Communication method, access network device, and core network device

A method for handover in a wireless communication system, comprising:

• establishing, by a source access network device, one or more sessions for a terminal device, the one or more sessions corresponding to one or more network slice;
• receiving, by the source access network device, data of the one or more sessions;
• sending, by the source access network device, the received data of the one or more sessions to the terminal device;
• sending, by the source access network device, to a core network device a first handover message for a handover of the one or more sessions from the source access network device to a target access network device, wherein the first handover message comprises information about the target access network device and identifier information of the one or more sessions;
• after receiving the first handover message, sending, by the core network device, a second handover message to the target access network device, wherein the second handover message comprises an session identifier of a session of the one or more sessions;
• sending, by the target access network device, a handover failure message to the core network device, wherein the handover failure message comprises indication information indicating that the target access network device fails to accept the session identified by the session identifier included in the second handover message because a radio resource is unavailable for a network slice corresponding to the session or the target access network device does not support the network slice;
• and
• after receiving the handover failure message, sending, by the core network device, a handover preparation failure message to the source access network device, wherein the handover preparation failure message comprises indication information indicating that the target access network device fails to accept the session because the radio resource is unavailable for the network slice corresponding to the session or the target access network device does not support the network slice.