Abstract: A method of performing MT services using an indication to avoid barring in access control is provided. UE sends an indication related to an MT service to the NAS layer when the MT service starts, or when a corresponding communication session of the MT service is handover to 3GPP access. Once the service has successfully been set up, then as long as the service is ongoing, the following access attempts are allowed to proceed without further access control checking in order to avoid barring: MMTEL voice, MMTEL video, and SMSoIP. In one novel aspect, based on the indication provided to the NAS layer when the MT service starts or when handover to 3GPP access occurs, UE skips access control after UE goes to idle mode and establishes an RRC connection to resume the MT service.

Abstract: A method can include receiving a non-access stratum (NAS) message for establishing or modifying a protocol data unit (PDU) session at a user equipment (UE) from a core network, determining whether there is a quality of service (QoS) flow description resulting from the establishment or modification of the PDU session that is associated with a guaranteed bit rate (GBR) QoS flow of the PDU session, and invalid, and when it is determined that there is the invalid QoS flow description associated with the GBR QoS flow of the PDU session, performing an error handling operation.

Abstract: Various examples and schemes pertaining to error handling on missing configuration for inter-system change in mobile communications are described. An apparatus performs a protocol data unit (PDU)-related procedure with a wireless network. The apparatus detects whether there is an error in the PDU-related procedure and the apparatus handles the error in response to detecting the error in the PDU-related procedure.

Abstract: In 5GS, Single-Network Slice Selection Assistance Information (S-NSSAI) based backoff (BO) timers (T3584/T3585) can be applied to either the registered PLMN or all the PLMNs based on a 5GSM congestion re-attempt indicator. For a specific PDU session, the corresponding BO timer applied to the registered PLMN and the BO timer applied to all PLMN can be both running concurrently. It is proposed for a UE to stop both the BO timer applied to all the PLMNs and the BO timer applied to the registered PLMN, if running, in all the following scenarios: 1) Receiving a PDU session release command without a BO timer, 2) Receiving a PDU session release command with 5GSM cause #39, 3) Receiving a PDU session modification command, 4) Receiving a 5GSM message with a 5GSM congestion control BO timer value, and 5) Receiving a PDU session authentication command.

Abstract: A method of handling mapped EPS bearer context with duplicate EPS bearer ID (EBI) for 5GS to EPS inter-system change enhancement is proposed. UE is provided with a mapped EPS bearer context IE by the network to create a new mapped EPS bearer associated with a PDU session. UE detects collision of the new mapped EPS bearer—it has the same EBI as an existing EPS bearer. Upon successfully process the create request, UE either replaces the existing EPS bearer with the new mapped EPS bearer, or deletes the EPS bearer with duplicate EBI by explicit signaling to the network. As a result, when inter-system change from 5G to EPS happens, there is no EPS collision.

Abstract: In a first novel aspect, UE receives a mapped EPS bearer context IE during a PDU session establishment or modification procedure. UE diagnoses whether an operation error occurs for a mapped EPS bearer context. If so, UE deletes the mapped EPS bearer context with a 5GSM cause. In a second novel aspect, UE receives a QoS flow description IE during a PDU session establishment or modification procedure. UE diagnoses whether an operation error occurs for a QoS flow description. If so, UE either rejects the modification command or deletes the QoS flow description with a 5GSM cause. In a third novel aspect, UE receives a QoS flow description IE during an EPS bearer activation or modification procedure. UE diagnoses whether an operation error occurs for a QoS flow description. If so, UE includes an ePCO/PCO IE with a 5GSM cause in an activation or modification accept message.

Abstract: A method of handling QoS error in an evolved packet system (EPS) session management (ESM) procedure to support interworking from EPS to 5G system (5GS) is proposed. A UE receives 5GSM parameters of QoS rule(s) and/or QoS flow description(s) included in a PCO/ePCO IE in an ESM message for performing a QoS operation. During the ESM procedure, only 5G QoS parameters related to the current EPS bearer been activated or modified are allocated and sent to the UE via PCO/ePCO. Otherwise, an operation error may occur for the QoS operation. Accordingly, the operation error is detected by the UE before intersystem change from S1 mode to N1 mode happens and the UE indicates such error to the network with a cause value.

Abstract: A method of handling a Packet Data Network (PDN) connection to support interworking to 5G system (5GS) is proposed. In a first novel aspect, both UE and the network stores mapped 5GSM parameters of a corresponding Protocol Data Unit (PDU) session when inter-system change from S1 (4G, EPS) mode to A/Gb (2G) mode or Iu (3G, UMTS) mode. In a second novel aspect, the PDN connection is enable to support interworking to 5GS, and the UE is allowed to allocate and indicate the PDU session ID by using the bearer resource modification procedure in EPS, or the mapped 5GSM parameters can be provided and modified in 2G/3G system.

Abstract: A method can include receiving a “create new evolved packet system (EPS) bearer” operation code in a mapped EPS bearer contexts information element (IE) in a first protocol data unit (PDU) session modification command message for creating a mapped EPS bearer context at a user equipment (UE) in a wireless communication system, and when there is neither a quality of service (QoS) flow descriptions IE in the first PDU session modification command message indicating a QoS flow description corresponding to an EPS bearer identity (EBI) in the mapped EPS bearer context, nor an existing QoS flow description at the UE corresponding to the EBI included in the mapped EPS bearer context, sending a PDU session modification request message including a mapped EPS bearer contexts IE to delete the mapped EPS bearer context.

Abstract: A method of handling insufficient resources in a user equipment (UE) during a PDU session establishment procedure is proposed. During a PDU session establishment procedure, UE sends a PDU SESSION ESTABLISHMENT REQUEST message to the network. UE then receives a PDU SESSION ESTABLISHMENT ACCEPT message from the network, the ACCEPT message carries various PDU session parameters including authorized QoS rules and QoS flows. If UE decides to reject the addition of the new authorized QoS flow description or the new authorized QoS rule due to lack of resources, UE may initiate a PDU session release procedure with 5G session management (5GSM) cause IE #26 “insufficient resources”. In an alternative embodiment, UE may synchronize with the network by sending a PDU session modification request message to delete certain QoS rules/flow descriptions with 5GSM cause IE #26 “insufficient resources”.

Abstract: A method of handling mapped Evolved Packet System (EPS) bearer context for invalid QoS flow description is proposed. During a PDU session establishment procedure or a PDU session modification procedure, a UE may receive a mapped EPS bearer context IE for creating a new mapped EPS bearer of a PDU session. If there is no corresponding QoS flow description associated to the new mapped EPS bearer, e.g., if there is no corresponding authorized QoS flow description IE in the PDU session establishment accept message or in the PDU session modification command message, then the UE should send another PDU session modification request message to the network to delete the new mapped EPS bearer context.

Abstract: A method of handling QoS flow descriptions with invalid EPS bearer context is proposed. During an EPS bearer activation or modification procedure, a UE may receive an ePCO/PCO IE for creating a new QoS flow description or modifying an existing QoS flow description. if UE detects that the to be created/modified QoS flow descriptions are associated with invalid EPS bearer context, then UE does, not create/modify the QoS flow descriptions. Instead, UE locally deletes the QoS flow descriptions provided by the network. In addition, UE indicates a 5GSM cause to the network via PCO/ePCO. As a result, when inter-system change from EPS to 5GS happens, UE no longer needs to handle the QoS flow descriptions with invalid EPS bearer context.

Abstract: Various examples and schemes pertaining to synchronization of quality of service (QoS) flows and rules in mobile communications are described. An apparatus establishes one or more protocol data unit (PDU) sessions with a wireless network. The apparatus then transmits a message to the wireless network to result in synchronization of status of at least one or more aspects related to QoS rules or QoS flows with respect to the one or more PDU sessions.

Abstract: A method of 5G session management (5GSM) state mapping is proposed when interworking. For each PDU session in 5GSM state of PDU SESSION active, PDU SESSION MODIFICATION PENDING, or PDU SESSION INACTIVE PENDING, UE maps the PDU session to a PDN connection in 4G ESM state BEARER CONTEXT ACTIVE. For any other PDU session in 5GSM state of PDU SESSION inactive, or PDU SESSION ACTIVE PENDING, UE maps the PDU session to a PDN connection in 4G ESM state BEARER CONTEXT INACTIVE.

Abstract: A method for Procedure Transaction Identity (PTI) exception handling on protocol data unit (PDU) session modification and establishment procedure is proposed. If a UE receives a PDU SESSION MODIFICATION COMMAND message in which the PTI value is an assigned value that does not match any PTI in use, the UE stays in the current 5GSM state and sends a 5GSM STATUS message including 5GSM cause #47 “PTI mismatch”, and the network will send another COMMAND message with the correct PTI value. If the UE receives a PDU SESSION ESTABLISHMENT ACCEPT or REJECT message in which the PTI value is an assigned value that does not match any PTI in use, the UE responds with a 5GSM STATUS message including 5GSM cause #47 “PTI mismatch”, and the network will send another ACCEPT or REJECT message with the correct PTI value.

Abstract: A method of QoS rule management with enhanced handling on QoS flow description is proposed. UE checks QoS configuration received from the network for QoS operation errors. When UE receives a QoS rule associated with a specific QFI but has no QoS flow description for the QFI, UE further determines whether the QoS rule is of a GBR QoS flow. If so, UE detects a QoS operation error. If the QoS rule is the default QoS rule, then UE releases the PDU session. If the QoS rule is not the default QoS rule, then UE either rejects a PDU session modification command that carries the QoS rule or deletes the QoS rule carried by a PDU session establishment accept with a 5GSM cause value indicating the QoS operation error.

Abstract: A method of handling a Packet Data Network (PDN) connection to support interworking to 5G system (5GS) is proposed. In a first novel aspect, both UE and the network stores mapped 5GSM parameters of a corresponding Protocol Data Unit (PDU) session when inter-system change from S1 (4G, EPS) mode to A/Gb (2G) mode or Iu (3G, UMTS) mode. In a second novel aspect, the PDN connection is enable to support interworking to 5GS, and the UE is allowed to allocate and indicate the PDU session ID by using the bearer resource modification procedure in EPS, or the mapped 5GSM parameters can be provided and modified in 2G/3G system.

Abstract: A method can include receiving a “create new evolved packet system (EPS) bearer” operation code in a mapped EPS bearer contexts information element (TB) in a first protocol data unit (PDU) session modification command message for creating a mapped EPS bearer context at a user equipment (UE) in a wireless communication system, and when there is neither a quality of service (QoS) flow descriptions IE in the first PDU session modification command message indicating a QoS flow description corresponding to an EPS bearer identity (EBI) in the mapped EPS bearer context, nor an existing QoS flow description at the UE corresponding to the EBI included in the mapped EPS bearer context, sending a PDU session modification request message including a mapped EPS bearer contexts IE to delete the mapped EPS bearer context.

Abstract: A method can include receiving a non-access stratum (NAS) message for establishing or modifying a protocol data unit (PDU) session at a user equipment (UE) from a core network, determining whether there is a quality of service (QoS) flow description resulting from the establishment or modification of the PDU session that is associated with a guaranteed bit rate (GBR) QoS flow of the PDU session, and invalid, and when it is determined that there is the invalid QoS flow description associated with the GBR QoS flow of the PDU session, performing an error handling operation.

Abstract: In a first novel aspect, UE receives a mapped EPS bearer context IE during a PDU session establishment or modification procedure. UE diagnoses whether an operation error occurs for a mapped EPS bearer context. If so, UE deletes the mapped EPS bearer context with a 5GSM cause. In a second novel aspect, UE receives a QoS flow description IE during a PDU session establishment or modification procedure. UE diagnoses whether an operation error occurs for a QoS flow description. If so, UE either rejects the modification command or deletes the QoS flow description with a 5GSM cause. In a third novel aspect, UE receives a QoS flow description IE during an EPS bearer activation or modification procedure. UE diagnoses whether an operation error occurs for a QoS flow description. If so, UE includes an ePCO/PCO IE with a 5GSM cause in an activation or modification accept message.