| 摘要 |
The identification of a mobile radio station in a radio transmission system may be based on a subscriber number allocated to the mobile radio station which is, for example, listed in the telephone directory and on an identifier formed according to a secret code rule from the subscriber number. By copying the answerback unit, e.g. a magnetic card on which the subscriber number and identifier are stored, or by eavesdropping on the exchange of information between the mobile radio station and a fixed radio station (radio switching centre) transmitted on the radio transmission channel, a manipulator can imitate an identifier belonging to another subscriber. In order to identify this imitation, additional data which vary during operation of the mobile radio station are combined with the fixed data (subscriber number and identifier of the mobile radio station) and evaluated in the radio switching centre. Varying data of this type may, for example, comprise the number of successful attempts made by the mobile radio station to log onto a radio transmission channel. |
