(1) A terminal device, also referred to as a terminal or user equipment, is a device that provides a user with voice and/or data connectivity, for example, a handheld device or a vehicle-mounted device having a wireless connection function. Common terminal devices include, for example, a mobile phone, a tablet, a notebook computer, a palmtop computer, a mobile internet device (MID), and a wearable device. The wearable device includes, for example, a smartwatch, a smart band, or a pedometer.

(2) A network device, also referred to as a radio access network (RAN) device, is a device that enables a terminal device to access a wireless network, and includes network devices in various communication standards, for example, includes but is not limited to a base station, an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NB), a network device controller (BSC), a network device transceiver station (BTS), a home network device (for example, Home evolved NodeB, or Home NodeB, HNB), and a baseband unit (BBU).

The network device includes network devices of various frequency standards, for example, including but not limited to a low-frequency network device and a high-frequency network device.

(3) A core network device is a device that is responsible for mobility management of a terminal, and includes core network devices in various communication standards, for example, including but not limited to a mobility management entity (MME) in a 4G network and an access management function (AMF) entity in a 5G network. The core network device may be a physical entity, a logical functional entity, or a chip disposed in a physical entity.