  Billions of people remain without Internet access due to availability or
affordability of service. In this paper, we present Magma, an open and flexible
system for building low-cost wireless access networks. Magma aims to connect
users where operator economics are difficult due to issues such as low
population density or income levels, while preserving features expected in
cellular networks such as authentication and billing policies. To achieve this,
and in contrast to traditional cellular networks, Magma adopts an approach that
extensively leverages Internet design patterns, terminating access
network-specific protocols at the edge and abstracting the access network from
the core architecture. This decision allows Magma to refactor the wireless core
using SDN (software-defined networking) principles and leverage other
techniques from modern distributed systems. In doing so, Magma lowers cost and
operational complexity for network operators while achieving resilience,
scalability, and rich policy support.
