Communication method between core network device and terminal in communication system

A method, comprising:

• receiving, by a terminal device, configuration information from a first access network device, wherein the configuration information comprises paging area information configured for the terminal device in a first mode;
• entering, by the terminal device, the first mode;
• sending, by the terminal device, a first message to a second access network device when the terminal device is in a cell that does not belong to a paging area corresponding to the paging area information, and the cell is managed by the second access network device, wherein the first message comprises a paging area update indication;
• receiving, by the terminal device, a connection establishment indication from the second access network device and establishing, by the terminal device, a connection between the terminal device and the second access network device;
• and
• sending, by the terminal device, a second message to a core network device using the established connection between the terminal device and the second access network device.

A terminal device, comprising:

• one or more processors, a transceiver, and a memory storing program codes;
• wherein the program codes, when executed by the processors, cause the terminal device to:
• receive configuration information from a first access network device, wherein the configuration information comprises paging area information configured for the terminal device in a first mode;
• enter the first mode;
• send a first message to a second access network device when the terminal device is in a cell that does not belong to a paging area corresponding to the paging area information;
• and the cell is managed by the second access network device, wherein the first message comprises a paging area update indication;
• receive a connection establishment indication from the second access network device and establish a connection between the terminal device and the second access network device;
• and
• send a second message to a core network device using the established connection between the terminal device and the second access network device.

An apparatus in a communication device, comprising one or more processing circuits that are configured to:

• obtain configuration information from a first access network device, wherein the configuration information comprises paging area information configured for the communication device in a first mode;
• cause the communication device to enter the first mode;
• cause the communication device to send a first message to a second access network device when the communication device is in a cell that does not belong to a paging area corresponding to the paging area information, and the cell is managed by the second access network device, wherein the first message comprises a paging area update indication;
• obtain a connection establishment indication from the second access network device and cause the communication device to establish a connection between the communication device and the second access network device;
• and
• cause the communication device to send a second message to a core network device using the established connection between the communication device and the second access network device.