Cause values for EPS mobility management

The main function of the mobility management sublayer is to support the mobility of a user equipment, such as informing the network of its present location and providing user identity confidentiality.

A further function of the mobility management sublayer is to provide connection management services to the session management (SM) sublayer and the short message services (SMS) entity of the connection management (CM) sublayer.

GTPv2 Cause Codes

The cause code value in the GTPv2 message can indicate what happened between MME, SGW, and PGW so as to simplify the troubleshooting process.

The cause value must be included in the GTPv2 message response. In the message response, the Cause value indicates the acceptance or rejection of the corresponding message request. Cause value indicates an explicit reason for the refusal.

Cause values ​​can also be included in message requests. In the request message, the Cause value indicates the reason for the request.

Cause values for EPS session management

The main function of the ESM sublayer is to support the EPS bearer context handling in the UE and in the MME.

The ESM comprises procedures for:

-     the activation, deactivation and modification of EPS bearer contexts;

-     the request for resources (IP connectivity to a PDN or dedicated bearer resources) by the UE; and

-     the transport of user data via the control plane between the UE and the MME.

Each EPS bearer context represents an EPS bearer between the UE and a PDN. EPS bearer contexts can remain activated even if the radio and S1 bearers constituting the corresponding EPS bearers between UE and MME are temporarily released.

Message types for EPS Session Management

Message types for EPS session management based on 3GPP TS 24.301 V14.0.1 (2016-06)

Source:
3GPP TS 24.301 V14.0.1 (2016-06)
3rd Generation Partnership Project;
Technical Specification Group Core Network and Terminals;
Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS);
Stage 3
(Release 14)

Message types for EPS mobility management

Message types for EPS mobility management based on 3GPP TS 24.301 V14.0.1 (2016-06)

Source:
3GPP TS 24.301 V14.0.1 (2016-06)
3rd Generation Partnership Project;
Technical Specification Group Core Network and Terminals;
Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS);
Stage 3
(Release 14)

S1AP Protocol Cause

The purpose of the Cause IE is to indicate the reason for a particular event for the S1AP protocol.

The meaning of the different cause values is described in the following table. In general, “not supported” cause values indicate that the related capability is missing. On the other hand, “not available” cause values indicate that the related capability is present, but insufficient resources were available to perform the requested action.

S1AP Elementary Procedure

Definition:

S1AP consists of Elementary Procedures (EPs). An Elementary Procedure is a unit of interaction between eNBs and the EPC. These Elementary Procedures are defined separately and are intended to be used to build up complete sequences in a flexible manner. If the independence between some EPs is restricted, it is described under the relevant EP description. Unless otherwise stated by the restrictions, the EPs may be invoked independently of each other as standalone procedures, which can be active in parallel. The usage of several S1AP EPs together or together with EPs from other interfaces is specified in stage 2 specifications (e.g., TS 23.401 [11] and TS 36.300 [14]).