  In this paper, we focus on the pattern reconfigurable multiple-input
multiple-output (PR-MIMO), a technique that has the potential to bridge the gap
between electro-magnetics and communications towards the emerging
Electro-magnetic Information Theory (EIT). Specifically, we focus on the
pattern design problem aimed at maximizing the channel capacity for
reconfigurable MIMO communication systems, where we firstly introduce the
matrix representation of PR-MIMO and further formulate a pattern design
problem. We decompose the pattern design into two steps, i.e., the correlation
modification process to optimize the correlation structure of the channel,
followed by the power allocation process to improve the channel quality based
on the optimized channel structure. For the correlation modification process,
we propose a sequential optimization framework with eigenvalue decomposition to
obtain near-optimal solutions. For the power allocation process, we provide a
closed-form power allocation scheme to redistribute the transmission power
among the modified subchannels. Numerical results show that the proposed
pattern design scheme offers significant improvements over legacy MIMO systems,
which motivates the application of PR-MIMO in wireless communication systems.
