RAN server, wireless communications system, and terminal attach method

A wireless communications system, comprising at least one radio access network (RAN) server, a fifth generation mobile communications technology (5G) core network, and base stations of a plurality of wireless communications standards, wherein

• the RAN server is connected to the 5G core network by using an interface, the RAN server is configured to manage the base stations of the plurality of wireless communications standards, and the RAN server comprises a receiver and a transmitter:
• the receiver is configured to receive an attach request message that is from a terminal apparatus and forwarded by a first base station, wherein the first base station is one of the base stations of the plurality of wireless communications standards;
• the transmitter is configured to send the attach request message to the 5G core network by using the interface;
• the receiver is further configured to receive, by using the interface, an attach accept message returned by the 5G core network in response to the attach request message;
• and
• the transmitter is further configured to send the attach accept message to the terminal apparatus by using a second base station, wherein the second base station is one of the base stations of the plurality of wireless communications standards;
• the base stations of the plurality of wireless communications standards are configured to forward an attach request message from a terminal apparatus to the RAN server;
• and
• the 5G core network is configured to return, when receiving the attach request message sent by the RAN server, an attach accept message to the RAN server.

A terminal apparatus attach method, comprising:

• receiving, by a radio access network (RAN) server, an attach request message that is from a terminal apparatus and forwarded by a first base station, wherein the RAN server is connected to a fifth generation mobile communications technology (5G) core network by using an interface, the RAN server is configured to manage base stations of a plurality of wireless communications standards, and the first base station is one of the base stations of the plurality of wireless communications standards;
• sending, by the RAN server, the attach request message to the 5G core network by using the interface;
• receiving, by the RAN server by using the interface, an attach accept message returned by the 5G core network in response to the attach request message;
• and
• sending, by the RAN server, the attach accept message to the terminal apparatus by using a second base station, wherein the second base station is one of the base stations of the plurality of wireless communications standards.