DIGITAL PLMN ACCESS SIGNALLING REFERENCE CONFIGURATION
1 General
This Recommendation provides the access signalling reference configuration for the digital
PLMN.
2 Definitions
2.1 reference configurations
Reference configurations are conceptual configurations useful in identifying various possible
physical access arrangements to the PLMN. Two concepts are useful in defining
reference configurations: reference points and functional groups.
2.2 functional groups
Functional groups are sets of functions which may be needed in PLMN access arrangements. In a
particular access arrangement, a specific function in a functional group may or may
not be present. Note that a specific function in a functional group may be performed in
one or more pieces of equipment.
2.3 reference points
Reference points are the conceptual points dividing functional groups. In a specific access
arrangement a reference point may correspond to a physical interface (e.g., Um)
between pieces of equipment or there may not be any physical interface corresponding to the
reference point.
3 Signalling reference configurations
3.1 The reference configurations for the PLMN access define reference points and types of functions
that can be provided. Figure 1/Q.1062 shows some of the signalling reference
configurations.
3.2 The Sm signalling reference point is the demarcation between RF transmission management and the
combined functions of call control and mobility management. Similarly, the Xm
signalling reference point is the demarcation between call control and mobility management.
The mobile station - base station Recommendations apply to interfaces at reference point Um.
These Recommendations are dependent on the pertaining RF transmission capabilities
and will not be dealt with in this document.
At the reference point S, ISDN installations in accordance with I-Series Recommendations may be
used. At reference point R, physical interfaces in accordance with other CCITT
Recommendations (e.g. the X-Series interface Recommendations) may by used.
FIGURE 1/Q.1062
Signalling reference configurations
3.3 The list of functions for each functional group is given below.
3.3.1 The RF transmission management block may perform functions similar to those of NT1, or combined
NT1 and NT2 of the CCITT I-Series Recommendations.
It may include functions for:
- radio transmission termination(s); and
- upper layer protocol capabilities for radio transmission channel management.
3.3.2 The mobility management block may perform functions associated with:
- location updating/registration;
- handover coordination; and
- upper layer protocol capabilities for coordination functions between terminal equipment and
RF transmission management.
3.3.3 A TEm may perform functions similar to those of the TE of the I-Series Recommendations. It may
include functions for:
- Layer 1 (physical) interface;
- Layer 2 (data link) protocol handling;
- Layer 3 protocol handling, and call control;
- maintenance functions; and
- switching and concentration (if applicable).
3.3.4 The PLMN call control adaptation block includes signalling related functions belonging to
Layer 1 and higher layers of the Recommendation X.200 reference model that allows a
TE1 or TE2 terminal to be served by the digital PLMN. It may also include rate
adaptation and flow control.
4 Physical realization of reference configurations
4.1 Mobile station implementations may require that the S, R, Xm and Sm reference points be combined into a single physical entity, as in the case of a fully integrated mobile
equipment.
Figure 2/Q.1062 shows possible realizations and/or configurations of the reference points
mentioned earlier. The examples shown are not exhaustive, but only serve to
illustrate possible configurations of the respective functional blocks.
FIGURE 2/Q.1062
Examples of physical realizations
4.2 Example a) of Figure 2/Q.1062 illustrates a fully integrated equipment where the Xm and Sm
reference points are logically identifiable, but physically do not exist.
4.3 Example b) of Figure 2/Q.1062 illustrates the S reference point with respect to a CCITT TE1. In
this example the PLMN call control adaptation function is integrated with the
remaining blocks as in a). As before the Xm and Sm reference points only bear logical
significance.
4.4 Example c) of Figure 2/Q.1062 illustrates the same configuration as in b), but now a CCITT TE2
is provided at reference point R. The PLMN call control adaptation procedures are
distinct with respect to the one identified in b), but nonetheless the functionality is
