From GSM to LTE-Advanced Pro and 5G, 4th Edition

65G New Radio (NR) and the 5G Core

6.1 Introduction and Overview

In 2015, the 3GPP standardization organization started first discussions on what a successor to 4G LTE system could look like. This phase took around 2 years and resulted in a number of Technical Report (TR) documents. These contained a thorough analysis of different options for various parts of a new 5G mobile communication system that could take a next generation system far beyond the original 4G LTE architecture and a conclusion regarding which of those options would be standardized. The next two years until the end of 2018 then saw those reports being turned into 3GPP Technical Specification (TS) documents in 3GPP Release 15. One of the central documents is 3GPP TS 38.401 [1], which gives a high‐level overview of the 5G Radio Access Network (RAN), also referred to as 5G New Radio (NR). Many other TS documents in the 38‐series then go into every detail of how the 5G access network shall be implemented in practice.

On a high level, the 5G NR air interface looks very similar to LTE. LTE, however, had initially been designed for only one specific use case: High‐speed Internet access. As described in the chapter on LTE, the LTE air interface specification was later extended to enable other use cases with significantly different requirements in terms of bandwidth, latency, and power consumption. The Narrow‐Band Internet of Things (NB‐IoT) extension is such an example. Many compromises were required to maintain ...