A real time cognitive radio testbed for physical and link layer experiments

Cognitive radios have been advanced as a technology for the opportunistic use of under-utilized spectrum. Cognitive radio is able to sense the spectrum and detect the presence of primary users. However, primary users of the spectrum are skeptical about the robustness of this sensing process and have raised concerns with regards to interference from cognitive radios. Furthermore, while a number of techniques have been advanced to aid the sensing process, none of these techniques have been verified in a practical system. To alleviate these concerns, a real time testbed is required, which can aid the comparison of these techniques and enable the measurement and evaluation of key interference and performance metrics. In this paper, we present such a testbed, which is based on the BEE2, a multi-FPGA emulation engine. The BEE2 can connect to 18 radio front-ends, which can be configured as primary or secondary users. Inherent parallelism of the FPGAs allows the simultaneous operation of multiple radios, which can communicate and exchange information via high speed low latency links