User equipment registration method, proximity service server, and mobility management entity

A proximity service server, comprising:

• a receiving module, configured to receive a proximity service request sent by a user equipment;
• an assigning module, configured to assign a device-to-device(D2D) identifier to the user equipment, wherein the D2D identifier comprises broadcast code and an identifier that is used for D2D communication;
• and
• a sending module, configured to send a proximity service response to the user equipment, wherein the proximity service response carries the D2D identifier assigned by the assigning module.

A proximity service server, comprising a transmitter, a receiver, a memory, and a processor connected to the transmitter, the receiver, and the memory separately, wherein:

• the receiver is configured to receive a proximity service request sent by a user equipment;
• the memory is configured to store a group of program code;
• the processor is configured to invoke the program code stored in the memory, to assign a device-to-device(D2D) identifier to the user equipment, wherein the D2D identifier comprises broadcast code and an identifier that is used for D2D communication;
• and
• the transmitter is configured to send a proximity service response to the user equipment, wherein the proximity service response carries the D2D identifier assigned by the processor to the user equipment.