3 A-Interface characteristics

08.013GPPGeneral Aspects on the BSS-MSC InterfaceRelease 1999TS

The interface is defined to be at the boundary of the MSC.

The MSC to BSS interface is specified by a set of characteristics, including:

i) Physical and electromagnetic parameters;

ii) Channel structures;

iii) Network operating procedures;

iv) Operation and Maintenance information support.

The definition of the MSC to BSS interface follows a layered approach similar to that in the ISDN. Layer 3 is for the most part based on Technical Specification 3GPP TS 04.08 with additional procedures added for the control of radio resources and the identification of transactions using the SCCP. Layer 2 is based on the signalling system No.7 (SS No.7) Message Transfer Part (MTP). Layer 1 is either digital (at 2 048 kbit/s, based on CCITT Rec. G703 clause 6) or analogue with the data being passed by the use of modems (this latter case is a national option).