5G NR Overview and Physical Layer

Abstract

This text deals primarily with the physical layer. However, to better understand its operation, it is helpful to stand back a bit and study, at a high level, its surrounding architecture and protocols. To this end, we review in this chapter the main architecture options for connection to the core network followed by the Radio Access Network (RAN) protocol architecture. The RAN is responsible for all radio-related functions such as coding, modulation, HARQ operation, physical transmission, scheduling, etc. Following this, we narrow our study within the RAN to the physical layer, with emphasis on how physical channels are structured, be they user data conveying or control data conveying, as well as how physical signals are created, such signals being those originating solely in the physical layer. Procedures such as initial access, scheduling, and uplink power and timing control are introduced. How maximum user data rates and low latency are achieved is demonstrated, 5G licensed operating frequency spectrum is reviewed, and some typical base station and UE parameters presented. Also addressed are certain key features introduced in release 16, namely operation in unlicensed bands, integrated access and backhaul, sidelink communication, multi-TRP transmission, and positioning. Finally, relevant 3GPP specifications are listed.