NG-RAN and 5G-NR

2NG-RAN Network – Protocol Architecture

2.1. The protocol architecture of the radio interface

The NG-RAN radio access network is divided into two strata (Figure 2.1):

1. – the access stratum AS includes air interface and provides functions related the to data link layer and the lower part of OSI layer 3. The access stratum deals with the radio protocols on the Uu interface and with the protocols managed on the NG (Next Generation) terrestrial interface;
2. – the non-access stratum (NAS) deals with the exchange of traffic and data between the mobile and the core network. As a result, NAS is concerned with all the protocols allowing the exchange of signaling between the mobile UE (User Equipment) and the AMF (Access and Mobility Management Function) entity of the 5G core network. The NAS protocol refers to the procedure related to mobility, authentication and management of service requests (data session or Voice over IP call).

Figure 2.1. Protocols on the 5G interface

The protocols on the Uu and NG interface concern:

1. – the user plane protocols used to transport the traffic data of the PDU (Protocol Data Unit) session;
2. – the control plane protocols allowing us to control the PDU sessions, the radio connection and the mobility during a session (handover).

2.1.1. Protocol stack on the Uu interface

The Uu radio interface is the interface between the mobile and the NG-RAN access node. ...