for the radio functionality in the CU side. 5G radio and the 5G core provide different means for interworking with LTE, rang- ing from the connected mode and idle mode mobility, all the way to dual connectivity. The architectures becoming operational first, non-standalone 5G operation with EPC followed by standalone 5G with 5G core, can interwork well and provide a solution for legacy co-existence together with full end-to-end 5G. The 5G core also enables connectivity from access networks other than 3GPP-based networks, as long as the devices support the 3GPP-based connection establishment signaling (3GPP NAS), as the 5G-core-related procedures have been made access inde- pendent. 5 5G Architecture References 1 3GPP Tdoc RP-161266 (2016).5G architecture options - full set, Deutsche Telecom. June 2016. 2 O-RAN Alliance. https://www.o-ran.org 3 Common Public Radio Interface. www.cpri.info 4 3GPP TR 38.801 (2017). Study on new radio access technology: Radio access architec- ture and interfaces. March 2017. 5G Physical Layer Mihai Enescu, Keeth Jayasinghe, Karri Ranta-Aho, Karol Schober, and Antti Toskala Nokia Bell Labs, Finland CHAPTER MENU Introduction, 87 5G Multiple Access Principle, 88 Physical Channels and Signals, 92 Basic Structures for 5G Frame Structure, 95 5G Channel Structures and Beamforming Basics, 98 Random Access, 100 Downlink User Data Transmission, 101 Uplink User Data Transmission, 103 Uplink Signaling Transmission, 105 Downlink Signaling Transmission, 108 Physical Layer Procedures, 111 5G MIMO and Beamforming Operation, 113 Channel Coding with 5G, 133 Dual Connectivity, 142 5G Data Rates, 144 Physical Layer Measurements, 145 UE Capability, 146 Summary, 147 References, 148 6.1 Introduction 5G multiple access, and the physical layer in general, has differences from Long Term Evolution (LTE) as discussed in Chapter 1. In the downlink direction, the multiple access is based on Orthogonal Frequency Division Multiple Access (OFDMA), similar to LTE. In the uplink direction, 5G has adopted both OFDMA and