A Novel Multiport Matching Network Model Of An Indoor MIMO System

MIMO (Multiple Input Multiple Output, MIMO) can effectively enhance the wireless channel capacity when the bandwidth is constant. It has been one of the NGN's main technologies. Thus, MIMO and the related technologies are the hot topic of the wireless communication.In this paper, a novel multiport matching (MPM) method is devised to directly maximize the mean capacity with rigorous consideration of the mutual coupling effects of the matching network. In the RF front end of the real communication circuits, the mutual couplings always exist. In this paper,1) the model of indoor path loss is expanded to describe the finite thick or lossy material; 2) a theoretical capacity upper bound of the 2-by-2 MIMO system with a matching network using the water-filling as the power allocation rule is analytically derived for the first time; 3) the Genetic Algorithm (GA) is employed to optimize the parameters of the matching network for the maximization of the mean capacity, and a coupled microstrip lines structure is devised to implement the matching network of the real MIMO receive circuits. The numerical results in the last section demonstrate that an optimized matching network obtained using our novel MPM method is capable to enhance the performance of the MIMO systems in a range of different indoor environments. This verifies that our method is not only effective but also practical.