Patent ID: 7974263

Claim:
A method for calculating a current time in a mobile communication system, comprising the steps of: receiving time information transmitted from a base station; obtaining date information and parameters for calculation of time on the basis of the received time information; calculating a lapse time length from a reference time on the basis of the parameters; calculating a current time using the calculated lapse time length and the date information, wherein the time information contains T 1 , T 2 and T 3 for indicating a frame number at a reference time, a parameter that is a frame count value of a complete hyperframe structure after the reference time, and date information including year, month and day, wherein the step of calculating the lapse time length on the basis of the parameters comprises: calculating a first time length from the reference time to a start of a complete hyperframe structure on the basis of a frame number from which the reference time starts; calculating a second time length from the start to the end of the complete hyperframe structure; calculating the lapse time length from a end of the complete hyperframe structure to the current time; and adding the first time length, the second time length and the lapse time length, and wherein the step of calculating the first time length comprises: calculating the frame number from which the reference time starts, using the values of T 1 , T 2 and T 3 among the parameters and the following equation Frame Number (FN)=51×(( T 3 −T 2)mod 26)+ T 3+51×26 ×T 1, where if (T 3 −T 2 )<0, (26−(T 3 −T 2 )) is used instead of (T 3 −T 2 ); and subtracting the start frame number from a maximum value of the frame number to obtain the number of frames and multiplying the obtained number by the time length of one frame.