A real-time cellular system architecture to experiment with UMTS/HSDPA in a laboratory

Nowadays wireless wide area networks (e.g. cellular networks) are also used to provide access to Internet and its services. However, protocols and applications not specifically designed for wireless links (e.g., TCP, VoIP) often require a deeper analysis when applied to such links. Performance analysis represents a valid method to evaluate such protocols and applications, modeling their behavior and then working on their improvement. An appropriate solution to support performance evaluation of a wireless system and its support to protocols and applications consists in building a close-to-real test environments. This paper presents MUSA, a testbed that allows experimentation of cellular networks in a laboratory. The presented testbed combines emulation components and real equipments in a single experimentation platform, with the flexibility, scalability and repeatability features of an emulated environment and the possibility of testing real equipments, e.g., real mobile terminals or UMTS/HSDPA wireless cards and base stations. The paper describes also the assessment and calibration of the testbed. It presents an extensive comparison with a commercial 3G network and discusses the unique properties of MUSA. Finally, the paper also presents two case studies in order to highlight the benefits of conducting experimental research in an in-lab fully controlled platform rather than in an operator-controlled network.