Integration of non-linear, radiation, and propagation CAD techniques for MIMO link design

The paper outlines an exhaustive CAD procedure for the circuit-level simulation of entire MIMO links. The multiple transmitting and receiving antennas are treated as multiport radiating systems characterized by EM analysis. The effects of mutual couplings in terms of the frequency-dependent near-field and far-field performance of each element are accounted for in a straightforward and rigorous way. The set of transmitters is treated as a unique nonlinear system loaded by the multiport antenna, and is analyzed by nonlinear circuit techniques. The same is done for the set of receivers. In order to establish the connection between transmitters and receivers, the radiated far-field is evaluated by EM analysis, and the field incident on each receiver antenna is computed by extending to the MIMO case an available ray tracing technique. EM theory is then used to describe the receiving array as a linear active multiport network. This technique allows analysis of several MIMO systems, exploiting different array element spatial locations and frequencies of operation in a straightforward and automatic way. BER computation and minimization is demonstrated at the circuit level.