Methods and arrangements (600) in a network node (110), for scrambling a timing advance value, to be received by a mobile station (120). The method comprises receiving (501) a signal from the mobile station (120), estimating (504) the timing advance value for the mobile station (120), determining (505) an offset value to be added to the estimated timing advance value, computing (506) a scrambled timing advance value by adding the determined offset value to the estimated timing advance value, and transmitting (507) the scrambled timing advance value, to be received by the mobile station (120). Also, methods and arrangements (800) in a mobile station (120), and methods and arrangements (1000) in a database (140) are disclosed.