The transition to 5G is happening, and unless you’ve been actively trying to ignore it, you’ve undoubtedly heard the hype. But if you are like 99% of the CS-trained, systems-oriented, cloud-savvy people in the world, the cellular network is largely a mystery. You know it’s an important technology used in the last mile to connect people to the Internet, but you’ve otherwise abstracted it out of your scope-of-concerns. Perhaps you’ve heard a conspiracy theory or two about how 5G is going to cause some awful side-effect—a sign that the hype around 5G might not be working as intended.

The important thing to understand about 5G is that it implies much more than a generational upgrade in bandwidth (although it does involve that too). It involves transformative changes to the access network that will make it much more like a modern cloud. Important technology trends such as software-defined networking (SDN) and open source software will lead to an access network that is much more nimble and innovative. And it will enable new classes of application, particularly a broad set of IoT (Internet of Things) applications. In fact we could even see the “Access-as-frontend-to-Internet” perspective being turned on its head, as the access network itself becomes a collection of clouds with new services delivered directly from “edge clouds”.

This book is written for someone who has a working understanding of the Internet and the cloud, but has had limited success penetrating the myriad of acronyms that dominate cellular networking. In fairness, the Internet has its share of acronyms, but it also comes with a sufficient set of abstractions to help manage the complexity. It’s hard to say the same for the cellular network, where pulling on one thread seemingly unravels the entire space. It has also been the case that the cellular network had been largely hidden inside proprietary devices, which has made it impossible to figure it out for yourself.

This book is the result of a mobile networking expert teaching a systems person about 5G as we’ve collaborated on an open source 5G implementation. The material has been used to train other software developers, and we are hopeful it will be useful to anyone who wants a deeper understanding of 5G and the opportunity for innovation it provides. Readers who want hands-on experience can also access the open source software introduced in the book.

This book will likely be a work-in-progress for the foreseeable future. It’s not intended to be encyclopedic—favoring perspective and end-to-end completeness over every last bit of detail—but we do plan to flesh out the content over time. Your suggestions (and contributions) to this end are welcome.


The software described in this book is due to the hard work of the ONF engineering team and the open source community that works with them. We acknowledge their contributions. We also thank Bruce Davie, Guru Parulkar, and Changhoon Kim for their feedback on early drafts of the manuscript.

Larry Peterson and Oguz Sunay
Open Networking Foundation
March 2020