Design of RFID system with DS-CDMA transmission

In this paper we describe an experimental RFID system composed of transmitter-only active tags and a flexible reader based on the software defined radio. The system employs DS-CDMA transmission to reduce the number of collisions. In our experiments we compare two detection algorithms: the noncoherent detector with successive interference cancellation, and the coherent one. The results show that the potential of DS-CDMA transmission can be utilized only when fully linear, coherent detection is used. The considered RFID system can be applied in situations when reliable detection of signals from monitored objects in a given area is required. As an example it can serve monitoring of environmental conditions or surveillance of valuable assets.