Abstract
Intelligent reflecting surface (IRS) is a cost-efficient technique to
improve power efficiency and spectral efficiency. However, IRS-aided
multi-antenna transmission needs to jointly optimize the passive and
active beamforming, imposing a high computational burden and high
latency due to its iterative optimization process. Making use of hybrid
analog-digital beamforming in high-frequency transmission systems, a
novel technique, coined dual-beam IRS, is proposed in this paper. The
key idea is to form a pair of beams towards the IRS and user,
respectively. Then, the optimization of passive and active beamforming
can be decoupled, resulting in a simplified system design. Simulation
results corroborate that it achieves a good balance between the
cell-edge and cell-center performance. Compared with the performance
bound, the gap is moderate, but it remarkably outperforms other
sub-optimal schemes.