 brings smaller form factor of large antenna arrays. Additionally, the signal processing techniques in terms of massive MIMO and transceiver design also improved 5G and Beyond Wireless Communication Networks, First Edition. Haijian Sun, Rose Qingyang Hu, and Yi Qian. © 2024 John Wiley & Sons Ltd. Published 2024 by John Wiley & Sons Ltd. 1 Introduction to 5G and Beyond Network High speed High density Figure 1.1 Four main goals for 5G. Up to 10Gbps 10 to 100x devices < 1 ms end-to-end ~10 years Latency, reliability Power efficiency significantly. (iii) New radios (NR). The physical layer in 5G will change dramatically, specifically the 5G NR, which includes the new multiple access technology, the new air interface, and a combination of several existing techniques. (iv) New schemes. It is expected that ultra dense networks (UDN) will be heavily deployed. The density of small base station (BS), such as micro BS, femto cell, and pico cells, will be much higher than that in 4G. But they share the similarity in terms of deploying BSs with different powers to provide seamless coverage, as well as performance improvements from short-range communications. (v) High intelligence. It is expected that beyond 5G systems should support higher level of intelligence. Emerging applications such as Artificial intelligence (AI), semantic communication, and robots will surely benefit from AI-friendly wireless technology. (vi) Pervasive wireless. It is anticipated that each person will carry more personal devices for enhanced life style and health monitoring. To support ubiquitous wireless connectivity, those devices need be connected. Current network architecture can hardly support such high number of devices simultaneously. 1.1.1 Technical Challenges The above promising technologies are able to deliver ambitious goals of 5G, but they ulti- mately encounter some challenges. First of all, even though high-frequency bands have major vacancy, mmWave signals are notorious for weak penetration and vulnerable block- age; hence, the transmis