COMMUNITY is a formal approach to software architecture. Its main characteristics are: a precise, yet intuitive mathematical semantics based on categorical diagrams; a clear separation between computation, coordination, and distribution (including mobility); and a simple state-based language, inspired by Unity, to describe behaviour. This paper discusses the applicability of this approach to location-aware systems through the modelling of the GSM handover protocol, namely the way communication with a moving cellular phone passes from one station to another. The case study was developed with the COMMUNITY Workbench, a tool that animates distributed and mobile architectural models.