proximity service (D2D) (ProSe)
Proximity Services (ProSe) are short-range services realized by means of D2D communication between mobile devices. For this purpose, the mobile devices must support the direct connection, which is comparable to the function of walkie-talkies.
The radio interface implemented for this purpose is called Sidelink.
The mobile devices with ProSe function have a search function for finding connection requests. For this purpose, a mobile device sends a special request code to the network operator, whichchecks the traffic load and other network functions, and sends a ProSe Application Code( PAC) to the requesting device, whereupon the latter sends the PAC code at regular intervals.