This paper describes the design and implementation of low-complexity multiple-input multiple-output (MIMO) signal processing techniques suitable for ultra-wideband (UWB) wireless communications. It provides the general system concept, description of the measurement set-up and modular FPGA platform for test and verification of the proposed multiple antenna schemes under real air-interface environment. We validate the performance of selected spatial multiplexing and diversity approaches applied to Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) and demonstrate the enhancements in capacity and link reliability of existing WiMedia devices through algorithm- and implementation-level investigations.