a third Squal associated with the third cell according to the plurality of parameters which include a measured cell quality value, a minimum required quality level in a cell, and an offset taken into account in a Squal evaluation as a result of a periodic search for a higher priority public land mobile network identity; the user equipment evaluating if the plurality of cells includes a second cell which satisfies a first cell reselection criterion when camping on the first cell if it is determined that the first cell is allowed to be selected in the cell reselection procedure or in a cell selection procedure; the method characterized by: the user equipment evaluating if the plurality of cells includes a third cell which satisfies a second cell reselection criterion when camping on the first cell if it is determined that the first cell is forbidden to be selected in the cell reselection procedure or in the cell selection procedure; the user equipment determining that the second cell satisfies the first cell reselection criterion when the first Squal remains smaller than a first threshold value and the second Squal remains larger than a second threshold value longer than a predetermined period of time; the user equipment determining that the third cell satisfies the second cell reselection criterion when the first Squal remains smaller than a third threshold value and the third Squal remains larger than the second threshold value longer than the predetermined period of time, wherein the third threshold value is larger than the first threshold value. the user equipment evaluating if the plurality of cells includes a third cell which satisfies a second cell reselection criterion when camping on the first cell if it is determined that the first cell is forbidden to be selected in the cell reselection procedure or in the cell selection procedure; the user equipment determining that the second cell satisfies the first cell reselection criterion when the first Squal remains smaller than a first threshold value and the second Squal remains larger than a second threshold value longer than a predetermined period of time; the user equipment determining that the third cell satisfies the second cell reselection criterion when the first Squal remains smaller than a third threshold value and the third Squal remains larger than the second threshold value longer than the predetermined period of time, wherein the third threshold value is larger than the first threshold value.