5 Framework for the description of connection types

3GPP43.010GSM Public Land Mobile Network (PLMN) connection typesRelease 16TS

5.1 Introduction

A PLMN provides a set of network capabilities, which enable telecommunication services to be offered to a user.

A PLMN connection is a connection established between PLMN reference points. A PLMN connection type is a way of referring to and describing PLMN connection. Thus a PLMN connection is a physical or a logical realization of a PLMN connection type. Each PLMN connection can be characterized as belonging to a PLMN connection type.

Figure 1 illustrates the concepts (see also figure 1 of 3GPP TS 22.001).

┌────┐ ┌────────┐ ┌───────────────┐ ┌───────────┐ ┌────┐

│ TE ├──┼───┼─ ─ ─ ─ ┼┼┼─ ─ ─ ─ ─ ─ ─ ─┼─┼─ ─ ─ ─ ─ ─┼─┼─┤ TE │

└────┘ · │ PLMN│·│Transit network│ │Terminating│ · └────┘

access │ │││ │ │ Network │ │

point └────────┘·└───────────────┘ └───────────┘ ·

│ PLMN │ │

· connection · ·

│<───────────>│ │

· Network connection ·

│<────────────────────────────────────────────>│

Figure 1: Framework for the description of GSM PLMN connections

5.2 Purpose of PLMN connection types

The definition of a set of PLMN connection types provides the necessary input to identify the network capabilities of a PLMN. Other key requirements of a PLMN are contained in other GSM specifications, in particular 3GPP TS 44.001 and 24.002. In addition to describing network capabilities of a PLMN, the identification of connection types facilitates the specification of network-to-network interfaces. It may also assist in the allocation of network performance parameters.

Note 1: The user specifies only the telecommunication service required while the GSM PLMN allocates the resources to set up a connection of the specific type as necessary to support the requested service. It is further noted that, for certain service offerings, additional network functions, e.g. additional lower layer functions and/or higher layer functions, may be required (see figure 2).

Service offering Network capability

┌───────────────────┐ ┌─────────────────────────┐

│ Telecommunication │<──────────────│ Limited set of PLMN │

│ Service │ │ connection types │

└───────────────────┘ ├─────────────────────────┤

│ Additional network │

│ functions where required│

│ to support the service, │

│ e.g., additional lower │

│ layer functions, higher │

│ layer functions. │

└─────────────────────────┘

Figure 2: The role of network capabilities in supporting service offerings

5.3 Functions associated with a PLMN connection

Any GSM PLMN connection involves an association of functions to support telecommunication services as shown in figure 3. Three sets of functions are required.

i) Connection means – including transmission and switching.

ii) Control functions and protocols – including signalling, flow/congestion control and routing functions.

iii) Operations and management functions – including network management and maintenance functions.

┌───────────────────────────────────────┐

────────┤ Connection means for user information ├───────

└────────┬───────────────────┬──────────┘

│ │

┌─────┴─────┐ ┌───────┴────────┐

│ Control │ │ Operations │

│ functions │ │ and management │

│ │ │ functions │

└───────────┘ └────────────────┘

Figure 3: Functional description

5.4 Applications of GSM PLMN connection types

The following situations to which GSM PLMN connection types apply (see figure 4) may arise:

– Between two GSM PLMN user access points (refer to 3GPP TS 22.001 and 24.002): see figure 4a.

– Between a PLMN user access point and a network-to-network interface: see figure 4b.

– Between a PLMN user access point and an interface to a specialized resource within the GSM PLMN: see figure 4c.

– Between a PLMN user access point and an interface to a specialized resource outside the GSM PLMN: see figure 4d.

a)

user access point user access point

┌──────────┐ (Note 1)

├───────────┼─ ─ ─ ─ ─ ┼─────────────┤

╖ │ GSM PLMN │ ╖

│ └──────────┘ │

╖ ╖

│<──────────────────────────────────>│

PLMN connection

b)

user access network-to-network

point ┌──────────┐ interface ┌─────────┐

├──────────┼ ─ ─ ─ ─ ─┼─────────────┤ ├─────┤ Network │

╖ │ PLMN │ ╖ ╖ │ Note 2 │

│ └──────────┘ │ │ └─────────┘

│<─────────────────────────────────>│

PLMN connection

c)

user access ┌─────────────────────────────────────────┐

point │ ┌────────┐ │

├───────────┼─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┼────┤ Note 3 │ │

╖ │ PLMN ╖ └────────┘ │

│ └────────────────────────┼────────────────┘

│<──────────────────────────────────>│

PLMN connection

d)

user access network-to-specialized

point ┌──────────┐ resource interface ┌─────────┐

├─────────┼ ─ ─ ─ ─ ─┼─────────────┤ ├──────┤ Network │

╖ │ PLMN │ ╖ ╖ │ Note 3 │

│ └──────────┘ │ │ └─────────┘

│<────────────────────────────────>│

PLMN connection

NOTE 1: See 3GPP TS 22.001.

NOTE 2: Network means here any fixed network as described in 3GPP TS 22.001.

NOTE 3: The box represents a specialized resource. Its use originates from a service request. Further study is required to give some examples.

Figure 4: Applications of PLMN connection types

5.5 PLMN connection involving several networks

A PLMN connection may comprise a number of tandem network connections. Figure 5 shows an example in which each end network is a PLMN. The intermediate network(s) must offer the appropriate network capabilities for the service provided by the (overall) PLMN connection. In (overall) PLMN connections involving several networks, each network provides a part of the connection and may be categorized by different attribute values.

The IWF/MSC can interwork with different type of networks, e.g.:

– analogue (A);

– digital circuit (D) with V.110/X.31 in band protocol;

Examples of such networks are:

– GSM (D);

– ISDN (A, D, P);

– PSTN (A).

(Overall) PLMN connection

│<──────────────────────────────────────────────────────>│

╖ ╖

│ PLMN Network PLMN │

╖ connection connection connection ╖

│<───────────────>│<───────────────────>│<──────────────>│

╖ ┌──────────┐ ╖ ┌─────────────────┐ ╖ ┌──────────┐ ╖

├────┼ ─ ─ ─ ─ ─┼─┼─┼ ─ ─ ─ ─ ─ ─ ─ ─ ┼─┼─┼─ ─ ─ ─ ─ ┼───┤

access │ PLMN │ ╖ │ Transit Network │ ╖ │ PLMN │access

point └──────────┘ │ └─────────────────┘ │ └──────────┘ point

network-to-network network-to-network

interface interface

Figure 5: Example of a PLMN connection involving several networks