Joint Tx-Rx Beam Design for in-Sector Compressed Sensing Beam Alignment in MIMO Systems

The paper is dedicated to the problem of large overhead required for beam alignment in MIMO systems. We assume a scenario when users are located in a predefined angular sector. In particular, we study the beam design problem for compressed sensing channel recovery in this scenario. The beam design task is twofold: the base station beams should scan only the predefined sector and the compressed sensing recovery should be stable independent from the position of the user within the sector. In our previous research we proposed a beam design method for joint Tx-Rx spatial scanning in Reconfigurable Intelligent Surface-assisted MISO systems. We show equivalence between channel recovery in MIMO system and cascaded channel recovery in RIS-assisted MISO systems. Then we propose a simple modification of the beam design method that allows to reuse it for in-sector scanning. Simulation shows, that in-sector scanning can reduce the number of measurements up to 2–3 times (for certain sectors) compared to full-scan beams. The method is competitive with popular codebook-based approach. We assume an analog beamforming scheme, and thus the resulting beams are unimodular. We do not impose constraints on the resolution of phase shifters, thus the method can be used as a reference for further development of practical solutions.