 eCPRI Layer 2 low Layer 2 low Layer 1 low Layer 1 Layer 1 Radio site Figure 3.26 Functionality split options in 5G radio network and approximate transport requirements for 3-sector base station with 100 MHz and massive MIMO antenna. RF while the other part of Layer 1 and the other layers are in the edge cloud. The interface in that case is called enhanced Common Public Radio Interface (eCPRI). If the transport latency is higher, then more functionalities are located at the antenna site, and only part of Layer 2 and Layer 3 are in the edge cloud. The interface in that case is called F1. Summary 5G networks are expected to deliver substantially higher capabilities, higher data rates and a number of new services from low latency and high reliability to low-cost IoT modules. New technology components are needed to fulfill those targets. This chapter summarized the main new technologies: new spectrum options with wideband carrier, beamforming optimized radio design, flexible physical and protocol layers, network slic- ing, dual connectivity, and cloud optimized network architecture. 5G implies a massive change in the network design and optimization. The following chapters provide more details about 5G design and specifications. Reference Nokia, Alcatel-Lucent Shanghai Bell 2016. Performance and complexity of Turbo, LDPC and Polar codes. 3GPP TSG-RAN WG1 #84bis, R1-162897. Busan, Korea, 11th - 15th April. https://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_84b/Docs/R1- 162897.zip Spectrum Harri Holma 1 and Takehiro Nakamura² 1 Nokia Bell Labs, Finland 2NTT DOCOMO, Japan CHAPTER MENU Introduction, 49 Millimeter Wave Spectrum Above 20 GHz, 52 Mid-Band Spectrum at 3.3-5.0 GHz and at 2.6 GHz, 55 Low-Band Spectrum Below 3 GHz, 58 Unlicensed Band, 59 Shared Band, 62 3GPP Frequency Variants, 64 Summary, 64 References, 64 4.1 Introduction Spectrum is the key asset for mobile operators. The available spectrum is a major factor in defining how much capacity and how wide a coverage the mobile network can pro- vide. This chapter discu