The development and operation of a reliable voice and data communication systems in remote or difficult-to-reach areas is still a challenge in the modern world. In this framework, the mission Alfa Crux, based on a nanosatellite system under development at the Laboratory of Simulation and Control of Aerospace Systems (LODESTAR), University of Brasilia (UnB), Brazil, proposes the use of narrow bandwidth to create data and voice connections from low orbit. The Alfa Crux system aims at contributing to improve agricultural monitoring, water level controlling in rivers and reservoirs, as well as improving the communications technology between devices (M2M) and the Internet of Things (IoT), especially in remote regions where communication infrastructures on land are unreliable or cost prohibitive. The main problem addressed in this work concerns the development of a nanosatellite communication system based on UHF amateur radio frequency band. The choice of the frequency band is based on the fact that the use of narrowband in nanosatellite communication systems has relevant characteristics such as energy efficiency, spectrum, reliability, performance, safety, communication range, among others. This paper presents an overview of the communication architecture of the space mission of the Alfa Crux nanosatellite
