Spectrum Sharing Between Radar and Communication Systems Based on Overlapped Virtual Subarrays

In this paper, we propose a new technique for spectrum sharing between radar and communication systems. The new technique enjoys the advantages of null-space projecting which can be used to mitigate the interference between radar and communication systems. In order to reduce the number of radar antennas and reduce the requirement of manufacture, deployment, and implementation, we also introduce virtual subarray architecture to reap a more effective transmit array aperture. The essence is to partition the multiple-input multiple-output (MIMO) antenna array into multiple overlapped subarrays to reap a compromise between coherent gain and diversity gain. We show that the configuration with overlapped subarrays can be used to form narrower beams with lower sidelobes, which is good for reaping higher performance in target detection. In order to evaluate the impact on the performance of radar systems with the implementation of spectrum sharing, the generalized likelihood ratio test for target detection is derived. It is shown that, although the implementation of the proposed spectrum sharing method would lose the radar system's target detection performance, we can reap the benefits of spectrum sharing. That is to say, we achieve a good tradeoff between spectrum sharing and target detecting.