Intelligent reflecting surface for sum rate enhancement in MIMO systems

The research for the Intelligent Reflecting Surface (IRS) which has the advantages of cost and energy efficiency has been studied. Channel capacity can be effectively increased by appropriately setting the phase value of IRS elements according to the channel conditions. However, the problem of obtaining an appropriate phase value of IRS is difficult to solve due to the non-convex problem. This paper proposes an iterative algorithm for the alternating optimal solution in the Single User Multiple-Input-Multiple-Output (SU-MIMO) systems. The proposed iterative algorithm finds an alternating optimal solution that is the phase value of IRS one by one. The results show that the proposed method has better performance than that of the randomized IRS systems. The number of iterations for maximizing the performance of the proposed algorithm depends on the channel state between the IRS and the receiver.