A Software Radio Testbed for UMTS TDD Systems

− Today’s and near future mobile communication systems need to provide universal seamless connection to the users between different standards and types of service. This requires a significant degree of flexibility that can be provided by Software Defined Radio (SDR) terminals. Eurécom and EPFL have started a joint project whose objective is to study and implement a real-time SDR communication platform to validate advanced algorithms for wireless communications. The platform is a real-time PC based system that can handle wide-band radio resources. It provides hardware, DSP software, and link-level software functionalities. Due to various practical design issues, the platform implements the essential physical layer features of the time-division duplex (TDD) mode of the UMTS standard proposal (air-interface and signal processing), although frequency-division duplex (FDD) mode and even other standards could also be implemented. In this paper we address the major general issues inherent to the design of a real-time SDR system. Then we focus on our SDR platform by describing the general architecture, the signal processing techniques adopted to implement the transmitter and receiver SDR front-end, the current set-up, and DSP performance measurements. Finally, we address the future perspectives for the platform evolution.