1 Introduction

The Network Exposure Function (NEF) is a functional element that supports the following functionalities:

• Securely exposes network capabilities and events provided by 3GPP Network Functions to AF.
• Provides a means for the AF to securely provide information to 3GPP network and may authenticate, authorize, and assist in throttling the AF.
• Translates the information received from the AF to the one sent to internal 3GPP NFs, and vice versa.
• Supports to expose information (collected from other 3GPP NFs) to the AF.
• Supports a PFD function that allows the AF to provision PFD(s) and may store and retrieve PFD(s) in the UDR. The NEF further provisions PFD(s) to the SMF.

A specific NEF instance may support one or more of the functionalities described above and consequently an individual NEF may support a subset of the APIs specified for capability exposure.