Architecture of the Radio Access Network

Chapter 3 addresses the architecture of the radio access network. The chapter begins by reviewing the architecture of the evolved UMTS terrestrial radio access network, and by introducing the concepts of carrier aggregation and dual connectivity. It then introduces the gNB, including its internal division into central and distributed units, and the next-generation radio access network, including the options that are available for multi-radio dual connectivity. The chapter concludes by discussing identification and addressing within the radio access network, the RRC state diagram, and the signalling protocols that the network uses.