Space-polarization MIMO testbed

Space-polarization multiple input multiple output (SP-MIMO) communication systems can provide improved reliability, increased data rates, and higher energy efficiency as compared to conventional co-polarized MIMO (CP-MIMO) systems. To achieve these gains relative to CP-MIMO arrays, SP-MIMO architectures employ a dual-polarized (DP) antenna at each of the antenna locations, effectively doubling the number of ports without substantially increasing the footprint of antenna arrays. CP-MIMO schemes have been explored rigorously in literature, however very few results are available for DP-MIMO and SP-MIMO systems, particularly over realistic and imperfect channels. In this paper, we present the design of a state-of-the-art 4×4 SP-MIMO wireless communications system testbed to enable comparative performance studies. The testbed incorporates baseband generators, MIMO channel emulators, a coherent multi-channel receiver, and a host computer for signal processing. We consider full spatial multiplexing schemes involving the simultaneous transmission of either two or four data streams through emulated physical channels for CP-MIMO and SP-MIMO, respectively. Operation, control and signal processing are performed on a host computer within a Matlab environment, giving a powerful, flexible, and efficient platform for analyzing MIMO algorithms in emulated channels. Examples show that SP-MIMO architectures achieve performance shifts in capacity (bit/s/Hz), bit-error-rate (BER), packet-error-rate (PER) and energy efficiencies (Joule/bit) relative to CP-MIMO systems.