Method and apparatus for essential slice service processing and recovery of service

A method for seeking service for an essential network slice by a user equipment (UE), comprising:

• identifying a plurality of network slices as essential based on at least one of a capability of or a current functionality of the UE;
• transmitting a request message to a network that includes an information bit that indicates that one or more essential services are requested without identifying the plurality of essential network slices, the request message causing the network to retrieve essential slice information associated with the UE from a separate network element;
• determining that the network does not support the plurality of essential network slices sought by the UE based on a received response message;
• in response to the determining that the network does not support the plurality of essential network slices sought by the UE or that the plurality of essential network slices are pending:
• initiating a search for a second network capable of supporting the plurality of essential network slices;
• tracking a backoff timer during the search;
• and
• in response to the search failing to locate a supporting network that supports all of the plurality of essential network slices, register with a network from among the searched networks that reported a maximum number of the plurality of essential network slices are supported;
• and
• while registered and camped on the registered network, in response to determining that all Protocol Data Unit (PDU) sessions are backed off for an essential slice or that all combinations of Data Network Name/Single Network Slice Selection Assistance Information (DNN/S-NSSAI) are backed off for the essential slice, conducting a subsequent network search for the supporting network that supports all of the plurality of essential network slices.

A method for seeking service for a plurality of essential network slices, the method comprising:

• identifying the plurality of essential network slices based on at least one of a capability of or current functionality of a user equipment (UE);
• transmitting a request message to a network that includes an information bit that indicates that one or more essential services are requested without identifying the plurality of essential network slices, the request message causing the network to retrieve essential slice information associated with the UE from a separate network element;
• receiving a response message from the network indicating whether the plurality of essential network slices are supported by the network;
• in response to the response message indicating that the network does not support the plurality of essential network slices sought by the UE or that the plurality of essential network slices are pending:
• initiating a network search for a supporting network that supports the plurality of essential network slice based on the received response message;
• and
• in response to the network search failing to locate a supporting network that supports all of the plurality of essential network slices, registering with a network from among the searched networks that reported a maximum number of the plurality of essential network slices are supported;
• and
• while registered and camped on the registered network, in response to determining that all Protocol Data Unit (PDU) sessions are backed off for an essential slice or that all combinations of Data Network Name/Single Network Slice Selection Assistance Information (DNN/S-NSSAI) are backed off for the essential slice, conducting a subsequent network search for thes supporting network that supports all of the plurality of essential network slices.