an umbrella for a range of applications that include remote healthcare, smart grid, smart city, intelligent transport, and smart cars. 5G systems are required to support a wide range of IoT applications including geographically and/or power constrained, low-data devices and/or sophisticated devices with requirements for large amounts of real-time data. The IoT is an area where direct communication between devices, rather than communication via the network, may be desirable. Augmented and virtual reality services are rapidly growing markets driven by advances in device capabilities, consumer excitement about new user experiences, and a range of practi- cal applications. These services are expected to be demanding in their requirements for high bandwidth (particularly for virtual reality) and low latency (particularly for augmented real- ity). Meeting users demand for these services is expected to be an important driver for 5G. Introduction and Background xxxvii Another emerging application area for cellular systems is in public safety and mission-critical communications for first responders and other users. 5G technology should maintain and extend the mission-critical communication technology being developed as part of LTE. This area will also have specific requirements for IoT devices and wearable technology. Users' growing reliance on mobile connectivity continues to present technical and economic chal- lenges for the provision of adequate coverage and capacity for these critical applications. 2.2 Deployment Scenarios The study of 5G deployment scenarios is the first step toward identifying service continuity and performance requirements. In this section, we discuss the prominent scenarios consid- ered for 5G systems deployment. While these scenarios are similar to the use cases, they are primarily focused on the deployment issues rather than user experience. As shown in Fig. 4, the initial deployments of 5G systems will likely be predominantly in the urban areas with high user density, low mobility, and extreme