Sparse RIS in Multi User MIMO Wireless System

The reconfigurable intelligent surfaces (RISs) have garnered a lot of interest in the development of smart radios. The acquisition of channel state information in RIS aided systems are extremely challenging as pilot overhead is considerably large. Previous works have shown an improvement in reducing pilot over head by exploiting the structured sparsity. In this contribution, we consider a sparse RIS under the environment of multiuser MIMO communication system by randomly selecting the elements of RIS in uniform planar arrays to eliminate unnecessary elements and to reduce the large pilot overhead. The random distribution models i.e Gaussian, Poisson and Geometric are adopted and analyzed for selection of sparse RIS. The numerical results show a significant improvement in NMSE performance with reduced pilot overhead.