016, infrastructure rollout has only started in 2019, with subscriber devices having become available in volume starting 2020. At the same time, 4G/LTE standards will continue to evolve and add more subscribers. Million Mobile Connections (4G, 5G) 4G and 5G (projected) subscriber growth (multiple public sources, indicated with data points). During 2G, 3G, and 4G network rollouts, wireless service providers and their system ven- dors built networks that, although providing predictable and high performance, are often characterized by their complexity, inflexibility, and associated high barrier to entrance. Like the wireline network transformation when migrating from circuit-switched to packet- switched (PS) networks in the early 2000s, the wireless network is migrating from this propri- etary nature to a true open-standards approach that allows "out-of-the-box" thinking and disruptive solutions in physical implementation and deployment. Consider, for example, the cost and execution requirements imposed by new operators like Reliance Jio in India, DISH in the United States, and Rakuten in Japan, needing to support fast ramp-up (quick provi- sioning), or the Facebook Terragraph project, bringing high-speed connectivity at a fraction of fiber deployment cost through the use of an unlicensed 60 GHz spectrum. Preface The rapid evolution of 5G standards combined with aggressive deployment schedules and cost targets drives a push for Radio Access Network (RAN) implementations on standard hardware and software platforms. This trend started with 4G networks where upper layer stacks are implemented on general purpose (GPP) compute platforms and the Linux operat- ing system (OS) and is increasing with 5G deployments. Examples include the trend to Ethernet for fronthaul replacing quasistandards such as CPRI as well as rigorous standardiza- tion efforts in 3GPP to define standard APIs between different components. Because of this trend, system vendors are moving increasingly aggressively toward Software Defined Radio (SDR) plat