Multi-Beam STAR MIMO Using Differential Arrays

As we are witnessing the surge of ongoing wireless communication systems, simultaneous transmit and receive (STAR) schemes are proving to be advantageous due to the doubling of spectral efficiency. However, for the successful realization of STAR, we need to overcome a major bottleneck in suppressing the self-interference from the transmitter onto the colocated receiver. Currently, mitigating this interference requires complex hardware and advanced algorithms when employing an array for applications such as multiple input, multiple output (MIMO), and beamforming. This interference can arise from both near-field and far-field coupling in a MIMO beamforming system. Consequently, this paper presents a unique STAR approach that provides an average isolation of 40 dB between Tx and Rx ports across all elements of the MIMO beamforming system. The proposed approach can be extended to large antenna arrays.