1. A tracking area assignment method, by an access and mobility management function (AMF) in a wireless communication system, the method comprising:receiving, from a session management function (SMF), session and service continuity (SSC) mode indication information for a protocol data unit (PDU) session generated for a user equipment (UE);
obtaining serving area information for a serving area of a serving user plane function (UPF) associated with the PDU session;
determining an assignment of a new tracking area to the UE is necessary based on a tracking area pre-assigned to the UE and the serving area; and
performing tracking area update for the assignment of the new tracking area to the UE if it is determined that the assignment of the new tracking area is necessary.