Cognitive radio testbed for Digital Beamforming of satellite communication

摘要

Digital Beamforming (DB) in satellite communication (SATCOM) has drawn significant attention in recent years. DB design is flexible and adaptive among frequencies, bandwidths, and interferences. In this work, we design a cognitive radio testbed for SATCOM for digital beamforming design and implementation. The testbed is capable of simultaneously capturing signals from multiple antennas. Considering the conditions of jamming or interference, the design implements spectrum detection and compressive sensing for channel condition monitoring in a real time. Using the analyzed jammer and interference information, the incoming signal can be moved into a different frequency where the channel is vacant or at least meets acceptable conditions. The beamforming design is also adaptive to the frequency where each beam is weighted differently for a given channel condition. In addition, the satellite antenna array is used to determine the signal direction of arrival (DoA), The DB is capable of forming the beam in the direction that avoids interference and jamming. Moreover, the detection of the jamming signal direction can help localize the jammer. In the testbed design, a Universal Software Radio Peripheral (USRP) is used as a radio frequency (RF) front end component and GNU radio connecting to computer as signal processing back end. The system architecture includes the transponder receiver. And a USRP ×310 with twinRx receiver is capable of obtaining multiple copies of the signal captured by multiple receiving antennas.