23.1083GPPMobile radio interface layer 3 specification, core network protocolsRelease 17Stage 2TS
The present document specifies the procedures used at the radio interface (Reference Point Um, see 3GPP TS 24.002 ) for Call Control (CC), Mobility Management (MM), and Session Management (SM).
When the notations for "further study" or "FS" or "FFS" are present in the present document they mean that the indicated text is not a normative portion of this standard.
These procedures are defined in terms of messages exchanged over the control channels of the radio interface. The control channels are described in 3GPP TS 44.003 .
The structured functions and procedures of this protocol and the relationship with other layers and entities are described in general terms in 3GPP TS 24.007 .
1.1 Scope of the Technical Specification
The procedures currently described in the present document are for the call control of circuit-switched connections, session management for GPRS services, mobility management and radio resource management for circuit-switched and GPRS services.
3GPP TS 24.010  contains functional procedures for support of supplementary services.
3GPP TS 24.011  contains functional procedures for support of point-to-point short message services.
3GPP TS 24.012  contains functional description of short message – cell broadcast.
3GPP TS 44.060  contains procedures for radio link control and medium access control (RLC/MAC) of packet data physical channels.
3GPP TS 44.018  contains the procedures for the RR protocol.
3GPP TS 24.008  contains the procedures for the CN protocols.
3GPP TS 44.071 [23a] contains functional descriptions and procedures for support of location services.
NOTE: "layer 3" includes the functions and protocols described in this Technical Specification. The terms "data link layer" and "layer 2" are used interchangeably to refer to the layer immediately below layer 3.
1.2 Application to the interface structures
The layer 3 procedures apply to the interface structures defined in 3GPP TS 44.003 . They use the functions and services provided by layer 2 defined in 3GPP TS 44.005  and 3GPP TS 44.006 . 3GPP TS 24.007  gives the general description of layer 3 including procedures, messages format and error handling.
1.3 Structure of layer 3 procedures
A building block method is used to describe the layer 3 procedures.
The basic building blocks are "elementary procedures" provided by the protocol control entities of the three sublayers, i.e. radio resource management, mobility management and connection management sublayer.
Complete layer 3 transactions consist of specific sequences of elementary procedures. The term "structured procedure" is used for these sequences.
1.4 Test procedures
Test procedures of the GSM radio interface signalling are described in 3GPP TS 51.010  and 3GPP TS 51.02x series.
1.5 Use of logical channels
The logical control channels are defined in 3GPP TS 45.002 . In the following those control channels are considered which carry signalling information or specific types of user packet information:
i) Broadcast Control CHannel (BCCH): downlink only, used to broadcast Cell specific information;
ii) Synchronization CHannel (SCH): downlink only, used to broadcast synchronization and BSS identification information;
iii) Paging CHannel (PCH): downlink only, used to send page requests to Mobile Stations (MSs);
iv) Random Access CHannel (RACH): uplink only, used to request a Dedicated Control CHannel;
v) Access Grant CHannel (AGCH): downlink only, used to allocate a Dedicated Control CHannel;
vi) Standalone Dedicated Control CHannel (SDCCH): bi-directional;
vii) Fast Associated Control CHannel (FACCH): bi-directional, associated with a Traffic CHannel;
viii)Slow Associated Control CHannel (SACCH): bi-directional, associated with a SDCCH or a Traffic CHannel;
ix) Cell Broadcast CHannel (CBCH): downlink only used for general (not point to point) short message information.
x) Notification CHannel (NCH): downlink only, used to notify mobile stations of VBS (Voice Broadcast Service) calls or VGCS (Voice Group Call Service) calls.
Two service access points are defined on signalling layer 2 which are discriminated by their Service Access Point Identifiers (SAPI) (see 3GPP TS 44.006 ):
i) SAPI 0: supports the transfer of signalling information including user-user information;
ii) SAPI 3: supports the transfer of user short messages.
Layer 3 selects the service access point, the logical control channel and the mode of operation of layer 2 (acknowledged, unacknowledged or random access, see 3GPP TS 44.005  and 3GPP TS 44.006 ) as required for each individual message.
1.6 Overview of control procedures
1.6.1 List of procedures
The following procedures are specified in the Technical Specification:
a) Clause 4 specifies elementary procedures for Mobility Management:
– mobility management common procedures (subclause 4.3);
– TMSI reallocation procedure (subclause 4.3.1);
– authentication procedure (subclause 4.3.2);
– identification procedure (subclause 4.3.3);
– IMSI detach procedure (subclause 4.3.4);
– abort procedure (subclause 4.3.5);
– MM information procedure (subclause 4.3.6);
– mobility management specific procedures (subclause 4.4);
– location updating procedure (subclause 4.4.1);
– periodic updating (subclause 4.4.2);
– IMSI attach procedure (subclause 4.4.3);
– generic location updating procedure (subclause 4.4);
– connection management sublayer service provision;
– mobility management connection establishment (subclause 4.5.1);
– mobility management connection information transfer phase (subclause 4.5.2);
– mobility management connection release (subclause 4.5.3);
– GPRS specific mobility management procedures (subclause 4.7);
– GPRS attach procedure (subclause 4.7.3);
– GPRS detach procedure (subclause 4.7.4);
– GPRS routing area updating procedure (subclause 4.7.5);
– GPRS common mobility management procedures (subclause 4.7);
– GPRS P-TMSI reallocation procedure (subclause 4.7.6);
– GPRS authentication and ciphering procedure (subclause 4.7.7);
– GPRS identification procedure (subclause 4.7.8);
– GPRS information procedure (subclause 4.7.12);
b) Clause 5 specifies elementary procedures for circuit switched Call Control comprising the following elementary procedures:
– mobile originating call establishment (subclause 5.2.1);
– mobile terminating call establishment (subclause 5.2.2);
– signalling procedures during the active state (subclause 5.3);
– user notification procedure (subclause 5.3.1);
– call rearrangements (subclause 5.3.2);
– DTMF protocol control procedure (subclause 5.5.7);
– in-call modification (subclause 5.3.4);
– call clearing initiated by the mobile station (subclause 5.4.3);
– call clearing initiated by the network (subclause 5.4.4);
– miscellaneous procedures;
– in-band tones and announcements (subclause 5.5.1);
– status enquiry procedure (subclause 5.5.3);
– call re-establishment procedure (subclause 5.5.4);
d) Clause 6 specifies elementary procedures for session management:
– GPRS session management procedures (subclause 6.1);
– PDP context activation (subclause 6.1.1);
– PDP context modification (subclause 6.1.2);
– PDP context deactivation (subclause 6.1.3);
– anonymous PDP context activation (subclause 6.1.4);
– anonymous PDP context deactivation (subclause 6.1.5).
The elementary procedures can be combined to form structured procedures. Examples of such structured procedures are given in clause 7. This part of the Technical Specification is only provided for guidance to assist implementations.
Clause 8 specifies actions to be taken on various error conditions and also provides rules to ensure compatibility with future enhancements of the protocol.
1.7 Applicability of implementations
The applicability of procedures of this technical specification for the mobile station is dependent on the services and functions which are to be supported by a mobile station.
1.7.1 Voice Group Call Service (VGCS) and Voice Broadcast Service (VBS)
For mobile stations supporting the Voice Group Call Service or the Voice Broadcast Service, it is explicitly mentioned throughout this technical specification if a certain procedure is applicable only for such a service and, if necessary, how mobile stations not supporting such a service shall behave.
For VGCS and VBS, the following possible mobile station implementations exist:
– support of listening to voice broadcast calls (VBS listening);
– support of originating a voice broadcast call (VBS originating);
– support of listening to voice group calls (VGCS listening);
– support of talking in voice group calls (VGCS talking. This always includes the implementation for VGCS listening);
– support of originating a voice group call (VGCS originating. This always includes the implementation for VGCS talking).
Apart from the explicitly mentioned combinations, all possible combinations are optional and supported by this technical specification.
The related terms are used in this technical specification, if information on these implementation options is required.
1.7.2 General Packet Radio Service (GPRS)
For mobile stations supporting the General Packet Radio Service (GPRS), it is explicitly mentioned throughout the technical specification if a certain procedure is applicable only for such a service and, if necessary, how mobile stations not supporting such a service shall behave.
A GPRS MS may operate in one of the following MS operation modes, see 3GPP TS 23.060 :
– MS operation mode A;
– MS operation mode B; or
– MS operation mode C.
The MS operation mode depends on the services that the MS is attached to, i.e., only GPRS or both GPRS and non-GPRS services, and upon the MS’s capabilities to operate GPRS and other GSM services simultaneously. Mobile stations that are capable to operate GPRS services are referred to as GPRS MSs.
NOTE: Other GSM technical specifications may refer to the MS operation modes A, B, and C as GPRS class‑A MS, GPRS class‑B MS, and GPRS class‑C MS.
It should be noted that it is possible that for a GPRS MS, the GMM procedures currently described in the ETS do not support combinations of VGCS, VBS and GPRS. The possible interactions are not studied yet.