Cooperative Reflection Design With Timing Offsets in Distributed Multi-RIS Communications

This letter investigates a wireless communication system deploying distributed reconfigurable intelligent surfaces (RISs). Existing works have assumed that perfect timing synchronization is available among all the cooperative RISs. For practical considerations, we first study reflection design for multi-RIS-aided systems taking into account errors. We aim to minimize mean-squared error of recovered data in presence offsets subject unit-modulus constraints imposed on phase shifts In order handle this sophisticated nonconvex problem, develop computationally-efficient algorithm based majorization-minimization framework where RIS shift matrices and offset equalizer are respectively developed semi-closed form closed form. Numerical examples validate improved performance our proposed compared with various schemes.