k slice) that the AMF supports per Tracking Area and to get the availability of the S-NSSAIs per Tracking Area that is supported by the AMF. The Nnssf_NSRestriction service enables a network service consumer to subscribe and unsubscribe to network slice instance restriction notifications. In this chapter, we have learned about the various services offered and consumed by the NFs in the 5G system, in order to process a data or voice call. We have gone over the services offered to police traffic and also to charge the subscriber. This is how the producer-consumer model in 5G works to realize the service-based infrastructure. Summary In this chapter, we went into detail about cloud-native infrastructure and service-based infrastructure, delved into the details of foundational REST concepts, and finally, the services offered by key NFs. This help us to build the fundamentals of a 5G system from the bottom up. These services and methods are used by the NFs to carry out various 5G procedures, such as attaching, voice calls, handovers, network registration, authentication, and detaching. In the next chapter, we will be introduced to the radio aspects of 5G, including the scheduling of radio resources. 5G Air Interface and Physical Layer Procedures - Part 1 In this chapter, we are going to introduce you to 5G New Radio (NR) physical layer procedures for control and user planes. We will start by looking at general physical layer procedures and then continue with waveform, numerology, and frame structure. Throughout the chapter, we will be comparing and contrasting NR and Long-Term Evolution (LTE). After reading this chapter, you will have a good understanding of NR's physical layer structure, downlink and uplink references, and synchronization signals. You will also have a good understanding of the numerology concept, which is the main difference between NR and LTE in the air interface. In this chapter, we'll cover the following topics: General physical layer procedures Waveform, numerology, and frame structure Let's get 