The challenges described in the previous chapter can result in significant attenuation and distortion of the signal at the receiver, which makes it challenging to correctly extract the transmitted bit stream from the signal. In this chapter, we give an overview of the physical layer techniques that are used to minimize the impact of these challenges on network throughput. Sections 3.1–3.9 focus on technologies that are primarily used in WiFi and Cellular, two technologies that are heavily optimized for high throughput. In Sect. 3.10, we describe spread spectrum, which is widely used in IoT protocols. More information on the topics covered in this chapter can be found in several textbooks on wireless communication and networking (Molisch 2022; Beard and Stallings 2016).