4 General aspects

38.4203GPPNG-RANRelease 17TSXn general aspects and principles

4.1 Introduction

The interface allowing to interconnect NG-RAN nodes with each other is referred to as the Xn interface.

4.2 Xn interface general principles

The general principles for the specification of the Xn interface are as follows:

– the Xn interface is open;

– the Xn interface supports the exchange of signalling information between two NG-RAN nodes, and the forwarding of PDUs to the respective tunnel endpoints;

– from a logical standpoint, the Xn is a point-to-point interface between two NG-RAN nodes. A point-to-point logical interface should be feasible even in the absence of a physical direct connection between the two NG-RAN nodes.

4.3 Xn interface specification objectives

The Xn interface specifications facilitate the following:

– inter-connection of NG-RAN nodes supplied by different manufacturers;

– support of continuation between NG-RAN nodes of the NG-RAN services offered via the NG interface;

– separation of Xn interface Radio Network functionality and Transport Network functionality to facilitate introduction of future technology.

4.4 Xn interface capabilities

The Xn interface supports:

– procedures to support intra-NG-RAN mobility;

– procedures to support dual connectivity between NG-RAN nodes.