08.083GPPMobile-services Switching Centre - Base Station system (MSC-BSS) Interface Layer 3 SpecificationRelease 1999TS
This sub-clause contains definition of terms:
Base Station System. This is the equipment which is accessed through the interface defined in the 08‑series of Technical Specifications. It contains the functionality described in 3GPP TS 08.02, and supports one or more cells. See 3GPP TS 01.04.
The Base Station System Application Part, this is the subsystem that contains the process dealing with radio resource control and management known as the Base Station System Management Application Part (BSSMAP) and transparent transfer of call control and mobility management information known as the Direct Transfer Application Part (DTAP). The BSSAPs at the BSS and the MSC are connected by means of SCCP connections.
The DTAP, Direct Transfer Application Part is a process which allows the direct transfer of messages between individual MSs and the MSC with no interpretation of layer 3 information at the BSS.
Base Station System Management Application Part. This is the process within the BSS that controls radio resources in response to instructions from the MSC.
An internal handover is a handover which takes place between channels on a cell or cells controlled by a single BSS. This handover operates without reference to the MSC (although the MSC will be informed on completion). Handovers of this type in one cell are called internal intra cell handovers and between cells are called internal inter cell handovers.
Handovers between channels on the same cell or between cells on the same BSS which are controlled by the MSC are external handovers and use identical procedures to those for inter-BSS handovers.
An intersystem handover is a handover which takes place between different radio access systems (e.g. GSM BSS and UTRAN or GSM BSS and cdma2000 RAN)..
Directed Retry is the process of assigning a Mobile Station to a TCH in a cell other than the serving cell, e.g. in situations of congestion. It is triggered by the assignment procedure and employs internal or external handover procedures.
VGCS/VBS call controlling SCCP connection: The VGCS/VBS call controlling SCCP connection is an SCCP connection which supports the signalling for call SETUP of a VGCS/VBS call. One of these connections is needed to support each instance of a VGCS/VBS call within a BSS.
VGCS/VBS resource controlling SCCP connection: The VGCS/VBS resource controlling SCCP connection is an SCCP connection which supports the allocation of resources for a VGCS/VBS call. One or more of these connections is needed to support each instance of a VGCS/VBS call. The eact number of these SCCP connections is equal to the number of cells to which the VGCS/VBS call is to be supported.