.3-2018, Standard for radio over Ethernet encapsulations and mappings, September 2018. [78] IEEE P1914.1/D4.1, Draft standard for packet-based fronthaul transport networks, April 2019. [79] D. Anzaldo, Backhaul alternatives for HetNet small cells, Part 1 and 2, Microwaves & RF, September 2015. [80] Wireless Backhaul Spectrum Policy Recommendations and Analysis Report, GSMA, November 2014. [81] R. Ravindran, et al., Realizing ICN in 3GPP's 5G NextGen core architecture, Cornell University Library, November 2017. 194 Chapter 1 [82] 4G-5G Interworking, RAN-level and CN-level Interworking, Samsung, June 2017. [83] Nomor Research, 5G RAN Architecture Interfaces and eCPRI, September 2017. [84] R. Vaez-Ghaemi, The evolution of fronthaul networks, Viavi Solutions, June 2017. [85] Sujuan Feng and Eiko Seidel, Self-Organizing Networks (SON) in 3GPP Long Term Evolution, Nomor Research GmbH, May 2008. CHAPTER 2 New Radio Access Layer 2/3 Aspects and System Operation 2.1 Overview of Layer 2 and Layer 3 Functions The NR radio interface protocols (alternatively referred to as layer-1, layer-2, and layer-3 protocols) operate between the NG-RAN and the UE and consist of user-plane protocols, for transfer of user data (IP packets) between the network and the UE, and control-plane protocols, for transporting control signaling information between the NG-RAN and the UE. The non-access stratum (NAS) protocols terminate in the UE and the AMF entity of the 5G core network and are used for core network related functions and signaling including regis- tration, authentication, location update and session management. In other words, the proto- cols over Uu and NG interfaces are categorized into user plane and control plane protocols. User plane protocols implement the actual PDU Session service which carries user data through the access stratum. Control plane protocols control PDU Sessions and the connec- tion between UE and the network from various aspects which include requesting the service, controlling different transmission resources, h