A "low-cost" software radio test bed

We describe a "low cost" software radio test bed that we used to test new protocols for the Personal Access Communications System (PACS) TDMA system. Our test bed consists of a 1.9 GHz mini-base station and two 1.9 GHz prototype handsets. Both the base station and handsets deliver I and Q signals to a DSP and receive I and Q signals from the DSP. The radio hardware was designed so that by changing IF filters and baseband filters, other technologies, i.e., CDMA, EDGE, W-CDMA could be easily supported. The DSP system was implemented by purchasing a single board solution that supports two daughter boards, one for the A/D converters and one for the D/A converters. Thus, the entire DSP subsystem used one full-length PCI slot in a PC. All lower layer protocols (MAC layer and physical layer: modulator, demodulator and timing) were implemented on the DSP. The upper layer protocols (TCP/IP, mobile IP and GPRS-PACS) were implemented in the PC.