The NSSF stands for Network Slice Selection Function. It is a network function in the 5G core network that is responsible for selecting the appropriate network slice for the users and devices accessing the 5G network. A network slice is a logical partition of the network resources and capabilities that can provide customized services and features for different use cases and scenarios, such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC).
Some of the main functions and features of the NSSF are:
• It supports the network slice discovery, which is a mechanism to provide the users and devices with the information about the available network slices and their characteristics, such as service type, coverage area, and quality of service (QoS).
• It supports the network slice selection, which is a mechanism to select the optimal network slice for the users and devices, based on various criteria, such as subscription, location, policy, and preference.
• It supports the network slice authorization, which is a mechanism to verify the eligibility and access rights of the users and devices for the selected network slice, based on the agreements and rules of the network operators and service providers.
The NSSF is a key component of the 5G core network that enables the implementation and management of network slicing, which is a new feature in 5G that can enhance the performance and efficiency of the network communication and services. It is part of the service-based architecture (SBA) of the 5G core network, and uses the Nnssf interface to communicate with other network functions, such as the AMF, the UDM, and the PCF.