Tensor-Based Joint Channel and Symbol Estimation with Subspace-Based Parameter Extraction for Multi-RIS Uplink MIMO Systems

This paper investigates joint channel and symbol estimation in a multiple user uplink multiple-input multiple-output (MIMO) system assisted by several reconfigurable intelligent surfaces (RISs). With Khatri–Rao space–time (KRST) coding at the users, A PARATUCK2-based tensor framework is developed. To tackle the challenges of multi-RIS deployment, an adaptive accelerated fitting for PARATUCK2-based decomposition (AAF-PDE) algorithm is proposed. The algorithm employs an accelerated adaptive fittin