| 摘要 |
PURPOSE:To process function corresponding to each level independently by providing a control structure corresponding the function of signal processing directly to the protocol and the standardized interlevel interface. CONSTITUTION:An ISPN subscriber state control, a D channel signal transmission control and inter-processor line No.7 transmission control section are processed in the level 4. Moreover, in the level 3, LAPD transmission control, D channel data, read/write control, inter-processor signal transmission control and No.7 data read/write control are applied. For example, in sending a signal to the ISDN subscriber terminal, an ISDN subscriber state control section 41 sets required information to the signal and a D channel signal transmission control section 43 edits the information required for the signal. Then a transmission request is given from the LAPD section 31 to the D channel data read/write section 32, which gives the signal information sent by the standardized interface between the levels 3 and 2 to a signal link control section 21.
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