Session and mobility management method using NAS protocols

A method performed by an access and mobility management function (AMF) in a communication system, the method comprising:

• receiving, from a terminal, a service request message including uplink status information over one access among a 3rd generation partnership project (3GPP) access and a non-3GPP access which are associated with a multi-access (MA) protocol data unit (PDU) session, the uplink status information indicating the MA PDU session associated with the one access having pending uplink data;
• and
• transmitting, to the terminal, a service accept message including information on a reactivation result of a user plane resource of the MA PDU session for the one access, based on the uplink status information,
• wherein, in case that the information on the reactivation result indicates a failure for reactivation of the user plane resource, the service accept message further includes information on an error cause of the failure, and
• wherein the error cause indicates insufficient resources for a specific slice.

A terminal in a communication system, the terminal comprising:

• a transceiver;
• and
• a controller coupled with the transceiver and configured to:
• establish a multi-access (MA) protocol data unit (PDU) session associated with a 3rd generation partnership project (3GPP) access and non-3GPP access,
• determine to reactivate a user plane resource of the MA PDU session for one access among the 3GPP access and the non-3GPP access,
• transmit, to an access and mobility management function (AMF), a service request message over the one access, the service request message including uplink status information, and the uplink status information indicating the MA PDU session associated with the one access having pending uplink data, and
• receive, from the AMF, a service accept message including information on a reactivation result for the user plane resource of the MA PDU session,
• wherein in case that the information on the reactivation result indicates a failure for reactivation of the user plane resource, the service accept message further includes information on an error cause of the failure, and
• wherein the error cause indicates insufficient resources for a specific slice.

An access and mobility management function (AMF) in a communication system, the AMF comprising:

• a transceiver;
• and
• a controller coupled with the transceiver and configured to:
• receive, from a terminal, a service request message including uplink status information over one access among a 3rd generation partnership project (3GPP) access and a non-3GPP access which are associated with a multi-access (MA) protocol data unit (PDU) session, the uplink status information indicating the MA PDU session associated with the one access having pending uplink data, and
• transmit, to the terminal, a service accept message including information on a reactivation result of a user plane resource of the MA PDU session for the one access, based on the uplink status information,
• wherein, in case that the information on the reactivation result indicates a failure for reactivation of the user plane resource, the service accept message further includes information on an error cause of the failure, and
• wherein the error cause indicates insufficient resources for a specific slice.