| 摘要 |
The renew characters (R1/R2 or, respectively, R1'/R2') that are entered into a transmission frame by the subscriber equipment (MS) or by the network equipment (IWF) upon setup or resetting of the information protection connection indicate a frame number of a frame that has not yet been sent or, respectively, of a frame that is guaranteed to have been received. The first numbered transmission frame (NFR) to be sent in the information transmission phase after the setup or resetting receives the frame number. As a result of the renew character, the same static starting value is not always employed for the numbering of the frames to be sent after the setup or resetting of the information protection connection. It can thus be reliably recognized whether the frame was sent before or after the setup or, respectively, resetting of the information protection connection. Despite different delays on the transmission paths that, for example, can effect a mutual overtaking of individual frames, the renew characters guarantee that an undetected information loss or, respectively, an undetected information generation does not occur at the receiver of the numbered frames. The receiver can reliably recognize the validity of the frames.
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